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==[[Choanal atresia overview|Overview]]==
==[[Choanal atresia overview|Overview]]==
The word “Choana” is derivative of a greek word “Xovan” which states the funnel and hence, the term “Posterior Choana” is known as posterior nasal aperture or posterior funnel. Choanal atresia (CA) is the most common form of congenital nasal airway abnormality which presents with variable clinical features ranging from acute airway obstruction to chronic recurrent sinusitis depending upon the degree of obstruction. It is caused by the abnormal rupturing of the buccopharyngeal or naso-buccal membrane which results in the failed recanalization of the nasal fossae during the embryological period and hence, occlude the posterior nasal cavity to communicate with the nasopharynx. CA presents with severe respiratory distress, difficulty feeding, and failure to thrive when the obstruction is bilateral; and chronic persistent nasal discharge in unilateral cases. Establishing an airway is an acute otolaryngological emergency because newborns are obligate nasal breathers and experiences the paradoxical cyanosis episodes while feeding. The diagnosis requires a high index of suspicion and usually initial clinical evaluation done by introduction of a six or eight Fr suction catheter via the nostrils, methylene blue dye test, cotton wisp test, and laryngeal mirror test. The obstruction may be further visualized with a narrow flexible nasopharyngoscope after the nasal cavity has been suctioned of mucus and the nasal mucosa has been constricted with a nasal decongestant (e.g., oxymetazoline). However, the final confirmation of the diagnosis is done by CT scan of the nasal cavity which will demonstrate the atresia, define the type of tissue (bony or membranous), and show the configuration of the entire nasal cavity. The treatment of choanal atresia is essentially surgical which can be divided into emergent and elective definitive categories. It may be successfully treated by removing the obstructing tissue by using the nasal endoscopic approach via transnasal route.  However, when the thick bony plate extremely narrows posterior nasal cavity, a transpalatal repair technique is more direct. An intraoperative topical application of mitomycin to inhibit fibroblast proliferation has shown to be an effective adjunct to the surgical repair of choanal atresia. Stents fashioned from endotracheal tubes are placed and secured alongwith sutures to the septum in order to prevent postoperative re-stenosis chances which are removed after 6 weeks of duration. The stents must be moistened with saline and suctioned several times daily to prevent mucus plugging and acute respiratory distress.
The word “Choana” is derivative of a greek word “Xovan” which states the funnel and hence, the term “Posterior Choana” is known as posterior nasal aperture or posterior funnel. Choanal atresia (CA) is the most common form of congenital nasal airway abnormality presenting with variable clinical features ranging from acute airway obstruction to chronic recurrent sinusitis depending upon the degree of obstruction. It is caused by the abnormal rupturing of the buccopharyngeal or nasobuccal membrane which results in the failed recanalization of the nasal fossae during the embryological period and hence, occluding the posterior nasal cavity from communicating with the nasopharynx. CA presents with severe respiratory distress, feeding difficulties, and failure to thrive when the obstruction is bilateral or total; and chronic persistent nasal discharge in partial or unilateral cases. Establishing a secure airway is an acute otolaryngological emergency because newborns are obligate nasal breathers and experiences the paradoxical cyanosis episodes while feeding. The diagnosis requires a high index of suspicion which is done by an introduction of a six or eight Fr suction catheter via the nostrils, methylene blue dye test, cotton wisp test, and laryngeal mirror test. The obstruction may be further visualized with a narrow flexible nasopharyngoscope after the nasal cavity has been suctioned of mucosal secretions and the nasal mucosa is constricted with a nasal decongestant (e.g., oxymetazoline). However, the final confirmatory diagnosis is done by CT scan of the nasal cavity which will demonstrate the atresia, define the tissue type (bony or membranous), and show the configuration of the entire nasal cavity. The treatment is essentially surgical which can be divided into emergent and elective approaches. It may be successfully treated by removing the obstructing tissue and reconstrucitng the posterior choanae  by using the preferable transnasal endoscopic route.  However,in cases where, the thick bony plate extremely narrows the posterior nasal cavity, a transpalatal repair technique is more approachable. An intraoperative topical application of Mitomycin-C to inhibit fibroblast proliferation has shown to be an effective adjunct to its surgical repair. Stents created from endotracheal tubes are placed and secured alongwith sutures to the septum in order to prevent postoperative re-stenosis incidence and are usually removed probably after 6 weeks of duration. The stents must be moistened with saline and suctioned several times daily to prevent mucus plugging and acute respiratory distress.


==[[Choanal atresia historical perspective|Historical Perspective]]==
==[[Choanal atresia historical perspective|Historical Perspective]]==
*1755: Johann Roderer noticed total obstruction of the posterior nasal choana while examining a newborn and hence was the first to describe the CA.
*1755: Johann Roderer noticed total obstruction of the posterior nasal choanae while examining a neonate and hence was the first to describe the CA.<ref name="FlakeFerguson2016">{{cite journal|last1=Flake|first1=Carlyle G.|last2=Ferguson|first2=Charles F.|title=XLIV Congenital Choanal Atresia in Infants and Children|journal=Annals of Otology, Rhinology & Laryngology|volume=73|issue=2|year=2016|pages=458–473|issn=0003-4894|doi=10.1177/000348946407300216}}</ref>
*1829: Oto et al. further characterized the CA anomalies in relation to the deformity of the palatine bones during an autopsy.
*1829: Oto et al. further characterized the CA anomalies in relation to the deformity of the palatine bones during an autopsy. <ref>OttoA,LehrbachD. Pathologischen Anatomic des Menschen und der Thiere.(Vol.1).Berlin:Recker(1830).p.181–3 </ref>
*1854: Carl Emmert was the first to use the curved trochar through the choanal obstruction in transnasal surgical repair of bilateral CA in a 7- year-old boy and thus, successfully corrected CA surgically.  
*1854: Carl Emmert was the first to use the curved trochar through the choanal obstruction in transnasal surgical repair of bilateral CA in a 7- year-old boy and thus, successfully corrected CA surgically.<ref>EmmertC. Stenochorie und AtresiederChoannen,Lehrbach der Speciellen Chirurgie. (Vol.2).Stuttgart:Dann(1854).p.535–8</ref>
*1880: Ronaldson described an importance of CA in his autopsy findings of the newborns who had died from asphyxia and acute respiratory distress.
*1880: Ronaldson described an importance of CA in his autopsy findings of the newborns who had died from asphyxia and acute respiratory distress. <ref>Ronaldson TR (1880) Bilateral membranous atresia. Edinburgh Med J 26:1035</ref>
*1979: Hall first reports the “CHARGE” syndrome association in 17 children with multiple congenital anomalies who were ascertained by CA. In the same year, Hittner et al found the same syndrome in 10 children with ocular colobomas and multiple congenital anomalies, hence coined the syndrome as “Hall-Hittner syndrome”.
*1979: Hall first reports the “CHARGE” syndrome association in 17 children with multiple congenital anomalies who were ascertained by CA. In the same year, Hittner et al. found the same syndrome in 10 children with ocular colobomas and multiple congenital anomalies, hence coined the syndrome as “Hall-Hittner syndrome”. <ref>Hall DB (1979) Choanal atresia and associated multiple anomalies. J Pediatr 95:395-398</ref>
*1981: Pagon et al. first elaborated the acronym "CHARGE" association (Coloboma, Heart defect, Atresia choanae, Retarded growth and development, Genital hypoplasia, Ear anomalies/deafness).
*1981: Pagon et al. first elaborated the acronym "CHARGE" association. <ref>Pagon RA, Graham JM, Zonana J, et al. (1981) Coloboma, congenital heart disease and choanal atresia with multiple anomalies: CHARGE association. J Pediatr 99:223-227</ref>
*1985: Dehaen conducted the first transnasal endoscopic repair of CA.
*1985: Dehaen conducted the first transnasal endoscopic repair of CA. <ref>Dehaen F, Clement PA (1985) Endonasal surgical treatment of bilateral choanal atresia under optic control in the infant. J Otolaryngol 14: 95-98 </ref>
*2008: Barbero et al found the association of CA with the maternal use of an antithyroid drug methimazole.  
*2008: Barbero et al. found the association of CA with the maternal use of an antithyroid drug methimazole. <ref name="BarberoValdez2008">{{cite journal|last1=Barbero|first1=Pablo|last2=Valdez|first2=Rita|last3=Rodríguez|first3=Hugo|last4=Tiscornia|first4=Carlos|last5=Mansilla|first5=Enrique|last6=Allons|first6=Adriana|last7=Coll|first7=Silvia|last8=Liascovich|first8=Rosa|title=Choanal atresia associated with maternal hyperthyroidism treated with methimazole: A case-control study|journal=American Journal of Medical Genetics Part A|volume=146A|issue=18|year=2008|pages=2390–2395|issn=15524825|doi=10.1002/ajmg.a.32497}}</ref>


==[[Choanal atresia classification|Classification]]==
==[[Choanal atresia classification|Classification]]==
CA can be classified on the basis of several variables such as morphology, laterality, association with congenital anomalies and surrounding structures involvement.
CA can be classified on the basis of several variables such as morphology, laterality, association with congenital anomalies and surrounding structures involvement as described in the following tables from Table 1 to 4.
   
   
'''''Based on the morphology''''': The atretic plate has a thickness of usually 4-6 mm which attaches 1 to 2 mm anteriorly to the posterior border of hard palate.
===Table 1: Based on the morphology <ref>FraserJ.Congenitalatresiaofthechoanae. BrMedJ (1910) 2:1968–71</ref> <ref name="BrownPownell1996">{{cite journal|last1=Brown|first1=Orval E.|last2=Pownell|first2=Patrick|last3=Manning|first3=Scott C.|title=Choanal Atresia|journal=The Laryngoscope|volume=106|issue=1|year=1996|pages=97–101|issn=0023852X|doi=10.1097/00005537-199601000-00019}}</ref>===
 
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! style="background:#4479BA; color: #FFFFFF;" | Past report (1910)
! style="background:#4479BA; color: #FFFFFF;" | Past report (1910)


! style="background:#4479BA; color: #FFFFFF;" | Recent data based on CT and histologic specimens (1996)
! style="background:#4479BA; color: #FFFFFF;" | Recent data based on CT and histologic specimens (1996)  


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'''''Based on the laterality''''':  
===Table 2: Based on the laterality<ref>Dobrowski JM, Grundfast KM, Rosenbaum KN, Zajtchuk JT. Otorhinolaryngic manifestations of CHARGE association. Otolaryngol Head Neck
Surg 1985; 93: 798-803</ref>===


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'''''Based on association with other congenital anomalies''''':
===Table 3: Based on association with other congenital anomalies<ref name= "Assoc">{{cite journal|doi=10.1001/archoto. 2009.53}}</ref>===


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'''''Based on structure involvement''''':  
===Table 4: Based on structure involvement<ref name="pmid19101042">{{cite journal| author=Aslan S, Yilmazer C, Yildirim T, Akkuzu B, Yilmaz I| title=Comparison of nasal region dimensions in bilateral choanal atresia patients and normal controls: a computed tomographic analysis with clinical implications. | journal=Int J Pediatr Otorhinolaryngol | year= 2009 | volume= 73 | issue= 2 | pages= 329-35 | pmid=19101042 | doi=10.1016/j.ijporl.2008.10.029 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19101042  }} </ref>===


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==[[Choanal atresia classification|Embryology]]==
==[[Choanal atresia classification|Embryology]]==


'''''Origin''''': Development of the nasal cavity starts with neural crest cells migration from their origin in the dorsal neural folds and hence, the development of choanae takes place between the 4th and 11th weeks of gestation.
'''Origin:''' Development of the nasal cavity begins with neural crest cells migration from their origin in the dorsal neural folds. The development of posterior choanae takes place between the 4th and 11th weeks of gestation which is elaborated in Table 5 <ref>Dunham ME, Miller RP. Bilateral choanal atresia associated with malformation of the anterior skull base: embryogenesis and clinical implications. Ann Otol Rhinol Laryngol. Nov 1992;101(11):916-919</ref>.
 
'''Table 5 explains the embryological process for the development of posterior choanae:<ref>Johnston MC. The neural crest in abnormalities of the face and brain. Birth Defects Orig Artic Ser. 1975;11(7):1-18</ref>'''


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*The nasal pits begin to fold inwards into the mesenchyme forming nasal sacs.
*The nasal pits begin to fold inwards into the mesenchyme forming the nasal sacs.
*These primitive nasal sacs are separated from oral cavity by oronasal membrane.
*These primitive nasal sacs are separated from oral cavity by an oronasal membrane.


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*The oronasal membrane ruptures creating nasal cavity and a primitive choana located at the junction of nasal cavities and nasopharynx.
*The oronasal membrane ruptures creating nasal cavity, and a primitive choanae located at the junction of nasal cavities and nasopharynx.
*During this phase of development, there is gradual proliferation of neural crest cells which contribute to the formation of skull base and nasal vaults.
*During this phase of development, there is gradual proliferation of neural crest cells which further contribute to the formation of skull base and nasal vaults.
*The lateral palatal shelves fuse in an anterior-to-posterior direction which forms the hard and soft palate.
*The lateral palatal shelves fuse in an anterior-to-posterior direction which subsequently forms the hard and soft palate.


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*The nasal septum and developing palate fuse.
*The nasal septum and developing palate fuse.
*The primitive choanae gets pushed posteriorly and forms “Secondary choanae”.
*The primitive choanae gets pushed posteriorly to form “Secondary choanae”.
*In normal fetus, these secondary choanae are patent for a functioning airway between the anterior nasal cavity and nasopharynx.
*In normal fetus, these secondary choanae are patent for a functional airway between the anterior nasal cavity and nasopharynx.


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*Normal anatomical relations of the atretic plate are as follows:  
*Normal anatomical relations of the atretic plate are as follows: <ref name="CA HARNER">Harner SG, McDonald TJ, Reese DF. The anatomy of congenital choanal atresia. Otolaryngol Head Neck Surg 1981; 89: 7-9 </ref>
# Superior surface: Under surface of body of sphenoid
# Superior surface: Under surface of body of sphenoid
# Lateral border: Medial pterygoid lamina
# Lateral border: Medial pterygoid lamina
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==[[Choanal atresia pathophysiology|Pathophysiology]]==
==[[Choanal atresia pathophysiology|Pathophysiology]]==
* Obligate nose breathers: In neonates, the epiglottis is more superiorly placed as compared to adult so when infant swallows, the larynx rises above epiglottis position and touch the nasopharynx and locks between soft palate and side of nasopharynx. Due to the elevated laryngeal position compared to the adult counterpart, newborns are obligate nose breathers until mouth breathing is established with the descent of the larynx approximately 4–6 weeks of life.
*'''Obligate nose breathers''': In neonates, the epiglottis is more superiorly placed in relation to adults so when infant swallows, the larynx rises above epiglottis position and touch the nasopharynx, and locks between soft palate and sides of nasopharynx. Due to this elevated laryngeal position compared to the adults, newborns are obligate nose breathers until mouth breathing is established with the subsequent descent of the larynx at approximately 4–6 weeks of life.
* During inspiration, the neonate sucks the tongue and the vacuum is created in the oropharynx which helps to move soft tissue of the floor of mouth up and back towards soft palate.  
* During '''inspiration,''' the neonate sucks the tongue and creates the vacuum in the oropharynx which moves soft tissue of the floor of mouth up and back towards soft palate.  
* During expiration the pressure in the airway causes soft palate to push forward against the soft tissue and tongue in the mouth, which further obstructs the oral airway.  
* During '''expiration,''' the airways pressure causes soft palate to push forward against the soft tissue and tongue in the mouth and further obstructs the oral airway. <ref>Winter LK (1978) Congenital choanal atresia: anatomic, physiological, and therapeutic aspects, especially the endonasal approach under endoscopic vision. Arch Otolaryngol
* Interrelation of respiration, feeding and crying episodes:  
104(2):72–78</ref>
**As the infants are obligate nasal breather, the oral airway is invariably blocked or used by them during normal respiration. Oral breathing is used by them only during crying.
*'''Interrelation of respiration, feeding and crying episodes:<ref>Fearon B, Dickson J (1968) Bilateral choanal atresia in the new born. Laryngoscope 78(9):1487–1499</ref>'''
**The 1/3rd reduction in the diameter of the nasal airway increase nasal airway resistance by 81 times resulting in severe distress in neonates. As a result, the infant with bilateral CA experiences episodes of asphyxia and severe distress in quiet respiration when its mouth is closed, especially during periods of sleep or during feeding.  
**As the infants are obligate nasal breather, the oral airway is used by them only during crying; otherwise it is invariably blocked or used by them during normal respiration.
**Feeding difficulty can be the initial alerting event in which the infants can present with progressive airway obstruction and choke episodes during feeding because of their inability to breathe and feed at the same time.
**The 1/3rd reduction in the diameter of the nasal airway increase nasal airway resistance by 81 times resulting in severe distress in neonates. As a result, the infant with bilateral CA experiences episodes of asphyxia and severe distress in quiet respiration when their mouth is normally closed, especially during sleep or feeding times.  
**Moreover, the infant can become cyanotic which is relieved by crying or gasping when the child opens the mouth widely, releasing the air obstruction and the cyanosis disappears. If the crying stops, the mouth closes and the cycle repeats itself.  
**Feeding difficulty can be the initial presenting event in which the infants can present with progressive airway obstruction and choke episodes while feeding because of their inability to breathe and feed at the same time.
**Similarly, as the child falls asleep the mouth closes and a progressive obstruction starts with stridor followed by increased respiratory effort and cyanosis. Either the observer opens the child's mouth or the child cries and the obstruction is cleared.
**Moreover, the infant can become cyanotic which is relieved by crying or gasping as the child opens the mouth widely, releases the air obstruction and subsequently, the cyanosis disappears. However, the cycle repeats itself if the crying stops and the mouth closes.  
**In resting state, child has severe retractions, and struggles to breath with rapid development of cyanosis. The infant with bilateral choanal atresia develops rarely an ability to breathe through mouth and hence, the medical emergency would exist in complete absence of patent both nasal cavities.
**Similarly, as the child falls asleep, the mouth closes and a progressive obstruction starts with stridor followed by increased respiratory effort and cyanosis. Either the observer opens the child's mouth or the child cries and the obstruction is cleared.
 
**In resting state, child has severe retractions, and struggles to breath with rapid cyclic development of cyanosis. Moreover, the infant with bilateral CA rarely develops an ability to breathe through mouth and hence, the medical emergency would exist in the complete absence of patent both nasal cavities.
*Hengerer and Strome attributed the CA embryological foundations to four factors which try to explain the embryological origin of congenital CA.
===Embryological theories===
 
*Hengerer and Strome proposed four embryological originating factors for the development of congenital CA. <ref>Hegerer AS, Strome M. Choanal atresia: a new embryologic theory and its influence on surgical management. Laryngoscope. 1982, 92(8):913-21 </ref> <ref name="pmid18197129">{{cite journal| author=Hengerer AS, Brickman TM, Jeyakumar A| title=Choanal atresia: embryologic analysis and evolution of treatment, a 30-year experience. | journal=Laryngoscope | year= 2008 | volume= 118 | issue= 5 | pages= 862-6 | pmid=18197129 | doi=10.1097/MLG.0b013e3181639b91 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18197129  }} </ref>
# Persistence of buccalpharyngeal membrane of anterior intestine;
# Persistence of buccopharyngeal membrane of anterior intestine;
# Failure of Hochstetter bucconasal membrane to rupture which usually occurs in the seventh gestational week;
# Failure of Hochstetter bucconasal membrane to rupture usually in the seventh gestational week;
# Abnormal adherence of the mesodermal tissue in the choanal region;
# Abnormal adherence of the mesodermal tissue in the choanal region;
# Abnormal guidance of mesodermal flow secondary to local factors.
# Abnormal guidance of mesodermal flow secondary to local factors.
 
*Other theories which are not so widely considered are:
*Other not so widely accepted theories are:
# Resorption of secondary nasal fossa floor
# Resorption of secondary nasal fossa floor
# Incomplete extension of nasal cavity dorsally
# Incomplete extension of nasal cavity dorsally
# Migration of dorsal part of fronto nasal process to fuse with the palatal shelves
# Migration of dorsal part of frontonasal process to fuse with the palatal shelves
*However, none of these proposed pathologies gives a confirmatory support for an obstructive or minimalized size of the choanal openings by developmental processes, and hence, currently there has been no definitive evidence supporting one theory over the others. <ref name="LesciottoHeuzé2018">{{cite journal|last1=Lesciotto|first1=Kate M.|last2=Heuzé|first2=Yann|last3=Jabs|first3=Ethylin Wang|last4=Bernstein|first4=Joseph M.|last5=Richtsmeier|first5=Joan T.|title=Choanal Atresia and Craniosynostosis|journal=Plastic and Reconstructive Surgery|volume=141|issue=1|year=2018|pages=156–168|issn=0032-1052|doi=10.1097/PRS.0000000000003928}}</ref>


*However, none of these proposed pathologies gives a precise explanation for obstruction or minimization of the size of the choanal openings by developmental processes, and currently, there has been no definitive evidence supporting one theory over the others.
===Anatomical deformities===
 
*Following deformitites are associated with CA:<ref name="CA HARNER">Harner SG, McDonald TJ, Reese DF. The anatomy of congenital choanal atresia. Otolaryngol Head Neck Surg 1981; 89: 7-9 </ref>
*Anatomical deformitites associated with CA includes:
# The bony atretic plate is situated in front of the posterior bony septum
# The bony atretic plate is situated in front of the posterior bony septum
# Nasal cavity is narrowed
# Narrowed nasal cavity  
# Lateral pterygoid plates are found to be thickened compromising the nasal airway
# Thickened lateral pterygoid plates compromising the nasal airway
# Medially vomer is thickened
# Thickening of medial aspect of vomer
# The membranous plate lies in between lateral pterygoid and vomer   
# The membranous plate situated in between lateral pterygoid and vomer   
# High arched palate is common in these patients
# High arched palate


==[[Choanal atresia causes|Etiology]]==
==[[Choanal atresia causes|Etiology]]==
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* Retinoic acid (RA) is produced from vitamin A by an enzyme retinaldehyde dehydrogenase (Raldh) which is important for ontogenesis and homeostasis of numerous tissues.
* Retinoic acid (RA) is produced from vitamin A by an enzyme retinaldehyde dehydrogenase (Raldh) which is important for ontogenesis and homeostasis of numerous tissues.
* However, studies have revealed that cranio facial anamolies with mesenchymal damage and cell disruption were reported among mothers with an ingestion of high doses of vitamin A during gestation period. It has been attributed to disturbances in migration pattern of neural crest cells which further led to the disturbances in mesoderm development in the cranio facial area.  
* However, studies have revealed that the cranio facial anamolies with mesenchymal developmental damage and disrupted neural crest cell migration pattern were reported among mothers with an ingestion of high doses of vitamin A during gestation period. <ref name= "Burrow">Burrow TA, Saal HM, de Alarcon A, Martin LJ, Cotton RT, Hopkin RJ. Characterization of congenital anomalies in individuals with choanal atresia. Arch Otolaryngol Head Neck Surg. Jun 2009;135(6):543-547</ref>
* Dupe et al.: Using a mouse model, they demonstrated that Raldh3 knockout suppressed RA synthesis and caused CA via following proposed mechanisms:
* Dupe et al.: Using a mouse model, they demonstrated that Raldh3 knockout suppressed RA synthesis and caused CA via following proposed mechanisms:<ref name="DupeMatt2003">{{cite journal|last1=Dupe|first1=V.|last2=Matt|first2=N.|last3=Garnier|first3=J.-M.|last4=Chambon|first4=P.|last5=Mark|first5=M.|last6=Ghyselinck|first6=N. B.|title=A newborn lethal defect due to inactivation of retinaldehyde dehydrogenase type 3 is prevented by maternal retinoic acid treatment|journal=Proceedings of the National Academy of Sciences|volume=100|issue=24|year=2003|pages=14036–14041|issn=0027-8424|doi=10.1073/pnas.2336223100}}</ref>
# Over-expression of fibroblast growth factor 8 (FGF-8),
# Over-expression of fibroblast growth factor 8 (FGF-8),
# Persistence of nasal fins whose rupture normally allowed the communication between nasal and oral cavities
# Persistence of nasal fins whose rupture normally allowed the communication between nasal and oral cavities
* They further demonstrated that the CA in the Raldh knockout mice could be prevented by maternal treatment of RA.  
* Furthermore, they demonstrated that the CA in the Raldh knockout mice could be prevented by maternal treatment of RA.  
* The role of FGF-8 in CA development was supported by the observation of prevalent CA among patients with craniosynostosis syndromes as a result of the elevated level of FGF-8 expression.
* The role of FGF-8 in CA development was further supported by the prevalence of CA among patients with craniosynostosis syndromes due to the raised levels of FGF-8 expression.<ref name="HehrMuenke1999">{{cite journal|last1=Hehr|first1=Ute|last2=Muenke|first2=Maximilian|title=Craniosynostosis Syndromes: From Genes to Premature Fusion of Skull Bones|journal=Molecular Genetics and Metabolism|volume=68|issue=2|year=1999|pages=139–151|issn=10967192|doi=10.1006/mgme.1999.2915}}</ref>


===The Role of Thioamides===
===The Role of Thioamides===
* ''Thioamides:'' Methimazole, carbimazole, and propylthiouracil, are commonly used as medical treatment for hyperthyroidism.  
* ''Thioamides:'' Methimazole, carbimazole, and propylthiouracil, are commonly used as medical treatment for hyperthyroidism.  
* Several case reports have been published demonstrating the potential association of CA in the newborns whose mothers had prenatal use of thioamides for their thyroid hyperfunctioning.  
* Several case reports have been published demonstrating the significant association of CA in the newborns with the maternal use of thioamides for the hyperfunctioning thyroid. <ref name="pmid12878343">{{cite journal| author=Chabrolle JP, Bruel H, El Khoury E, Poinsot J, Amusini P, Benouada A | display-authors=etal| title=[Methimazole and choanal atresia]. | journal=Arch Pediatr | year= 2003 | volume= 10 | issue= 5 | pages= 463-4 | pmid=12878343 | doi=10.1016/s0929-693x(03)00097-6 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12878343  }} </ref>
* Moreover, Barbero et al. conducted a case- control study which further supported the relation of prenatal exposure to maternal hyperthyroidism treated with methimazole with CA development.  
* Moreover, Barbero et al. conducted a case- control study which further concluded the positive relation of prenatal exposure to methimazole for the maternal hyperthyroidism with CA development.<ref name="BarberoValdez2008">{{cite journal|last1=Barbero|first1=Pablo|last2=Valdez|first2=Rita|last3=Rodríguez|first3=Hugo|last4=Tiscornia|first4=Carlos|last5=Mansilla|first5=Enrique|last6=Allons|first6=Adriana|last7=Coll|first7=Silvia|last8=Liascovich|first8=Rosa|title=Choanal atresia associated with maternal hyperthyroidism treated with methimazole: A case-control study|journal=American Journal of Medical Genetics Part A|volume=146A|issue=18|year=2008|pages=2390–2395|issn=15524825|doi=10.1002/ajmg.a.32497}}</ref>
* Methimazole crosses the placenta and enters the fetal circulation which in turn reduces the T4 levels of the fetus. Therefore, infants born with CA have shown a marked decrease in their T4 levels.
* Methimazole crosses the placenta and hence, enters the fetal circulation which in turn reduces the fetal T4 levels. Therefore, infants born with CA have shown a marked decrease in their T4 levels.
* Teratogenic syndromes causing bilateral CA includes:
* Teratogenic syndromes causing bilateral CA includes:<ref name="BarberoValdez2008">{{cite journal|last1=Barbero|first1=Pablo|last2=Valdez|first2=Rita|last3=Rodríguez|first3=Hugo|last4=Tiscornia|first4=Carlos|last5=Mansilla|first5=Enrique|last6=Allons|first6=Adriana|last7=Coll|first7=Silvia|last8=Liascovich|first8=Rosa|title=Choanal atresia associated with maternal hyperthyroidism treated with methimazole: A case-control study|journal=American Journal of Medical Genetics Part A|volume=146A|issue=18|year=2008|pages=2390–2395|issn=15524825|doi=10.1002/ajmg.a.32497}}</ref> <ref>Wolf D, Foulds N, Daya H. Antenatal carbimazole and choanal atresia: a new embryopathy. Arch Otolaryngol Head Neck Surg. Sep 2006;132(9):1009-1011 </ref>
# Methimazole embryopathy
# Methimazole embryopathy
# Carbimazole embryopathy
# Carbimazole embryopathy
* However, it is not completely supported because of lack of significant evidences.  
* However, it is not completely supported because of lack of significant evidences.  
* ''Maternal Hyperthyroidism'': Although, based on the thorough study of case reports and critical literature reviews, it was stated that the mother’s hyperthyroidism rather than the methimazole treatment might be the causal factor for CA.  
* ''Maternal Hyperthyroidism'': Contrarily, based on the thorough study of case reports and critical literature reviews, it was stated that the maternal hyperthyroidism rather the methimazole treatment might be underlying the causal factor for CA.  
* Elevated thyroid-stimulating hormones (TSH) level was associated with increased level of FGF, FGF receptor, and other proliferating growth factors, which hypothetically form the basis for CA development.  
* Elevated thyroid-stimulating hormones (TSH) level was associated with increased level of FGF, FGF receptor, and other proliferating growth factors, which hypothetically form the pathological basis for CA development. <ref name="pmid12746216">{{cite journal| author=Cocks HC, Thompson S, Turner FE, Logan A, Franklyn JA, Watkinson JC | display-authors=etal| title=Role and regulation of the fibroblast growth factor axis in human thyroid follicular cells. | journal=Am J Physiol Endocrinol Metab | year= 2003 | volume= 285 | issue= 3 | pages= E460-9 | pmid=12746216 | doi=10.1152/ajpendo.00519.2002 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=12746216  }} </ref>
* ''Hence'', further studies are required to further delineate the causes and pathogenesis of CA.
* Hence, more research studies are required to further delineate the causes and pathogenesis of CA.


===Excessive Coffee Intake===  
===Excessive Coffee Intake <ref name="pmid19591116">{{cite journal| author=Collier SA, Browne ML, Rasmussen SA, Honein MA, National Birth Defects Prevention Study| title=Maternal caffeine intake during pregnancy and orofacial clefts. | journal=Birth Defects Res A Clin Mol Teratol | year= 2009 | volume= 85 | issue= 10 | pages= 842-9 | pmid=19591116 | doi=10.1002/bdra.20600 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19591116  }} </ref>===  
Excessive consumption of coffee in the form of more than 3 cups/day increases the chances of CA by interrupting the membrane rupture which leads to an outgrowth of palate towards the medial side and further blocks the communication between the nasal cavities and the pharynx.
Excessive consumption of coffee in the form of more than 3 cups/day increases the chances of CA by interrupting the membrane rupture which leads to an outgrowth of palate towards the medial side and further blocks the communication between the nasal cavities and the pharynx.


===Genetics===
===Genetics===
* Familial cases: About 8%.  
* Familial cases: About 8%. <ref>Gorlin, R. J. Personal Communication. Minneapolis, Minn. 1982</ref>
* Multifactorial trait: The fact is supported by both affected successive generations and affected single generations.  
* Multifactorial trait: The fact is supported by both affected successive and single generations. <ref name="pmid14775107">{{cite journal| author=McGOVERN FH| title=Congenital choanal atresia. | journal=Laryngoscope | year= 1950 | volume= 60 | issue= 8 | pages= 815-31 | pmid=14775107 | doi=10.1288/00005537-195008000-00005 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14775107  }} </ref>
* CHARGE syndrome: The abnormalities in the chromodomain helicase DNA binding protein-7 (CHD7) gene have been identified in 64% of patients diagnosed with CHARGE, and hence, allowing screening of the gene for patients with CA and other related anomalies. However, the exact function of the CHD7 gene is largely unknown.
* CHARGE syndrome: The abnormalities in the chromodomain helicase DNA binding protein-7 (CHD7) gene have been identified in 64% of patients diagnosed with CHARGE, and hence, allowing screening of the gene for patients with CA and other related anomalies. However, the exact function of the CHD7 gene is largely unknown. <ref name= "CHARGE">Lalani SR, Hefner MA, Belmont JW, et al. CHARGE Syndrome. 2006 Oct 2 [Updated 2012 Feb 2]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1117/</ref>


==[[Differentiating Choanal atresia from other diseases|Differentiating Choanal atresia from other Diseases]]==
==[[Differentiating Choanal atresia from other diseases|Differentiating Choanal atresia from other Diseases]]==


Following conditions must be ruled out in any neonates, infant or child presented with acute or frequent episodes of nasal or upper airway obstruction.
Following conditions listed in Table 6 must be ruled out in any neonates, infant or child presented with acute or frequent episodes of nasal or upper airway obstruction.<ref name= "Stat">Andaloro C, La Mantia I. Choanal Atresia. [Updated 2020 Aug 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507724/</ref>
 
'''Table 6 lists the differential diagnosis for choanal atresia:'''


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==[[Choanal atresia epidemiology and demographics|Epidemiology and Demographics]]==
==[[Choanal atresia epidemiology and demographics|Epidemiology and Demographics]]==
* “Rule of 2:1” states the ratio of unilateral to bilateral CA, female to male and the right sided to the left sided CA.
* “Rule of 2:1” states the ratio of unilateral to bilateral CA, female to male and the right sided to the left sided CA.<ref name= "Stat">Andaloro C, La Mantia I. Choanal Atresia. [Updated 2020 Aug 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507724/</ref>
* The incidence is 1:5,000 to 1:8,000 per live-born children.  
* The incidence is 1:5,000 to 1:8,000 per live-born children.<ref name= "Stat">Andaloro C, La Mantia I. Choanal Atresia. [Updated 2020 Aug 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507724/</ref>
* Although its incidence is rare, it represents the most common congenital abnormality of the nose.
* Although its incidence is rare, it represents the most common congenital abnormality of the nose. <ref name="CaseMitchell2011">{{cite journal|last1=Case|first1=Amy P.|last2=Mitchell|first2=Laura E.|title=Prevalence and patterns of choanal atresia and choanal stenosis among pregnancies in Texas, 1999-2004|journal=American Journal of Medical Genetics Part A|volume=155|issue=4|year=2011|pages=786–791|issn=15524825|doi=10.1002/ajmg.a.33882}}</ref>
* Maternal age and parity does not affect the frequency of this congenital anomaly.
* Maternal age and parity does not affect the frequency of this congenital anomaly.<ref name="CaseMitchell2011">{{cite journal|last1=Case|first1=Amy P.|last2=Mitchell|first2=Laura E.|title=Prevalence and patterns of choanal atresia and choanal stenosis among pregnancies in Texas, 1999-2004|journal=American Journal of Medical Genetics Part A|volume=155|issue=4|year=2011|pages=786–791|issn=15524825|doi=10.1002/ajmg.a.33882}}</ref>
* Slightly increased risk exists in twin pregnancy.
* Slightly increased risk exists in twin pregnancy.<ref name= "DIAG">{{cite web |url=https://www.diagnosticimaging.com/view/choanal-atresia |title=Choanal Atresia |format= |work= |accessdate=}}</ref>
* It is observed with equal frequency among all races and hence, no racial or ethnic preference is seen.
* It is observed with equal frequency among all races and hence, no racial or ethnic preference is seen.<ref name= "DIAG">{{cite web |url=https://www.diagnosticimaging.com/view/choanal-atresia |title=Choanal Atresia |format= |work= |accessdate=}}</ref>


==[[Choanal atresia risk factors|Risk Factors]]==
==[[Choanal atresia risk factors|Risk Factors]]==


* The relation of risk factors and its implications is always complex. A risk factor increases the predisposition towards a disease in comparison to an individual with no risk factors. However, some risk factors are more important than others; hence, acquiring a single or multiple risk factor does not mean that one will develop the disorder. Moreover, absence of a risk factor does not guarantee the disease free state.  
* The relation of risk factors and its implications is always complex. A risk factor increases the predisposition towards a disease in comparison to an individual with no risk factors. However, some risk factors are more important than others; hence, acquiring a single or multiple risk factor does not guarantee the disease development. Contrarily, absence of a risk factor does not ensure the disease free state.  
*2010: An epidemiological report found higher associations between increased incidence of CA and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake and exposure to anti-infective urinary tract medications.
*2012: An epidemiological survey studied “atrazine” a commonly used herbicide in the US to treat agricultural crops, and stated that women living in the counties in Texas with the highest levels of this chemical were 80 times more likely to give birth to neonates with CA in relation to women who lived in the areas with its lowest levels.<ref name="AgopianCai2013">{{cite journal|last1=Agopian|first1=A. Jack|last2=Cai|first2=Yi|last3=Langlois|first3=Peter H.|last4=Canfield|first4=Mark A.|last5=Lupo|first5=Philip J.|title=Maternal Residential Atrazine Exposure and Risk for Choanal Atresia and Stenosis in Offspring|journal=The Journal of Pediatrics|volume=162|issue=3|year=2013|pages=581–586|issn=00223476|doi=10.1016/j.jpeds.2012.08.012}}</ref>
*2012: Another epidemiological study studied “atrazine” a commonly used herbicide in the U.S. used to treat agricultural crops, and found that women who lived in counties in Texas with the highest levels of this chemical being were 80 times more likely to give birth to neonates with CA in relation to women who lived in the counties with its lowest levels.
*2014: Another epidemiological National Birth Defects Prevention Study (NBDPS) summarized the higher association between the increased development of CA and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake, and use of thyroid medications.<ref name="KancherlaRomitti2014">{{cite journal|last1=Kancherla|first1=Vijaya|last2=Romitti|first2=Paul A.|last3=Sun|first3=Lixian|last4=Carey|first4=John C.|last5=Burns|first5=Trudy L.|last6=Siega-Riz|first6=Anna Maria|last7=Druschel|first7=Charlotte M.|last8=Lin|first8=Angela E.|last9=Olney|first9=Richard S.|title=Descriptive and risk factor analysis for choanal atresia: The National Birth Defects Prevention Study, 1997–2007|journal=European Journal of Medical Genetics|volume=57|issue=5|year=2014|pages=220–229|issn=17697212|doi=10.1016/j.ejmg.2014.02.010}}</ref>
*To sum up, the risk factors for the development of Choanal Atresia are following listed:
*To sum up, the risk factors for the development of CA are listed below:
# Exposure to endocrine disrupters such as chemicals (atrazine) and medications (methimazole) during gestation.<ref name="BarberoValdez2008">{{cite journal|last1=Barbero|first1=Pablo|last2=Valdez|first2=Rita|last3=Rodríguez|first3=Hugo|last4=Tiscornia|first4=Carlos|last5=Mansilla|first5=Enrique|last6=Allons|first6=Adriana|last7=Coll|first7=Silvia|last8=Liascovich|first8=Rosa|title=Choanal atresia associated with maternal hyperthyroidism treated with methimazole: A case-control study|journal=American Journal of Medical Genetics Part A|volume=146A|issue=18|year=2008|pages=2390–2395|issn=15524825|doi=10.1002/ajmg.a.32497}}</ref><ref name="AgopianCai2013">{{cite journal|last1=Agopian|first1=A. Jack|last2=Cai|first2=Yi|last3=Langlois|first3=Peter H.|last4=Canfield|first4=Mark A.|last5=Lupo|first5=Philip J.|title=Maternal Residential Atrazine Exposure and Risk for Choanal Atresia and Stenosis in Offspring|journal=The Journal of Pediatrics|volume=162|issue=3|year=2013|pages=581–586|issn=00223476|doi=10.1016/j.jpeds.2012.08.012}}</ref>
# Exposure to chemicals (atrazine) and medications (methimazole) that act as endocrine disrupters during gestation.
# Exposure to secondhand smoke during gestational period.<ref name="KancherlaRomitti2014">{{cite journal|last1=Kancherla|first1=Vijaya|last2=Romitti|first2=Paul A.|last3=Sun|first3=Lixian|last4=Carey|first4=John C.|last5=Burns|first5=Trudy L.|last6=Siega-Riz|first6=Anna Maria|last7=Druschel|first7=Charlotte M.|last8=Lin|first8=Angela E.|last9=Olney|first9=Richard S.|title=Descriptive and risk factor analysis for choanal atresia: The National Birth Defects Prevention Study, 1997–2007|journal=European Journal of Medical Genetics|volume=57|issue=5|year=2014|pages=220–229|issn=17697212|doi=10.1016/j.ejmg.2014.02.010}}</ref>
# Exposure to secondhand smoke during gestational period.
# Excessive consumption of coffee by pregnant mothers exposes the developing fetus to caffeine <ref name="pmid19591116">{{cite journal| author=Collier SA, Browne ML, Rasmussen SA, Honein MA, National Birth Defects Prevention Study| title=Maternal caffeine intake during pregnancy and orofacial clefts. | journal=Birth Defects Res A Clin Mol Teratol | year= 2009 | volume= 85 | issue= 10 | pages= 842-9 | pmid=19591116 | doi=10.1002/bdra.20600 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=19591116  }} </ref>
# Excessive consumption of coffee by pregnant mothers exposes the developing fetus to caffeine
# Elevated levels of vitamin B-12 and  zinc in a pregnant woman exposes the fetus to the same <ref name="KancherlaRomitti2014">{{cite journal|last1=Kancherla|first1=Vijaya|last2=Romitti|first2=Paul A.|last3=Sun|first3=Lixian|last4=Carey|first4=John C.|last5=Burns|first5=Trudy L.|last6=Siega-Riz|first6=Anna Maria|last7=Druschel|first7=Charlotte M.|last8=Lin|first8=Angela E.|last9=Olney|first9=Richard S.|title=Descriptive and risk factor analysis for choanal atresia: The National Birth Defects Prevention Study, 1997–2007|journal=European Journal of Medical Genetics|volume=57|issue=5|year=2014|pages=220–229|issn=17697212|doi=10.1016/j.ejmg.2014.02.010}}</ref>
# Elevated levels of vitamin B-12 and  zinc in a pregnant woman exposes the fetus to the same
# Multiple pregnancies such as twins carries a higher risk <ref name= "DIAG">{{cite web |url=https://www.diagnosticimaging.com/view/choanal-atresia |title=Choanal Atresia |format= |work= |accessdate=}}</ref>
# Multiple pregnancies, such as twins, carries a higher risk  
# Presence of certain congenital disorders that are associated with CA including Crouzon syndrome, Antley-Bixler syndrome, and Pfeiffer syndrome further increase its chances of development.<ref name= "Assoc">{{cite journal|doi=10.1001/archoto. 2009.53}}</ref>
# Presence of certain congenital disorders that are associated with Choanal Atresia including Crouzon syndrome, Antley-Bixler syndrome, and Pfeiffer syndrome further increase its chances of development.


==[[Choanal atresia screening|Screening]]==
==[[Choanal atresia screening|Screening]]==
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==[[Choanal atresia natural history, complications and prognosis|Clinical Associations and Complications]]==
==[[Choanal atresia natural history, complications and prognosis|Clinical Associations and Complications]]==


Any condition that causes significant depression of the nasal bridge or midface retraction can be associated with it.
Any condition that causes significant depression of the nasal bridge or midface retraction due to underlying genetic or environmental factors can be associated with it.


'''Table 7 lists the clinical associations and complications of the choanal atresia:'''<ref name= "Assoc">{{cite journal|doi=10.1001/archoto. 2009.53}}</ref> <ref name= "CHARGE">Lalani SR, Hefner MA, Belmont JW, et al. CHARGE Syndrome. 2006 Oct 2 [Updated 2012 Feb 2]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1117/</ref> <ref name= "Stat">Andaloro C, La Mantia I. Choanal Atresia. [Updated 2020 Aug 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507724/</ref>
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===CHARGE Syndrome===
===CHARGE Syndrome <ref name= "CHARGE">Lalani SR, Hefner MA, Belmont JW, et al. CHARGE Syndrome. 2006 Oct 2 [Updated 2012 Feb 2]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1117/</ref>===
* The most commonly associated congenital anomaly.  
* The most commonly associated congenital anomaly.  
* Choanal atresia is present in 10 to 30% of CHARGE syndrome cases.  
* Choanal atresia is present in 10 to 30% of CHARGE syndrome cases.  
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* The prognosis is usually considered to be very good with timely and effective management unless other complex syndrome associations seen.  
* The prognosis is usually considered to be very good with timely and effective management unless other complex syndrome associations seen.  
* Full recovery is expected with no possibility for any long term problem in both groups of patients.
* Full recovery is expected with no possibility for any long term problem in both groups of patients. <ref name= "medline">{{cite web |url=https://medlineplus.gov/ency/article/001642.htm#:~:text=The%20cause%20of%20choanal%20atresia,twice%20as%20often%20as%20males |title=Choanal atresia: MedlinePlus Medical Encyclopedia |format= |work= |accessdate=}}</ref>


==Clinical presentation==
==Clinical presentation==


Clinical presentation of CA varies from acute airway obstruction to chronic recurrent sinusitis depending on whether CA is unilateral, bilateral, or associated with other coexisting airway abnormalities.
Clinical presentation of CA varies from acute airway obstruction to chronic recurrent sinusitis depending on whether CA is unilateral, bilateral, or associated with other coexisting airway abnormalities. <ref name= "Assoc">{{cite journal|doi=10.1001/archoto. 2009.53}}</ref> <ref name= "Burrow">Burrow TA, Saal HM, de Alarcon A, Martin LJ, Cotton RT, Hopkin RJ. Characterization of congenital anomalies in individuals with choanal atresia. Arch Otolaryngol Head Neck Surg. Jun 2009;135(6):543-547</ref> <ref name= "Stat">Andaloro C, La Mantia I. Choanal Atresia. [Updated 2020 Aug 16]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507724/</ref> <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref>


'''Table 8 elaborates and compares both forms of Choanal Atresia: Bilateral and Unilateral::'''
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'''''Effect of CA on the facial structures growth:''''' The face, specifically the maxilla and mandible, grows in a dynamic fashion throughout childhood under the influence of bony deposition and resorption, soft-tissue contouring, and hormonal influences. In a reciprocal fashion, the skull base or neurocranium influences midfacial development via the growth of the sinuses, which in turn influence the skull base. Displacement of these structures of the nasomaxillary complex occurs in horizontal, vertical, and anteroposterior axes. These changes ultimately affect the proportions of the face and the morphology of all other facial structures, including the upper airway. Hence, upper airway obstruction while breathing is common because the intraoral airway has foreshortened due to abnormal placement of anterior choanal aperture, and further the diagnostic visualization of the laryngeal structures becomes difficult. Moreover, a chronic case of CA may progress to the development of obstructive sleep apnea.  
===Effect of CA on the facial structures growth <ref name="Holzman2011">{{cite journal|last1=Holzman|first1=Robert S.|title=Airway Management|year=2011|pages=344–364|doi=10.1016/B978-0-323-06612-9.00012-2}}</ref>===
*The face, specifically the maxilla and mandible, grows in a dynamic fashion throughout childhood under the influence of bony deposition and resorption, soft-tissue contouring, and hormonal influences. In a reciprocal fashion, the skull base or neurocranium influences midfacial development via the growth of the sinuses, which in turn influence the skull base. Displacement of these structures of the nasomaxillary complex occurs in horizontal, vertical, and anteroposterior axes. These changes ultimately affect the proportions of the face and the morphology of all other facial structures, including the upper airway. Hence, an upper airway obstruction while breathing is common because the intraoral airway has foreshortened due to abnormal placement of anterior choanal aperture, and further the diagnostic visualization of the laryngeal structures becomes difficult. Moreover, a chronic case of CA may progress to the development of obstructive sleep apnea later in life.


'''''CA with Multiple Congenital Anomalies:'''''
===CA with Multiple Congenital Anomalies===
* Other airway abnormalities: About 34% have other respiratory anomalies such as tracheomalacia, laryngomalacia, and subglottic stenosis
* Other airway abnormalities: About 34% have other respiratory anomalies such as tracheomalacia, laryngomalacia, and subglottic stenosis <ref name= "Burrow">Burrow TA, Saal HM, de Alarcon A, Martin LJ, Cotton RT, Hopkin RJ. Characterization of congenital anomalies in individuals with choanal atresia. Arch Otolaryngol Head Neck Surg. Jun 2009;135(6):543-547</ref>
* Craniofacial abnormalities: About 21% had it in the form of CHARGE, Treacher Collins, Pfeiffer, Apert, Mandibulofacial dysostosis, and Crouzon syndromes.
* Craniofacial abnormalities: About 21% had it in the form of CHARGE, Treacher Collins, Pfeiffer, Apert, Mandibulofacial dysostosis, and Crouzon syndromes. <ref name= "Assoc">{{cite journal|doi=10.1001/archoto. 2009.53}}</ref>
* Hence, this subgroup of patients always presents with more acute and severe respiratory symptoms due to the underlying complex airway abnormalities and hence, they requires stable alternative airway management such as tracheostomy in addition to the surgical correction of CA.
* Hence, these subgroup of patients always presents with more acute and severe respiratory symptoms due to the underlying complex airway abnormalities; and hence, they requires stable alternative airway management such as tracheostomy in addition to the surgical correction of CA.


==Diagnosis==
==Diagnosis==
 
*The diagnosis and management of CA requires the combined and coordinated efforts of both the neonatologists and otolaryngologists. Due to its associations with other syndromes (Table 7), infants born with CA often need other subspecialty evaluations for an interprofessional approach from the departments of cardiology, ophthalmology, geneticists, gastroenterology, etc in the multidisciplinary settings especially for Pediatric Airway Disorders.
*The diagnosis and management of CA requires the combined and coordinated efforts of both the neonatologists and otolaryngologists. Due to its associations with other syndromes (Table 6), infants born with CA often need other subspecialty evaluations for an interprofessional approach from the departments of cardiology, ophthalmology, gastroenterology,geneticists, etc in the multidisciplinary settings especially for Pediatric Airway Disorders.
*A thorough diagnostic work up is required to rule out other clinical conditions (Table 6) to arrive at a definitive diagnosis and to make a timely diagnosis as if left unestablished till later ages, it tend to impair the quality of life through repeated hospital visits.
 
*''Aero-digestive evaluation:'' An infant diagnosed with CA must be evaluated for both airway and feeding issues which need to be addressed by speech pathologists and GI specialists respectively.  
*A thorough diagnostic work up is required to rule out other clinical conditions (Table 5) to arrive at a definitive diagnosis and to make a timely diagnosis as if left unestablished till later ages, it tend to impair the quality of life through repeated hospital visits.
 
*Aero-digestive evaluation:  An infant diagnosed with CA must be evaluated for both airway and feeding issues which need to be addressed by speech pathologists and GI specialists respectively.  
 
*Following methods can be employed to diagnose the condition accurately.
*Following methods can be employed to diagnose the condition accurately.
# Assessment of detailed history including the maternal drug intake history and symptoms should be done as mentioned in Table 8.
# Assessment of detailed history including the maternal drug intake history and symptoms should be done as mentioned in Table 8.
# A thorough diagnostic physical and radiological examination procedures should be done.
# A thorough diagnostic physical and radiological examination procedures should be performed as listed below. <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref>
# Ultrasonography of the cardiac and renal systems can be performed for possible syndromic associations.
# Ultrasonography of the cardiac and renal systems can be conducted for the possible syndromic associations.
# Breath sounds can be heard with either a '''stethoscope''' or a '''Toynbee auscultation tube'''.
# Breath sounds can be heard with either a '''stethoscope''' or a '''Toynbee auscultation tube''' to detect the aerated lung fields.
# Air can be gently blown into each nasal cavity with a '''Politzer bag'''.
# Air can be gently blown into each nasal cavity with a '''Politzer bag''' to observe any degree of nasal obstructive signs.
 
=== Suction catheter test <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref>===  
=== Suction catheter test===  
*After performing proper preparation by the use of nasal topical decongestants and nasal suctioning, a fine six or eight French suction catheter introduced into the nose via each nostrils and into the child's oral cavity.
*After performing proper preparation by the use of nasal decongestants and nasal suctioning, a fine six or eight French suction catheter introduced into the nose via each nostrils and into the child's oral cavity.
*If there is ''no atresia'', the catheter will effortlessly pass through the nasal cavity into the nasopharynx.
*If there is no atresia the catheter will effortlessly pass through the nasal cavity into the nasopharynx.
*The distance of encountered resistance can provide insights into the etiology of nasal obstruction.
*The distance of encountered resistance can provide insights into the etiology of nasal obstruction.
**If there is CA then a typical solid feeling would be encountered at about 3-5 cm cms from the alar rim and indicates obstruction at the level posterior choanae.
**''3-5 cms from the anterior nares/alar rim:'' A typical solid feeling would be felt at this point and possibly indicates obstruction at the posterior choanal level.
**If obstruction is encountered within 1-2 cms from the anterior nares/ alar rim, then it could be caused due to traumatic deflection of nasal septum due to trauma during delivery or inferior turbinate pathologies. If obstruction is due to mucosal oedema it can be shrinked using nasal decongestants like oxymetazoline / xylometazoline.
**''1-2 cms from the anterior nares/alar rim:'' If obstruction is encountered at this distance, then traumatic deflection of nasal septum due to trauma during delivery or inferior turbinate pathologies might be the pathologies. Nasal decongestants such as oxymetazoline/xylometazoline can be used to shrink the obstruction caused by mucosal edema.
*Hence, an inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on chest radiograph confirms the diagnosis. However, care must be taken in patients with other craniofacial abnormalities to prevent intracranial passage of the catheter.
*Hence, an inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on chest radiograph confirms the diagnosis. However, care must be taken in patients with other craniofacial abnormalities to prevent intracranial passage of the catheter.


=== Cotton wisp test===  
=== Cotton wisp test <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref> ===  
*Movement of a wisp of cotton wool held directly underneath the nares during inspiration and expiration while the mouth is closed. It would move in the presence of air flow; however, the lack of movement indicates the diagnosis.  
*Movement of a wisp of cotton wool held directly underneath the nares while the closed mouth during inspiration and expiration. It would move in the presence of free air flow; however, the lack of movement indicates the probable obstructive diagnosis.


=== Laryngeal mirror test===  
=== Laryngeal mirror test <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref>===  
*A shiny laryngeal mirror held under the nares will reveal nasal misting in patients with patent nasal airways. Contrarily, the absence of fog on a mirror when it is placed under the one nostril after the other to check for fogging indicates the diagnosis.
*A laryngeal mirror held under the nares will reveal nasal misting in patients with patent nasal airways. Contrarily, the absence of fog on a mirror when it is placed under the one nostril after the other to check for fogging supports the CA diagnosis.


=== Acoustic rhinometry===  
=== Acoustic rhinometry <ref>Djupesland P, Kaastad E, Franzen G. Acoustic rhinometry in the evaluation of congenital choanal malformations. Int J Pediatr Otorhinolaryngol 1997;
*Acoustic rhinometry can be used for the diagnosis, but is especially helpful in the postoperative period to check the patients on restenosis.
41: 319-37.</ref>===  
*Acoustic rhinometry can be used for the diagnosis, but is especially helpful in the postoperative period to check the patients on restenosis or postoperative nasal complications.


=== Methylene blue dye test===   
=== Methylene blue dye test <ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804
doi: 10.9754/journal.wmc.2012.003804</ref>===   
*Administration of methylene blue dye into the anterior nasal cavity can be seen passing through the nasopharynx. However, obstruction due to CA will prevent the flow into the nasopharynx and supports the diagnosis.
*Administration of methylene blue dye into the anterior nasal cavity can be seen passing through the nasopharynx. However, obstruction due to CA will prevent the flow into the nasopharynx and supports the diagnosis.


=== Automatic tympanometer===  
=== Automatic tympanometer <ref name="Effat2006">{{cite journal|last1=Effat|first1=Kamal G|title=Use of the automatic tympanometer as a screening tool for congenital choanal atresia|journal=The Journal of Laryngology & Otology|volume=119|issue=2|year=2006|pages=125–128|issn=0022-2151|doi=10.1258/0022215053419925}}</ref>===
*It has been revealed that the novel method of screening for choanal atresia in newborns using the automatic tympanometer is simple, minimally invasive and highly reproducible with 100% sensitivity and specificity rate.  
*An examination using the automatic tympanometer is considered to be simple, minimally invasive, and highly reproducible with 100% sensitivity and specificity rate.


=== Genetic Screening===
=== Genetic Screening <ref name= "CHARGE">Lalani SR, Hefner MA, Belmont JW, et al. CHARGE Syndrome. 2006 Oct 2 [Updated 2012 Feb 2]. In: Adam MP, Ardinger HH, Pagon RA, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2020. Available from: https://www.ncbi.nlm.nih.gov/books/NBK1117/</ref>===
*The CHD7 gene screening test and other cytogenetic anomalies such as chromosome deletions detections related to the several syndromes (Table 7) associated with CA can be done.
*The CHD7 gene screening test and other cytogenetic anomalies such as chromosome deletions related to the several syndromes (Table 7) associated with CA can be done.


=== Prenatal ultrasound===  
=== Prenatal ultrasound <ref name="CrispiPuerto2018">{{cite journal|last1=Crispi|first1=Fatima|last2=Puerto|first2=Bienvenido|title=Choanal Atresia|year=2018|pages=319–320.e1|doi=10.1016/B978-0-323-44548-1.00067-X}}</ref>===  
*The clinical presentation and diagnosis of CA is usually postnatal, hence the prenatal ultrasound diagnosis is rare, and very few cases have been reported in the literature. It can be suspected prenatally in the presence of nose anomalies, mainly nasal septal deviation or the presence of a single nostril.  
*The clinical presentation and diagnosis of CA is usually postnatal, hence the prenatal ultrasound diagnosis is rare, and very few cases have been reported in the literature. However, it can be suspected prenatally in the presence of other nose anomalies such as nasal septal deviation or a single nostril.


=== Lateral skull X-ray===   
=== Lateral skull X-ray <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref> ===   
*The traditional method of diagnosis can be used with a lateral skull X-ray after filling the nose with radiopaque dye with the patient in a supine position, and demonstrating hold-up of the dye in the posterior nasal cavity.
*The traditional method of diagnosis which involves the filling the nose with radiopaque dye with the patient lying in a supine position, and thus, demonstrating the hold-up of the dye in the posterior nasal cavity.


=== Nasal Endoscopy===
=== Nasal Endoscopy<ref>Stamm A, Mekhitarian L (1995) Atresia coanal: cirurgia microendoscopica trans nasal. In: Stamm A (ed) Microcirurgia naso-sinusal. Revinter, Rio de Janeiro, pp 279-287</ref>===  
*An appropriate age-related otorhinolaryngology examination is performed directed to the nasal cavity. After aspiration of any nasal secretions and preparation of the nasal cavity, examination in very small children is performed with the 3.2-mm-diameter flexible endoscope. When possible, we prefer the 0° and 30° rigid endoscopes with a diameter of 4.0 mm or 2.7 mm. Direct visualization of the point of obstruction in the nasal passage with a flexible nasendoscope confirms the presence of an atretic plate in the choana. Therefore, it has become the preferred method for confirming the diagnosis.  
[[Image:Unilateral CA-page0001.jpg|left|thumb|100px|Retropalatal endoscopic view demonstrating unilateral choanal atresia|Source: www.entdev.uct.ac.za]]
[[Image:Bilateral CA 3.jpg|right|thumb|150px|Retropalatal endoscopic view demonstrating bilateral choanal atresia|Source: www.entdev.uct.ac.za]]
*An appropriate age-related otorhinolaryngology examination is performed after the nasal cavity preparation, an examination in a very small children is performed with the 3.2 mm diameter flexible endoscope. When possible, the 0° and 30° rigid endoscopes are preferred with a diameter of 4.0 mm or 2.7 mm. Direct visualization of the point of obstruction in the nasal passage with a flexible nasendoscope confirms the presence of an atretic plate in the choana. Therefore, it has become the preferred method for confirming the diagnosis.


=== CT scan===   
=== CT scan===   
*CT scan imaging of the paranasal sinuses and skull base is virtually diagnostic modality of choice. It should be done after stabilization of the patient in supine position.
*CT scan imaging of the paranasal sinuses and skull base is virtually diagnostic modality of choice. It should be done after symptomatic stabilization of the patient in supine position.
*''Objective:''  
*'''Objective:'''  
# To confirm the diagnosis and it’s involvement on one or both sides.
#To confirm the diagnosis and it’s involvement on unilateral or bilateral sides.
# To determine the anatomy of the atretic area, including the width of the Vomer bone and the medial displacement of the sides of the lateral wall of the nose.
#To determine the anatomy of the atretic area, including the width of the vomer bone and the medial displacement of the sides of the lateral wall of the nose.
# To measure the thickness of the atretic plate and the presence and thickness of a bony plate.
#To measure the thickness of the atretic plate.
# To determine if any other sites of obstruction or differential abnormalities exist in the nasal, nasopharyngeal or sinus cavities.
#To determine if any other sites of obstruction or differential abnormalities exist in the nasal, nasopharyngeal or sinus cavities.
# To detect the abnormal anatomy required in surgical planning and in determining the choice of the operative technique to be used.
#To detect the abnormal anatomy useful for a surgical planning, and in determining the choice of the operative technique to be used.
*''Patient preparation before the scanning:'' A nasal decongestant (0.5% xy-lometazaline) is applied to reduce mucosal swelling 30 minutes prior to the CT scan, and suctioning of the nose done immediately before the CT scan to remove all nasal secretions in order to enable accurate radiological diagnosis as it is difficult to distinguish radiologically a membranous occlusion from mucus in the unprepared nose.
[[Image:CT unilateral bony.jpg|right|thumb|250px|CT scan demonstrating unilateral osseous choanal atresia]]
*''CT scan technique:''  
*'''Patient preparation before the scanning:''' A nasal topical decongestant (0.5% xylometazaline) is applied to reduce mucosal swelling 30 minutes prior to the CT scan, and suctioning of the nose done immediately before the CT scan to remove all nasal secretions in order to detect accurate radiological diagnosis due to the difficulty in radiologically distinguishing  a membranous occlusion from mucus in the unprepared nose.<ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref>
**Anatomical landmark: the level of the pterygoid plates in the axial plane. At this level the width of both posterior choanae at maximum stenosis and the maximum width of the inferoposterior vomer are measured. Below this level the hard palate is visualised and above this level structures within the nasal cavity make measurement difficult.  
*'''CT scan technique:<ref name="CT">Slovis TL,Renfro B,Watts FB,Kuhns LR,Belenky W,Spoylar J. Choanal atresia: precise CTevaluation. Radiology (1985) 155(2):345–8. doi:10.1148/radiology. 155.2.3983384</ref>'''  
**Scanning angle: The gantry is angled 5° cephalad to a plane parallel to the hard palate to interpret the images for the measurements of the posterior vomer, the choanal openings and the shape of the posteromedial maxilla.  
**''Anatomical landmark:'' The level of the pterygoid plates in the axial plane. At this level, the width of both posterior choanae at maximum stenosis and the maximum width of the inferoposterior vomer are measured. Below this level, the hard palate is visualised; and above this level, structures within the nasal cavity make measurements difficult.  
**Partial skull ossification: Conventional bone-window settings may not show the bony margins, hence high resolution bone filters may overcome this problem. One to 1.5 mm thick uncontrasted scans are obtained contiguously.  
**''Scanning angle:'' The gantry is angled 5° cephalad to a plane parallel to the hard palate to interpret the images for the measurements of the posterior vomer, the choanal openings, and the shape of the posteromedial maxilla.  
*''CT scan findings:'' 
**''Partial skull ossification:'' Conventional bone-window settings may not show the bony margins; however, a high resolution bone filters may overcome this problem. Hence, 1 to 1.5 mm thick noncontrasted scans are done contiguously.  
# Narrowing of the posterior nasal cavity with medial bowing and thickening of the lateral wall of the nasal cavity, with airway width < 3 mm.
*'''CT scan findings:<ref name="CT">Slovis TL,Renfro B,Watts FB,Kuhns LR,Belenky W,Spoylar J. Choanal atresia: precise CTevaluation. Radiology (1985) 155(2):345–8. doi:10.1148/radiology. 155.2.3983384</ref> <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref>''' 
# Narrowing of the posterior nasal cavity with medial bowing and thickening of the lateral wall of the nasal cavity with airway width < 3 mm.
# Impingement and thickening  at the level of the anterior aspect of the pterygoid plates  
# Impingement and thickening  at the level of the anterior aspect of the pterygoid plates  
# Enlargement of the posterior portion of the vomer, with or without a central membranous connection. In patients less than 8 years of age, the vomer generally measures less than 0.23 cm in width and should not exceed 0.34 cm; in children over 8 years, the mean vomer width is 0.28 cm and should not exceed 0.55 cm.  
# Enlargement of the posterior portion of the vomer, with or without a central membranous connection. In patients less than 8 years of age, the vomer generally measures less than 0.23 cm in width and should not exceed 0.34 cm; in children over 8 years, the mean vomer width is 0.28 cm and should not exceed 0.55 cm.  
# The mean width of the posterior choanal airspace in the newborn (measured from the lateral wall of the nasal cavity to the vomer) is 0.67 cm, increasing to 0.86 cm at 6 years and to 1.13 cm by 16 years of age.
# The mean width of the posterior choanal airspace in the newborn measured from the lateral wall of the nasal cavity to the vomer is 0.67 cm, increasing to 0.86 cm at 6 years and to 1.13 cm by 16 years of age.
# An air-fluid level of the nasal secretions above the obstruction point can be seen.
# An air-fluid level of the nasal secretions above the obstruction point can be seen.
# Membranous atresias: Soft-tissue densities will be seen in the posterior choanae, and narrowing of the posterior choanae just anterior to the pterygoid plates.  
# Membranous atresias: Soft-tissue densities will be seen in the posterior choanae, and noticed narrowing of the posterior choanae just anterior to the pterygoid plates.  
# Bony atresia: the thickness of the atretic plate should be taken for surgical planning.
# Bony atresia: The thickness of the atretic plate should be taken for surgical repair planning.
*''Disadvantages:'' The main disadvantages of using CT in pediatric populations are  
[[Image:CT bilateral bony.jpg|right|thumb|250px|CT scan demonstrating bilateral osseous choanal atresia]]
# High radiation exposure dose: due to an inadequate positioning of some patients in such an age group while achieving a scanning angle and imaging place necessitates the repetition of the scan, and hence, resulting in a subsequent increase in the radiation dose.   
*'''Disadvantages:''' The main disadvantages of using CT in pediatric populations are:
# Sedation: Need for sedation to avoid movement artifacts, which render the examination of fine details less reliable. Using contrast material in the nose will help to overcome that.  
#''High radiation exposure dose:'' Due to an inadequate positioning of infants in such an age group while achieving a scanning angle and imaging plane necessitates the repetition of the scan; and hence, subsequently results in an increased exposure of the radiation dose.   
# Child’s lens: The angle of the imaging plane might increases the risk to it.
# Sedation: Need for sedation to avoid movement artifacts which render the examination of fine details less reliable. However, the contrast material used in the nose will help to overcome it.  
#''Child’s lens:'' The angle of the imaging plane might enhances the risk to it.


==Treatment==
==Treatment==


*The patient should ideally be managed in a neonatal or paediatric intensive care unit with a combination of supportive, medical and surgical care. However, the treatment is essentially surgical which can be divided into emergent and elective definitive categories.
*The patient should ideally be managed in a neonatal or paediatric intensive care unit with a combined supportive, medical and surgical care. However, the treatment is essentially surgical which can be divided into emergent and elective definitive categories.
===Objectives===
===Objectives===
# To restore choanal patency,  
# To restore choanal patency,  
# Not to interfere with the patient normal craniofacial development,  
# Avoid damaging interference to the surrounding normal craniofacial structures,  
# To minimize invasiveness, and
# To minimize invasiveness and postoperative complications,
# To avoid recurrences.
# To avoid recurrences.
===Systematic treatment approach===
===Systematic treatment approach===
# Establish oral airway immediately to ensure breathing
# Establish an immediate oral airway to ensure breathing
# Membranous atresia may be perforated upon passage of nasogastric tube
# Membranous atresia may be perforated upon passage of nasogastric tube
# Surgical repair for alleviating respiratory symptoms and feeding difficulties
# Surgical CA repair for alleviating respiratory symptoms and feeding difficulties
# Postoperative scar, complications, & incomplete resection of atresia plate evaluation with bone CT
# Postoperative scars, complications, & incomplete resection of atresia plate evaluation with bone CT scans
 
===Severity assessment===  
===Severity assessment===  
*The severity of the anomaly is assessed by evaluating its laterality (unilateral or bilateral), the degree of obstruction affecting the child's breathing and feeding, and its associations with other anomalies; the treatment can be further divided into mild and severe cases.
*Assessment is done by evaluating its laterality (unilateral or bilateral), the degree of obstruction affecting the child's breathing and feeding, and its associations with other anomalies; hence, the treatment can be further divided into mild and severe cases.<ref>{{cite web |url=https://www.chop.edu/conditions-diseases/choanal-atresia# |title=Choanal Atresia &#124; Children's Hospital of Philadelphia |format= |work= |accessdate=}}</ref>
*Treatment for mild cases: In mild cases where there is no significant respiratory distress or feeding difficulty treatment could include the following:
*''Treatment for mild cases:'' In the mild cases with no significant respiratory distress or feeding difficulty; treatment includes the following:
** The condition may be managed by keeping the baby under close observation and providing him with supplemental oxygen periodically.
**The neonate should be kept under close observation and provided with supplemental oxygen periodically.
**To keep the nasal passages clear of discharge and prevent any further impediments to nasal breathing, nasal saline may be administered to keep the nasal linings healthy.
**The nasal passages should be maintained by administering the nasal saline to keep the nasal linings healthy by clearing the discharge and preventing any further impediments to nasal breathing.
**Parents can opt to delay surgical correction of the nasal structure until the child is older as the anatomy of the region is more similar to that in adults.
**Parents can opt to delay surgical correction of the nasal structure until the child is older to develop the regional anatomy more similar to that of the adults.
**In some of the unilateral cases, it is ideal to delay surgical treatment until the infant is at least 6 months old, when the operative field is larger and the opportunity for control during surgery is better.
**In some of the unilateral cases, the surgical treatment can be delayed until the infant is at least 6 months old and weigh more than 2kgs as it allows better operative field and opportunity for control during surgery.
**When properly identified, unilateral atresia is ideally fixed before 5 years of age in order to avoid persistent unilateral nasal drainage, which can be socially and medically problematic.
**However, it should be ideally fixed before 5 years of age in order to avoid persistent unilateral nasal drainage which can be socially and medically problematic.
*Treatment for severe cases: In severe cases where there is a life threatening risk, usually because of bilateral choanal atresia, there is no room for delays in treatment.  
*''Treatment for severe cases:'' In severe cases carrying life threatening risk usually because of bilateral CA, the delay in treatment should be avoided.  
**Surgery should be performed as soon as the patient is stable and has been evaluated for other anomalies.  
**Surgery should be performed as soon as the patient is stable and has completed evaluation for other anomalies.  
**There are different surgical approaches to dealing with choanal atresia and all of which are performed in an operating theatre under general anesthesia.
**Different surgical approaches are available and selected on case to case basis.  
*To sum up, whether or not surgery is performed, if your infant suffers from choanal atresia, periodic evaluation is necessary to ensure normal functioning of the airways and to rule out the presence of any feeding issues. Feeding and swallowing issues may be persistent and it is advisable to seek specialized care from speech pathologists and gastrointestinal specialists. If the child suffers from a syndrome like CHARGE or has other congenital birth defects, it would be best to get subspecialty evaluations and coordinated care.
*To sum up, whether or not surgery is performed, if an infant suffers from CA, a periodic evaluation is necessary to ensure normal upper airway breathing and feeding habits in both preoperative and postoperative period.
===Airway Management===  
 
*It is the initial goal of treatment for infants with bilateral CA to maintain an adequate airway by inserting an oral airway to break the seal formed by the tongue against the palate to tide over an immediate crisis.  
===Airway Management <ref name="Holzman2011">{{cite journal|last1=Holzman|first1=Robert S.|title=Airway Management|year=2011|pages=344–364|doi=10.1016/B978-0-323-06612-9.00012-2}}</ref> <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}} </ref>===  
*An oral airway is generally adequate to temporarily secure an airway for several weeks in a newborn with bilateral choanal atresia and respiratory distress.   
*It is an initial goal of treatment especially for infants with bilateral CA by inserting an oral airway to break the seal formed by the tongue against the palate to have a tide over an immediate crisis.  
*It is important to realize that even bilateral choanal atresia is not always a surgical emergency (despite the presence of an innate reflex for nasal breathing), because it is possible to establish and maintain a patent airway with the use of a McGovern nipple or a cannula of Guedel or a standard feeding bottle teat or dummy with the tip cut off (Figure 9) to facilitate oral breathing.
*An oral airway provides a temporary secure of several weeks in a newborn with bilateral CA and severe respiratory distress.   
*The preferred oral airway is McGovern nipple, an intraoral nipple with a large opening by cutting its end off, secured in the mouth with ties around the infant’s occiput. A small feeding tube can be placed through another hole in the nipple or alongside the nipple to provide feeding needs. This helps to buy time till the child has gained adequate weight to withstand corrective surgery.
*Surgery can be delayed for bilateral CA due to the presence of an innate reflex for nasal breathing and possibility of establishing and maintaining a patent airway with the use of a McGovern nipple or a cannula of Guedel or a standard feeding bottle teat or dummy with the tip cut off to facilitate oral breathing.
*In the short-term this has the effect of stenting the oral cavity open to allow mouth breathing; however it is not a long-term solution.  
*The preferred oral airway is '''McGovern nipple''', an intraoral nipple with a large opening by cutting its end off, which is placed in the mouth and tied around the infant’s occiput. A small feeding tube can be placed through another hole in the nipple or alongside the nipple to provide feeding needs. This helps the child to gain adequate weight for withstanding corrective surgical procedures.<ref>McGovern F, Fitz-Hugh GS (1961) Surgical management of congenital choanal atresia. Arch Otolaryngol 73:627-643</ref>
*If a patient still fails to maintain an adequate airway, endotracheal intubation must be performed as the initial management.
*It provides the short-term benefits by the effect of stenting the oral cavity to open and allow mouth breathing; however it is not a permanent treatment.  
*A tracheostomy may be required in patients with severe comorbidities but it is not necessary in cases of isolated (even bilateral) CA.  
*If a patient still fails to maintain an adequate airway on it, an endotracheal intubation must be performed as the initial management.
*A tracheostomy may be required in patients with severe comorbidities, but it is not necessary in cases of isolated or even bilateral CA.
 
===Role of tracheostomy===
===Role of tracheostomy===
*This should be considered only on rarest of rare occasions when the patient is not able to adequately maintain oral airway.
*''Indications:
*Tracheostomy may be required if the definitive surgical treatment needs to be deferred due to patient’s other comorbidities such as cardiopulmonary instability and multi-level airway obstruction.  
** Fail to adequately maintain an oral airway.
*Patients with bilateral CA and CHARGE syndrome are more likely to fail atresia repair because of the following reasons:  
** To defer the definitive surgical treatment in patients with other comorbidities such as cardiopulmonary instability and multi-level airway obstruction.  
*Patients with bilateral CA and CHARGE syndrome are more likely to fail atresia repair because of the following reasons:<ref name="ConiglioManzione2016">{{cite journal|last1=Coniglio|first1=John U.|last2=Manzione|first2=James V.|last3=Hengerer|first3=Arthur S.|title=Anatomic Findings and Management of Choanal Atresia and the Charge Association|journal=Annals of Otology, Rhinology & Laryngology|volume=97|issue=5|year=2016|pages=448–453|issn=0003-4894|doi=10.1177/000348948809700503}}</ref>
# More contracted nasopharynx in a lateral and/or vertical dimension,  
# More contracted nasopharynx in a lateral and/or vertical dimension,  
# Narrower posterior choanal region than those with isolated CA and  
# Narrower posterior choanal region than those with isolated CA, and  
# Poor tongue/pharyngeal muscle control.
# Poor tongue/pharyngeal muscle control.
*Moreover, Asher et al. in their retrospective review of patients with CHARGE syndrome demonstrated that early repair of their CA was rarely successful as patients had a propensity for airway instability which leads to hypoxic events.  
*Moreover, Asher et al. in their retrospective review of patients with CHARGE syndrome suggested that an early repair of their CA was rarely successful as patients had a propensity for airway instability during the operative time predisposing them to hypoxic events. <ref name="AsherMcGill1990">{{cite journal|last1=Asher|first1=B. F.|last2=McGill|first2=T. J. I.|last3=Kaplan|first3=L.|last4=Friedman|first4=E. M.|last5=Healy|first5=G. B.|title=Airway Complications in CHARGE Association|journal=Archives of Otolaryngology - Head and Neck Surgery|volume=116|issue=5|year=1990|pages=594–595|issn=0886-4470|doi=10.1001/archotol.1990.01870050094014}}</ref>
*Therefore, recommended early tracheotomy rather than early CA repair to secure the airway for CA patients with CHARGE syndrome.
*Therefore, recommended early tracheotomy rather than early CA repair to secure the airway for CA patients with CHARGE syndrome.
===Feeding Issues===
 
===Feeding Issues <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be-586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref>===
* Do not feed in the cases where there is high index of suspicion for CA.  
* Do not feed in the cases where there is high index of suspicion for CA.  
* A feeding tube is required due to the increased risk of aspiration which should be established via orogastric tube until surgical correction of the atresia is performed.
* A feeding orogastric tube is required until surgical correction of the atresia is performed due to higher risk for aspiration.
 
===Timing of Surgery===
===Timing of Surgery===
*The exact timing of surgery is variable and decided upon studying the entire situation.
*The exact timing of surgery is variable and decided upon studying the entire case scenario.
*If the infant learns to breathe orally, surgery may not be required as urgently and can be delayed for a while.  
*If the infant learns to breathe orally, surgery can be delayed for a while.  
*Urgent surgery required in following cases:
*Urgent surgery required in following cases: <ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be 586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref>
# Bilateral CA;
# Bilateral CA;
# Symptomatic unilateral CA;  
# Symptomatic unilateral CA;  
# Syndromic babies with respiratory complications from unilateral atresia.
# Syndromic babies with respiratory complications from unilateral atresia.
*Delayed surgery till the child reaches its first birthday in asymptomatic unilateral atresia because  
*Delay surgery till the child reaches its first birthday in asymptomatic unilateral atresia because of the following:<ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
# This allows the surgery site to enlarge thereby reducing the risk Of post op stenosis.
# This allows the surgery site to enlarge thereby reducing the risk of post operative restenosis.
# Bleeding is also reduced if surgery is delayed.
# Blood loss is reduced.
# Older infants tolerate stenting better than young ones.
# Older infants tolerate stenting better than young ones.
# The younger the patient, the higher the risk of intraoperative and postoperative complications and re-stenosis.
# The younger the patient, the higher the risk of intraoperative and postoperative complications and re-stenosis.
===Use of Anaesthesia===
 
*The anesthetic approach depends on the child's condition. In general, intravenous induction with a muscle relaxant of intermediate duration, endotracheal intubation with an oral Right Angle Endotracheal (RAE) tube, and maintenance with an inhaled agent and opioid or propofol and remifentanil infusion suffice.
===Use of Anaesthesia <ref name="LandsmanWerkhaven2011">{{cite journal|last1=Landsman|first1=Ira S.|last2=Werkhaven|first2=Jay A.|last3=Motoyama|first3=Etsuro K.|title=Anesthesia for Pediatric Otorhinolaryngologic Surgery|year=2011|pages=786–820|doi=10.1016/B978-0-323-06612-9.00024-9}}</ref>===
*The anesthetic approach depends on the child's condition. In general, intravenous induction with a muscle relaxant of intermediate duration, endotracheal intubation with an oral Right Angle Endotracheal (RAE) tube, and maintenance with an inhaled agent and opioid or propofol and remifentanil infusion preferred.
 
===Surgical Approaches===
===Surgical Approaches===
*Since Emmert's initial trocar perforation in 1853, the five different surgical approaches to correct choanal atresia have been described which includes the following:
*Since Emmert's initial trocar perforation in 1854, the five different surgical approaches to correct CA have been described which includes the following:
# Transnasal,  
# Transnasal,  
# Transpalatal,  
# Transpalatal,  
Line 599: Line 614:
# Transantral and
# Transantral and
# External rhinoplasty.
# External rhinoplasty.
*As per the research done in March 1999 by ASPO (American Society of Pediatric Otolaryngology), the most used techniques in descending order are:
*As per the research done in March 1999 by American Society of Pediatric Otolaryngology (ASPO), the most used techniques in descending order are:<ref>Chung D, Lessa MM, Lorenzetti FT, Goto EY, Voegels RL, Butugan O. Atresia congenital bilateral de coanas em paciente de 13 anos: relato de caso. Rev Bras Otorrinolaringol. 2001, 67(4):586-90 </ref>
# Transnasla with endoscope use,   
# Transnasal with endoscope use,   
# Transpalatal, perforation with Fearon dilator,   
# Transpalatal perforation with Fearon dilator,   
# Transnasal with microscope use   
# Transnasal with microscope use,  
# Transnasal with laser use  
# Transnasal with laser use  
*The transasal technique is slightly better than the transpalatal technique.
*The transasal technique is considered better than the transpalatal approach.
===Transpalatal approach===
 
*The transpalatal approach was the most frequently used until the advent of the endoscopic endonasal approach.  
===Transpalatal approach <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref>===
*In rare circumstances where the skull base is abnormally developed, the atresia is thick or other craniofacial anomalies are present, the surgeon may need to use a transpalatal approach to reach the area of choanal atresia through the roof of the mouth.
*This approach was the most frequently used to reach the area of CA through the roof of the mouth until the advent of the endoscopic endonasal approach.  
*''Operating procedure:'' This procedure is performed under general anaesthesia and considered more suitable for bilateral choanal atresia. A Dingman-Denhardt mouth gag with the infant tongue blade is used. The palate is injected with 0.5% lidocaine with 1:200,000 epinephrine in the area of the mucosal incision which serves the dual purpose of helping in flap elevation and providing much needed hemostasis during the entire surgical procedure. A Owens type (U-shaped) mucosal incision is made beginning just behind the maxillary tuberosity on one side and then continued medial to the alveolar ridge up to the canine region and then angled back to the nasopalatine foramen. A likewise incision is made on the opposite side and the mucosal flap is elevated taking care not to damage the greater palatine arteries. Mucosa of the nose and nasopharynx is elevated up to the edge of the hard palate and preserved. The soft palate is now retracted posteriorly and superiorly exposing the posterior edge of hard palate. This area is the area for dissection. Then the palatine bones posterior to the greater palatine foramina, the atresia plates and the posterior vomer are carefully drilled away using a kerrison’s punch or drill. Two 14 or 16 French catheters are passed simultaneously into each nostril to check the patency of the newly created choanea. The preserved mucosa is then used to cover the superior and inferior surfaces of the newly formed choanea and then sutured in place to cover the bone. Stents are left in place for 4 weeks.  
*Indications:
# Abnormally developed skull base;
# Thick atresia plate;
# Associated craniofacial anomalies; and/or
# Bilateral CA
*''Operating procedure:'' This procedure is conducted in a full sedation with the use of a general anaesthesia. A Dingman-Denhardt mouth gag with the infant tongue blade is used. The palate is injected with 0.5% lidocaine and 1:200,000 epinephrine in the area of the mucosal incision to serves the dual purpose of flap elevation and required hemostasis during the entire surgical procedure. A Owens type (U-shaped) mucosal incision starts from just behind the maxillary tuberosity on one side and then continued medial to the alveolar ridge up to the canine region and further angled back to the nasopalatine foramen. A likewise incision is made on the opposite side; and the mucosal flap is elevated with efforts to avoid any damage to the greater palatine arteries. Nasopharynx and nasal mucosa is elevated up to the edge of the hard palate and preserved. The soft palate is now retracted posteriorly and superiorly to expose the posterior edge of hard palate which is the area for dissection and surgical repair. Then, the palatine bones posterior to the greater palatine foramina, the atresia plates, and the posterior vomer are carefully drilled away using a kerrison’s punch or drill. Two 14 or 16 French catheters are passed simultaneously into each nostril to check the patency of the newly created choanae. The preserved mucosa is then used to cover the superior and inferior surfaces of the newly formed choanea and then sutured in place to cover the bone. Stents are usually left in-situ for 4 weeks. <ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
*''Advantages:''
*''Advantages:''
# Better visualisation and exposure
# Better field of visualisation and exposure
# Both hands are free
# Both hands are free
# Less stenting period (a portex endotracheal tube can be cut and used as a stent)
# Shortened stenting duration (a portex endotracheal tube can be cut and used as a stent)
# Less failure rate
# Reduced failure rate
*''Disadvantages:''
*''Disadvantages:''
# The incisions, which are identical to those for a cleft palate repair, may have a banding effect on maxillary growth due to scar formation. (Therefore, most surgeons prefer to wait to use this approach until some teeth are in occlusion - at approx.12-18 months).  
# The incisions made are similar to those for a cleft palate repair and can have a banding effect on maxillary growth due to scar formation. Hence, most surgeons prefer to wait for some teeth to appear in occlusion to use this approach at approximately 12-18 months of age.  
# Palatal growth can be stunted in 50 % of individuals
# Stunted palatal growth seen in 50 % of operated patients
# Increased blood loss due to a higher risk of injury to the greater palatine artery  
# An injury to the greater palatine artery can result in an increased blood loss
# Increased risk of development of palatal fistulas post operatively
# Postoperative complications: restenosis of the choanae, palatal fistulas, flap necrosis, bleeding, fistulas, infections, defective growths of the jaw and the palate bone, and orthodontic problems such as cross bite. <ref>Stieve M,Kempf HG,Lenarz T. Management of choanal atresia in cases of craniofacial malformation. J Maxillofac Oral Surg (2009) 8(1):52–4. doi:10.1007/s12663-009-0013-z</ref>
# Other post op complications include restenosis of the choanae, palatal fistulas, flap necrosis, bleeding, fistulas, infections and growth defects of the jaw and the palate bone and orthodontic problems, like cross bite.  
*''Postop Care:''
*''Care of the post op patient:''
# The parents must be taught to maintain the patency of stents by frequent suctioning and a saline-moistened pipe cleaner or cotton applicator 3 to 6 times a day.  
# The parents must be taught to maintain the stents with frequent suction and a saline-moistened pipe cleaner or cotton applicator 3 to 6 times per day.  
# Antibiotics and decongestants are prescribed in suspicion of rhinitis  
# Antibiotics and decongestants are prescribed if there is evidence of rhinitis  
# Regular follow up should be advised until the stents are removed.
# Patients must be followed up regularly till the stents are removed.


===Transseptal approach===
===Transseptal approach<ref>Hall WJ, Watanabe T, Kenan PD, Baylin G. Trans-septal repair of unilateral choanal atresia. Arch Otolaryngol. 1982;108:659---61.</ref>===
*The transseptal approach is effective but is used very little because of the resultant impairment of facial growth. However, it is considered effective in patients older than 8 years with unilateral CA and impractical in infants.  
*It is effective but rarely used due to the resultant impairment of facial growth in infants. However, it is considered effective in patients older than 8 years diagnosed later with unilateral CA.  
*An important technical point is the need to remove the posterior portion of the vomer.  
*An operative key point is the need to remove the posterior portion of the vomer.  
*It permits better correction of any deviations of the septum, resection of the posterior part of the vomer and preservation of mucosal flaps for coverage of the bleeding area.12
*It permits better correction of any septal deviations, resection of the posterior part of the vomer, and preservation of mucosal flaps for coverage of the bleeding area.
*Complications of transeptal approach:
*Complications of transeptal approach:<ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
# Pressure necrosis of columella
# Pressure necrosis of columella
# Plugging of stent
# Plugging of stent
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# Granulation tissue formation around the stents.
# Granulation tissue formation around the stents.


===Sublabial approach===
===Sublabial approach<ref>Koltai PJ (1994) The surgical management of choanal atresia. Operative Tech Otolaryngol Head Neck Surg 5:5-11</ref>===
*The sub labial, trans-septal access has advantages and disadvantages similar to those of the trans-septal approach, and it further reduces the likelihood of postoperative granulation tissue formation and stenosis by avoiding surgical trauma to nasal mucosa.
*The sub labial, trans-septal access has advantages and disadvantages similarities to the trans-septal approach, and it further reduces the likelihood of postoperative granulation tissue formation and restenosis by avoiding surgical trauma to nasal mucosa.


===Transantral approach===
===Transantral approach<ref>Kamel R. Transnasal endoscopic approach in congenital choanal atresia. Laryngoscope. 1994;104:642---6.</ref>===
*Transantral access is the least-used approach, because it requires a well-developed maxillary sinus that is not present in infants and many older children and adults with choanal atresia. However, it permits an adequate exposure of the surgical field, allowing a quick check for any bleeding source, and reduced risk of damaging the sphenopalatine arteries, veins and nerves, but can significantly increase the risk of deformities of growing structures such as the maxilla and upper teeth.
*Transantral access is the least-used approach because it requires a well-developed maxillary sinus which is not found in infants, many older children, and even adults with CA. However, it permits an adequate exposure of the surgical field, allowing a quick check for any bleeding source, and reduces the risk of damaging the sphenopalatine arteries, veins and nerves; but can significantly increase the risk of deformities of growing structures such as the maxilla and upper teeth.


===Transnasal approach===
===Transnasal approach <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref> <ref name= "nasal">Stamm A.C., Mekhitarian L., Pignatari S.S.N. (2000) Choanal Atresia: Transnasal Micro-endoscopic Surgery. In: Stamm A.C., Draf W. (eds) Micro-endoscopic Surgery of the Paranasal Sinuses and the Skull Base. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-57153-4_33</ref>===
*The growing experience in both instrumentation and technique in endoscopic sinus surgery have led many CHOP surgeons to make more frequent use of the endoscopic endonasal technique for the repair of choanal atresia due to the modern refinements of endoscopic techniques as it does not affect the growth of the mandibular arch, causes no malocclusions or cosmetic alterations to the face.
*The growing experiences and modern refinements in both instrumentation and techniques in endoscopic sinus surgery have encouraged many CHOP surgeons to prefer the use of the endoscopic endonasal technique for the CA repair as it does not affect the growth of the mandibular arch, causes no malocclusions or cosmetic alterations to the face.
*For stable infants with choanal atresia, the endoscopic endonasal technique should be considered the first choice for the surgical treatment of choanal atresia as it offers a direct approach to the atretic plate, reduces intraoperative bleeding, reduces hospitalization time, lowers morbidity, faster post-operative recovery, and can be done safely on infants just a few days old. If the bony atretic plate is less than 3 mm in thickness, a transnasal approach is the most commonly recommended for membranous atresia or where bony plate is thin. The simplest procedure is perforation of the atretic lamina followed by dilatation.
*For stable infants with CA, the endoscopic endonasal technique should be considered the first choice for the surgical treatment for membranous atresia or where bony plate is thin which involves the perforation of the atretic lamina followed by dilatation and full choanal reconstruction.
*Definitive surgical correction by nasal endoscopic approach is performed when appropriate and when feasible (weight >2kg). Given the relatively low morbidity of unilateral CA, definitive treatment is delayed until a later age (>18 months of age), when possible, as the chance of successful surgical repair increases with age.  
*Operating procedure using endoscopes:<ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
*Options include:
**The surgery is performed under general anesthesia using a combination of tiny scope, dilators, sinus instruments, ear curettes and drills. A self retaining nasal speculum is used to expose the nasal cavity and the atretic plate with minimal trauma to the nasal vestibule. For the membranous atresia, a simple perforation of the same under endoscopic guidance would suffice. The nasal cavity is decongested using 4% xylocaine with adrenaline in the concentration of 1 in 10,000 concentration. A endoscope is used transnasally with a simultaneous view of the nasopharynx through a transoral 120° endoscope. It is important to use both the transnasal and transoral views in order to avoid potentially entering the anterior skull base. Under endoscopic guidance, a mucosal incision is made and the mucosal flaps are elevated exposing the posterior vomer and lateral pterygoid lamina. A diamond burr on an angled hand piece is used to drill the atretic bony plate. It is perforated at the junction of the hard palate and the vomer. Incidentally, this is the thinnest part of the atretic plate. To improve visualization, the inferior turbinate can be out fractured or even be trimmed. After drilling, care is taken to preserve the mucosal flaps. A silastic stent is placed into each nostril passing through the drilled neo-choanae. This helps in reducing the incidence of restenosis and crusting at the site of the bony atresia. Stent is kept in place for atleast 6 weeks. Opening made should be large enough to allow smooth passage of suction catheter. 3-4 size Endotracheal tube can be used as stent to prevent restenosis and maintain patency while the area heals. The size of ET tubes should be choosen carefully to prevent restensosis and nasal regurgitation. However, a recent meta-analysis found similar success rates for bilateral CA repair regardless of whether stents were used; and hence, stenting is not required in all the cases. Thus, these stents will be removed at the bedside or during an office visit in weeks to months after demonstrating the child for an airway stability and feeding evaluation.<ref name= "stent">Strychowsky JE, Kawai K, Moritz E, et al. To stent or not to stent? A meta-analysis of endonasal congenital bilateral choanal atresia repair. Laryngoscope 2016; 126(1):218–27.</ref>
**Endoscopic perforation for membranous types
*Caution: While performing this procedure, caution must be taken not to injure the sphenopalatine vessels behind the middle turbinate.
**Full choanal reconstruction
*Advantages:<ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
*Operating procedure using endoscopes: The surgery is performed under general anesthesia. The posterior nasal airway is opened using a combination of tiny scope, dilators, sinus instruments, ear curettes and drills. A self retaining nasal speculum is used to expose the nasal cavity and the atretic plate without causing trauma to the nasal vestibule. If the atresia is membranous in nature a simple perforation of the same under endoscopic guidance would suffice. The nasal cavity is decongested using 4% xylocaine with adrenaline in the concentration of 1 in 10,000 concentration. A 0_ endoscope is used transnasally with a simultaneous view of the nasopharynx through a transoral 120_ endoscope. It is important to use both the transnasal and transoral views in order to avoid potentially entering the anterior skull base. Under endoscopic guidance a mucosal incision is made and the mucosal flaps are elevated exposing the posterior vomer and lateral pterygoid lamina. A diamond burr on an angled hand piece is used to drill the atretic bony plate. It is perforated at the junction of the hard palate and the vomer. Incidentally this is the thinnest part of the atretic plate. To improve visualisation the inferior turbinate can be out fractured or even be trimmed. After drilling, care is taken to preserve the mucosal flaps. A silastic stent is placed into each nostril passing through the drilled neo choana. This helps in reducing the incidence of restenosis and crusting at the site of the bony atresia. Stent is kept in place for atleast 6 weeks. Opening made should be large enough to allow smooth passage of suction catheter. 3-4 size Endotracheal tube can be used as stent to prevent restenosis and maintain patency while the area heals. The size should be choosen carefully in such a way that it should be adequate to prevent restensosis and inadequate to cause nasal regurgitation. Sometimes stenting is not required as a recent meta-analysis found similar success rates for bilateral choanal atresia repair regardless of whether stents were used.7. These stents will be removed at the bedside or during an office visit in weeks to months, after the child demonstrates airway stability and feeding evaluation.
# This process is faster and easier as it offers a direct approach to the atretic plate;
*Caution: While performing this procedure caution must be taken not to injure the sphenopalatine vessels behind the middle turbinate.
# Reduces intraoperative bleeding;
*Advantages:
# Can be performed in children of all ages who do not have associated external nasal deformities;
# This process is faster and easier
# faster post-operative recovery, reduces hospitalization time, and lowers morbidity;
# Blood loss is minimal
# Child can be immediately breast fed;
# Can be performed in children of all ages who do not have associated external nasal deformities
# Child can be discharged on the postop 3rd day
# Child can be immediately breast fed
*Disadvantages:<ref name= "literature">Thiagarajan B, Kothandaraman S. Choanal Atresia a Literature Review. WebmedCentral OTORHINOLARYNGOLOGY 2012;3(11):WMC003804 doi: 10.9754/journal.wmc.2012.003804</ref>
# Child can be discharged on the 3rd day itself
*Disadvantages:
# Vision is highly limited especially in the new born
# Vision is highly limited especially in the new born
# Inability to adequately remove enough of the posterior vomerine septal bone and prevent restenosis
# Inability to adequately remove enough of the posterior vomerine septal bone and prevent restenosis
# Longer stenting time
# Longer stenting time
# Endoscopes do not offer binocular vision
# Endoscopes do not offer binocular vision
# Can not be done safely and with good results on patients with multiple nasal and nasopharyngeal anomalies.
# Can not be done safely with good results on patients with multiple nasal and nasopharyngeal anomalies.


===Rhinoplasty===
===Rhinoplasty<ref>Koltai PJ (1991) The external rhinoplasty for the correction of unilateral choanal atresia in young children. Ear Nose Throat J 70:450-453</ref>===
*Correction of CA using an external rhinoplasty approach is usually restricted to unilateral cases when the child is 1 year of age or older. The medial crura are separated, and the cartilaginous edge of the nasal septum is exposed. The mucoperichondrium and the mucoperiosteum are elevated to the region of the atresia. The atresia plate is then removed, and the posterior portion of the vomer is resected.
*Correction of CA using an external rhinoplasty approach is usually restricted to unilateral cases when the child is 1 year of age or older. The medial crura are separated, and the cartilaginous edge of the nasal septum is exposed. The mucoperichondrium and the mucoperiosteum are elevated to the region of the atresia. The atresia plate is then removed, and the posterior portion of the vomer is resected.


===Stenting===
===Stenting <ref name="Kwong2015">{{cite journal|last1=Kwong|first1=Kelvin M.|title=Current Updates on Choanal Atresia|journal=Frontiers in Pediatrics|volume=3|year=2015|issn=2296-2360|doi=10.3389/fped.2015.00052}}</ref> <ref name= "stent">Strychowsky JE, Kawai K, Moritz E, et al. To stent or not to stent? A meta-analysis of endonasal congenital bilateral choanal atresia repair. Laryngoscope 2016; 126(1):218–27.</ref>===
===Mitomycin-C===
[[Image:CA stenting 2.jpg|right|thumb|200px|Retropalatal view of bilateral stents in position in the posterior choanae|Source: www.entdev.uct.ac.za]]
===Alternative techniques===
*The effectiveness of using stents after CA repair is a controversial topic with some of the major complications originating following its use.
===Postoperative monitoring===
# Formation of granulation tissue
===Surgical Complications===
# Crust formation
===Success Rate===
# Septal perforation
# Persistent nasal discharge
# Foreign body tissue reaction
# Nasal alar erosion
# Columellar pressure necrosis
 
===Mitomycin-C<ref>Bozkurt MK, Keles B, Azimov A, Ozturk K, Arbag H. The use of adjunctive topical mitomycin in endoscopic congenital choanal atresia repair. Int J Pediatr Otorhinolaryngol. 2010;4:733---6.</ref>===
*It is an aminoglycoside which inhibit fibroblast growth and migration; and it's topical application was proposed to reduce restenosis risk after surgery and improve the healing process as it has not caused any systemic adverse effects and anesthetic complications. However, its use is still controversial.
 
===Postoperative monitoring <ref name="LandsmanWerkhaven2011">{{cite journal|last1=Landsman|first1=Ira S.|last2=Werkhaven|first2=Jay A.|last3=Motoyama|first3=Etsuro K.|title=Anesthesia for Pediatric Otorhinolaryngologic Surgery|year=2011|pages=786–820|doi=10.1016/B978-0-323-06612-9.00024-9}}</ref>===
*After CA is surgically corrected, the surgeon is often faced with the problem of restenosis; however, recent innovations have reduced its rate. 
*Newer endoscopic techniques with powered instrumentation along with the use of stenting and mitomycin-c have enhanced the safety and efficacy for CA repair.
*The postoperative period is generally well for patients with unilateral obstruction and require no special monitoring. However, infants undergoing bilateral repair can exhibit partial or intermittent upper airway obstruction that persists for some time and thus, the infant should be observed closely in the ICU with appropriate monitoring until breathing dynamics have normalized.
 
===Surgical Complications<ref name= "nasal">Stamm A.C., Mekhitarian L., Pignatari S.S.N. (2000) Choanal Atresia: Transnasal Micro-endoscopic Surgery. In: Stamm A.C., Draf W. (eds) Micro-endoscopic Surgery of the Paranasal Sinuses and the Skull Base. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-57153-4_33</ref>===
*Factors resulting in the failure of microendoscopic surgery for the CA treatment are as follows:
# Surgery performed too early,
# Inadequate area of surgery exposure due to association with other malformations,
# Inappropriate surgical technique with insufficient removal of the atresial plate and the posterior nasal septum, and
# Inadequate postoperative care.
 
===Success Rate <ref name="tips">Teissier N, Kaguelidou F, Couloigner V, Francois M, VanDenAbbeele T. Predictive factors for success after transnasal endoscopic treatment of choanal atresia. Arch Otolaryngol Head Neck Surg (2008) 134(1):57–61. doi:10.1001/archoto.2007.20</ref>===
*Successful CA surgical outcomes are influenced by the presence/absence of following factors:
# Nasopharyngeal reflux,
# GERD,
# Age <10 days associated with limited visualization of the nasal area and limited resection of the vomer,
# Bilateral CA with purely bony atretic plate, and
# Associated syndromic malformations.
 
===Prevention===
===Prevention===
*Currently, there are no known methods or guidance reported for the prevention of Choanal Atresia. However, pregnant women should consider the general health measures that may minimise the risk factors for the condition as described in the "Risk Factors" section.
*Currently, there are no known methods or guidance reported for the prevention of CA. However, maternal mothers should consider the general health measures for minimizing the risk factors for the condition as listed in the "Risk Factors" section. <ref name= "medline">{{cite web |url=https://medlineplus.gov/ency/article/001642.htm#:~:text=The%20cause%20of%20choanal%20atresia,twice%20as%20often%20as%20males |title=Choanal atresia: MedlinePlus Medical Encyclopedia |format= |work= |accessdate=}}</ref>


===Tips to remember===
===Tips to remember <ref name="tips">Teissier N, Kaguelidou F, Couloigner V, Francois M, VanDenAbbeele T. Predictive factors for success after transnasal endoscopic treatment of choanal atresia. Arch Otolaryngol Head Neck Surg (2008) 134(1):57–61. doi:10.1001/archoto.2007.20</ref>===
*Regardless of surgical approach, the key to a successful outcome is to create a large 3-dimensional opening by a combination of following:
# Puncturing the membranous obstruction,
# Widening the medial bony thickening of the medial pterygoid plate, and
# Thinning the thickened vomer
*Postoperative considerations:<ref name= "open">{{cite web |url=https://vula.uct.ac.za/access/content/group/ba5fb1bd-be95-48e5-81be 586fbaeba29d/Surgical%20correction%20of%20choanal%20atresia.pdf |title=vula.uct.ac.za |format= |work= |accessdate= | source=www.entdev.uct.ac.za}}</ref>
# After successful CA surgery, the child should be extubated and managed in a general paediatric ward with regular nasal suctioning
# Start oral feeding as early as possible
# Postoperative nasal decongestant drops (0.5% xylometazalone) should be advised for a week
# Saline and steroid drops should be used for 2 weeks to reduce postoperative inflammation and granulations


==See also==
==See also==
Line 684: Line 738:


==References==
==References==
<references/>
{{Reflist|2}}





Latest revision as of 16:37, 9 October 2020

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Jaspinder Kaur, MBBS[2]

Synonyms and keywords: Atresia, Choanal; Atresias, Choanal; Choanal Atresias; Bosma arhinia microphthalmia syndrome; Bosma Henkin Christiansen syndrome; Congenital absence of nose and anterior nasopharynx

Overview

The word “Choana” is derivative of a greek word “Xovan” which states the funnel and hence, the term “Posterior Choana” is known as posterior nasal aperture or posterior funnel. Choanal atresia (CA) is the most common form of congenital nasal airway abnormality presenting with variable clinical features ranging from acute airway obstruction to chronic recurrent sinusitis depending upon the degree of obstruction. It is caused by the abnormal rupturing of the buccopharyngeal or nasobuccal membrane which results in the failed recanalization of the nasal fossae during the embryological period and hence, occluding the posterior nasal cavity from communicating with the nasopharynx. CA presents with severe respiratory distress, feeding difficulties, and failure to thrive when the obstruction is bilateral or total; and chronic persistent nasal discharge in partial or unilateral cases. Establishing a secure airway is an acute otolaryngological emergency because newborns are obligate nasal breathers and experiences the paradoxical cyanosis episodes while feeding. The diagnosis requires a high index of suspicion which is done by an introduction of a six or eight Fr suction catheter via the nostrils, methylene blue dye test, cotton wisp test, and laryngeal mirror test. The obstruction may be further visualized with a narrow flexible nasopharyngoscope after the nasal cavity has been suctioned of mucosal secretions and the nasal mucosa is constricted with a nasal decongestant (e.g., oxymetazoline). However, the final confirmatory diagnosis is done by CT scan of the nasal cavity which will demonstrate the atresia, define the tissue type (bony or membranous), and show the configuration of the entire nasal cavity. The treatment is essentially surgical which can be divided into emergent and elective approaches. It may be successfully treated by removing the obstructing tissue and reconstrucitng the posterior choanae by using the preferable transnasal endoscopic route. However,in cases where, the thick bony plate extremely narrows the posterior nasal cavity, a transpalatal repair technique is more approachable. An intraoperative topical application of Mitomycin-C to inhibit fibroblast proliferation has shown to be an effective adjunct to its surgical repair. Stents created from endotracheal tubes are placed and secured alongwith sutures to the septum in order to prevent postoperative re-stenosis incidence and are usually removed probably after 6 weeks of duration. The stents must be moistened with saline and suctioned several times daily to prevent mucus plugging and acute respiratory distress.

Historical Perspective

  • 1755: Johann Roderer noticed total obstruction of the posterior nasal choanae while examining a neonate and hence was the first to describe the CA.[1]
  • 1829: Oto et al. further characterized the CA anomalies in relation to the deformity of the palatine bones during an autopsy. [2]
  • 1854: Carl Emmert was the first to use the curved trochar through the choanal obstruction in transnasal surgical repair of bilateral CA in a 7- year-old boy and thus, successfully corrected CA surgically.[3]
  • 1880: Ronaldson described an importance of CA in his autopsy findings of the newborns who had died from asphyxia and acute respiratory distress. [4]
  • 1979: Hall first reports the “CHARGE” syndrome association in 17 children with multiple congenital anomalies who were ascertained by CA. In the same year, Hittner et al. found the same syndrome in 10 children with ocular colobomas and multiple congenital anomalies, hence coined the syndrome as “Hall-Hittner syndrome”. [5]
  • 1981: Pagon et al. first elaborated the acronym "CHARGE" association. [6]
  • 1985: Dehaen conducted the first transnasal endoscopic repair of CA. [7]
  • 2008: Barbero et al. found the association of CA with the maternal use of an antithyroid drug methimazole. [8]

Classification

CA can be classified on the basis of several variables such as morphology, laterality, association with congenital anomalies and surrounding structures involvement as described in the following tables from Table 1 to 4.

Table 1: Based on the morphology [9] [10]

Type of morphology Past report (1910) Recent data based on CT and histologic specimens (1996)
Membranous 10% 0%
Bony 90% 30%
Mixed membranous and bony atresia 0% 70%

Table 2: Based on the laterality[11]

Characteristics features Unilateral Bilateral
Type of obstruction Partial or one nasal passage blocked Total or both nasal passages blocked
Incidence 70% 30%
Side: Right or left Right (70%) Both
Severity Carries low morbidity Life threatening
Onset of symptoms Immediately after birth Appears later in childhood or adulthood

Table 3: Based on association with other congenital anomalies[12]

Characteristics features Associated with other anomalies No associations
Incidence 50% 50%
Type of CA Bilateral CA Unilateral CA
Syndromes associated CHARGE syndrome, 9p monosomy, Crouzon syndrome, Marshall-Smith syndrome None

Table 4: Based on structure involvement[13]

Characteristics features Membranous Bony
Surrounding structural abnormalities Failure of the bucconasal membrane to rupture between the 5th and 6th weeks of fetal development.
  • Medial thickening of the medial pterygoid plates;
  • Lateral thickening of the posterior vomer;
  • Narrow nasal cavity

Embryology

Origin: Development of the nasal cavity begins with neural crest cells migration from their origin in the dorsal neural folds. The development of posterior choanae takes place between the 4th and 11th weeks of gestation which is elaborated in Table 5 [14].

Table 5 explains the embryological process for the development of posterior choanae:[15]

Gestational week Developmental process
3rd and 4th week
  • Neural crest cells commence their caudal migration to reach the midface by the 4th week of gestation.
  • The nasal processes or placodes on the lateral surface of head invaginate to form the nasal pits.
5th week
  • The nasal pits begin to fold inwards into the mesenchyme forming the nasal sacs.
  • These primitive nasal sacs are separated from oral cavity by an oronasal membrane.
8th week
  • The oronasal membrane ruptures creating nasal cavity, and a primitive choanae located at the junction of nasal cavities and nasopharynx.
  • During this phase of development, there is gradual proliferation of neural crest cells which further contribute to the formation of skull base and nasal vaults.
  • The lateral palatal shelves fuse in an anterior-to-posterior direction which subsequently forms the hard and soft palate.
10th week
  • The nasal septum and developing palate fuse.
  • The primitive choanae gets pushed posteriorly to form “Secondary choanae”.
  • In normal fetus, these secondary choanae are patent for a functional airway between the anterior nasal cavity and nasopharynx.
  • Normal anatomical relations of the atretic plate are as follows: [16]
  1. Superior surface: Under surface of body of sphenoid
  2. Lateral border: Medial pterygoid lamina
  3. Medial border: Vomer
  4. Inferior surface: Horizontal plate of palatine bone

Pathophysiology

  • Obligate nose breathers: In neonates, the epiglottis is more superiorly placed in relation to adults so when infant swallows, the larynx rises above epiglottis position and touch the nasopharynx, and locks between soft palate and sides of nasopharynx. Due to this elevated laryngeal position compared to the adults, newborns are obligate nose breathers until mouth breathing is established with the subsequent descent of the larynx at approximately 4–6 weeks of life.
  • During inspiration, the neonate sucks the tongue and creates the vacuum in the oropharynx which moves soft tissue of the floor of mouth up and back towards soft palate.
  • During expiration, the airways pressure causes soft palate to push forward against the soft tissue and tongue in the mouth and further obstructs the oral airway. [17]
  • Interrelation of respiration, feeding and crying episodes:[18]
    • As the infants are obligate nasal breather, the oral airway is used by them only during crying; otherwise it is invariably blocked or used by them during normal respiration.
    • The 1/3rd reduction in the diameter of the nasal airway increase nasal airway resistance by 81 times resulting in severe distress in neonates. As a result, the infant with bilateral CA experiences episodes of asphyxia and severe distress in quiet respiration when their mouth is normally closed, especially during sleep or feeding times.
    • Feeding difficulty can be the initial presenting event in which the infants can present with progressive airway obstruction and choke episodes while feeding because of their inability to breathe and feed at the same time.
    • Moreover, the infant can become cyanotic which is relieved by crying or gasping as the child opens the mouth widely, releases the air obstruction and subsequently, the cyanosis disappears. However, the cycle repeats itself if the crying stops and the mouth closes.
    • Similarly, as the child falls asleep, the mouth closes and a progressive obstruction starts with stridor followed by increased respiratory effort and cyanosis. Either the observer opens the child's mouth or the child cries and the obstruction is cleared.
    • In resting state, child has severe retractions, and struggles to breath with rapid cyclic development of cyanosis. Moreover, the infant with bilateral CA rarely develops an ability to breathe through mouth and hence, the medical emergency would exist in the complete absence of patent both nasal cavities.

Embryological theories

  • Hengerer and Strome proposed four embryological originating factors for the development of congenital CA. [19] [20]
  1. Persistence of buccopharyngeal membrane of anterior intestine;
  2. Failure of Hochstetter bucconasal membrane to rupture usually in the seventh gestational week;
  3. Abnormal adherence of the mesodermal tissue in the choanal region;
  4. Abnormal guidance of mesodermal flow secondary to local factors.
  • Other theories which are not so widely considered are:
  1. Resorption of secondary nasal fossa floor
  2. Incomplete extension of nasal cavity dorsally
  3. Migration of dorsal part of frontonasal process to fuse with the palatal shelves
  • However, none of these proposed pathologies gives a confirmatory support for an obstructive or minimalized size of the choanal openings by developmental processes, and hence, currently there has been no definitive evidence supporting one theory over the others. [21]

Anatomical deformities

  • Following deformitites are associated with CA:[16]
  1. The bony atretic plate is situated in front of the posterior bony septum
  2. Narrowed nasal cavity
  3. Thickened lateral pterygoid plates compromising the nasal airway
  4. Thickening of medial aspect of vomer
  5. The membranous plate situated in between lateral pterygoid and vomer
  6. High arched palate

Etiology

The exact cause of this anomaly is unknown but considered to be both genetic and environmental.

The Role of Retinoic Acid

  • Retinoic acid (RA) is produced from vitamin A by an enzyme retinaldehyde dehydrogenase (Raldh) which is important for ontogenesis and homeostasis of numerous tissues.
  • However, studies have revealed that the cranio facial anamolies with mesenchymal developmental damage and disrupted neural crest cell migration pattern were reported among mothers with an ingestion of high doses of vitamin A during gestation period. [22]
  • Dupe et al.: Using a mouse model, they demonstrated that Raldh3 knockout suppressed RA synthesis and caused CA via following proposed mechanisms:[23]
  1. Over-expression of fibroblast growth factor 8 (FGF-8),
  2. Persistence of nasal fins whose rupture normally allowed the communication between nasal and oral cavities
  • Furthermore, they demonstrated that the CA in the Raldh knockout mice could be prevented by maternal treatment of RA.
  • The role of FGF-8 in CA development was further supported by the prevalence of CA among patients with craniosynostosis syndromes due to the raised levels of FGF-8 expression.[24]

The Role of Thioamides

  • Thioamides: Methimazole, carbimazole, and propylthiouracil, are commonly used as medical treatment for hyperthyroidism.
  • Several case reports have been published demonstrating the significant association of CA in the newborns with the maternal use of thioamides for the hyperfunctioning thyroid. [25]
  • Moreover, Barbero et al. conducted a case- control study which further concluded the positive relation of prenatal exposure to methimazole for the maternal hyperthyroidism with CA development.[8]
  • Methimazole crosses the placenta and hence, enters the fetal circulation which in turn reduces the fetal T4 levels. Therefore, infants born with CA have shown a marked decrease in their T4 levels.
  • Teratogenic syndromes causing bilateral CA includes:[8] [26]
  1. Methimazole embryopathy
  2. Carbimazole embryopathy
  • However, it is not completely supported because of lack of significant evidences.
  • Maternal Hyperthyroidism: Contrarily, based on the thorough study of case reports and critical literature reviews, it was stated that the maternal hyperthyroidism rather the methimazole treatment might be underlying the causal factor for CA.
  • Elevated thyroid-stimulating hormones (TSH) level was associated with increased level of FGF, FGF receptor, and other proliferating growth factors, which hypothetically form the pathological basis for CA development. [27]
  • Hence, more research studies are required to further delineate the causes and pathogenesis of CA.

Excessive Coffee Intake [28]

Excessive consumption of coffee in the form of more than 3 cups/day increases the chances of CA by interrupting the membrane rupture which leads to an outgrowth of palate towards the medial side and further blocks the communication between the nasal cavities and the pharynx.

Genetics

  • Familial cases: About 8%. [29]
  • Multifactorial trait: The fact is supported by both affected successive and single generations. [30]
  • CHARGE syndrome: The abnormalities in the chromodomain helicase DNA binding protein-7 (CHD7) gene have been identified in 64% of patients diagnosed with CHARGE, and hence, allowing screening of the gene for patients with CA and other related anomalies. However, the exact function of the CHD7 gene is largely unknown. [31]

Differentiating Choanal atresia from other Diseases

Following conditions listed in Table 6 must be ruled out in any neonates, infant or child presented with acute or frequent episodes of nasal or upper airway obstruction.[32]

Table 6 lists the differential diagnosis for choanal atresia:

Conditions mimicking Choanal Atresia
  • Antrochoanal polyp
  • Chordoma
  • Deviated nasal septum
  • Dislocated nasal septum
  • Hematoma
  • Isolated piriform aperture stenosis
  • Nasal dermoid
  • Nasal harmatoma
  • Nasal haemangioma
  • Nasal cerebral heterotopia (glioma)
  • Nasolacrimal duct cyst
  • Encephaloceles: the encephaloceles can be frontonasal, frontoethmoidal or frontosphenoidal
  • Turbinate hypertrophy

Epidemiology and Demographics

  • “Rule of 2:1” states the ratio of unilateral to bilateral CA, female to male and the right sided to the left sided CA.[32]
  • The incidence is 1:5,000 to 1:8,000 per live-born children.[32]
  • Although its incidence is rare, it represents the most common congenital abnormality of the nose. [33]
  • Maternal age and parity does not affect the frequency of this congenital anomaly.[33]
  • Slightly increased risk exists in twin pregnancy.[34]
  • It is observed with equal frequency among all races and hence, no racial or ethnic preference is seen.[34]

Risk Factors

  • The relation of risk factors and its implications is always complex. A risk factor increases the predisposition towards a disease in comparison to an individual with no risk factors. However, some risk factors are more important than others; hence, acquiring a single or multiple risk factor does not guarantee the disease development. Contrarily, absence of a risk factor does not ensure the disease free state.
  • 2012: An epidemiological survey studied “atrazine” a commonly used herbicide in the US to treat agricultural crops, and stated that women living in the counties in Texas with the highest levels of this chemical were 80 times more likely to give birth to neonates with CA in relation to women who lived in the areas with its lowest levels.[35]
  • 2014: Another epidemiological National Birth Defects Prevention Study (NBDPS) summarized the higher association between the increased development of CA and exposure to second-hand-smoke, coffee consumption, high maternal zinc and B-12 intake, and use of thyroid medications.[36]
  • To sum up, the risk factors for the development of CA are listed below:
  1. Exposure to endocrine disrupters such as chemicals (atrazine) and medications (methimazole) during gestation.[8][35]
  2. Exposure to secondhand smoke during gestational period.[36]
  3. Excessive consumption of coffee by pregnant mothers exposes the developing fetus to caffeine [28]
  4. Elevated levels of vitamin B-12 and zinc in a pregnant woman exposes the fetus to the same [36]
  5. Multiple pregnancies such as twins carries a higher risk [34]
  6. Presence of certain congenital disorders that are associated with CA including Crouzon syndrome, Antley-Bixler syndrome, and Pfeiffer syndrome further increase its chances of development.[12]

Screening

When neonate/infant/child presented with a nasal/upper airway obstruction or respiratory distress, CA must be screened with other differential diagnosis and anomalies.

Clinical Associations and Complications

Any condition that causes significant depression of the nasal bridge or midface retraction due to underlying genetic or environmental factors can be associated with it.

Table 7 lists the clinical associations and complications of the choanal atresia:[12] [31] [32]

Syndromic associations Single anomalies associations
  • CHARGE syndrome
  • Crouzon syndrome
  • DiGeorge syndrome
  • Amniotic band syndrome
  • Fetal alcohol syndrome
  • Treacher Collins syndrome
  • Pfeiffer syndrome
  • Antley-Bixler syndrome
  • Down’s syndrome
  • Intestinal malrotation
  • Craniosynostosis
  • Congenital heart disease
  • Polydactyly
  • Nasal / auricular deformities
  • Palatal deformities
  • Mid face hypoplasia
  • Meningocele
  • Menigoencephalocele

CHARGE Syndrome [31]

  • The most commonly associated congenital anomaly.
  • Choanal atresia is present in 10 to 30% of CHARGE syndrome cases.
  • It elaborates as following:
    • C- Coloboma: of the iris, choroid, and/or microphthalmia
    • H- Heart disease: such as atrial septal defect (ASD) and/or conotruncal lesion
    • A- Choanal atresia
    • R- Mental and growth retardation
    • G- Genitourinary abnormalities: such as cryptorchidism, microphallus, and/or hydronephrosis
    • E- Ear deformities: associated deafness (the external, middle, and/or inner ear may be involved).

Prognosis

  • The prognosis is usually considered to be very good with timely and effective management unless other complex syndrome associations seen.
  • Full recovery is expected with no possibility for any long term problem in both groups of patients. [37]

Clinical presentation

Clinical presentation of CA varies from acute airway obstruction to chronic recurrent sinusitis depending on whether CA is unilateral, bilateral, or associated with other coexisting airway abnormalities. [12] [22] [32] [38]

Table 8 elaborates and compares both forms of Choanal Atresia: Bilateral and Unilateral::

Characteristics Bilateral Unilateral
Onset of symptoms Immediately after birth Typically presents later in life
Severity Can be life threatening Relatively low morbidity
Nursing difficulties Sucking disabilities; Inability to nurse and breathe at same time Uncommon
Respiratory distress Acute or cyclical episodes seen with intermittent cyanosis characteristically relieved by crying Uncommon until obstruction of the contralateral side from infection or adenoid enlargement precipitates airway obstruction symptoms
Respiratory infections Common due to aspiration Common due to persistent mucoid rhinorrhea, and/or a history of chronic sinusitis
Recurrent nasal allergies Common due to inability to clear nasal secretions Common due to purulent nasal discharge accumulated over several weeks
Cyanosis Worsens while feeding and improves on crying (paradoxical cyanosis) Uncommon
Crying Abnormal Change in voice noted due to loss of normal nasal intonation (Rhinolalia clausa)
Stridor, Grunting, Snorting Common Uncommon
Foul smelling breath Common Common either due to mouth breathing and its attendant drying effects, or due to the inability to clear the nasal cavity of its secretions
Failure to thrive Common due to feeding difficulties Uncommon
Loss of sensation of smell Common due to accumulated nasal secretions Common
Multiple failed extubation attempts Common especially in those with secondary airway issues Uncommon
Timing of diagnosis Improved respiratory distress after crying may delay the diagnosis Usually delayed until adulthood due to the non-specific symptoms of unilateral nasal obstruction
Treatment Timely airway management and surgical repair Delayed until the later age

Effect of CA on the facial structures growth [39]

  • The face, specifically the maxilla and mandible, grows in a dynamic fashion throughout childhood under the influence of bony deposition and resorption, soft-tissue contouring, and hormonal influences. In a reciprocal fashion, the skull base or neurocranium influences midfacial development via the growth of the sinuses, which in turn influence the skull base. Displacement of these structures of the nasomaxillary complex occurs in horizontal, vertical, and anteroposterior axes. These changes ultimately affect the proportions of the face and the morphology of all other facial structures, including the upper airway. Hence, an upper airway obstruction while breathing is common because the intraoral airway has foreshortened due to abnormal placement of anterior choanal aperture, and further the diagnostic visualization of the laryngeal structures becomes difficult. Moreover, a chronic case of CA may progress to the development of obstructive sleep apnea later in life.

CA with Multiple Congenital Anomalies

  • Other airway abnormalities: About 34% have other respiratory anomalies such as tracheomalacia, laryngomalacia, and subglottic stenosis [22]
  • Craniofacial abnormalities: About 21% had it in the form of CHARGE, Treacher Collins, Pfeiffer, Apert, Mandibulofacial dysostosis, and Crouzon syndromes. [12]
  • Hence, these subgroup of patients always presents with more acute and severe respiratory symptoms due to the underlying complex airway abnormalities; and hence, they requires stable alternative airway management such as tracheostomy in addition to the surgical correction of CA.

Diagnosis

  • The diagnosis and management of CA requires the combined and coordinated efforts of both the neonatologists and otolaryngologists. Due to its associations with other syndromes (Table 7), infants born with CA often need other subspecialty evaluations for an interprofessional approach from the departments of cardiology, ophthalmology, geneticists, gastroenterology, etc in the multidisciplinary settings especially for Pediatric Airway Disorders.
  • A thorough diagnostic work up is required to rule out other clinical conditions (Table 6) to arrive at a definitive diagnosis and to make a timely diagnosis as if left unestablished till later ages, it tend to impair the quality of life through repeated hospital visits.
  • Aero-digestive evaluation: An infant diagnosed with CA must be evaluated for both airway and feeding issues which need to be addressed by speech pathologists and GI specialists respectively.
  • Following methods can be employed to diagnose the condition accurately.
  1. Assessment of detailed history including the maternal drug intake history and symptoms should be done as mentioned in Table 8.
  2. A thorough diagnostic physical and radiological examination procedures should be performed as listed below. [40]
  3. Ultrasonography of the cardiac and renal systems can be conducted for the possible syndromic associations.
  4. Breath sounds can be heard with either a stethoscope or a Toynbee auscultation tube to detect the aerated lung fields.
  5. Air can be gently blown into each nasal cavity with a Politzer bag to observe any degree of nasal obstructive signs.

Suction catheter test [38]

  • After performing proper preparation by the use of nasal topical decongestants and nasal suctioning, a fine six or eight French suction catheter introduced into the nose via each nostrils and into the child's oral cavity.
  • If there is no atresia, the catheter will effortlessly pass through the nasal cavity into the nasopharynx.
  • The distance of encountered resistance can provide insights into the etiology of nasal obstruction.
    • 3-5 cms from the anterior nares/alar rim: A typical solid feeling would be felt at this point and possibly indicates obstruction at the posterior choanal level.
    • 1-2 cms from the anterior nares/alar rim: If obstruction is encountered at this distance, then traumatic deflection of nasal septum due to trauma during delivery or inferior turbinate pathologies might be the pathologies. Nasal decongestants such as oxymetazoline/xylometazoline can be used to shrink the obstruction caused by mucosal edema.
  • Hence, an inability to pass nasogastric tube through nasal cavity beyond 3-4 cm despite aerated lungs on chest radiograph confirms the diagnosis. However, care must be taken in patients with other craniofacial abnormalities to prevent intracranial passage of the catheter.

Cotton wisp test [40]

  • Movement of a wisp of cotton wool held directly underneath the nares while the closed mouth during inspiration and expiration. It would move in the presence of free air flow; however, the lack of movement indicates the probable obstructive diagnosis.

Laryngeal mirror test [38]

  • A laryngeal mirror held under the nares will reveal nasal misting in patients with patent nasal airways. Contrarily, the absence of fog on a mirror when it is placed under the one nostril after the other to check for fogging supports the CA diagnosis.

Acoustic rhinometry [41]

  • Acoustic rhinometry can be used for the diagnosis, but is especially helpful in the postoperative period to check the patients on restenosis or postoperative nasal complications.

Methylene blue dye test [42]

  • Administration of methylene blue dye into the anterior nasal cavity can be seen passing through the nasopharynx. However, obstruction due to CA will prevent the flow into the nasopharynx and supports the diagnosis.

Automatic tympanometer [43]

  • An examination using the automatic tympanometer is considered to be simple, minimally invasive, and highly reproducible with 100% sensitivity and specificity rate.

Genetic Screening [31]

  • The CHD7 gene screening test and other cytogenetic anomalies such as chromosome deletions related to the several syndromes (Table 7) associated with CA can be done.

Prenatal ultrasound [44]

  • The clinical presentation and diagnosis of CA is usually postnatal, hence the prenatal ultrasound diagnosis is rare, and very few cases have been reported in the literature. However, it can be suspected prenatally in the presence of other nose anomalies such as nasal septal deviation or a single nostril.

Lateral skull X-ray [40]

  • The traditional method of diagnosis which involves the filling the nose with radiopaque dye with the patient lying in a supine position, and thus, demonstrating the hold-up of the dye in the posterior nasal cavity.

Nasal Endoscopy[45]

Source: www.entdev.uct.ac.za
Source: www.entdev.uct.ac.za
  • An appropriate age-related otorhinolaryngology examination is performed after the nasal cavity preparation, an examination in a very small children is performed with the 3.2 mm diameter flexible endoscope. When possible, the 0° and 30° rigid endoscopes are preferred with a diameter of 4.0 mm or 2.7 mm. Direct visualization of the point of obstruction in the nasal passage with a flexible nasendoscope confirms the presence of an atretic plate in the choana. Therefore, it has become the preferred method for confirming the diagnosis.

CT scan

  • CT scan imaging of the paranasal sinuses and skull base is virtually diagnostic modality of choice. It should be done after symptomatic stabilization of the patient in supine position.
  • Objective:
  1. To confirm the diagnosis and it’s involvement on unilateral or bilateral sides.
  2. To determine the anatomy of the atretic area, including the width of the vomer bone and the medial displacement of the sides of the lateral wall of the nose.
  3. To measure the thickness of the atretic plate.
  4. To determine if any other sites of obstruction or differential abnormalities exist in the nasal, nasopharyngeal or sinus cavities.
  5. To detect the abnormal anatomy useful for a surgical planning, and in determining the choice of the operative technique to be used.
CT scan demonstrating unilateral osseous choanal atresia
  • Patient preparation before the scanning: A nasal topical decongestant (0.5% xylometazaline) is applied to reduce mucosal swelling 30 minutes prior to the CT scan, and suctioning of the nose done immediately before the CT scan to remove all nasal secretions in order to detect accurate radiological diagnosis due to the difficulty in radiologically distinguishing a membranous occlusion from mucus in the unprepared nose.[40]
  • CT scan technique:[46]
    • Anatomical landmark: The level of the pterygoid plates in the axial plane. At this level, the width of both posterior choanae at maximum stenosis and the maximum width of the inferoposterior vomer are measured. Below this level, the hard palate is visualised; and above this level, structures within the nasal cavity make measurements difficult.
    • Scanning angle: The gantry is angled 5° cephalad to a plane parallel to the hard palate to interpret the images for the measurements of the posterior vomer, the choanal openings, and the shape of the posteromedial maxilla.
    • Partial skull ossification: Conventional bone-window settings may not show the bony margins; however, a high resolution bone filters may overcome this problem. Hence, 1 to 1.5 mm thick noncontrasted scans are done contiguously.
  • CT scan findings:[46] [38]
  1. Narrowing of the posterior nasal cavity with medial bowing and thickening of the lateral wall of the nasal cavity with airway width < 3 mm.
  2. Impingement and thickening at the level of the anterior aspect of the pterygoid plates
  3. Enlargement of the posterior portion of the vomer, with or without a central membranous connection. In patients less than 8 years of age, the vomer generally measures less than 0.23 cm in width and should not exceed 0.34 cm; in children over 8 years, the mean vomer width is 0.28 cm and should not exceed 0.55 cm.
  4. The mean width of the posterior choanal airspace in the newborn measured from the lateral wall of the nasal cavity to the vomer is 0.67 cm, increasing to 0.86 cm at 6 years and to 1.13 cm by 16 years of age.
  5. An air-fluid level of the nasal secretions above the obstruction point can be seen.
  6. Membranous atresias: Soft-tissue densities will be seen in the posterior choanae, and noticed narrowing of the posterior choanae just anterior to the pterygoid plates.
  7. Bony atresia: The thickness of the atretic plate should be taken for surgical repair planning.
CT scan demonstrating bilateral osseous choanal atresia
  • Disadvantages: The main disadvantages of using CT in pediatric populations are:
  1. High radiation exposure dose: Due to an inadequate positioning of infants in such an age group while achieving a scanning angle and imaging plane necessitates the repetition of the scan; and hence, subsequently results in an increased exposure of the radiation dose.
  2. Sedation: Need for sedation to avoid movement artifacts which render the examination of fine details less reliable. However, the contrast material used in the nose will help to overcome it.
  3. Child’s lens: The angle of the imaging plane might enhances the risk to it.

Treatment

  • The patient should ideally be managed in a neonatal or paediatric intensive care unit with a combined supportive, medical and surgical care. However, the treatment is essentially surgical which can be divided into emergent and elective definitive categories.

Objectives

  1. To restore choanal patency,
  2. Avoid damaging interference to the surrounding normal craniofacial structures,
  3. To minimize invasiveness and postoperative complications,
  4. To avoid recurrences.

Systematic treatment approach

  1. Establish an immediate oral airway to ensure breathing
  2. Membranous atresia may be perforated upon passage of nasogastric tube
  3. Surgical CA repair for alleviating respiratory symptoms and feeding difficulties
  4. Postoperative scars, complications, & incomplete resection of atresia plate evaluation with bone CT scans

Severity assessment

  • Assessment is done by evaluating its laterality (unilateral or bilateral), the degree of obstruction affecting the child's breathing and feeding, and its associations with other anomalies; hence, the treatment can be further divided into mild and severe cases.[47]
  • Treatment for mild cases: In the mild cases with no significant respiratory distress or feeding difficulty; treatment includes the following:
    • The neonate should be kept under close observation and provided with supplemental oxygen periodically.
    • The nasal passages should be maintained by administering the nasal saline to keep the nasal linings healthy by clearing the discharge and preventing any further impediments to nasal breathing.
    • Parents can opt to delay surgical correction of the nasal structure until the child is older to develop the regional anatomy more similar to that of the adults.
    • In some of the unilateral cases, the surgical treatment can be delayed until the infant is at least 6 months old and weigh more than 2kgs as it allows better operative field and opportunity for control during surgery.
    • However, it should be ideally fixed before 5 years of age in order to avoid persistent unilateral nasal drainage which can be socially and medically problematic.
  • Treatment for severe cases: In severe cases carrying life threatening risk usually because of bilateral CA, the delay in treatment should be avoided.
    • Surgery should be performed as soon as the patient is stable and has completed evaluation for other anomalies.
    • Different surgical approaches are available and selected on case to case basis.
  • To sum up, whether or not surgery is performed, if an infant suffers from CA, a periodic evaluation is necessary to ensure normal upper airway breathing and feeding habits in both preoperative and postoperative period.

Airway Management [39] [40]

  • It is an initial goal of treatment especially for infants with bilateral CA by inserting an oral airway to break the seal formed by the tongue against the palate to have a tide over an immediate crisis.
  • An oral airway provides a temporary secure of several weeks in a newborn with bilateral CA and severe respiratory distress.
  • Surgery can be delayed for bilateral CA due to the presence of an innate reflex for nasal breathing and possibility of establishing and maintaining a patent airway with the use of a McGovern nipple or a cannula of Guedel or a standard feeding bottle teat or dummy with the tip cut off to facilitate oral breathing.
  • The preferred oral airway is McGovern nipple, an intraoral nipple with a large opening by cutting its end off, which is placed in the mouth and tied around the infant’s occiput. A small feeding tube can be placed through another hole in the nipple or alongside the nipple to provide feeding needs. This helps the child to gain adequate weight for withstanding corrective surgical procedures.[48]
  • It provides the short-term benefits by the effect of stenting the oral cavity to open and allow mouth breathing; however it is not a permanent treatment.
  • If a patient still fails to maintain an adequate airway on it, an endotracheal intubation must be performed as the initial management.
  • A tracheostomy may be required in patients with severe comorbidities, but it is not necessary in cases of isolated or even bilateral CA.

Role of tracheostomy

  • Indications:
    • Fail to adequately maintain an oral airway.
    • To defer the definitive surgical treatment in patients with other comorbidities such as cardiopulmonary instability and multi-level airway obstruction.
  • Patients with bilateral CA and CHARGE syndrome are more likely to fail atresia repair because of the following reasons:[49]
  1. More contracted nasopharynx in a lateral and/or vertical dimension,
  2. Narrower posterior choanal region than those with isolated CA, and
  3. Poor tongue/pharyngeal muscle control.
  • Moreover, Asher et al. in their retrospective review of patients with CHARGE syndrome suggested that an early repair of their CA was rarely successful as patients had a propensity for airway instability during the operative time predisposing them to hypoxic events. [50]
  • Therefore, recommended early tracheotomy rather than early CA repair to secure the airway for CA patients with CHARGE syndrome.

Feeding Issues [40]

  • Do not feed in the cases where there is high index of suspicion for CA.
  • A feeding orogastric tube is required until surgical correction of the atresia is performed due to higher risk for aspiration.

Timing of Surgery

  • The exact timing of surgery is variable and decided upon studying the entire case scenario.
  • If the infant learns to breathe orally, surgery can be delayed for a while.
  • Urgent surgery required in following cases: [40]
  1. Bilateral CA;
  2. Symptomatic unilateral CA;
  3. Syndromic babies with respiratory complications from unilateral atresia.
  • Delay surgery till the child reaches its first birthday in asymptomatic unilateral atresia because of the following:[42]
  1. This allows the surgery site to enlarge thereby reducing the risk of post operative restenosis.
  2. Blood loss is reduced.
  3. Older infants tolerate stenting better than young ones.
  4. The younger the patient, the higher the risk of intraoperative and postoperative complications and re-stenosis.

Use of Anaesthesia [51]

  • The anesthetic approach depends on the child's condition. In general, intravenous induction with a muscle relaxant of intermediate duration, endotracheal intubation with an oral Right Angle Endotracheal (RAE) tube, and maintenance with an inhaled agent and opioid or propofol and remifentanil infusion preferred.

Surgical Approaches

  • Since Emmert's initial trocar perforation in 1854, the five different surgical approaches to correct CA have been described which includes the following:
  1. Transnasal,
  2. Transpalatal,
  3. Transseptal,
  4. Sublabial trans-septal,
  5. Transantral and
  6. External rhinoplasty.
  • As per the research done in March 1999 by American Society of Pediatric Otolaryngology (ASPO), the most used techniques in descending order are:[52]
  1. Transnasal with endoscope use,
  2. Transpalatal perforation with Fearon dilator,
  3. Transnasal with microscope use,
  4. Transnasal with laser use
  • The transasal technique is considered better than the transpalatal approach.

Transpalatal approach [38]

  • This approach was the most frequently used to reach the area of CA through the roof of the mouth until the advent of the endoscopic endonasal approach.
  • Indications:
  1. Abnormally developed skull base;
  2. Thick atresia plate;
  3. Associated craniofacial anomalies; and/or
  4. Bilateral CA
  • Operating procedure: This procedure is conducted in a full sedation with the use of a general anaesthesia. A Dingman-Denhardt mouth gag with the infant tongue blade is used. The palate is injected with 0.5% lidocaine and 1:200,000 epinephrine in the area of the mucosal incision to serves the dual purpose of flap elevation and required hemostasis during the entire surgical procedure. A Owens type (U-shaped) mucosal incision starts from just behind the maxillary tuberosity on one side and then continued medial to the alveolar ridge up to the canine region and further angled back to the nasopalatine foramen. A likewise incision is made on the opposite side; and the mucosal flap is elevated with efforts to avoid any damage to the greater palatine arteries. Nasopharynx and nasal mucosa is elevated up to the edge of the hard palate and preserved. The soft palate is now retracted posteriorly and superiorly to expose the posterior edge of hard palate which is the area for dissection and surgical repair. Then, the palatine bones posterior to the greater palatine foramina, the atresia plates, and the posterior vomer are carefully drilled away using a kerrison’s punch or drill. Two 14 or 16 French catheters are passed simultaneously into each nostril to check the patency of the newly created choanae. The preserved mucosa is then used to cover the superior and inferior surfaces of the newly formed choanea and then sutured in place to cover the bone. Stents are usually left in-situ for 4 weeks. [42]
  • Advantages:
  1. Better field of visualisation and exposure
  2. Both hands are free
  3. Shortened stenting duration (a portex endotracheal tube can be cut and used as a stent)
  4. Reduced failure rate
  • Disadvantages:
  1. The incisions made are similar to those for a cleft palate repair and can have a banding effect on maxillary growth due to scar formation. Hence, most surgeons prefer to wait for some teeth to appear in occlusion to use this approach at approximately 12-18 months of age.
  2. Stunted palatal growth seen in 50 % of operated patients
  3. An injury to the greater palatine artery can result in an increased blood loss
  4. Postoperative complications: restenosis of the choanae, palatal fistulas, flap necrosis, bleeding, fistulas, infections, defective growths of the jaw and the palate bone, and orthodontic problems such as cross bite. [53]
  • Postop Care:
  1. The parents must be taught to maintain the patency of stents by frequent suctioning and a saline-moistened pipe cleaner or cotton applicator 3 to 6 times a day.
  2. Antibiotics and decongestants are prescribed in suspicion of rhinitis
  3. Regular follow up should be advised until the stents are removed.

Transseptal approach[54]

  • It is effective but rarely used due to the resultant impairment of facial growth in infants. However, it is considered effective in patients older than 8 years diagnosed later with unilateral CA.
  • An operative key point is the need to remove the posterior portion of the vomer.
  • It permits better correction of any septal deviations, resection of the posterior part of the vomer, and preservation of mucosal flaps for coverage of the bleeding area.
  • Complications of transeptal approach:[42]
  1. Pressure necrosis of columella
  2. Plugging of stent
  3. Displacement of stent
  4. Palatal dehiscence
  5. Maxillary hypoplasia causing malocclusion
  6. Granulation tissue formation around the stents.

Sublabial approach[55]

  • The sub labial, trans-septal access has advantages and disadvantages similarities to the trans-septal approach, and it further reduces the likelihood of postoperative granulation tissue formation and restenosis by avoiding surgical trauma to nasal mucosa.

Transantral approach[56]

  • Transantral access is the least-used approach because it requires a well-developed maxillary sinus which is not found in infants, many older children, and even adults with CA. However, it permits an adequate exposure of the surgical field, allowing a quick check for any bleeding source, and reduces the risk of damaging the sphenopalatine arteries, veins and nerves; but can significantly increase the risk of deformities of growing structures such as the maxilla and upper teeth.

Transnasal approach [38] [57]

  • The growing experiences and modern refinements in both instrumentation and techniques in endoscopic sinus surgery have encouraged many CHOP surgeons to prefer the use of the endoscopic endonasal technique for the CA repair as it does not affect the growth of the mandibular arch, causes no malocclusions or cosmetic alterations to the face.
  • For stable infants with CA, the endoscopic endonasal technique should be considered the first choice for the surgical treatment for membranous atresia or where bony plate is thin which involves the perforation of the atretic lamina followed by dilatation and full choanal reconstruction.
  • Operating procedure using endoscopes:[42]
    • The surgery is performed under general anesthesia using a combination of tiny scope, dilators, sinus instruments, ear curettes and drills. A self retaining nasal speculum is used to expose the nasal cavity and the atretic plate with minimal trauma to the nasal vestibule. For the membranous atresia, a simple perforation of the same under endoscopic guidance would suffice. The nasal cavity is decongested using 4% xylocaine with adrenaline in the concentration of 1 in 10,000 concentration. A 0° endoscope is used transnasally with a simultaneous view of the nasopharynx through a transoral 120° endoscope. It is important to use both the transnasal and transoral views in order to avoid potentially entering the anterior skull base. Under endoscopic guidance, a mucosal incision is made and the mucosal flaps are elevated exposing the posterior vomer and lateral pterygoid lamina. A diamond burr on an angled hand piece is used to drill the atretic bony plate. It is perforated at the junction of the hard palate and the vomer. Incidentally, this is the thinnest part of the atretic plate. To improve visualization, the inferior turbinate can be out fractured or even be trimmed. After drilling, care is taken to preserve the mucosal flaps. A silastic stent is placed into each nostril passing through the drilled neo-choanae. This helps in reducing the incidence of restenosis and crusting at the site of the bony atresia. Stent is kept in place for atleast 6 weeks. Opening made should be large enough to allow smooth passage of suction catheter. 3-4 size Endotracheal tube can be used as stent to prevent restenosis and maintain patency while the area heals. The size of ET tubes should be choosen carefully to prevent restensosis and nasal regurgitation. However, a recent meta-analysis found similar success rates for bilateral CA repair regardless of whether stents were used; and hence, stenting is not required in all the cases. Thus, these stents will be removed at the bedside or during an office visit in weeks to months after demonstrating the child for an airway stability and feeding evaluation.[58]
  • Caution: While performing this procedure, caution must be taken not to injure the sphenopalatine vessels behind the middle turbinate.
  • Advantages:[42]
  1. This process is faster and easier as it offers a direct approach to the atretic plate;
  2. Reduces intraoperative bleeding;
  3. Can be performed in children of all ages who do not have associated external nasal deformities;
  4. faster post-operative recovery, reduces hospitalization time, and lowers morbidity;
  5. Child can be immediately breast fed;
  6. Child can be discharged on the postop 3rd day
  1. Vision is highly limited especially in the new born
  2. Inability to adequately remove enough of the posterior vomerine septal bone and prevent restenosis
  3. Longer stenting time
  4. Endoscopes do not offer binocular vision
  5. Can not be done safely with good results on patients with multiple nasal and nasopharyngeal anomalies.

Rhinoplasty[59]

  • Correction of CA using an external rhinoplasty approach is usually restricted to unilateral cases when the child is 1 year of age or older. The medial crura are separated, and the cartilaginous edge of the nasal septum is exposed. The mucoperichondrium and the mucoperiosteum are elevated to the region of the atresia. The atresia plate is then removed, and the posterior portion of the vomer is resected.

Stenting [38] [58]

Source: www.entdev.uct.ac.za
  • The effectiveness of using stents after CA repair is a controversial topic with some of the major complications originating following its use.
  1. Formation of granulation tissue
  2. Crust formation
  3. Septal perforation
  4. Persistent nasal discharge
  5. Foreign body tissue reaction
  6. Nasal alar erosion
  7. Columellar pressure necrosis

Mitomycin-C[60]

  • It is an aminoglycoside which inhibit fibroblast growth and migration; and it's topical application was proposed to reduce restenosis risk after surgery and improve the healing process as it has not caused any systemic adverse effects and anesthetic complications. However, its use is still controversial.

Postoperative monitoring [51]

  • After CA is surgically corrected, the surgeon is often faced with the problem of restenosis; however, recent innovations have reduced its rate.
  • Newer endoscopic techniques with powered instrumentation along with the use of stenting and mitomycin-c have enhanced the safety and efficacy for CA repair.
  • The postoperative period is generally well for patients with unilateral obstruction and require no special monitoring. However, infants undergoing bilateral repair can exhibit partial or intermittent upper airway obstruction that persists for some time and thus, the infant should be observed closely in the ICU with appropriate monitoring until breathing dynamics have normalized.

Surgical Complications[57]

  • Factors resulting in the failure of microendoscopic surgery for the CA treatment are as follows:
  1. Surgery performed too early,
  2. Inadequate area of surgery exposure due to association with other malformations,
  3. Inappropriate surgical technique with insufficient removal of the atresial plate and the posterior nasal septum, and
  4. Inadequate postoperative care.

Success Rate [61]

  • Successful CA surgical outcomes are influenced by the presence/absence of following factors:
  1. Nasopharyngeal reflux,
  2. GERD,
  3. Age <10 days associated with limited visualization of the nasal area and limited resection of the vomer,
  4. Bilateral CA with purely bony atretic plate, and
  5. Associated syndromic malformations.

Prevention

  • Currently, there are no known methods or guidance reported for the prevention of CA. However, maternal mothers should consider the general health measures for minimizing the risk factors for the condition as listed in the "Risk Factors" section. [37]

Tips to remember [61]

  • Regardless of surgical approach, the key to a successful outcome is to create a large 3-dimensional opening by a combination of following:
  1. Puncturing the membranous obstruction,
  2. Widening the medial bony thickening of the medial pterygoid plate, and
  3. Thinning the thickened vomer
  • Postoperative considerations:[40]
  1. After successful CA surgery, the child should be extubated and managed in a general paediatric ward with regular nasal suctioning
  2. Start oral feeding as early as possible
  3. Postoperative nasal decongestant drops (0.5% xylometazalone) should be advised for a week
  4. Saline and steroid drops should be used for 2 weeks to reduce postoperative inflammation and granulations

See also

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