Zenker's diverticulum pathophysiology: Difference between revisions

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{{Zenker's diverticulum}}
{{Zenker's diverticulum}}
{{CMG}} {{AE}}
{{CMG}} {{AE}} {{Ajay}}


==Overview==
==Overview==
[[Zenker's diverticulum]] (ZD) is thought to be due to the result of motor abnormalities of the [[esophagus]]. The defect over the [[Killian's dehiscence|Killian's triangle]], a point of [[Muscle weakness|weakness]] in the [[muscular]] wall of the [[hypopharynx]] results in ZD. [[Killian's dehiscence|Killian's triangle]] is surrounded by the [[Cricopharyngeal muscle|cricopharyngeal]] [[sphincter]] and [[oblique]] fibers of the [[Inferior pharyngeal constrictor muscle|inferior constrictor of the pharyngeal muscle]]. It is considered a pseudodiverticulum as it includes only [[Mucosal|mucosa]] and [[submucosa]]. Chronic strain on the [[Killian's dehiscence|Killian's triangle]] leads to an evagination of the [[sphincter]], which may be because of the high pressures in the food [[Bolus (digestion)|bolus]] in the course of [[swallowing]] and the abnormalities of the [[upper esophageal sphincter]] (UES). This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the [[Hypopharynx|hypopharyngeal]] pressure gradient. Increased intra-[[bolus]] pressures found in patients with [[Zenker's diverticulum|ZD]] can be secondary to impaired bolus passage combined with the [[gastroesophageal reflux disease]] ([[GERD]]) or as a result of the [[GERD]]. As the [[diverticulum]] enlarges, it may compress the [[Pharyngoesophageal diverticulum|pharyngoesophageal]] segment as well as increased stiffness and the intrabolus pressure. Increased intrabolus pressure is also increased in older patients who perform multiple swallows to achieve bolus clearance. Acid reflux is thought to lead to increased [[spasm]] of the [[Upper esophageal sphincter|UES]] which in turn increases the intra-[[bolus]] pressures during [[swallowing]], given that [[swallowing]] is frequently distinct from episodes of acid [[reflux]] disease.
[[Zenker's diverticulum]] (ZD) is thought to occur due to the result of [[Motor skill|motor]] abnormalities of the [[esophagus]]. A defect over the [[Killian's dehiscence|Killian's triangle]], a point of [[Muscle weakness|weakness]] in the [[muscular]] wall of the [[hypopharynx]] results in ZD. [[Killian's dehiscence|Killian's triangle]] is surrounded by the [[Cricopharyngeal muscle|cricopharyngeal]] [[sphincter]] and [[oblique]] fibers of the [[Inferior pharyngeal constrictor muscle|inferior constrictor of the pharyngeal muscle]]. It is considered a pseudodiverticulum as it includes only [[Mucosal|mucosa]] and [[submucosa]]. Chronic strain on the [[Killian's dehiscence|Killian's triangle]] leads to an evagination of the [[sphincter]], which may be because of the high pressures caused by the food [[Bolus (digestion)|bolus]] in the course of [[swallowing]] and the abnormalities of the [[upper esophageal sphincter]] (UES). This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the [[Hypopharynx|hypopharyngeal]] pressure gradient. Increased intra-[[bolus]] pressures found in patients with [[Zenker's diverticulum|ZD]] can be secondary to impaired bolus passage combined with the [[gastroesophageal reflux disease]] ([[GERD]]) or as a result of the [[GERD]]. As the [[diverticulum]] enlarges, it may compress the [[Pharyngoesophageal diverticulum|pharyngoesophageal]] segment as well as increased stiffness and the intra-bolus pressure. Increased intra-bolus pressure is also increased in older patients who perform multiple swallows to achieve bolus clearance. [[Acid reflux]] is thought to lead to increased [[spasm]] of the [[Upper esophageal sphincter|UES]] which in turn increases the intra-[[bolus]] pressures during [[swallowing]], given that [[swallowing]] is frequently distinct from episodes of acid [[reflux]] disease.


==Pathophysiology==
==Pathophysiology==
The [[pathophysiology]] of the [[Zenker's diverticulum]] is as follows<ref name="pmid24043908">{{cite journal |vauthors=Bizzotto A, Iacopini F, Landi R, Costamagna G |title=Zenker's diverticulum: exploring treatment options |journal=Acta Otorhinolaryngol Ital |volume=33 |issue=4 |pages=219–29 |year=2013 |pmid=24043908 |pmc=3773964 |doi= |url=}}</ref><ref name="pmid25309667">{{cite journal |vauthors=Elbalal M, Mohamed AB, Hamdoun A, Yassin K, Miskeen E, Alla OK |title=Zenker's diverticulum: a case report and literature review |journal=Pan Afr Med J |volume=17 |issue= |pages=267 |year=2014 |pmid=25309667 |pmc=4191700 |doi=10.11604/pamj.2014.17.267.4173 |url=}}</ref><ref name="pmid9618133">{{cite journal |vauthors=Achkar E |title=Zenker's diverticulum |journal=Dig Dis |volume=16 |issue=3 |pages=144–51 |year=1998 |pmid=9618133 |doi= |url=}}</ref><ref name="pmid23128778">{{cite journal |vauthors=Bergeron JL, Long JL, Chhetri DK |title=Dysphagia characteristics in Zenker's diverticulum |journal=Otolaryngol Head Neck Surg |volume=148 |issue=2 |pages=223–8 |year=2013 |pmid=23128778 |pmc=3752429 |doi=10.1177/0194599812465726 |url=}}</ref><ref name="pmid8790732">{{cite journal |vauthors=Westrin KM, Ergün S, Carlsöö B |title=Zenker's diverticulum--a historical review and trends in therapy |journal=Acta Otolaryngol. |volume=116 |issue=3 |pages=351–60 |year=1996 |pmid=8790732 |doi= |url=}}</ref><ref name="pmid12903677">{{cite journal |vauthors=van Overbeek JJ |title=Pathogenesis and methods of treatment of Zenker's diverticulum |journal=Ann. Otol. Rhinol. Laryngol. |volume=112 |issue=7 |pages=583–93 |year=2003 |pmid=12903677 |doi=10.1177/000348940311200703 |url=}}</ref><ref name="pmid21306794">{{cite journal |vauthors=May JT, Padhya TA, McCaffrey TV |title=Endoscopic repair of Zenker's diverticulum by harmonic scalpel |journal=Am J Otolaryngol |volume=32 |issue=6 |pages=553–6 |year=2011 |pmid=21306794 |doi=10.1016/j.amjoto.2010.11.009 |url=}}</ref><ref name="pmid1634178">{{cite journal |vauthors=Fulp SR, Castell DO |title=Manometric aspects of Zenker's diverticulum |journal=Hepatogastroenterology |volume=39 |issue=2 |pages=123–6 |year=1992 |pmid=1634178 |doi= |url=}}</ref><ref name="pmid1397879">{{cite journal |vauthors=Cook IJ, Gabb M, Panagopoulos V, Jamieson GG, Dodds WJ, Dent J, Shearman DJ |title=Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening |journal=Gastroenterology |volume=103 |issue=4 |pages=1229–35 |year=1992 |pmid=1397879 |doi= |url=}}</ref>
The [[pathophysiology]] of the [[Zenker's diverticulum]] is as follows:<ref name="pmid24043908">{{cite journal |vauthors=Bizzotto A, Iacopini F, Landi R, Costamagna G |title=Zenker's diverticulum: exploring treatment options |journal=Acta Otorhinolaryngol Ital |volume=33 |issue=4 |pages=219–29 |year=2013 |pmid=24043908 |pmc=3773964 |doi= |url=}}</ref><ref name="pmid25309667">{{cite journal |vauthors=Elbalal M, Mohamed AB, Hamdoun A, Yassin K, Miskeen E, Alla OK |title=Zenker's diverticulum: a case report and literature review |journal=Pan Afr Med J |volume=17 |issue= |pages=267 |year=2014 |pmid=25309667 |pmc=4191700 |doi=10.11604/pamj.2014.17.267.4173 |url=}}</ref><ref name="pmid9618133">{{cite journal |vauthors=Achkar E |title=Zenker's diverticulum |journal=Dig Dis |volume=16 |issue=3 |pages=144–51 |year=1998 |pmid=9618133 |doi= |url=}}</ref><ref name="pmid23128778">{{cite journal |vauthors=Bergeron JL, Long JL, Chhetri DK |title=Dysphagia characteristics in Zenker's diverticulum |journal=Otolaryngol Head Neck Surg |volume=148 |issue=2 |pages=223–8 |year=2013 |pmid=23128778 |pmc=3752429 |doi=10.1177/0194599812465726 |url=}}</ref><ref name="pmid8790732">{{cite journal |vauthors=Westrin KM, Ergün S, Carlsöö B |title=Zenker's diverticulum--a historical review and trends in therapy |journal=Acta Otolaryngol. |volume=116 |issue=3 |pages=351–60 |year=1996 |pmid=8790732 |doi= |url=}}</ref><ref name="pmid12903677">{{cite journal |vauthors=van Overbeek JJ |title=Pathogenesis and methods of treatment of Zenker's diverticulum |journal=Ann. Otol. Rhinol. Laryngol. |volume=112 |issue=7 |pages=583–93 |year=2003 |pmid=12903677 |doi=10.1177/000348940311200703 |url=}}</ref><ref name="pmid21306794">{{cite journal |vauthors=May JT, Padhya TA, McCaffrey TV |title=Endoscopic repair of Zenker's diverticulum by harmonic scalpel |journal=Am J Otolaryngol |volume=32 |issue=6 |pages=553–6 |year=2011 |pmid=21306794 |doi=10.1016/j.amjoto.2010.11.009 |url=}}</ref><ref name="pmid1634178">{{cite journal |vauthors=Fulp SR, Castell DO |title=Manometric aspects of Zenker's diverticulum |journal=Hepatogastroenterology |volume=39 |issue=2 |pages=123–6 |year=1992 |pmid=1634178 |doi= |url=}}</ref><ref name="pmid1397879">{{cite journal |vauthors=Cook IJ, Gabb M, Panagopoulos V, Jamieson GG, Dodds WJ, Dent J, Shearman DJ |title=Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening |journal=Gastroenterology |volume=103 |issue=4 |pages=1229–35 |year=1992 |pmid=1397879 |doi= |url=}}</ref>
* [[Zenker's diverticulum|Zenker's diverticulum]] (ZD) is thought to be due to the result of [[Motor control|motor]] abnormalities of the esophagus.  
 
* [[Zenker's diverticulum|ZD]] is a defect over the [[Killian's dehiscence|Killian's triangle]], a point of [[Muscle weakness|weakness]] in the [[muscular]] wall of the [[hypopharynx]].
'''Killian's dehiscence'''
* [[Zenker's diverticulum|Zenker's diverticulum]] (ZD) is thought to be due to the result of [[Motor control|motor]] abnormalities of the [[esophagus]].  
* [[Zenker's diverticulum|ZD]] is a defect over the [[Killian's dehiscence|Killian's triangle]], a point of [[Muscle weakness|weakness]] in the [[muscular]] wall of the [[hypopharynx]].
* [[Killian's dehiscence|Killian's triangle]] is surrounded by the [[Cricopharyngeal muscle|cricopharyngeal]] [[sphincter]] and [[oblique]] fibers of the [[Inferior constrictor muscle|inferior constrictor]] of the [[pharyngeal]] [[muscle]].  
* [[Killian's dehiscence|Killian's triangle]] is surrounded by the [[Cricopharyngeal muscle|cricopharyngeal]] [[sphincter]] and [[oblique]] fibers of the [[Inferior constrictor muscle|inferior constrictor]] of the [[pharyngeal]] [[muscle]].  
* ZD should be considered a pseudodiverticulum as it includes only [[Mucous membrane|mucosa]] and [[submucosa]].
* ZD should be considered a pseudodiverticulum as it includes only [[Mucous membrane|mucosa]] and [[submucosa]].
* Chronic strain on the [[Killian's dehiscence|Killian's triangle]] leads to an evagination of the sphincter, which may be because of the high pressures in the food [[bolus]] in the course of [[swallowing]] and the abnormalities of the [[upper esophageal sphincter]] (UES).
'''Chronic straining'''
* Chronic strain on the [[Killian's dehiscence|Killian's triangle]] leads to an evagination of the sphincter, which may be because of the high intra-luminal pressures caused by the food [[bolus]] in the course of [[swallowing]] and the abnormalities of the [[upper esophageal sphincter]] (UES).
* This failure to achieve adequate diameter for effective [[Bolus (digestion)|bolus]] clearance leads to a subsequent increase in the [[Hypopharynx|hypopharyngeal]] [[Pressure gradient|pressure gradient.]]
* This failure to achieve adequate diameter for effective [[Bolus (digestion)|bolus]] clearance leads to a subsequent increase in the [[Hypopharynx|hypopharyngeal]] [[Pressure gradient|pressure gradient.]]
* Increased [[Bolus|intrabolus]] pressures found in patients with ZD can be secondary to impaired bolus passage combined with the [[gastroesophageal reflux disease]] ([[GERD]]) or as a result of the [[Gastroesophageal reflux disease|GERD]].  
* Increased [[Bolus|intrabolus]] pressures found in patients with ZD can be secondary to impaired [[Bolus (digestion)|bolus]] passage combined with the [[gastroesophageal reflux disease]] ([[GERD]]) or as a result of the [[Gastroesophageal reflux disease|GERD]].  
* As the [[diverticulum]] enlarges, it may compress the [[Pharyngoesophageal diverticulum|pharyngoesophageal]] segment as well as increased [[stiffness]] and the [[Bolus|intrabolus]] [[pressure]].  
'''Enlargement of Zenker's diverticulum'''
* As the [[diverticulum]] enlarges, it may compress the [[Pharyngoesophageal diverticulum|pharyngoesophageal]] segment as well as causing increased [[stiffness]] and the [[Bolus|intrabolus]] [[pressure]].  
* Increased [[Bolus|intrabolus]] pressure is also increased in older patients who perform multiple [[Swallow|swallows]] to achieve [[bolus]] clearance.
* Increased [[Bolus|intrabolus]] pressure is also increased in older patients who perform multiple [[Swallow|swallows]] to achieve [[bolus]] clearance.
* Various [[hypothesis]] involved in the [[pathogenesis]] of the [[Zenker's diverticulum]] are as follows<ref name="pmid1397879">{{cite journal |vauthors=Cook IJ, Gabb M, Panagopoulos V, Jamieson GG, Dodds WJ, Dent J, Shearman DJ |title=Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening |journal=Gastroenterology |volume=103 |issue=4 |pages=1229–35 |year=1992 |pmid=1397879 |doi= |url=}}</ref><ref name="pmid1283083">{{cite journal |vauthors=Cook IJ, Blumbergs P, Cash K, Jamieson GG, Shearman DJ |title=Structural abnormalities of the cricopharyngeus muscle in patients with pharyngeal (Zenker's) diverticulum |journal=J. Gastroenterol. Hepatol. |volume=7 |issue=6 |pages=556–62 |year=1992 |pmid=1283083 |doi= |url=}}</ref><ref name="pmid1634178">{{cite journal |vauthors=Fulp SR, Castell DO |title=Manometric aspects of Zenker's diverticulum |journal=Hepatogastroenterology |volume=39 |issue=2 |pages=123–6 |year=1992 |pmid=1634178 |doi= |url=}}</ref><ref name="pmid12928096">{{cite journal |vauthors=Sasaki CT, Ross DA, Hundal J |title=Association between Zenker diverticulum and gastroesophageal reflux disease: development of a working hypothesis |journal=Am. J. Med. |volume=115 Suppl 3A |issue= |pages=169S–171S |year=2003 |pmid=12928096 |doi= |url=}}</ref><ref name="pmid7923848">{{cite journal |vauthors=Resouly A, Braat J, Jackson A, Evans H |title=Pharyngeal pouch: link with reflux and oesophageal dysmotility |journal=Clin Otolaryngol Allied Sci |volume=19 |issue=3 |pages=241–2 |year=1994 |pmid=7923848 |doi= |url=}}</ref><ref name="pmid11715923">{{cite journal |vauthors=Mulder CJ, Costamagna G, Sakai P |title=Zenker's diverticulum: treatment using a flexible endoscope |journal=Endoscopy |volume=33 |issue=11 |pages=991–7 |year=2001 |pmid=11715923 |doi=10.1055/s-2004-826106 |url=}}</ref><ref name="pmid5428852">{{cite journal |vauthors=Hunt PS, Connell AM, Smiley TB |title=The cricopharyngeal sphincter in gastric reflux |journal=Gut |volume=11 |issue=4 |pages=303–6 |year=1970 |pmid=5428852 |pmc=1411416 |doi= |url=}}</ref>
'''Hypotheses for mechanism of development of Zenker's diverticulum'''
# [[Zenker's diverticulum]] is a disorder of diminished [[Upper esophageal sphincter|upper esophageal sphincter,]] incomplete [[sphincter]] opening is probably the cause of [[dysphagia]]. Increased [[Hypopharynx|hypopharyngeal]] [[pressures]] throughout [[swallowing]] are probably important in the [[pathogenesis]] of the [[diverticulum]].
 
# The [[Nemaline myopathy|nemaline]] bodies and red ragged fibers are usually the normal [[Cricopharyngeal muscle|cricopharyngeous]] findings, whereas the [[Zenker's diverticulum]] is characterized by [[adipose tissue]] [[Deposition (chemistry)|deposition]] and [[degeneration]] of the [[Fiber optic|fiber]] these structural modifications can impair the UES opening and dysphagia ensues.
Various [[hypothesis]] involved in the [[pathogenesis]] of the [[Zenker's diverticulum]] are as follows:<ref name="pmid1397879">{{cite journal |vauthors=Cook IJ, Gabb M, Panagopoulos V, Jamieson GG, Dodds WJ, Dent J, Shearman DJ |title=Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening |journal=Gastroenterology |volume=103 |issue=4 |pages=1229–35 |year=1992 |pmid=1397879 |doi= |url=}}</ref><ref name="pmid1283083">{{cite journal |vauthors=Cook IJ, Blumbergs P, Cash K, Jamieson GG, Shearman DJ |title=Structural abnormalities of the cricopharyngeus muscle in patients with pharyngeal (Zenker's) diverticulum |journal=J. Gastroenterol. Hepatol. |volume=7 |issue=6 |pages=556–62 |year=1992 |pmid=1283083 |doi= |url=}}</ref><ref name="pmid1634178">{{cite journal |vauthors=Fulp SR, Castell DO |title=Manometric aspects of Zenker's diverticulum |journal=Hepatogastroenterology |volume=39 |issue=2 |pages=123–6 |year=1992 |pmid=1634178 |doi= |url=}}</ref><ref name="pmid12928096">{{cite journal |vauthors=Sasaki CT, Ross DA, Hundal J |title=Association between Zenker diverticulum and gastroesophageal reflux disease: development of a working hypothesis |journal=Am. J. Med. |volume=115 Suppl 3A |issue= |pages=169S–171S |year=2003 |pmid=12928096 |doi= |url=}}</ref><ref name="pmid7923848">{{cite journal |vauthors=Resouly A, Braat J, Jackson A, Evans H |title=Pharyngeal pouch: link with reflux and oesophageal dysmotility |journal=Clin Otolaryngol Allied Sci |volume=19 |issue=3 |pages=241–2 |year=1994 |pmid=7923848 |doi= |url=}}</ref><ref name="pmid11715923">{{cite journal |vauthors=Mulder CJ, Costamagna G, Sakai P |title=Zenker's diverticulum: treatment using a flexible endoscope |journal=Endoscopy |volume=33 |issue=11 |pages=991–7 |year=2001 |pmid=11715923 |doi=10.1055/s-2004-826106 |url=}}</ref><ref name="pmid5428852">{{cite journal |vauthors=Hunt PS, Connell AM, Smiley TB |title=The cricopharyngeal sphincter in gastric reflux |journal=Gut |volume=11 |issue=4 |pages=303–6 |year=1970 |pmid=5428852 |pmc=1411416 |doi= |url=}}</ref>
# Nineteen patients in the sample were found to have [[reflux]] and 20 had dysmotility. These findings suggest that [[pharyngeal]] pouches are not a purely localized [[incoordination]] of the [[Cricopharyngeal muscle|cricopharyngeal sphincter]] but are associated with a generalized [[esophageal]] [[muscle]] [[dysfunction]].
# [[Zenker's diverticulum]] is a disorder of diminished [[Upper esophageal sphincter|upper esophageal sphincter,]] incomplete [[sphincter]] opening is probably the cause of [[dysphagia]]. Increased [[Hypopharynx|hypopharyngeal]] pressures throughout [[swallowing]] are probably important in the [[pathogenesis]] of the [[diverticulum]].
# Acid reflux induces longitudinal [[esophageal]] shortening, which in turn increases the chance for the development of [[herniation]] between two spatially associated structures, the [[Pharyngeal|pharyngeal constrictors]] and [[Cricopharyngeus muscle|cricopharyngeus muscles]], leading to the development of [[Zenker's diverticulum|Zenker]] [[diverticulum]]
# The [[Nemaline myopathy|nemaline]] bodies and red ragged fibers are usually the normal [[Cricopharyngeal muscle|cricopharyngeous]] findings, whereas the [[Zenker's diverticulum]] is characterized by [[adipose tissue]] [[Deposition (chemistry)|deposition]] and [[degeneration]] of the [[Fiber optic|fiber]] these structural modifications can impair the UES opening and [[dysphagia]] ensues.
# The [[pharyngeal]] pouches are not a purely localized [[incoordination]] of the [[Cricopharyngeal muscle|cricopharyngeal sphincter]] but are associated with a generalized [[esophageal]] [[muscle]] [[dysfunction]].
# [[Acid reflux]] induces longitudinal [[esophageal]] shortening, which in turn increases the chance for the development of [[herniation]] between two spatially associated structures, the [[Pharyngeal|pharyngeal constrictors]] and [[Cricopharyngeus muscle|cricopharyngeus muscles]], leading to the development of [[Zenker's diverticulum|Zenker]] [[diverticulum]].
# [[Zenker's diverticulum]] is thought to result from disordered [[Motor coordination|coordination]] among the [[pharynx]] and [[upper esophageal sphincter]].  
# [[Zenker's diverticulum]] is thought to result from disordered [[Motor coordination|coordination]] among the [[pharynx]] and [[upper esophageal sphincter]].  
#* [[Manometry|Manometric]] studies of the upper esophagus were used in testing the [[hypothesis]] of [[dysmotility]] in the formation and growth of a [[Zenker's diverticulum]]; however, the data have provided conflicting evidence.  
#* [[Manometry|Manometric]] studies of the upper [[esophagus]] were used in testing the [[hypothesis]] of dysmotility in the formation and growth of a [[Zenker's diverticulum]]; however, the data have provided conflicting evidence.  
#* [[Manometry|Manometric]] studies show that resting [[upper esophageal sphincter]] strain is normal in some patients with [[Zenker's diverticulum]] and decreased in others. [[abnormal]] [[premature]] [[relaxation]] and [[contraction]] of the [[upper esophageal sphincter]] seen in some patients with [[Zenker's diverticulum]] may be accompanied with the aid of [[pharyngeal]] [[contractions]] against a closed [[sphincter]].  
#* [[Manometry|Manometric]] studies show that resting [[upper esophageal sphincter]] strain is normal in some patients with [[Zenker's diverticulum]] and decreased in others. Abnormal [[premature]] [[relaxation]] and [[contraction]] of the [[upper esophageal sphincter]] seen in some patients with [[Zenker's diverticulum]] may be accompanied with the aid of [[pharyngeal]] [[contractions]] against a closed [[sphincter]].  
#* This abnormality is thought by a few investigators to be the cause of Zenker's diverticulum, but not by others who have found normal upper sphincter relaxation.
#* This abnormality is thought by a few investigators to be the cause of Zenker's diverticulum, but not by others who have found normal upper sphincter relaxation.
# In summary, in-coordination of [[pharyngeal]] [[contraction]] and UES opening has also been variably demonstrated by some investigator.
# In summary, in-coordination of [[pharyngeal]] [[contraction]] and UES opening has also been variably demonstrated by some investigator.
'''Abnormal esophageal motility'''
* All the above-mentioned [[hypotheses]] lead to herniation within the [[Killian's dehiscence|Killian's triangle]], inclusive of disorders associated with altered [[Upper esophageal sphincter|UES]] function, unusual [[Esophageal motility disorder|esophageal motility]], esophageal [[shortening]].   
* All the above-mentioned [[hypotheses]] lead to herniation within the [[Killian's dehiscence|Killian's triangle]], inclusive of disorders associated with altered [[Upper esophageal sphincter|UES]] function, unusual [[Esophageal motility disorder|esophageal motility]], esophageal [[shortening]].   
* This leads to the creation of a sac with a narrow neck that can trap liquid and food, the distended sac may compress the [[cervical]] [[esophagus]].   
* This leads to the creation of a sac with a narrow neck that can trap liquid and food, the distended sac may compress the [[cervical]] [[esophagus]].   
* Impaired [[bolus]] passage leads to increases intrabolus pressure which leads to [[herniation]] in the [[Killian's dehiscence|Killian's triangle]].   
* Impaired [[bolus]] passage leads to increases intra-[[Bolus (digestion)|bolus]] pressure which leads to [[herniation]] in the [[Killian's dehiscence|Killian's triangle]].   
'''Role of acid reflux'''
* [[Acid]] [[reflux]] is thought to lead to increased [[spasm]] of the UES which in turn increases the [[Bolus|intrabolus]] pressures during [[swallowing]], given that [[swallowing]] is frequently distinct from episodes of [[acid reflux disease]].  
* [[Acid]] [[reflux]] is thought to lead to increased [[spasm]] of the UES which in turn increases the [[Bolus|intrabolus]] pressures during [[swallowing]], given that [[swallowing]] is frequently distinct from episodes of [[acid reflux disease]].  


=== Histopathological Findings: Zenker's diverticulum ===
==Gross Pathology==
On [[gross pathology]], [[esophageal diverticulum]] or a sac are characteristic findings of Zenker's diverticulum.


[[Image:Micro Zenker.jpg|400px|center|<br> Source:Librepathology<ref name="urlFile:Pharyngoesophageal diverticulum - alt -- very low mag.jpg - Libre Pathology">{{cite web |url=https://librepathology.org/wiki/File:Pharyngoesophageal_diverticulum_-_alt_--_very_low_mag.jpg |title=File:Pharyngoesophageal diverticulum - alt -- very low mag.jpg - Libre Pathology |format= |work= |accessdate=}}</ref>
==Microscopic Pathology==
<nowiki></gallery></nowiki>]]
On [[microscopic]] [[histopathological]] analysis, Zenker's diverticulum presents with the following findings:
*Psuedo [[diverticulum]]
*Only [[mucosa]] and [[submucosa]] present
*[[Chronic]] [[submucosal]] [[inflammation]]
*[[Epithelial]] [[atypia]] or [[dysplasia]]
*[[Squamous cell carcinoma]] of [[esophagus]] (in advanced cases)
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Latest revision as of 18:50, 6 February 2018

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Ajay Gade MD[2]]

Overview

Zenker's diverticulum (ZD) is thought to occur due to the result of motor abnormalities of the esophagus. A defect over the Killian's triangle, a point of weakness in the muscular wall of the hypopharynx results in ZD. Killian's triangle is surrounded by the cricopharyngeal sphincter and oblique fibers of the inferior constrictor of the pharyngeal muscle. It is considered a pseudodiverticulum as it includes only mucosa and submucosa. Chronic strain on the Killian's triangle leads to an evagination of the sphincter, which may be because of the high pressures caused by the food bolus in the course of swallowing and the abnormalities of the upper esophageal sphincter (UES). This failure to achieve adequate diameter for effective bolus clearance leads to a subsequent increase in the hypopharyngeal pressure gradient. Increased intra-bolus pressures found in patients with ZD can be secondary to impaired bolus passage combined with the gastroesophageal reflux disease (GERD) or as a result of the GERD. As the diverticulum enlarges, it may compress the pharyngoesophageal segment as well as increased stiffness and the intra-bolus pressure. Increased intra-bolus pressure is also increased in older patients who perform multiple swallows to achieve bolus clearance. Acid reflux is thought to lead to increased spasm of the UES which in turn increases the intra-bolus pressures during swallowing, given that swallowing is frequently distinct from episodes of acid reflux disease.

Pathophysiology

The pathophysiology of the Zenker's diverticulum is as follows:[1][2][3][4][5][6][7][8][9]

Killian's dehiscence

Chronic straining

Enlargement of Zenker's diverticulum

Hypotheses for mechanism of development of Zenker's diverticulum

Various hypothesis involved in the pathogenesis of the Zenker's diverticulum are as follows:[9][10][8][11][12][13][14]

  1. Zenker's diverticulum is a disorder of diminished upper esophageal sphincter, incomplete sphincter opening is probably the cause of dysphagia. Increased hypopharyngeal pressures throughout swallowing are probably important in the pathogenesis of the diverticulum.
  2. The nemaline bodies and red ragged fibers are usually the normal cricopharyngeous findings, whereas the Zenker's diverticulum is characterized by adipose tissue deposition and degeneration of the fiber these structural modifications can impair the UES opening and dysphagia ensues.
  3. The pharyngeal pouches are not a purely localized incoordination of the cricopharyngeal sphincter but are associated with a generalized esophageal muscle dysfunction.
  4. Acid reflux induces longitudinal esophageal shortening, which in turn increases the chance for the development of herniation between two spatially associated structures, the pharyngeal constrictors and cricopharyngeus muscles, leading to the development of Zenker diverticulum.
  5. Zenker's diverticulum is thought to result from disordered coordination among the pharynx and upper esophageal sphincter.
  6. In summary, in-coordination of pharyngeal contraction and UES opening has also been variably demonstrated by some investigator.

Abnormal esophageal motility

Role of acid reflux

Gross Pathology

On gross pathology, esophageal diverticulum or a sac are characteristic findings of Zenker's diverticulum.

Microscopic Pathology

On microscopic histopathological analysis, Zenker's diverticulum presents with the following findings:


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References

  1. ↑ Bizzotto A, Iacopini F, Landi R, Costamagna G (2013). "Zenker's diverticulum: exploring treatment options". Acta Otorhinolaryngol Ital. 33 (4): 219–29. PMC 3773964. PMID 24043908.
  2. ↑ Elbalal M, Mohamed AB, Hamdoun A, Yassin K, Miskeen E, Alla OK (2014). "Zenker's diverticulum: a case report and literature review". Pan Afr Med J. 17: 267. doi:10.11604/pamj.2014.17.267.4173. PMC 4191700. PMID 25309667.
  3. ↑ Achkar E (1998). "Zenker's diverticulum". Dig Dis. 16 (3): 144–51. PMID 9618133.
  4. ↑ Bergeron JL, Long JL, Chhetri DK (2013). "Dysphagia characteristics in Zenker's diverticulum". Otolaryngol Head Neck Surg. 148 (2): 223–8. doi:10.1177/0194599812465726. PMC 3752429. PMID 23128778.
  5. ↑ Westrin KM, Ergün S, Carlsöö B (1996). "Zenker's diverticulum--a historical review and trends in therapy". Acta Otolaryngol. 116 (3): 351–60. PMID 8790732.
  6. ↑ van Overbeek JJ (2003). "Pathogenesis and methods of treatment of Zenker's diverticulum". Ann. Otol. Rhinol. Laryngol. 112 (7): 583–93. doi:10.1177/000348940311200703. PMID 12903677.
  7. ↑ May JT, Padhya TA, McCaffrey TV (2011). "Endoscopic repair of Zenker's diverticulum by harmonic scalpel". Am J Otolaryngol. 32 (6): 553–6. doi:10.1016/j.amjoto.2010.11.009. PMID 21306794.
  8. ↑ 8.0 8.1 Fulp SR, Castell DO (1992). "Manometric aspects of Zenker's diverticulum". Hepatogastroenterology. 39 (2): 123–6. PMID 1634178.
  9. ↑ 9.0 9.1 Cook IJ, Gabb M, Panagopoulos V, Jamieson GG, Dodds WJ, Dent J, Shearman DJ (1992). "Pharyngeal (Zenker's) diverticulum is a disorder of upper esophageal sphincter opening". Gastroenterology. 103 (4): 1229–35. PMID 1397879.
  10. ↑ Cook IJ, Blumbergs P, Cash K, Jamieson GG, Shearman DJ (1992). "Structural abnormalities of the cricopharyngeus muscle in patients with pharyngeal (Zenker's) diverticulum". J. Gastroenterol. Hepatol. 7 (6): 556–62. PMID 1283083.
  11. ↑ Sasaki CT, Ross DA, Hundal J (2003). "Association between Zenker diverticulum and gastroesophageal reflux disease: development of a working hypothesis". Am. J. Med. 115 Suppl 3A: 169S–171S. PMID 12928096.
  12. ↑ Resouly A, Braat J, Jackson A, Evans H (1994). "Pharyngeal pouch: link with reflux and oesophageal dysmotility". Clin Otolaryngol Allied Sci. 19 (3): 241–2. PMID 7923848.
  13. ↑ Mulder CJ, Costamagna G, Sakai P (2001). "Zenker's diverticulum: treatment using a flexible endoscope". Endoscopy. 33 (11): 991–7. doi:10.1055/s-2004-826106. PMID 11715923.
  14. ↑ Hunt PS, Connell AM, Smiley TB (1970). "The cricopharyngeal sphincter in gastric reflux". Gut. 11 (4): 303–6. PMC 1411416. PMID 5428852.

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