Zenker's diverticulum pathophysiology

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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

  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:

Source:Librepathology[15] </gallery>

Source:Librepathology[15] </gallery>


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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.
  15. "File:Pharyngoesophageal diverticulum - alt -- very low mag.jpg - Libre Pathology".

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