Zenker's diverticulum (ZD), also known as cricopharyngeal, pharyngoesophgeal or hypo pharyngeal diverticulum, is an acquired out pouching of the mucosal and sub mucosal layers (false diverticulum) originating from the pharyngoesophgeal junction. This diverticulum occurs dorsally at the pharyngoesophgeal wall between the inferior pharyngeal constrictor and the cricopharyngeal muscle, a region of relative weakness known as Killian's triangle or Killian's dehiscence. Zenker's diverticulum is a rare condition with a reported prevalence of 0.01-0.11% in the general population.
Zenker's diverticulum may cause dysphagia by two mechanisms: incomplete opening of the upper esophageal sphincter (UES) and extrinsic compression of the cervical esophagus by the diverticulum itself. The pathophysiology of Zenker's diverticulum involves altered compliance of the cricopharyngeal muscle and raised intrabolus pressure. Decreased compliance of the UES and failure to open completely for effective bolus clearance both lead to an increase in the hypo pharyngeal pressure gradient. Greater intrabolus pressures have been documented in patients with Zenker's diverticulum compared with an age-matched healthy population. Since these diverticula occur in the elderly, UES dysfunction and muscular weakness have been considered. Different open surgical techniques and trans oral endoscopic approaches have been described for the management of Zenker's diverticulum, although there is no consensus about the best option.
Zenker's diverticula typically present in middle aged adults and elderly individuals, especially during the seventh and eighth decades of life, with a 1.5-fold male predominance. There is a geographical variation in its occurrence, and Zenker's diverticulum is more frequent in northern Europe. The estimated annual incidence is 2 per 100,000 with prevalence between 0.01 and 0.11% 11. However, although Zenker's diverticula are the most common type that cause symptoms, its incidence and prevalence may be underestimated as many diverticula may remain clinically silent, and many elderly patients with small pouches and minimal symptoms may not seek medical advice. As Zenker's diverticulum is directly related to aging, the prevalence of Zenker's diverticulum is expected to increase due to the increased aging population.
The commonest symptoms of Zenker's diverticulum at presentation are dysphagia, regurgitation of undigested food, choking, chronic cough, halitosis, weight loss, and less commonly hoarseness. The most consistent sign, however, is dysphagia. Physical examination finding that is rarely seen is a swelling in the neck that my gurgle on palpation (Boyce's sign). In the reported cases, there is variable time of presentation, from onset to diagnosis, ranging from weeks to years. The patient presented with odynophagia and dysphagia initially to solid and later to fluids. Then he developed regurgitation of undigested food. There were complaints of weight loss but no signs of malnutrition. There was no palpable neck swelling on examination and the duration of symptoms at presentation was only one year.
Barium swallow is the most important diagnostic tool for dysphagia. Contrast video fluoroscopy allows constant monitoring of the swallowing mechanism which is valuable as single shot barium swallow may miss a small diverticulum. Barium suspension video fluoroscopy was done on this case and clearly demonstrated the presence of proximal esophageal pouch and absence of hiatus hernia or reflux esophagitis.
Zenker's diverticulum can be posterior, posterolateral, or lateral but the most common type is the posterior pulsion diverticulum. Many authors classify the lesion according to size, measured in craniocaudal dimension. The diameter up to 2 cm is categorized as small, 2-4 cm-medium and 4-6 cm-large. The diverticulum in this case was a posterior pulsion and was medium size (3.4 cm).
A barium swallow study is the mainstay in diagnosis of Zenker's diverticulum, which allows determination of its size and location, but careful endoscopic evaluation is mandatory to rule out malignancy.
Though it is widely accepted that the primary cause of a Zenker's diverticulum appears to be impaired relaxation of the upper esophageal sphincter, generating an abnormally increased pharyngeal intrabolus pressure, as corroborated by manometric investigations, Zenker's diverticulum is likely to be a multifactorial disorder. The noncompliant cricopharyngeal muscle shows structural changes in terms of histological reduction in muscle component combined with qualitative fiber alterations, increase in fibrotic tissue and significant increase of the collagen to elastin ratio. The aging process might play a role because of the loss of tissue elasticity and the decrease in muscle tone. This belief is reinforced by the evidence of rare familial cases in addition to geographical and racial differences, and further supported by the results of morphometric and anthropometric studies of the Killian's triangle showing that the dimension of the triangle correlates with anthropometric features. This might account for the geographical variations in incidence of Zenker's diverticulum and for its male predominance. Because gastro esophageal reflux contributes to cricopharyngeal dysfunction, a relation between gastro esophageal reflux disease and Zenker's diverticulum has finally been assumed, but never been consistently investigated.
The primary purpose of Zenker's diverticulum management is, to alleviate symptoms and to improve the quality of life in which it was achieved in our patient. Zenker's diverticulum is managed surgically either by open left cervical incision or minimally invasive endoscopic approach. Several surgical procedures have been reported: open diverticulectomy, rigid/flexible endoscopic diverticulotomy, diverticulopexy, diverticular inversion with or without myotomy, and myotomy alone. Endoscopic approach is gaining popularity due to its improved post-surgical morbidity of elderly patients. The open surgical approach showed multiple disadvantages compared to endoscopic interventions especially in elderly and debilitating patients. The postoperative complication of open surgical approach in the general population was slightly higher than the flexible endoscopic approach, and higher mortality rate of 0.6 versus 0.2% of endoscopic approach. However, endoscopic approach showed no consistent long-term outcome in the literature with general estimated success rate of 63 to 100% and recurrence rate between 0 and 33%. Recurrent nerve injury, wound infection, hospital stay and fistula formation showed to reduce with endoscopic approach while intraoperative bleeding, and esophageal mucosal injury increased. The patient was managed by flexible endoscopic diverticulotomy. There were no immediate or late post-operative complications.