Dysfunction of the Upper Esophageal Sphincter

Introduction

The cricopharyngeus muscle is the major component of the upper esophageal sphincter (UES). The cricopharyngeus muscle is innervated by the pharyngeal plexus, which is composed of contributions from the vagus and glossopharyngeal nerves. Increasing evidence suggests that contributions from the recurrent laryngeal nerve (RLN) also innervate the cricopharyngeus muscle. The origin of the parasympathetic innervation is vagal, whereas sensory branches are derived from the glossopharyngeal nerve. Sympathetic fibers arise from the superior cervical ganglion and also join the pharyngeal plexus.

In its normal resting state, the cricopharyngeus muscle is in tonic contraction. When a swallow occurs, the cricopharyngeus relaxes during pharyngeal contraction (mediated by the vagus nerve), and anterior-superior movement of the larynx opens the UES to allow passage of the bolus into the esophagus; the bolus itself causes further distention of the UES. Dysphagia related to dysfunction of the UES results from (1) failure of cricopharyngeal relaxation, which can be due to lack of vagal innervation or loss of the normal viscoelastic properties of the muscle; (2) discoordination between cricopharyngeal relaxation and pharyngeal contraction; or (3) weakness of the suprahyoid musculature with poor elevation (anterosuperior movement) of the laryngeal complex.

Cricopharyngeal myotomy is used for alleviating cricopharyngeal dysfunction caused by lesions of the central and peripheral nervous systems, which affect laryngeal and pharyngeal muscle activity and coordination, as well as for the treatment of postsurgical dysphagia.

One of the most widely recognized manifestations of UES dysfunction is Zenker’s diverticulum. Although the first description of a pharyngoesophageal diverticulum is attributed to Ludlow in 1769, this entity became known as Zenker’s diverticulum after it was described in Zenker and Ziemssen’s Krankheiten des Oesophagus, a landmark compilation of esophageal pathology published in 1877. Killian clarified the anatomic site of origin as the space between the inferior constrictor muscle and the cricopharyngeus muscle—hence its name Killian’s triangle. Zenker’s diverticulum is a pulsion diverticulum that forms in the muscular dehiscence of Killian’s triangle as the UES fails to open with pharyngeal contraction, thus raising pressure in the pharynx ( Fig. 46.1 ). Other areas of weakness have been identified and can lead to variations of the site of origin of the diverticulum (Killian-Jamieson and Lamier triangles). Failure of UES opening may be the result of failure of cricopharyngeal relaxation or weakness of laryngeal elevation.

The standard treatment of a Zenker’s diverticulum includes a myotomy of the UES, which may be combined with resection of the diverticulum through a left-sided cervical incision; however, other techniques are also in common use. Dohlman and Mattson described an endoscopic technique for cricopharyngeal myotomy that has been modified with the introduction of bivalved endoscopes to provide better exposure of the party wall between the diverticulum and esophagus (containing the cricopharyngeus muscle) and the use of lasers, staplers, and harmonic scalpels for its transection. Advances in endoscopic instrumentation enabled Collard and associates to perform the first esophagodiverticulostomy with an endoscopic stapler in 1993. This procedure involves endoscopic division of the cricopharyngeus muscle with marsupialization of the diverticulum into the pharyngoesophagus. Modification of the stapler as described by Lang and colleagues allows the division to extend as close as possible to the inferior aspect of the diverticulum. Alternative endoscopic approaches use the CO ₂ laser or the harmonic scalpel to divide the party wall between the esophagus and diverticulum.

Key Learning Points

• 1.

  History of dysphagia and confirmation of upper esophageal dysfunction with imaging are essential in the diagnosis of dysfunction of the UES.

• 2.

  Presence of normal or nearly normal pharyngeal function will optimize swallowing outcomes following cricopharyngeal myotomy.

• 3.

  Transcervical and endoscopic approaches are valid treatments for Zenker’s diverticulum and multiple factors should be considered in selecting the best approach for each patient.

Preoperative Period

Operative Period