Motility Disorders Of The Pharynx And Esophagus
Clinical Manifestations
What are Bacteria?
Dysphagia (difficulty in swallowing) is the primary symptom of esophageal motor disorders. Its perception by the patient is a bal¬ance between the severity of the underlying abnormality causing the dysphagia, and the adjustment made by the patient in altering eating habits. Consequently, any complaint of dysphagia must include an assessment of the patient’s dietary history. It must be known whether the patient experiences pain, chokes, or vomits with eating: whether the patient requires liquids with the meal, is the last to finish, or is forced to interrupt a social meal; and whether he or she has been admitted to the hospital for food impaction. These assessments, plus an evaluation of the patient’s nutritional status, help to determine how severe the dysphagia is and evaluate the indications for surgical therapy.
A surgical myotomy is designed to improve the symptoms of dysphagia caused by a motility disorder. The results can profoundly improve the patient’s ability to ingest food, but rarely return the function of the foregut to normal. The principle of the procedure is to destroy esophageal contractility in order to correct a defect in esophageal motility, resulting in improvement but never a return to normal function. To use a surgical myotomy to treat the prob¬lem of dysphagia, the surgeon needs to know the precise functional abnormality causing the symptom. This usually entails a complete esophageal motility evaluation sometimes using compound light microscopes to evaluate tissue samples. A clear understanding of the physi¬ologic mechanism of swallowing, and determination of the motility abnormality, giving rise to the dysphagia, are essential for deter¬mining if surgery is indicated and the extent of the myotomy to be performed. Endoscopy is necessary only to exclude the presence of tumor (diagnosed with the use of compound light microscopes) or inflammatory changes as the cause of dysphagia.
Motility Disorders of the Pharyngoesophageal Segment
Disorders of the pharyngoesophageal phase of swallowing result from a discoordination of the neuromuscular events involved in chewing, initiation of swallowing, and propulsion of the material from the oropharynx into the cervical esophagus. They can be categorized into one or a combination of the following abnormal¬ities: (t) inadequate oropharyngeal bolus transport; (2) inability to pressurize the pharynx; (3) inability to elevate the larynx; (4) dis¬coordination of pharyngeal contraction and cricopharyngeal relax¬ation; and (5) decreased compliance of the pharyngoesophageal segment secondary to muscle pathology. The latter results in incomplete anatomic relaxation of the cricopharyngeus as well as the cervical esophagus.
Pharyngoesophageal swallowing disorders are usually congen¬ital or due to acquired disease involving the central and periph¬eral nervous system. This includes cerebrovascular accidents, brain stem tumors, poliomyelitis, multiple sclerosis, Parkinson’s disease, pseudobulbar palsy, peripheral neuropathy, and operative damage to the cranial nerves involved in swallowing. Muscular diseases such as radiation-induced myopathy, dermatomyositis, myotonic dystro¬phy, and myasthenia gravis are less common causes. Rarely, ex¬trinsic compression by thyromegaly, cervical lymphadenopathy, or hyperostosis of the cervical spine can cause pharyngoesophageal dysphagia.
Diagnostic Assessment of the Cricopharyngeal Segment
Abnormalities of pharyngoesophageal swallowing are difficult to assess with standard manometric techniques because of the rapidity of the oropharyngeal phase of swallowing, the movement of the gul¬let, and the asymmetry of the cricopharyngeus. Video- or cineradio¬graphy is currently the most objective test to evaluate oropharyngeal bolus transport, pharyngeal compression, relaxation of the pharyn¬ooesophageal segment, and the dynamics of airway protection dur¬ing swallowing. It readily identifies a diverticulum stasis of the contrast medium in the valleculae, a cricopharyngeal bar, and/or narrowing of the pharyngoesophageal segment. These are anatomic manifestations of neuromuscular disease, and result from the loss of muscle compliance in portions of the pharynx and esophagus composed of skeletal muscle.
Careful analysis of video- or cineradiographic studies combined with manometry using specially designed catheters and even the use of compound light microscopes can identify the cause of a pharyngoesophageal dysfunction in most situations.
Motility studies may demonstrate inadequate pha¬ryngeal pressurization, insufficient or lack of cricopharyngeal re¬laxation, marked discoordination of pharyngeal pressurization, cricopharyngeal relaxation and cervical esophageal contraction, or a hypopharyngeal bolus pressure suggesting decreased compliance of the skeletal portion of the cervical esophagus.
In many patients with cricopharyngeal dysfunction, including those with Zenker’s diverticulum, it has been difficult to consistently demonstrate a motility abnormality or discoordination of pharyngoesophageal events. The abnormality most apt to be present is a loss of compliance in the pharyngoesophageal segment manifested by an increased bolus pressure. Cook and colleagues have demonstrated an increased resistance to the movement of a bolus through what appears on manometry to be a completely relaxed cricopharyngeal sphincter. Using simultaneous manometry and videofluoroscopy with the use of specialized medical microscopes they showed that in these patients the cricopharyngeus is only partially relaxed; that is, the sphincter is relaxed enough to allow a drop of its pressure to esophageal baseline on manometry, but insuf¬ficiently relaxed to allow unimpaired passage of the bolus into the esophagus. This incomplete relaxation is due to a loss of compliance of the muscle in the pharyngoesophageal segment, and may be associated with a cricopharyngeal bar or Zenker’s divertic¬ulum. This decreased compliance of the cricopharyngeal sphincter can be recognized on esophageal manometry by a “shoulder” on the pharyngeal pressure wave, the amplitude of which correlates directly with the degree of outflow obstruction.
Increasing the diameter of this noncompliant segment reduces the resistance imposed on the passage of a bolus. Consequently, patients with low pharyngeal pressure (i.e., poor piston function of the phar¬ynx), or patients with increased resistance of the pharyngocervical esophageal segment from loss of skeletal muscle compliance, are improved by a pharyngocricocervical esophageal myotomy. This enlarges the pharyngoesophageal segment and reduces outflow re¬sistance. Esophageal muscle biopsy specimens from patients with Zenker’s diverticulum have shown histologic evidence of the restric¬tive myopathy in the pharyngoesophageal segment when examined under compound light microscopes. These findings correlate well with the observation of a decreased compliance of the upper esophagus demonstrated by videoradiography and the find¬ings on detailed manometric studies of the pharynx and cervical esophagus. They suggest that the diverticulum develops as a con¬sequence of the outflow resistance to bolus transport through the noncompliant muscle of the pharyngoesophageal segment.
The requirements for a successful pharyngoesophageal my¬otomy are (1) adequate oropharyngeal bolus transport; (2) the pres¬ence of an intact swallowing reflex; (3) reasonable coordination of pharyngeal pressurization with cricopharyngeal relaxation; and (4) a cricopharyngeal bar, Zenker’s diverticulum, or a narrowed pharyngoesophageal segment on videoesophagogram and/or the presence of excessive pharyngoesophageal shoulder pressure on motility study.
Zenker’s Diverticulum
In the past, the most common recognized sign of pharyngo¬esophageal dysfunction was the presence of a Zenker’s diverticu¬lum, originally described by Ludlow in 1769. The eponym resulted from Zenker’s classic clinicopathologic descriptions of 34 cases published in 1878. Pharyngoesophageal diverticula have been re¬ported to occur in 0.1 % of 20,000 routine barium examinations, and classically occur in elderly, white males. Zenker’s diverticula tend to enlarge progressively with time due to the decreased compliance of the skeletal portion of the cervical esophagus that occurs with aging.
Presenting symptoms include dysphagia associated with the spontaneous regurgitation of undigested, bland material, often inter¬rupting eating or drinking. The symptom of dysphagia is due initially to the loss of muscle compliance in the pharyngoesophageal seg¬ment, later augmented by the presence of an enlarging diverticulum. On occasion, the dysphagia can be severe enough to cause debili¬tation and significant weight loss. Chronic aspiration and repetitive respiratory infection are common associated complaints. Once sus¬pected, a barium swallow establishes the diagnosis. Endoscopy is usually difficult in the presence of a cricopharyngeal diverticu¬lum, and potentially dangerous, owing to obstruction of the true esophageal lumen by the diverticulum and the attendant risk of di¬verticular perforation.
