Functional Esophageal Disorders comprise a diverse group of disorders involving esophageal skeletal or smooth muscle.
A. Motor disorders of esophageal skeletal muscle
Motor disorders of esophageal skeletal muscle result in defective swallowing and aspiration. Potential causes can be classified into five major subgroups: neurogenic, myogenic, structural, iatrogenic, and mechanical. Most causes of oropharyngeal dysphagia are not correctable surgically. However, when manometric studies demonstrate that pharyngeal contractions, although weak, are still reasonably well coordinated, cricopharyngeal myotomy can provide relief.
B. Motor disorders of esophageal smooth muscle
Motor disorders of esophageal smooth muscle can be subdivided into primary dysmotilities and disorders that involve the esophagus secondarily and produce dysmotility.
Achalasia is rare (1/100,000 population) but is the most common primary esophageal motility disorder. It typically presents between the ages of 35 and 45 years. Chagas disease, caused by Trypanosoma cruzi and seen primarily in South America, can mimic achalasia and produce similar esophageal pathology. Achalasia is a disease of unknown etiology, characterized by loss of effective esophageal body peristalsis and failure of the LES to relax with swallowing, resulting in esophageal dilatation. LES pressure is often (but not invariably) elevated. The characteristic pathology is alteration in the ganglia of Auerbach plexus.
Symptoms include progressive dysphagia, noted by essentially all patients; regurgitation immediately after meals (>70%); odynophagia (30%); and aspiration, with resultant bronchitis and pneumonia (10%). Some patients experience chest pain due to esophageal spasms.
The diagnosis is suggested by a chest x-ray, which often shows a fluid-filled, dilated esophagus and absence of a gastric air bubble. A barium esophagogram demonstrates tapering (“bird’s beak”) of the distal esophagus and a dilated proximal esophagus. The bird’s-beak deformity is not specific for achalasia and can be seen in any process that narrows the distal esophagus (e.g., benign strictures or carcinoma). Esophageal manometry is the definitive diagnostic test for achalasia. Characteristic manometric findings include the absence of peristalsis, mirror-image contractions, and limited or absent relaxation of the LES with swallowing. Endoscopy should be performed to rule out benign strictures or malignancy, so-called pseudoachalasia.
Medical treatment is aimed at decreasing the LES tone and includes nitrates, calcium channel blockers, and endoscopic injection of botulinum toxin (blocks acetylcholine release from nerve terminals) in the area of the LES.
Surgical treatment with a modified Heller esophagomyotomy has been shown to produce excellent results in 95% of patients, compared with only 65% achieving excellent results using forceful pneumatic bougienage (Gut 1989;30:299). Many esophageal surgeons favor extending the myotomy onto the stomach and a concomitant antireflux procedure with the esophagomyotomy to avoid the two major causes of operative failure: (1) an incomplete myotomy due to inadequate mobilization of the esophagogastric junction and (2) late stricture due to GER disease caused by the incompetent LES combined with the inability of the aperistaltic esophagus to evacuate refluxed material. Video-assisted thoracoscopic approaches have been tried, with early results showing a higher incidence of postoperative GER than with the open procedure (Ann Thorac Surg 1993;56:680). More recently, laparoscopic esophagomyotomy combined with a partial fundoplication has been reported, and it is rapidly being adopted by most centers as the primary surgical option
Vigorous achalasia is a term used to describe a variant of achalasia in which patients present with the clinical and manometric features of classic achalasia and diffuse esophageal spasm. These patients have spastic pain and severe dysphagia, likely because of residual disordered peristalsis ineffective in overcoming the nonrelaxed LES. Treatment is the same as for classic achalasia, except that consideration should be given to performing a longer esophagomyotomy (to the aortic arch). With relief of the obstruction caused by the nonrelaxing LES, the pain usually disappears.
Diffuse esophageal spasm is characterized by loss of the normal peristaltic coordination of the esophageal smooth muscle. This results in simultaneous contraction of segments of the esophageal body.
The primary symptom is severe spastic pain, which can occur spontaneously and at night. In addition, dysphagia, regurgitation, and weight loss are common.
The diagnosis is confirmed with esophageal manometry, which usually demonstrates spontaneous activity, repetitive waves, and prolonged, high-amplitude contractions. Characteristic broad, multipeaked contractions with or without propagation are seen, and normal peristaltic contractions also may be present. Intravenous injection with the parasympathomimetic bethanechol (Urecholine) can provoke pain and abnormal contractions.
Treatment with calcium channel blockers and nitrates can reduce the amplitude of the esophageal contractions but usually is not beneficial. Surgical treatment consists of a long esophagomyotomy, extending from the stomach to the aortic arch, and often a concomitant antireflux procedure. Nutcracker esophagus refers to a condition characterized manometrically by prolonged, high-amplitude peristaltic waves associated with chest pain that may mimic cardiac symptoms. Treatment with calcium channel blockers and long-acting nitrates has been helpful. Esophagomyotomy is of uncertain benefit.
Secondary dysmotility represents the esophageal response to inflammatory injury or systemic disorders, such as scleroderma, multiple sclerosis, or diabetic neuropathy. Inflammation can produce fibrosis, which can lead to loss of peristalsis and esophageal contractility. The most common cause of secondary dysfunction is the reflux of gastric contents into the esophagus.
Progressive systemic sclerosis, or scleroderma, produces esophageal manifestations in 60% to 80% of patients, and often the esophagus is the earliest site of GI involvement. It is characterized by atrophy of the smooth muscle of the distal esophagus, deposition of collagen in connective tissue, and subintimal arteriolar fibrosis. Normal contractions are present in the striated muscle of the proximal esophagus.
In a subset of patients with severe long-standing GER disease, erosive esophagitis and stricture formation occur as a result of the combination of an incompetent LES and poor esophageal emptying secondary to low-amplitude, disordered peristaltic contractions. Intensive medical treatment of the reflux is essential before operation. Most surgeons prefer a Collis gastroplasty and a Belsey antireflux procedure for these patients because of the presence of esophageal shortening and impaired peristalsis.