Primary esophageal motility disorders are characterized by abnormalities of esophageal peristalsis or contractions that interfere with swallowing and transit of food through the esophagus, producing symptoms of dysphagia and chest pain. The disorder is considered primary (idiopathic) when the cause of the patient’s symptoms and altered motility cannot be attributed to other systemic diseases (e.g., diabetes mellitus, scleroderma, amyloidosis, or neuromuscular disorders that affect striated muscle). The classic presentation is achalasia, a disorder characterized by failure of the lower esophageal sphincter (LES) to relax. There are several nonspecific esophageal motility disorders, including diffuse esophageal spasm (DES), nutcracker esophagus, ineffective esophageal motility (IEM), and other abnormalities of the LES. Whether these represent true disorders, a continuum of disease, or merely abnormal motility patterns that are associated with but not the physiologic causes of symptoms remains a controversy (Table 33-1). Lack of a meaningful classification system adds to this confusion. Current systems classify the disorder based on aberrant esophageal motility patterns documented on manometric studies in the context of dysphagia and pain that cannot be explained by other thoracic or cardiac disease. These systems fall short because the cause of most motility abnormalities is unknown. Patients can have abnormal manometric tracings and be perfectly healthy. Conversely, therapies may correct the abnormal tracing, but symptoms do not improve. Strategies for managing esophageal dysmotility disorders include conservative management, treatment with drugs and other agents, and surgery. In the sections that follow we review current knowledge about the pathophysiology of the primary esophageal motility disorders and recent advances in diagnosis and treatment.
Table 33-1CHICAGO CLASSIFICATION V3.0 FOR DIAGNOSIS OF ESOPHAGEAL MOTILITY DISORDERS
The normal human esophagus uses two sphincters to control the passage of food and prevent the reflux of stomach contents: the upper esophageal sphincter (UES) and the LES. The LES is often adversely affected in primary esophageal motility disorders. The normal LES is located in the most distal portion of the esophagus and acts as the barrier between the esophagus and the stomach. It has a resting pressure of 15 to 25 mm Hg, which is usually sufficient to prevent gastroesophageal reflux. The body of the esophagus is composed of layers of motor, mixed, and smooth muscle that contract and relax in a coordinated fashion during peristalsis. A normal swallow begins with the relaxation of the LES and initiation of a peristaltic wave that moves the food bolus through the entire esophagus, terminating at the gastroesophageal junction (GEJ), where the relaxed LES permits the food bolus to progress into the stomach. Immediately after the bolus passes, the sphincter resumes its contracted state, forming a barrier between the highly caustic stomach contents and the esophageal lumen (Fig. 33-1).