Motor obstruction caused by hypertensive lower esophageal sphincter (LES), incomplete relaxation of LES, or loss of peristalsis in smooth-muscle portion of esophagus. Causes include the following: primary (idiopathic) or secondary due to Chagas' disease, lymphoma, carcinoma, chronic idiopathic intestinal pseudoobstruction, ischemia, neurotropic viruses, drugs, toxins, radiation therapy, postvagotomy.

EVALUATION
Chest x-ray shows absence of gastric air bubble. Barium swallow shows dilated esophagus with distal beaklike narrowing and air-fluid level. Endoscopy is done to rule out cancer, particularly in persons >50 years. Manometry shows normal or elevated LES pressure, decreased LES relaxation, absent peristalsis.

TREATMENT
Pneumatic balloon dilatation is effective in 85%, with 3-5% risk of perforation or bleeding. Injection of botulinum toxin at endoscopy to relax LES is safe and effective, but effects last only ~12 months. Myotomy of LES (Heller procedure) is effective, but 10-30% of pts develop gastroesophageal reflux. Nifedipine, 10-20 mg, or isosorbide dinitrate, 5-10 mg S/L ac, may avert need for dilatation or surgery. Sildenafil may also augment swallow-induced relaxation of the LES.