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USMLE – Achalasia

Pathophysiology
1. Chronic, usually progressive, disorder of myenteric plexus of the esophagus
2. Lower esophageal sphincter does not relax with swallowing
3. Contractions are simultaneous and nonperistaltic in nature
4. Classified as primary (idiopathic) or secondary (if cause is known)

Signs and Symptoms
1. Regurgitation of undigested food
2. Dysphagia for both solids and liquids (worse if eating is hurried or patient is under stress)
3. Weight loss
4. Chest pain
5. Pulmonary aspiration
6. Difficulty belching

Characteristic Test Findings
1. Loss of gastric bubble on abdominal series
2. Air-fluid level in mediastinum (represents food in esophagus) on chest radiograph
3. Beak-like narrowing with proximal esophageal dilation on barium swallow
4. Increased resting pressure in esophagus
5. Normal or increased lower esophageal sphincter pressure
6. Defective swallow-induced relaxation of lower esophageal sphincter with CCK administration

Histology/Gross Pathology
1. Initial loss of inhibitory intramural neurons containing VIP and nitric oxide
2. Later in disease, decreased cholinergic neurons

Associated Conditions
1. Lyme disease
2. Lymphoma
3. Chagas’ disease
4. Gastric carcinoma involving the gastroesophageal junction
5. Viral infections
6. Eosinophilic gastroenteritis
7. Neurodegenerative diseases

Treatment
1. Short-term palliation (to increase relaxation of sphincter) with nitrates (nitroglycerin sublingually before meals), calcium channel blockers (nifedipine), and endoscopic botulinum injections
2. Balloon dilatation with mechanical tearing of muscle fibers (effective in 85% of patients)
3. Laparoscopic Heller myotomy (extramucosal excision of circular muscle layer) is treatment of choice

Tips for USMLE
1. Achalasia has simultaneous contractures of the esophagus – if amplitude is low, it is classic achalasia; if amplitude is large, it is vigorous achalasia
2. Normally, CCK stimulation causes lower esophageal sphincter to relax; in achalasia, CCK causes sphincter to contract
3. Achalasia and GERD are usually considered mutually exclusive
4. If lower esophageal sphincter does not relax or has increased pressure, think achalasia
5. If bird’s beak esophagus is mentioned, think achalasia
6. If the patient is a 34-year-old woman who develops increasing chest discomfort and difficult swallowing when she eats, who has vomited after eating 6 times in the past 2 weeks, and whose chest radiograph shows lung consolidation in the right upper and middle lung fields, think achalasia

Lillian Thompson By Lillian Thompson

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