Diseases of the esophagus (achalasia, GERD, esophagitis) - etiology, pathogenesis, and clinical manifestations.
Achalasia
Etiology
- Primary (idiopathic): Most common; degeneration of ganglion cells in the myenteric (Auerbach) plexus.
- Secondary: Chagas disease (Trypanosoma cruzi infection), diabetes mellitus, infiltrative malignancies.
Pathogenesis
- Loss of inhibitory neurons (NO and VIP-producing) in lower esophageal sphincter (LES) and esophageal body.
- LES fails to relax properly during swallowing → functional obstruction.
- Decreased peristalsis in distal esophagus → food stasis.
- Progressive dilation of proximal esophagus.
Clinical manifestations
- Dysphagia for both solids and liquids.
- Regurgitation of undigested food.
- Chest pain.
- Weight loss.
- Increased risk of aspiration and esophageal squamous cell carcinoma.
Gastroesophageal reflux disease (GERD)
Etiology
- Transient or permanent lower esophageal sphincter (LES) hypotension.
- Hiatal hernia.
- Obesity.
- Pregnancy (↑ intra- abdominal pressure).
- Delayed gastric emptying.
Pathogenesis
- LES incompetence → gastric contents reflux into esophagus.
- Acid and pepsin damage esophageal mucosa → inflammation.
- Chronic exposure → erosions, ulcerations, or metaplasia (Barrett’s esophagus).
Clinical manifestations
- Heartburn (burning retrosternal pain, often postprandial, worse on lying down).
- Regurgitation (sour taste).
- Dysphagia.
- Chronic cough, laryngitis, or asthma (due to microaspiration).
- In severe cases: odynophagia (painful swallowing), weight loss.