In normal adults esophageal lumen can distend up to a diameter of 4 cm. If esophagus can not distend more than 2.5 cm, there will be dysphagia for solid foods. If esophagus can not distend more than 1.3 cm (due to any cause) dysphagia is permanent feature. If any lesion in esophagus is present in whole circumference, presence of dysphagia is common in compare to lesion only in a portion of esophageal circumference, because the unaffected portion of esophagus retain its distensibility.
Esophageal dysphagia can also be divided into mechanical and motor causes. Common causes of esophageal dysphagia include carcinoma, stricture due to regurgitation of stomach acids (gastroesophageal reflux disease), benign growth etc. Abnormalities in peristalsis of esophagus and inhibition of deglutition due to diseases of the esophageal striated or smooth muscle may result in dysphagia.
Esophageal dysphagia due to mechanical causes:
- Defect in esophageal wall, such as congenital defect or due to tracheoesophageal fistula.
- Narrowing/stricture of esophagus: inflammation in esophagus may lead to narrowing. Inflammation may be due to infection by bacteria, virus (herpes simplex, varicella-zoster, and cytomegalovirus), fungus (candida), eosinophilia or it may be due to injury by heat (thermal injury), chemical injury or caustic injury. Tumors (benign as well as malignant tumors) can cause stricture of esophagus. Narrowing of esophagus may also result due to caustic, peptic, ischemic, inflammatory, postoperative, post radiation or drug induced causes.
- Extrinsic compression such as mass in posterior mediastinum, hematoma/fibrosis due to vagotomy or vascular compression due to right subclavian artery, right-sided aorta, left atrial hypertrophy, aortic aneurysm etc.
Esophageal dysphagia due to motor causes:
Disease in thoracic esophagus:
- Disorders of smooth muscles of esophagus: weak tone of LES (lower esophageal sphincter) or weak muscle contraction due to collagen vascular diseases (e.g. Scleroderma), visceral myopathy, drugs (such as anticholinergics, smooth muscle relaxants), metabolic neuromyopathy (due to alcohol, diabetes etc.) or de to idiopathic cases.
- Increased muscle contraction such as hypercontracting and hypertensive lower esophageal sphincter.
- Disorders of innervations may result in esophageal spasm, innervations disorder may be due to muscular lower esophageal ring or achalasia.
Disorders in cervical esophagus:
- The same problems that results in oropharyngeal dysphagia due to motor disorder can occur in esophageal motor problems in cervical esophagus also.