An Immunohistochemical Study of the Myenteric Plexus in Idiopathic Achalasia

Background: Achalasia is a primary esophageal motor disorder characterized by degenerative changes of the myenteric plexus. The pathophysiologic abnormalities may be the final result of several intermeshing mechanisms, and more than one single factor may cause the motor abnormalities. Aims: To report our experience in investigating the myenteric plexus of achalasia patients undergoing esophagomyotomy. Patients and Methods: Tissue samples from 12 patients undergoing Heller myotomy for achalasia were evaluated and compared with esophageal tissue specimens from 7 controls. Enteric neurons and interstitial cells of Cajal (ICC) were assessed by immunohistochemical methods, and the presence of vasoactive intestinal polypeptide ergic fibers and of CD3(+) lymphocytes. The possible presence of herpesvirus was also assessed by immunohistochemistry, whereas that of papillomavirus was assessed by in-situ hybridization. Results: Compared with controls, achalasia patients displayed a significant decrease of both enteric neurons and ICC. Immunoreactivity for vasoactive intestinal polypeptide was completely absent in each patient. CD3 staining disclosed myenteric plexitis in 5 (42%) patients; no control patient had plexitis. All patients were completely negative for the presence of both herpes simplex virus and human papillomavirus. Conclusions: The enteric nervous system of the lower esophageal sphincter area is impaired in patients with idiopathic achalasia, and the abnormalities involve ICC and neurons in many patients. The triggering factors for these abnormalities are, however, still unknown.