Which condition involves a constriction of the lower esophageal sphincter?

Achalasia is the condition characterized by a constriction of the lower esophageal sphincter (LES). In achalasia, the muscles of the esophagus fail to relax properly, which leads to difficulty in swallowing (dysphagia) and a backup of food in the esophagus. This condition occurs when the nerve cells in the esophagus become damaged, resulting in the LES becoming overly tight and preventing food from passing into the stomach.

This understanding of how achalasia affects the lower esophageal sphincter is crucial in differentiating it from other conditions. For instance, icterus refers to jaundice, a condition related to liver function and yellowing of the skin or eyes rather than esophageal constraints. Diverticular disease primarily involves the formation of pouches in the colon and does not pertain to the function of the lower esophageal sphincter. Diarrhea is a symptom experienced in various gastrointestinal disorders and does not directly relate to sphincter constriction. Thus, achalasia is specifically associated with the abnormal functioning of the lower esophageal sphincter.