Which statement describes the pathophysiology of achalasia during swallowing?

• A. The LES opens to allow bolus entry
• B. The LES fails to open during swallowing
• C. Peristalsis is absent but the LES opens
• D. The LES contracts to prevent reflux

Answer: (B)

Achalasia specifically disrupts the swallow at the level of the gastroesophageal junction. The lower esophageal sphincter fails to relax in response to a swallow because inhibitory neurons in the esophageal wall are lost. Normally, a swallowed bolus triggers the LES to relax and the esophageal body to propel the bolus into the stomach. In achalasia, the LES remains contracted and does not open, creating a functional obstruction at the opening to the stomach. With impaired or absent peristalsis in the esophagus, the bolus cannot pass efficiently, leading to difficulty swallowing liquids and solids and progressive dilation above the narrowed junction. So the statement that best describes the pathophysiology during swallowing is that the LES fails to open.