Achalasia is best described as which physiological failure?

• A. Esophageal cancer
• B. Failure of the lower esophageal sphincter to relax due to lack of innervation
• C. Rapid relaxation of the LES causing reflux
• D. Peptic ulcer disease

Answer: (B)

Achalasia is a motility disorder where the normal relaxation of the lower esophageal sphincter during swallowing fails because the inhibitory neurons in the esophageal wall are lost. This lack of innervation means the LES remains tonically closed and cannot relax to allow food to enter the stomach, while the esophagus itself loses peristalsis. The result is a functional obstruction at the gastroesophageal junction with proximal dilation of the esophagus. This stems from degeneration of the myenteric (Auerbach) plexus and a deficiency of inhibitory neurotransmitters like nitric oxide and VIP. Clinically, patients have difficulty swallowing both liquids and solids, may regurgitate undigested food, and can lose weight. It’s not cancer, not peptic ulcer disease, and it’s the opposite of rapid LES relaxation—achalasias’ hallmark is failure of LES relaxation due to loss of innervation.