True about achalasia cardia, all except:
**Core Concept**
Achalasia cardia is a primary esophageal motility disorder characterized by the failure of the lower esophageal sphincter (LES) to relax, leading to difficulty in swallowing and regurgitation of food. This condition is often associated with a decrease in the amplitude of peristaltic waves and impaired esophageal emptying.
**Why the Correct Answer is Right**
Achalasia cardia is caused by the degeneration of the myenteric plexus, which is the nerve network that regulates the smooth muscle contraction and relaxation in the esophagus. The loss of these neurons disrupts the normal coordination of esophageal contractions, leading to the characteristic symptoms of achalasia. The decreased LES relaxation is a result of the impaired inhibitory neurotransmission mediated by nitric oxide and vasoactive intestinal peptide (VIP).
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as achalasia cardia is indeed characterized by the failure of the lower esophageal sphincter (LES) to relax.
**Option B:** This option is incorrect as the decreased LES relaxation is a hallmark of achalasia cardia, not an increased LES relaxation.
**Option C:** This option is incorrect as achalasia cardia is a primary esophageal motility disorder, not a secondary disorder caused by external compression.
**Clinical Pearl / High-Yield Fact**
Achalasia cardia is often associated with a characteristic "bird's beak" appearance on barium swallow studies, which is a result of the dilated esophagus and the narrow distal esophagus.
**Correct Answer: D.**