**Question:** POEM is done for which of the following diseases?

A. Gastroesophageal reflux disease (GERD)
B. Esophageal cancer
C. Achalasia
D. Esophageal stricture

**Core Concept:** Peroral endoscopic myotomy (POEM) is a minimally invasive endoscopic procedure used to treat specific esophageal motility disorders.

**Why the Correct Answer is Right:**

POEM is performed for the treatment of achalasia, a rare disorder characterized by the inability of the lower esophageal sphincter (LES) to relax, leading to impaired esophageal emptying. Achalasia results from damage to the lower esophageal sphincter and the underlying smooth muscle layers of the esophagus. In POEM, an endoscopist creates a myotomy (muscle-cutting incision) through the submucosal layer of the esophagus, effectively weakening the LES and allowing for proper emptying of the esophagus into the stomach.

**Why Each Wrong Option is Incorrect:**

A. Gastroesophageal reflux disease (GERD) is a condition characterized by the backflow of stomach contents into the esophagus, causing symptoms like heartburn and acid indigestion. GERD is not a suitable indication for POEM, as it aims to improve esophageal emptying, while GERD treatment focuses on reducing stomach acid production or strengthening the LES.

B. Esophageal cancer is a malignant tumor that affects the esophagus, and POEM is not a treatment for esophageal cancer. Instead, various surgical or chemoradiation therapies are employed for treating esophageal cancer.

C. Achalasia is the correct indication for POEM, as mentioned above. In contrast, POEM is not suitable for treating esophageal diseases associated with muscle contractions, such as gastroesophageal reflux or achalasia with concurrent conditions like cancer.

D. Esophageal stricture refers to a narrowing or constriction of the esophagus, often due to injury or inflammation. POEM is not a treatment for esophageal stricture, as it is designed to treat esophageal motility disorders like achalasia.

**Clinical Pearls:**

1. POEM is a minimally invasive procedure that allows for precise targeting and treatment, making it a valuable tool in managing esophageal motility disorders like achalasia.
2. In achalasia, the smooth muscle layers of the lower esophagus and LES do not relax, causing difficulty in swallowing and regurgitation of undigested food into the throat (odynophagia and regurgitation).
3. POEM is a modern surgical alternative to traditional open myotomy (Heller's surgery) for treating primary achalasia without the risks and complications associated with open surgery.