Endoscopic injection of which toxin is used in the treatment of achalasia?

• A. Botulinum toxin
• B. Tetanus toxin
• C. Diphtheria toxin
• D. Hyaluronidase

Answer: (A)

Achalasia involves impaired relaxation of the lower esophageal sphincter. Endoscopic injection of botulinum toxin relaxes the LES by blocking acetylcholine release from nerve endings to the smooth muscle. Botulinum toxin cleaves SNARE proteins, preventing vesicle fusion and acetylcholine release, which lowers LES pressure and improves passage of food from the esophagus into the stomach. This approach is especially useful for patients who are high surgical or procedural risks, since the effect is temporary and injections may need to be repeated. Tetanus toxin and diphtheria toxin are primarily harmful toxins with no therapeutic role here, and hyaluronidase is an enzyme used to help spread injected substances but does not relax the LES.