Endoscopic injection therapy for achalasia and other esophageal motility disorders

Botulinum toxin (BT) injections have been proposed to treat achalasia and hypertensive esophageal motility disorders. They affect lower esophageal sphincter (LES) and esophageal muscle function by inhibiting acetylcholine release and thus preventing neuromuscular conduction. BT injection in the LES is effective to treat achalasia but the improvement is limited to few months. As a consequence, recent guidelines recommend BT in achalasia patients who are not good candidates for more definitive therapy with pneumatic dilation or myotomy. BT might be a good option for patients with esophago-gastric junction obstruction without a firm diagnosis of achalasia. However, response to BT injection is not predictive of response to a more invasive therapy. BT injection in both the LES and the esophageal body might have a short-term efficacy to relieve dysphagia in patients with diffuse esophageal spasm or nutcracker esophagus. Usually BT is administrated as 1 cc aliquots with 20 units of toxin per milliliter into the LES and/or the esophageal body for a total dose of 100 unit international. BT injections are usually safe. Moderate chest pain might be reported following the injection. Three cases of death were reported due to acute mediastinitis and pseudoaneurysm. Finally, there is a theoretical risk of increased difficulty to perform esophageal myotomy in patients who previously received BT therapy due to the potential risk of fibrosis.