Abstract
Dysphagia may result from dysfunction of any of the components involved in the complex neuromuscular interaction of swallowing. Hyperfunction of any of the muscles involved in swallowing is a frequent cause of dysphagia. The cricopharyngeus muscle (CPM) is a key component of the upper esophageal sphincter. Cricopharyngeus muscle dysfunction (CPD) refers to the muscle's failure to appropriately and completely relax or expand during deglutition. A variety of disease processes may cause CPD and accurate diagnosis is paramount for appropriate treatment. In appropriately selected patients, intervention at the CPM may yield significant improvement in dysphagia. Interventions include nonsurgical, pharyngoesophageal segment dilatation, botulinum toxin (BoNT) injection, and criccopharyngeal myotomy. Injections of BoNT in patients with CPD have been reported to result in marked relief of dysphagia. Different techniques for instilling BoNT into the CPM have been described. Awake, in-office CPM BoNT injection with electromyography and/or fluoroscopic or ultrasound guidance is performed transcervically or via flexible endoscopy. Operative CPM BoNT injection involves rigid laryngoscopy and esophagoscopy with direct visualization of the CPM. BoNT should be prepared in low-volume, high-concentration dilutions to minimize the potential for undesired diffusion of the toxin. The effects of BoNT occur within weeks of injection and typically last up to 5 or 6 months.
