Swallowing disorders in paralysis of the lower cranial nerves: a functional analysis

Deficits of the lower cranial nerves (nerves IX, X, XI, and XII) occurring after treatment of skull base tumors may cause disabling swallowing disorders. To assess the mechanisms of swallowing disorders involved in such cases, we performed functional examinations: a videoendoscopic swallowing study and simultaneous manometry and videofluoroscopy in 7 patients. This study shows that the main mechanism of the swallowing disorders was a disturbance of the pharyngeal stage, including a decrease of pharyngeal propulsion, reduced laryngeal closure, and cricopharyngeal dysfunction, which led to aspiration. Decreased pharyngeal propulsion was found in 6 patients, with a very high correlation between fiberoscopy and simultaneous manometry-fluoroscopy. The responsibility of the upper esophageal sphincter in swallowing disorders was more difficult to assess. The role of the upper esophageal sphincter and pharyngeal propulsion in the onset of the problem is discussed in regard to the cricopharyngeal myotomy.