Dysphagia as a Complication of Posterior Fossa Surgery in Adults

Abstract

Dysphagia is a swallowing dysfunction and a known complication after posterior fossa surgery. It may lead to aspiration, dehydration, and malnutrition, all lifethreatening complications. Swallowing is a complex process that is activated in several phases, each involving both sensory and motor fibers. To understand the implications of dysphagia, we will briefly review the anatomy and physiology of the swallowing process. The first phase is the oral preparatory stage, or food mastication starting after the food is introduced into the mouth. This stage involves the trigeminal nerve that innervates the mastication muscles, the facial nerve that innervates the labial and buccinator muscles, and the hypoglossal nerve that innervates the tongue to move the food to the posterior teeth. This is followed by the oral stage, when the food is moved to the posterior part of the oral cavity, mainly controlled by the tongue (hypoglossal nerve). The third part is the pharyngeal stage, a reflex action that transports the food through the pharynx to the esophagus, but not to the nasopharynx or larynx that should be closed, thus protecting the airway from aspiration (mediated by cranial nerves IXeXI). The esophageal stage is a reflexive stage that transports the food by the esophageal peristaltic movement and relaxation of the lower esophageal sphincter (again, mediated by cranial nerves IXeXI). The posterior fossa is a small region containing the brain stem, cerebellum, and fourth ventricle and controls many vital functions, such as speech, hearing, movement, sensation, and swallowing. Expansion of a mass in the posterior fossa occurs at the expense of the normal structures in the region and may result in brain stem or cerebellar dysfunction. Less than 5% of all adult tumors originate in the posterior fossa, whereas approximately 50% of primary central nervous system tumors occurring in