Normal and disordered swallowing: new insights

Abstract

Swallowing is a complex sequence of integrated motor events which is programmed entirely within a 'pattern generator', the medullary swallow centre. The swallow is not a reflex but rather a programmed response which is only initiated given the right combination of cortical and peripheral sensory cues to the medulla. Interruption of these afferent pathways profoundly influences the ability to initiate a swallow. While the basic sequence of motor events that constitutes a swallow is constant, the temporal relationships among component events are modifiable according to the characteristics of the swallowed bolus. The pathophysiology of dysphagia can be categorized on the basis of dysfunction of one or more of seven broad mechanisms that make up the swallow: bolus preparation, lubrication, oral delivery, palatal closure, airway closure, pharyngeal propulsion and UOS opening. This mechanistic approach originates directly from the videoradiographic observations and provides a rational basis for treatment. Videoradiography is the single most valuable technique in the evaluation of oral pharyngeal dysphagia. Oesophagoscopy and laryngoscopy should be performed in most cases because small tumours in the region can mimic pharyngeal motor disorders and may be easily overlooked. Manometry is providing valuable physiological and pathophysiological information about swallowing but, as an adjunct to videoradiography, only provides additional important information in the minority of patients undergoing investigation.