Introduction

After a traumatic brain injury (TBI) a wide range of swallowing disorders may occur. TBI associated with focal and diffuse cortical and brainstem damage may impair swallowing ability and lead to the development of dysphagia and aspiration (Morgan & Ward 2001). Dysphagia is defined as difficulty or discomfort with swallowing. Aspiration is defined as the entry of material into the airway below the level of the true vocal cords. The two terms are not synonymous as many patients with dysphagia do not aspirate; although, they are closely associated. Swallowing has four sequential coordinated phases which are summarized in the table and figure below.

Table: The Four Phases of Normal Swallowing (Platt, 2001)

Phase

Characteristics

Oral Preparatory Phase

Food in the oral cavity is manipulated, masticated and mixed with saliva in preparation for swallowing.  The back of the tongue controls the position of the food, preventing it from falling into the pharynx.

Oral Propulsive Phase

The tongue transfers the bolus of food to the pharynx, triggering the pharyngeal swallow.

Pharyngeal Phase

Complex and coordinated movements of the tongue and pharyngeal structures propel the bolus into the esophagus, while protecting the airway.

Esophageal Phase

Coordinated contractions of the muscles of the esophagus move the bolus through the esophagus towards the stomach.

 

Figure: The Phases of Swallowing