Dysphagia is a disruption in the ability to move food or liquid from the mouth through the pharynx and esophagus into the stomach safely and efficiently. Swallowing disorders can occur at any point in the life span from infancy through old age. It is estimated that approximately 6,228,000 Americans over age 60 have dysphagia, and that it occurs in 32% of all patients in intensive care units. If untreated, dysphagia can result in dehydration, weight loss, malnutrition, pneumonia, and, in rare cases, death.
In order to understand dysphagia, it helps to understand the normal swallow. A normal swallow rapidly carries a bolus of food or liquid through the mouth, pharynx, and esophagus, leaving these structures substantially clear of residue at its completion. It involves a complex interaction of sensory stimuli and motor responses that encompass both voluntary and involuntary behaviors.
A normal swallow consists of four phases: the oral preparatory phase, the oral phase, the pharyngeal phase, and the esophageal phase.
The oral preparatory phase readies the food or liquid for swallowing. The lips close and seal to contain the material in the mouth. Solid food is chewed and mixed with saliva. The tongue gathers the liquid or solid material into a bolus and holds it. During this phase, the entry into the airway is open and nasal breathing continues.
The oral phase begins when the tongue starts to move the bolus backward toward the pharynx. It ends when the head of the bolus passes into the pharynx.
The pharyngeal phase begins when the bolus enters the pharynx and ends when it passes into the esophagus. In this phase, sensory stimuli interact with reflex and volitional movements to trigger the swallow response, which includes:
elevation and retraction of the soft palate to prevent material from entering the nose
elevation and forward movement of the hyoid and larynx, which moves them out of the path of the bolus as it travels downward, thus helping to prevent it from entering the airway below
closure of the larynx, which stops respiration momentarily and prevents the bolus from entering the airway below
retraction of the tongue base and contraction of the posterior pharyngeal wall, which build pressure to propel the bolus downward
progressive top to bottom contraction of the pharyngeal constrictor muscles, placing additional downward pressure on the bolus
opening of the pharyngoesophageal segment to allow the bolus to pass into the esophagus
The esophageal phase of the swallow begins when the bolus enters the esophagus and ends when it passes into the stomach. Muscular contractions push the bolus downward through the lower esophageal sphincter into the stomach.
Mary Boyle Ph.D., CCC-SLP, BC-NCD, The Gale Group Inc., Gale, Detroit,