Dysphagia

DEFINITION
Difficulty swallowing, resulting from the inability to prehend, form, and move a bolus of food through the oropharynx into the esophagus
Esophageal dysphagia is discussed under the topics Megaesophagus and Regurgitation.

PATHOPHYSIOLOGY
Swallowing difficulties can be caused by mechanical obstruction of the oral cavity or pharynx, neuromuscular dysfunction resulting in weak or uncoordinated swallowing movements, or pain associated with prehension, mastication, or swallowing.
Oral dysphagia refers to difficulty with the voluntary components of swallowing—prehending and forming a bolus of food at the base of the tongue
Pharyngeal dysphagia occurs when there is a malfunction of the involuntary movement of the food bolus through the oropharynx.
Cricopharyngeal dysphagia refers to abnormal movement of the food bolus from the pharynx through the cricopharyngeus muscle, caused by either failure of the cricopharyngeus to relax (cricopharyngeal achalasia) or asynchrony between pharyngeal contractions and cricopharyngeus opening (cricopharyngeal asynchrony).
Deglutition is coordinated by the swallowing center in the brainstem; sensory afferents are transmitted to the swallowing center by CNs V and IX.
Motor efferents responsible for swallowing are carried by CN V, VII, XII (prehension and mastication) and IX and X (pharyngeal contraction); disorders in any of these areas may result in dysphagia.