Ronald S. Siegel, M.D.

Syncope, or the sudden transient loss of conscious-ness due to a decrease in cerebral perfusion, is a frequently seen event, caused either by peripheral vasodilatation or a decrease in cardiac output leading to a fall in systemic blood pressure. Underlying causes range from benign conditions to life-threat-ening diseases. These events are either neurally mediated (vasovagal syncope) or cardiogenic (arrhythmias, outflow obstruction) in origin. Syncope is estimated to account for up to 5% of acute medical hospital admissions and 3% of emergency room visits.¹ On occasion, syncope will present in an unusual form as illustrated by the following case.

Case Report

A 68-year-old female in her usual state of good health was observed to suddenly faint while standing at the sink, drinking a glass of milk. She was only briefly unconscious, and awakened within a few seconds with no sequelae. She was completely well until 3 months later when she had another syncopal episode while eating a bagel. She reported no warning signs prior to the event and had no sequelae, but did recall having several "light-headed" episodes while swal-lowing pills in the preceding 3 months. She denied any history of neurological disease, chest pain, palpi-tations, heart murmur, shortness of breath with exertion, or cough. She had no history of nausea, vomiting, gastroesophageal reflux, dysphasia, or odynophagia. Past medical history and family history were noncontributory. Her only medication was ator-vastatin. Physical examination was completely normal. Laboratory test results were within normal limits. Further studies including a barium swallow esophagram, esophageal motility testing and upper endoscopy were normal. In addition, an electrocardio-gram and a 24-hour Holter monitor were normal as well. She was treated with an anticholinergic medica-tion and has had no further syncopal episodes.

Discussion

Deglutition syncope, also known as swallow syncope, is an uncommon entity, although there are reports in the literature as early as 1958.² The typical description of the event includes dizziness, light-headedness, confusion and fainting during swallowing of food or liquids, without aura or warning signs. The food can be of any size, consistency or temperature. The episodes are usually intermittent and unpredictable, and frequently no etiology can be found. In a review of 204 patients with syncope, Kapoor et al³ found cardiovascular disorders accounted for 25%, non-cardiac disorders accounted for 25%, and 50% had no definable cause.

Although most reported cases have had no identifiable cause, numerous disorders of the esophagus have been reported with deglutition syncope including diffuse esophageal spasm,⁴ hiatal hernia,⁵ as well as esophageal diverticulum, esophageal cancer and achalasia.⁶ Cardiac abnormalities reported with swallow syncope include supraventricular tachyarrhythmias,⁷ complete atrioventricular block,⁸ and paroxysmal atrial fibrillation.⁹ Although the exact mechanism is unknown, esophageal stimulation during swallowing is thought to activate upper gastrointestinal cardiac-vasovagal reflexes resulting in sympathetic withdrawal and parasympathetic acti-vation leading to vasodilatation and bradycardia producing various cardiac arrhythmias.¹⁰

Any patient presenting with syncope during swallowing should have an esophagram, an esophageal motility study and an upper endoscopy, as well as an electrocardiogram and a Holter monitor study to assess for any correctable causes. Treatment should include avoiding any inciting food or beverage, as well as the use of anticholinergic medication. In selected cases, a pacemaker may be of benefit, although this has not been well studied.