[A case of swallow syncope associated with Parkinson disease]

A 73-year-old woman with Parkinson disease (PD) was admitted to our hospital because of aspiration pneumonia. She presented with recurrent episodes of loss of consciousness with bradycardia while swallowing solid foods or fluids. Upper endoscopy revealed a normal esophagus without hiatus hernia, cancer, diverticulum, stenosis, or achalasia. Balloon inflation at the cervical esophagus induced sinus arrest and bradycardia followed by a loss of consciousness. The diagnosis of swallow syncope (SS) was confirmed. Esophageal dilatation and an increase in the esophageal pressure induced by esophageal peristaltic disturbance associated with PD can cause SS by stimulating the vagal reflex. In addition, the head-up tilt test showed that she had orthostatic hypotension, and the coefficients of variations of the R-R intervals on electrocardiograms and the total number of beat-to-beat differences greater than 50 mseconds in the RR interval during a 24 hour ambulatory electrocardiogram were normal. The cardiovascular autonomic dysfunction characterized by the presence of sympathetic inhibition and a preserved parasympathetic function might be involved in the onset of SS. Permanent pacemaker implantation improved her clinical symptoms. The recognition of SS on the examination of a PD patient with loss of consciousness while eating is important, as PD patients might develop SS due to peristaltic disturbance and autonomic dysfunction caused by PD.