EEG in cough syncope.

In 17 patients with cough syncope, electroencephalograms showed normal interictal recordings in 12 patients, minimally abnormal recordings in 4, and a moderately abnormal recording in 1. Fourteen episodes of cough syncope (six patients) were recorded, with the EEGs showing diffuse theta and delta slowing during the episodes. These findings were similar to those seen during other types of syncope. Although eight patients had rhythmic or clonic-like movements during the episodes, no epileptiform activity was seen. The exact mechanism of cough syncope is not known, but the vigorous coughing probably increases CSF pressure enough to impair intracranial circulation, causing syncope due to cerebral ischemia.