Headache of neurally mediated syncope

Background Neurally mediated syncope and migraine have a complex relationship. Aim The aim of this study was to investigate whether patients developing syncope in the laboratory would experience migraine. Methods Thirty-one consecutive patients were evaluated for precipitation of headache during head-up tilt (HUT)-induced syncope (reduction of systolic blood pressure [SBP] >20mmHg and prodromal symptoms with or without loss of consciousness). Autonomic functions were assessed using heart rate response to deep breathing (HRDB), Valsalva maneuver and HUT. Blood pressure and heart rate (via electrocardiography) were continuously monitored. Headache diagnosis was based on ICHD-3 criteria. Results Eighteen patients (58%) experienced syncope without headache and 13 (42%) had syncope and headache (SH). No difference was observed in time of syncope onset, reduction in SBP, Valsalva ratio, HRDB or tachycardia during initial 10minutes of HUT. Of the 13 SH patients, 11 (85%) had a past history of migraine. Two reported headache just before tilt, eight developed headache during tilt and three developed headache only after tilt. Headache resolved within 1-15 minutes in 10 out of 13 patients. No patient experienced migraine. Conclusions Syncope did not precipitate migraine. Headache during syncope may be due to cerebral hypoperfusion, and cerebral hyperperfusion may cause post-syncopal headache.