Seizure-like activities in patients with head-up tilt test-induced syncope

The purpose of this study was to assess the prevalence and the characteristics of seizure-like activities during head-up tilt test (HUT)-induced syncope, in patients with suspected vasovagal syncope (VVS). We also evaluated the differences in hemodynamic parameters between patients with and without seizure-like activities. A total of 71 patients with suspected VVS, who showed syncope during HUT between October 2010 and May 2013, were analyzed. Electrocardiogram and hemodynamic parameters were continuously monitored during HUT. We also performed video recording of patients during HUT to identify eyeball deviation or seizure-like limb movements. In all, 47 patients (66.2%) showed seizure-like activities at the time of syncope during HUT, 14 patients presented eyeball deviation, without abnormal limb movements, and 33 patients showed abnormal limb movements, such as myoclonic or tonic-clonic activities, as well as eyeball deviation. Upon comparison of the 2 groups with or without seizure-like activities, patients showing seizure-like activities presented a significantly lower heart rate at the time of syncope in HUT (38.51 ± 16.81 vs 49.67 ± 20.12, P < .05). Also, upon comparison within patients showing seizure-like activities, the patients who showed abnormal limb movements with eyeball deviation demonstrated a significantly lower systolic blood pressure and cardiac output at the time of syncope (34.30 ± 12.24 vs 49.00 ± 14.14, P < .05; 0.58 ± 0.40 vs 1.32 ± 0.97, P < .05). Seizure-like activities were observed in high percentage in about 66% of patients during HUT-induced syncope. The occurrence of seizure-like activities was associated with more severe transient hemodynamic changes, such as lower heart rate, systolic blood pressure, and cardiac output at the time of the HUT-induced syncope.