Increased Cerebral Oxygenation Precedes Generalized Tonic Clonic Seizures (S14.002)

OBJECTIVE: To highlight that generalized tonic clonic seizures (GTCS) are marked by pre-ictal increases in cerebral oxygenation. BACKGROUND: Based on previous fMRI and SPECT studies, it has been suggested seizures may be preceded by increased cerebral blood flow. Recently, we demonstrated transcutaneous regional cerebral oxygen saturation (rSO2) sensors are feasible for use in patients undergoing video EEG monitoring. We reanalyzed our data to determine if seizures were consistently marked by increased cerebral oxygenation. DESIGN/METHODS: Patients with histories of GTCS were recruited into our IRB-approved study. All subjects were evaluated with continuous 30-channel scalp EEG and 2 rSO2 sensors placed on each side of the forehead. Data from the rSO2 sensors were recorded by a Nonin Equanox Model 7600 Regional Oximeter (Nonin, Plymouth, MN, U.S.A.). We calculated the mean rS02 value for the 1 hour epochs in the non-ictal (2 hours prior to seizure onset) and pre-ictal (1 hour prior to onset) periods. The occurrence and timing of rSO2 values in the pre-ictal period >=3 standard deviations (SDs) from the mean rSO2 value calculated in the non-ictal period were recorded. RESULTS: Five patients underwent monitoring, during which 7 primary/secondarily GTCS were captured. The mean rSO2 value in the non-ictal period was 75.6+/-5.7[percnt]. This increased to 76.0+/-6[percnt] in the pre-ictal period (Paired Samples T Test 2 tailed p=0.032). Four of the 7 GTCs (57.1[percnt]) were marked by at least 3 sequential rSO2 values in the pre-ictal period that were >=3 SDs greater than the mean non-ictal rSO2 value. Three GTCS (42.9[percnt]) were marked by sustained cerebral hyperemia for >=15 consecutive readings. CONCLUSIONS: Increased cerebral oxygenation occurred in a majority of recorded GTCS. This suggests increased cerebral blood flow could be noninvasively used to predict seizure occurrence. Study Supported by: Mayo Clinic Department of Neurology Research Committee. Device provided by Nonin Medical.