WASHINGTON, DC—Increased cerebral oxygenation occurred in a majority of generalized tonic–clonic seizures in a study of five patients who were monitored with transcutaneous regional cerebral oxygen saturation sensors, according to research presented at the 67th Annual Meeting of the American Academy of Neurology. This finding suggests increased cerebral blood flow could be noninvasively used to predict seizure occurrence, researchers said.
Brian D. Moseley, MD, Assistant Professor of Neurology at the University of Cincinnati Neuroscience Institute, and colleagues investigated whether generalized tonic–clonic seizures are marked by increases in cerebral oxygenation before the seizures occur, a possibility that prior fMRI and SPECT studies had suggested.
The researchers analyzed data from a previous study that demonstrated transcutaneous regional cerebral oxygen saturation sensors are feasible for use in patients undergoing video EEG monitoring. In the prior study, Dr. Moseley and colleagues monitored five patients with histories of generalized tonic–clonic seizures. Subjects were evaluated with continuous 30-channel scalp EEG and two oxygen saturation sensors placed on each side of the forehead. Readings were taken every four seconds and recorded by a Nonin Equanox Regional Oximeter.
Researchers calculated the mean cerebral oxygen saturation value for the one-hour epochs in the nonictal (ie, two hours prior to seizure onset) and preictal (ie, one hour prior to onset) periods. The occurrence and timing of regional oxygen saturation values in the preictal period that were three or more standard deviations from the mean oxygen saturation value that was calculated in the nonictal period were recorded. Seven seizures were recorded.
The average oxygen saturation value in the nonictal period was 75.6%. The oxygen saturation value increased to 76% in the preictal period. Four of the seven seizures (57.1%) were marked by at least three sequential oxygen saturation values in the preictal period that were three or more standard deviations greater than the mean nonictal oxygen saturation value. Three seizures (42.9%) were marked by sustained cerebral hyperemia for 15 or more consecutive readings. The researchers reported that increased cerebral blood flow was noted on average 18 minutes and 30 seconds before seizure onset, as measured by EEG, and resolved before the seizure began.
“If our findings are confirmed in larger studies of people with epilepsy, they could dramatically improve quality of life by allowing patients to take extra medication or other precautions when they receive warnings that a seizure is more likely to occur,” said Dr. Moseley. “One might imagine someone with epilepsy receiving a warning that they are at high risk of having a seizure while driving, allowing them to pull to the side of the road, stop their vehicle, and call for help. The potential of such technology to give people living with uncontrolled seizures renewed control over their lives and independence cannot be understated.”
Researchers only evaluated data recorded around the time of seizure.
—Jake Remaly