Abstracts

Rationale: Cortical spreading depolarization (CSD) and spreading depression (SD) are associated with neuronal dysfunction, cell death, and seizure, but their association with seizures in chronic epilepsy is unknown. We sought to survey the feasibility of observing CSD waves in epilepsy patients undergoing long term stereoelectroencephaolography (sEEG) monitoring. Methods: Four patients with medically refractory epilepsy undergoing robotic SEEG electrodes implantation were consented for EEG and CSD monitoring. The signal of two leads was diverted using a splitter and simultaneously recorded by the Natus EEG Systems and the Moberg CNS Monitor with a DC-coupled amplifier for EEG and CSD respectively. With the exception of a cortical strip in one patient, all the leads recorded were depth electrodes. The Moberg utilized the following settings: sensitivity 100 uv / mm, low filter none and high filter 50Hz. A monopolar montage was selected with one of the electrode’s contact as a reference and a scalp ground. Results: The average number of depth electrodes implanted per patient was 14.16. One patient had also four cortical strips implanted through a single burr hole.  2 CSD were captured in one patient on a strip electrode and 13 CSD were captured in all four patients on depth electrodes. In the patient with both strip and depth electrodes, CSD events correlated between the two leads.11/12 seizures captured during the monitoring period were associated with CSD.  Two CSD were detected without apparent temporal association to radiographic seizure. Conclusions: sEEG is a feasible and effective way of monitoring CSD and SD.  Both CSD and SD are relevant biophysical phenomena to chronic epilepsy. Funding: None