Abstracts

Patients diagnosed with mesial temporal lobe epilepsy (MTLE) were implanted with the RNS[trade] responsive neurostimulator as part of a larger multicenter feasibility study to assess safety and potential efficacy. This analysis examines the onset patterns and seizure frequency associated with lead type., 20 of 65 subjects enrolled in an RNS Investigation were diagnosed with intractable MTLE and are evaluated here. Hippocampal depth and/or temporal subdural leads were implanted chronically to monitor electrographic activity from and deliver stimulation to the presumed seizure onset region(s). Onset patterns were assessed via review of electrographic activity stored by the RNS; clinical response was evaluated by comparing seizure count over the most recent 84 days (post-implant) to an 84-day pre-implant baseline., Follow-up was 6 months to 2 years. There were no serious, unanticipated device-related adverse events.[table1]In most subjects implanted unilaterally, the earliest onsets were on the depth lead except in 2 cases, the onset appeared earlier in the subtemporal strip with rapid spread to the depth. In the bilateral cases, earliest onsets were observed on both leads.
Eighty percent of subjects had at least one depth lead. The most common onset patterns were alpha/beta (48% of depth onsets, 69% of strip onsets), 1-2 Hz spiking (44% of depth and 23% of strip onsets) and low-voltage fast activity (8% of depth and strip onsets)., Although the sample size of subjects with intractable MTLE is small, detection and stimulation provided by depth lead(s) was associated with a greater reduction in seizures than with strip electrodes alone. Depth electrodes may also be more sensitive than strip electrodes in detecting ictal spiking., (Supported by NeuroPace, Inc.)