Abstracts

As part of a multicenter feasibility study with the primary endpoint of patient safety, patients with intractable partial onset seizures were implanted with a responsive neurostimulator system (NeuroPace RNS^TM). This continuously monitors and records ECoGs from depth/subdural electrodes and delivers electrical stimulation when ictal discharges are detected. A significant aspect of safety relates to the tolerability of multiple stimulations at or near an epileptogenic focus. Patients ages 18-65 with [underline][gt][/underline] 4 disabling, partial seizures/month for 3 consecutive months were implanted with the RNS system. Responsive stimulation (therapy) was enabled after surgery according to the IRB approved protocol. Each participant underwent test stimulation when therapy was enabled to ensure that acute stimulation was well tolerated. Although some received less, the maximum responsive stimulation current delievered to any patient was 12 mA. Adverse events (AEs) were assessed throughout the study. The number of stimulations per day was recorded for each subject. Data is current as of 5/3/2005. 13 subjects were enrolled at 3 Mayo Clinic sites (Phoenix AZ, Rochester MN, and Jacksonville FL). 80 Aes of any nature were reported for these 13 subjects, with no definite device related adverse events. 10 events were recorded as uncertain to be related to the device. One subject experienced eye blinking associated with stimulation but this habituated within minutes. Therapy was enabled in 11 subjects with a range of 48 to 260 days (mean 142.8). Therapies per day ranged from 136.8 to 592 (mean 345.6). The maximum total duration of stimulation received over 24 hours was 1.7 minutes.[table1] The RNS system has been implanted in 13 subjects with no definite device related adverse events. Responsive stimulation was activated in 11 subjects at both cortical and subcortical locations near seizure focii, and was well tolerated in all. Despite delivery of multiple stimulations per day, total daily stimulation duration ranged from seconds to 2 minutes. In this small sample, there were no differences in numbers of stimulations delivered according to the anatomic location of treatment. This feasibility data suggests that responsive stimulation is well tolerated, even when delivered hundreds of times each day at or near an epileptogenic focus. (Supported by NeuroPace, Inc.)