Abstracts

Rationale: Rationale: Approximately 30-40% of patients with epilepsy are refractory to medications. While many of these patients benefit from resective surgery, patients with seizure foci that primarily involve eloquent cortex are not considered to be surgical candidates due to the risk for post-operative neurological deficits. Responsive neurostimulation represents a new treatment option for these patients ≥18 years old with frequent and disabling partial onset seizures arising from 1 or 2 seizure foci. Data are presented for subjects treated with responsive stimulation in primary motor, visual, or language cortex while participating in clinical trials of a responsive neurostimulator. Methods: Methods: All subjects were participating in clinical trials of the RNS^® System. The percent change from baseline in the total disabling seizure rate was calculated for the most recent 3 months (84 days) of seizure diary data (last observation carried forward). The region treated with responsive stimulation was identified as primary motor cortex if subjects had simple partial motor seizures, had an onset either in the frontal or parietal lobe and received stimulation on one or more leads placed on the primary motor cortex. Subjects treated in visual cortex had seizure onsets exclusive to the occipital lobe(s). Finally, subjects were considered to be treated in language areas if leads were placed in the posterior superior temporal gyrus or had seizure onsets in primary language cortex (Wernicke's or Broca's areas). Results: Results: Primary Motor. Fifteen of 191 subjects had one or more leads in primary motor cortex and received responsive therapy on those leads during the analysis window. The median percent change in seizures was -90% (range -100 to +4%). Two subjects were seizure-free. There were no serious adverse events relating to unintentional motor movements. Visual cortex. Four of 256 subjects were identified as having occipital onsets. These subjects had a change in seizures compared to baseline of -100%, -100%, -90%, and -36%. There were no serious adverse events related to positive or negative visual phenomenon. Language areas. Two of 256 subjects had onsets in Broca's area. One of these subjects had leads placed on the frontal and the other on the temporal lobe. These subjects experienced a -100% and a -46% change in seizures, respectively. Six additional subjects had leads placed on the posterior superior temporal gyrus. The change in seizures compared to baseline was ‑91%, -59%, -45%, -24%, -8%, and +229%. None of these subjects reported any language related serious adverse events. Conclusions: Conclusions: This is the first report of chronic ambulatory responsive neurostimulation in eloquent cortex. While the groups are small, the reduction in seizures was consistent with the overall response of patients with onsets in other brain areas. In addition, stimulation was delivered to primary motor cortex, visual cortex and language areas without reports of motor, visual or language related serious adverse events respectively.