Abstracts

Responsive neurostimulation with the RNS system is being investigated as a treatment for medically intractable partial onset seizures in a feasibility trial. Intractable epilepsy of unilateral or bilateral mesial temporal origin is a common syndrome. This analysis assessed safety and whether there is preliminary evidence for efficacy of treatment with the RNS neurostimulator in treating MTLE., Subjects were adults with unilateral or bilateral (MTLE) who did not have a suspected extrahippocampal seizure focus and no prior resective epilepsy surgery. Analyses included efficacy as a function of unilateral vs. bilateral hippocampal onset (using a permutation test), and correlation of demographic variables such as age at implant, onset age, gender, and etiology with efficacy (by determining the corresponding correlation coefficients and their significance using a t-statistic under the null hypothesis of no correlation). Efficacy was evaluated by measuring the percent change in total disabling seizures (TDS; consisting of SP motor, CPS, and GTC) with respect to baseline during two post-implant periods; the 84-days period beginning 28-days post-implant (EVAL), and the most recent 84-day period during which a patient could receive therapy (MR84D)., For the 18 patients (7 male), the average age at implant was 32 yrs (19-56 yrs), and the mean onset age was 18.6 yrs (0-46yrs). The mean follow-up time was 481 days (210-681 days). One anticipated serious adverse event was reported (depression) in a subject with bilateral leads; relationship to the RNS was uncertain. There were no device related serious adverse events. Subjects with bilateral leads experienced a 19% reduction in TDS during the EVAL period and 53% reduction during the MR84D period. Subjects with unilateral leads experienced a 31% reduction in TDS during the EVAL period and 43% reduction during the MR84D period. The difference in seizure response between unilateral and bilateral subjects was not significant (p =0.25). No correlation was observed between seizure response and subject age (p=0.96, r=0.014), onset age (p=0.56, r=-0.15), gender (p=0.52, r=0.16), or etiology (p=0.58, r=0.14)., Preliminary results suggest that responsive stimulation is safe and may have efficacy in treating seizures in patients with MTLE. Results also suggest that the RNS system may be a treatment option for patients with intractable bilateral MTLE for whom resective surgery is not an option., (Supported by NeuroPace, Inc.)