Vagus Nerve Stimulation versus Responsive Neurostimulator System in Patients with Temporal Lobe Epilepsy

Patients with medically refractory temporal lobe epilepsy (TLE) are candidates for neuromodulation procedures. While vagus nerve stimulation (VNS) was historically the procedure of choice for this condition, the responsive neurostimulation system (RNS) has come into favor for its more targeted approach. While both VNS and RNS have been reported as efficacious treatments for TLE, the outcomes of these 2 procedures have not been directly compared. This study aims to compare outcomes following VNS versus RNS for TLE.

We retrospectively reviewed the records of all patients with TLE who underwent VNS or RNS placement at our institution from 2003 to 2018. The primary outcome was change in seizure frequency. Other outcomes included Engel score, change in anti-epileptic medications, and complications.

Twenty-three patients met inclusion criteria; 11 underwent VNS and 12 underwent RNS. At baseline, the 2 groups were statistically similar regarding age at surgery, epilepsy duration, and preoperative seizure frequency. At last follow-up, both groups displayed reduced seizure frequency (mean reduction of 46.3% for the VNS group and 58.1% for the RNS group, p = 0.49). Responder rate, Engel score, and change in medications were statistically similar between groups. Compared to 0.0% of the VNS group, 13.3% of the RNS group experienced infection requiring re-operation.

Despite their different mechanisms, VNS and RNS resulted in similar response rates for patients with TLE. We suggest that VNS should not be excluded as a treatment for patients with medically refractory TLE who are not candidates for resective or ablative procedures.