Efficacy of neuromodulation of the pulvinar nucleus for drug-resistant epilepsy

Objective: The pulvinar nucleus of the thalamus has extensive cortical connections with the temporal, parietal, and occipital lobes. Deep brain stimulation (DBS) targeting the pulvinar nucleus, therefore, carries the potential for therapeutic benefit in patients with drug-resistant posterior quadrant epilepsy (PQE) and neocortical temporal lobe epilepsy (TLE). Here, we present a single-center experience of patients managed via bilateral DBS of the pulvinar nucleus.

Methods: A single-institution retrospective review of five patients who underwent bilateral pulvinar DBS for drug-resistant TLE or PQE was performed. Stimulation parameters were adjusted monthly as needed, and side effects were monitored. The primary outcome was the percentage reduction in patient-reported seizure frequency in comparison to the preimplant baseline. The location of the active electrode contacts in relation to pulvinar thalami that produced the best seizure outcome was identified. Chronic sensing of the pulvinar local field potentials (LFPs) and circadian pattern of modulation of the LFP amplitudes were analyzed.

Results: Four patients (80%) experienced a >70% reduction in seizure frequency, whereas one patient had >50% reduction in seizure. Mean seizure reduction was 79% at a median follow-up of 13 months (range = 9-21 months). No significant side effects were noted. Of all the pulvinar subnuclei, stimulation of the medial pulvinar nucleus (MPN) produced the best seizure outcome in all patients except for two, in whom active contacts in the MPN but also in more lateral and inferior locations resulted in the most significant reduction in seizures. Chronic timeline data identified changes in LFP amplitude associated with stimulation and seizure occurrences.

Significance: In this first ever report on a series of patients undergoing bilateral pulvinar DBS for drug-resistant epilepsy, we demonstrate that stimulation of the pulvinar and in particular the MPN is a safe and viable option for patients with nonlesional PQE or TLE. The optimal target for stimulation and relative merits of open versus closed loop stimulation should be delineated in future studies.