Bilateral thalamic responsive neurostimulation for multifocal, bilateral frontotemporal epilepsy: illustrative case

Patients with refractory, bilateral, multifocal epilepsy have few treatment options that typically include a combination of antiseizure medications (ASMs) and vagus nerve stimulation (VNS). A man in his 40s presented with epilepsy refractory to a combination of five ASMs plus VNS; he was still experiencing 7-10 seizures per week. His seizure network involved multiple foci in both frontal and temporal lobes. Bilateral depth electrodes were implanted into the centromedian/parafascicular (CM/PF) complex of the thalamus and connected to the responsive neurostimulation (RNS) system for closed-loop stimulation and neurophysiological monitoring.

The patient reported clear improvement in his seizures since the procedure, with a markedly reduced number of seizures and decreased seizure intensity. He also reported stretches of seizure freedom not typical of his preoperative baseline, and his remaining seizures were milder, more often with preserved awareness. Generalized seizures with loss of consciousness have decreased to about one per month. RNS data confirmed a right-sided predominance of the bilateral seizure onsets.

In this patient with multifocal, bilateral frontotemporal epilepsy, RNS of the CM/PF thalamic complex combined with VNS was found to be beneficial. The RNS device was able to detect seizures propagating through the thalamus, and stimulation produced a decrease in seizure burden and intensity.