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

Area of Science:

• Neurology
• Neurosurgery
• Epileptology

Background:

• Refractory epilepsy, particularly bilateral and multifocal forms, presents limited treatment avenues.
• Standard treatments include antiseizure medications (ASMs) and vagus nerve stimulation (VNS).
• A patient with severe, drug-resistant epilepsy continued to experience frequent seizures despite maximal medical and VNS therapy.

Purpose of the Study:

• To evaluate the efficacy of responsive neurostimulation (RNS) targeting the centromedian/parafascicular (CM/PF) complex of the thalamus in a patient with refractory epilepsy.
• To assess the potential of RNS for closed-loop stimulation and neurophysiological monitoring in managing complex seizure networks.

Main Methods:

• Bilateral depth electrodes were implanted into the CM/PF thalamic complex.
• The electrodes were connected to an RNS system for adaptive stimulation and data acquisition.
• The patient continued VNS therapy concurrently with RNS.

Main Results:

• The patient experienced a significant reduction in seizure frequency and intensity.
• Periods of seizure freedom were observed, which were atypical for the patient's baseline.
• Generalized seizures with loss of consciousness decreased substantially, and remaining seizures were milder with preserved awareness.
• RNS data indicated a right-sided predominance of seizure onsets.

Conclusions:

• Responsive neurostimulation of the CM/PF thalamic complex is a potentially beneficial adjunctive therapy for refractory multifocal epilepsy.
• The RNS system effectively detected seizure activity propagating through the thalamus.
• Thalamic RNS, in conjunction with VNS, demonstrated a notable decrease in overall seizure burden and severity.