Long-term outcomes of responsive neurostimulation in dominant-hemisphere Rasmussen encephalitis

Area of Science:

• Neuroscience
• Neurology
• Epileptology

Background:

• Rasmussen encephalitis (RE) is a rare, immune-mediated disorder causing progressive brain dysfunction and intractable epilepsy.
• Epilepsia partialis continua (EPC) is a particularly disabling seizure type in RE.
• Hemispheric disconnection offers seizure control but carries significant functional risks, especially in dominant hemisphere involvement.

Purpose of the Study:

• To evaluate the efficacy and safety of responsive neurostimulation (RNS) in a pediatric patient with dominant-hemisphere RE and refractory EPC.
• To assess RNS as an alternative to surgical disconnection in a patient with high functional risk.

Main Methods:

• A 13-year-old male with drug-resistant RE and EPC underwent off-label RNS implantation.
• Intracranial EEG and fMRI guided electrode placement in the left perisylvian region.
• RNS therapy was initiated, and outcomes were monitored over 30 months, including seizure frequency, functional status, and adverse events.

Main Results:

• RNS significantly reduced EPC burden by over 50%, decreasing long episodes from 4000-6000/day to ~600/day.
• Cognitive, speech, and motor functions remained stable throughout the treatment period.
• No device- or stimulation-related adverse effects were observed, even with concurrent immunosuppressive therapy.

Conclusions:

• Responsive neurostimulation provides meaningful seizure reduction and functional stabilization in RE patients unsuitable for hemispheric disconnection.
• RNS serves as a valuable biomarker for monitoring epileptiform activity and guiding therapy.
• Neuromodulation, including RNS, represents a promising and evolving strategy for managing refractory EPC in RE, particularly in dominant hemisphere cases.