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

Rasmussen encephalitis (RE) is a rare, immune-mediated disorder characterized by drug-resistant focal epilepsy, progressive unilateral hemispheric dysfunction, and cognitive and motor decline, with epilepsia partialis continua (EPC) as a particularly disabling feature. Hemispheric disconnection can control seizures in up to 80% of cases but carries high risk of severe deficits, particularly in dominant-hemisphere involvement. Responsive neurostimulation (RNS) is FDA-approved for medically intractable focal epilepsy, but experience in RE-related EPC remains limited. We describe a 13-year-old right-handed male with dominant-hemisphere RE and refractory EPC. He failed 10 antiseizure medications, steroids, IVIG, and rituximab. MRI revealed left basal ganglia, mesial temporal, insular, and frontal hyperintensities; fMRI confirmed left hemispheric language dominance. Intracranial EEG localized seizure onset to the left perisylvian region. Hemispheric disconnection was declined due to functional risk, and off-label RNS therapy was pursued. Three cortical strip electrodes were implanted over the left posterior frontal convexity, with two connected to the device. Initial RNS recordings demonstrated near-continuous epileptiform discharges. Lead-to-lead stimulation reduced EPC propagation to the right shoulder and neck by > 50% over 30 months, though facial EPC persisted. Long episode burden decreased from 4000-6000/day to ~ 600/day. Cognitive, speech, and motor function remained stable. No device- or stimulation-related adverse effects occurred despite ongoing rituximab-induced immunosuppression. Initiation of cenobamate correlated with further reduction in long episodes. This case demonstrates that RNS can provide meaningful seizure reduction and functional stabilization in RE patients who are not candidates for hemispheric disconnection, while preserving cognition and language. RNS also allows longitudinal monitoring of epileptiform activity, offering an objective biomarker to guide therapy. Literature reports similarly show 50-75% seizure reduction with RNS, status epilepticus control, and stabilization of cognitive function, while other neuromodulation approaches-including chronic cortical stimulation, thalamic DBS, GPi and zona incerta stimulation, rTMS, tDCS, and VNS-also show promise. Overall, neuromodulation represents a feasible and evolving strategy for managing RE-related EPC, especially in dominant-hemisphere cases where conventional surgery carries high risk.