Thalamic responsive neurostimulation signals and seizure semiology in pediatric patients

OBJECTIVE: To identify correlations between thalamic electroencephalographic (EEG) signal patterns and clinical seizure semiology in pediatric patients with drug-resistant epilepsy (DRE) treated with responsive neurostimulation (RNS). METHODS: We conducted a retrospective analysis of 14 pediatric patients (≤17 years old) with DRE who received thalamic RNS implants. EEG recordings from the RNS Patient Data Management System were reviewed and correlated with seizure semiology obtained from medical records and structured family interviews. Patterns between seizure types, EEG onset signals, and electrode placement were examined. RESULTS: Absence seizures were associated with bilateral 3 Hz delta spike-wave complexes in the centromedian (CM) nucleus. Drop seizures corresponded with bilateral hypersynchronous slow-to-fast gamma activity, primarily in patients with CM or anterior nucleus leads. Generalized tonic-clonic seizures exhibited the greatest variability, with gamma-to-delta transitions, synchronous gamma waves, or asynchronous slow-to-gamma patterns depending on whether leads were placed in the CM or pulvinar nuclei. These EEG patterns were consistent within nuclei, suggesting semiology-specific thalamic activity. SIGNIFICANCE: This study demonstrates that seizure onset EEG signals are nucleus- and semiology-specific in pediatric patients receiving thalamic RNS therapy. These findings highlight the CM nucleus's central role in seizure propagation and support individualized RNS programming based on EEG frequency signatures. While limited by sample size, this work provides early evidence that thalamic EEG biomarkers can inform more precise neuromodulation strategies for pediatric DRE.