Epileptiform Discharges and High-Frequency Oscillations (HFOs) Aid in Identifying Seizure Location

Interictal spikes and high-frequency oscillations (HFOs) are promising biomarkers for identifying epileptogenic zones in refractory epilepsy. This study investigated their potential for localizing seizure sites in patients, regardless of antiepileptic drug (AED) use. Electrocorticography (ECoG) data were collected from three focal epilepsy patients in two states: on AEDs and off AEDs. Spikes and HFOs-classified as ripples (80-250 Hz) and fast ripples (250-500 Hz)-were automatically detected using custom algorithms. Spike propagation and co-occurring spikes with ripples were analyzed to identify pathological HFOs. On AEDs, an average of 398 spikes, 150 ripples, and 16 fast ripples were detected per patient, along with 48 spike propagation events and 198 pathological HFOs. Off AEDs, these numbers increased to 573 spikes, 199 ripples, 44 fast ripples, 86 propagation events, and 302 pathological HFOs. Spike sequences and pathological HFOs consistently showed the strongest correlation with seizure foci, both in terms of event rates and proximity to epileptogenic zones. Across an average of 143 electrodes and 22-minute recordings per patient, biomarkers derived from spike propagation and spike-HFO combinations demonstrated superior performance in identifying seizure locations compared to other measures. These findings highlight the potential of integrating spike and HFO analysis into automated workflows to enhance precision in epilepsy surgery, irrespective of AED status.Clinical Relevance- This study demonstrates that integrating spike propagation and pathological HFOs analysis enhances the precision of localizing seizure onset zones, offering a robust approach for guiding epilepsy surgery irrespective of antiepileptic drug status.