Can Electrical Stimulation Replace Spontaneous Seizures in Epilepsy Surgery?

Seizures are often induced by electrical stimulation (stim seizures) during intracranial EEG (iEEG) evaluation for epilepsy surgery, but their value for localizing seizure generating tissue remains unclear. We compared 441 low-frequency (1 Hz) stim and spontaneous seizures in a multi-center cohort of 105 patients using a novel, state-of-the-art validated automated seizure mapping algorithm. We found that stim seizures recruit a smaller, more spatially restricted network than spontaneous seizures that overlaps with their onset and propagation. Stim seizures with habitual semiology exhibited onset zones indistinguishable from spontaneous seizures. Both clinically habitual and non-habitual stim seizure onset zones were rapidly recruited during spontaneous seizures, suggesting that they arise from hyperexcitable, epileptogenic, tissue. Stim seizures preferentially originated from pathological mesial temporal structures, especially in adult-onset epilepsy. We propose that stimulation mapping has potential to supplant recording spontaneous seizures, and hypothesize that the method may identify portions of epileptic networks susceptible to seizure recurrence after focal interventions.