Continuous ictal discharges with high frequency oscillations confined to the non-sclerotic hippocampus in an epileptic patient with radiation-induced cavernoma in the lateral temporal lobe.

Background: Intraoperative electrocorticography (iECoG) recording is recommended for treating cavernoma related epilepsy. However, "interictal" paroxysmal activities are generally recordable but are not always identical to the epileptogenic zone.

Case Description: We surgically treated a 15-year-old girl with drug-resistant epilepsy associated with radiation-induced cavernoma in the right lateral temporal lobe. iECoG revealed paroxysmal activities in the cortex around the cavernoma. Additionally, continuous subclinical "ictal" discharges with high-frequency oscillations (HFO), confined to the histologically non-sclerotic hippocampus, were recorded. Following additional hippocampectomy, a good seizure outcome was obtained.

Conclusion: iECoG and HFO analysis revealed high epileptogenicity in the non-sclerotic hippocampus of this patient.