High Frequency Oscillation in Pediatric Epilepsy Surgery (HFO)

High Frequency Oscillation (HFO) on ElectroCorticoGraphy (ECoG) has been identified as a new biomarker for epileptogenic tissue. The purpose of this study is to see if epilepsy surgery guided by the combination of HFO on ECoG and standard clinical practice can result in a greater likelihood of seizure freedom, versus standard clinical practice alone, without HFOs.

Intra-operative electrocorticography (ECoG), based on interictal spike and spike patterns, is performed to optimize delineation of the epileptogenic tissue in the operating room during epilepsy surgery. Similarly, extra-operative electrocorticography is often recorded over days to weeks with intracranial grids and depth electrodes, when the epileptogenic zone is not clearly localized with non-invasive studies and/or with intra-operative ECoG. Surgical resection following extra-operative ECoG is then "tailored' by the seizure onset zone as the gold standard. High frequency oscillations have been identified as a more precise biomarker for epileptogenic tissue. The aim of this double-blind randomized surgical trial is to determine if HFO- tailored surgery combining HFOs and current standard of care, compared to current standard of care alone, will lead to a better seizure outcome.

A double-blinded randomized control trial including children with refractory focal epilepsy who undergo surgery with intra- or extra-operative electrocorticography. Surgery is tailored by HFOs and standard ECoG interpretation (spikes on intra-operative ECoG or seizure onset on extra-operative ECoG) (arm 1), or tailored by standard ECoG alone (arm 2). Informed consent will be obtained 1 to 7 days to up to 3 months prior to the day of surgery. Prior to surgery, the subject will be randomized into the cohort arms in a 1:1 ratio. Blinding of the clinical neurophysiologists and neurosurgeons for treatment allocation is not feasible because of the character of the intervention. Therefore, this is a double-blinded trial as subjects will be blinded to the cohort arm to minimize bias of the follow-up results. The treating neurologist will also be blinded.

Surgery is tailored by HFOs and standard ECoG interpretation (spikes on intra-operative ECoG or seizure onset on extra-operative ECoG) (arm 1).

We hypothesize that the strategy of incorporating HFO data to a standard ECoG-guided resection in pediatric epilepsy surgery will result in improved postoperative seizure outcome than the traditional approach.

The primary outcome measure is the number of patients seizure-free after surgery in the treatment arm of combined HFO and standard of care, compared to the number of patients seizure-free in the control arm of standard of care alone, at 1 year after surgery.

Inclusion Criteria: Age 0-21 years Refractory focal epilepsy Planned resective epilepsy neurosurgery Includes intraoperative or extraoperative electrocorticography with grids Planned resective epilepsy surgery approved by institutional surgery board Exclusion Criteria: Subjects undergoing non-resective neurosurgery Does not include intraoperative or extraoperative electrocorticography with grids Planned resective surgery is a hemispherectomy/hemispherotomy