Resection of individually identified high-rate high-frequency oscillations region is associated with favorable outcome in neocortical epilepsy
Abstract
ObjectivesHigh-frequency oscillations (HFOs) represent a novel electrophysiologic marker of endogenous epileptogenicity. Clinically, this propensity can be utilized to more accurately delineate the resection margin before epilepsy surgery.
Currently, prospective application of HFOs is limited because of a lack of an exact quantitative measure to reliably identify HFO-generating areas necessary to include in the resection. Here, we evaluated the potential of a patient-individualized approach of identifying high-rate HFO regions to plan the neocortical resection.
MethodsFifteen patients with neocortical seizure-onset zones (SOZs) underwent intracranial electroencephalographic monitoring. To identify interictal HFOs, we applied an automated, hypersensitive HFO-detection algorithm followed by post hoc processing steps to reject false detections.
The spatial relationship between HFO distribution and the SOZ was evaluated. To address high interpatient variability in HFO properties, we evaluated the high-rate HFO region, an unbiased statistical parameter, in each patient.
The relationship between resection of the high-rate HFO region and postoperative outcome was examined. ResultsGrouped data demonstrated that the rate of ripple (60-200Hz) and fast ripple (200-500Hz) was increased in the SOZ (both p<0.01).
Intrapatient analysis of the HFO distribution localized the SOZ in 11 patients. High-rate HFO regions were determined in all patients by an individually adjusted threshold.
Resection of high-rate HFO regions was significantly associated with a seizure-free outcome (p<0.01). The extent/ratio of SOZ or spiking region resection did not differ between seizure-free and seizure-persistent groups.
SignificanceIntrapatient analysis of high-rate HFOs provides more detailed description of HFO-generating areas and can mark the areas of clinically significant epileptogenicitya crucial component of the neocortical epileptic network that should be removed to achieve a good outcome.