Effectiveness of perampanel for focal seizures determined by interictal gamma oscillation regularity analysis.

Although perampanel (PER) has received approval as an antiseizure medication, reports quantifying its antiseizure effects using electroencephalography (EEG) remain scarce. In a previous study, we demonstrated that the interictal high gamma oscillation regularity (GOR) on scalp EEG is an excellent marker of epileptogenicity. Herein, we investigated whether the antiseizure effect of PER could be quantified through interictal GOR analysis of scalp EEG data. To investigate this, we examined the interictal GOR from 20 s of scalp EEG data before and after PER administration collected from five patients with epilepsy with focal seizures. Prior to PER administration, each patient presented with localized areas with high GOR consistent with brain lesions or seizure semiology. In all patients, the seizures improved following PER administration, and the localized high GOR, which is considered an epileptogenic focus, disappeared. These results indicate that interictal GOR analysis may be a useful tool for the quantitative assessments of the antiseizure effects of PER in focal epilepsy. PLAIN LANGUAGE SUMMARY: This study explored whether perampanel (PER)'s antiseizure effects can be quantified using interictal high gamma oscillation regularity (GOR) analysis from scalp EEG data. Analyzing 20-second EEG segments before and after PER administration in five patients with focal epilepsy, we found that high GOR areas, indicative of epileptogenic foci, disappeared following PER administration. The results suggest that interictal GOR analysis could effectively quantify the antiseizure effects of PER.