Distribution characteristics and clinical implications of high-frequency oscillations in awake and sleep states for identification of epileptogenic zone in drug-resistant epilepsy patients
Objective To explore the distribution characteristics of high-frequency oscillations(HFOs)in different wakefulness states and to clarify their relationship to the epileptogenic zone.Methods A prospective inclusion of drug-resistant epilepsy patients treated at the Neurosurgery Center,Beijing Tiantan Hospital,Capital Medical University from January to June 2023.All patients underwent stereo-electroencephalogram(SEEG)monitoring.EEG recordings during wakefulness and non-rapid eye movement sleep(NREM)interictal periods were selected.HFO analysis was conducted using an automatic detection algorithm,classifying them into ripple(R)and fast ripple(FR).A comparative analysis of HFO discharge frequency and the number of high HFO discharge electrodes in the seizure onset zone(SOZ)and non-SOZ during wakefulness and sleep states was performed.Additionally,the spatial distribution of HFO and its relationship with the epileptogenic zone were observed.Results A total of 17 patients were included,with an average of 11.6± 0.5 electrodes implanted(range:8-14),100.1±4.2 effective contacts,and 18.0±2.2 SOZ contacts.Compared with that in the non-SOZ area,the frequency of R discharges in the SOZ during wakefulness(6.93±1.35 times/min vs.1.63±0.41 times/min)and sleep(12.13±1.65 times/min vs.3.52± 0.75 times/min)was significantly higher,with statistically significant differences(both P＜0.01).The frequency of FR discharges in the SOZ during wakefulness(5.29±1.92 times/min vs.0.14± 0.03 times/min)and sleep(6.05±1.71 times/min vs.0.30±0.07 times/min)was also significantly higher than in the non-SOZ area(both P＜0.05).The data above showed that the frequency of HFO discharges during sleep was generally higher than during wakefulness.In the SOZ,the frequency of R discharges during sleep was significantly higher than during wakefulness(P＜0.001),while the increase in FR discharge frequency was not significant(P=0.613).In the non-SOZ area,the frequencies of R and FR discharges during wakefulness and sleep were both increased with significant differences(all P＜0.05).Compared with wakefulness,the numbers of high discharge leads for R(13.06±2.27 vs.4.59±0.21)and FR(9.88± 1.70 vs.4.59±0.21)during sleep were significantly increased(both P＜0.01).SOZ leads with R distribution during wakefulness were 67.4±5.5％in the HFO distribution area and were 69.8±5.8％during sleep.For FR,it was 68.1±5.8％and 71.1±5.6％respectively.In wakefulness and sleep states,HFO in the SOZ leads was stably discharged.Conclusions SEEG monitoring shows that the frequency of HFO discharges in drug-resistant patients during sleep is significantly higher than during wakefulness.The distribution range of HFO during sleep is significantly increased.In wakefulness and sleep states,the SOZ area leads are mostly HFO frequently-bursting leads.the leads in the SOZ are mostly high-frequency HFO leads.The values of HFO during wakefulness and sleep in assisting the localization of the epileptogenic zone seem similar.
Drug resistant epilepsyStereo-electroencephalographyHigh-frequency oscillationsSeizure onset zoneLocalization
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