Advanced Neurophysiological Biomarkers in Epilepsy Surgery

Background/Purpose: The aim of this study is to investigate two advanced neurophysiological biomarkers: (1) first, high frequency oscillations in invasive EEG, specifically fast ripples (FR, 250–500 Hz), which are known to occur in pathological brain tissue and have been shown to be strongly linked to epileptogenicity. (2) Second, high gamma (80–150 Hz) activity phase-locked to low-frequency invasive EEG discharges (PLHG) are explored.

Methods: This retrospective study included 21 children and adolescents with refractory epilepsy aged 5 to 18 years who were admitted to the telemetry ward at Great Ormond Street Hospital for Children for invasive EEG monitoring (15 SEEG, 6 subdural grid implantations). This study is the first to test the reproducibility of PLHG results in a pediatric cohort. Furthermore, this study tests the hypothesis that removal of FR-, PLHG- or a combination of biomarker-generating brain areas results in better surgical outcome compared to the current SOZ detection standards.

Results: The only combination of biomarkers improving outcome classification was the two-stage analysis of SOZ and FR together, which improved AUROC to 0.81. SOZ, PLHG, FR information alone as well as other combinations of biomarkers did not show any improvement in accuracy of outcome classification. They all showed close to random performances.

Conclusion: This study demonstrates that PLHG recruitment is reproducible in a cohort of pediatric patients. Compared to previous work, FR and PLHG do not have a localizing value, neither does the SOZ. Incorporation of PLHG or FR into the clinical practice needs further evaluation in this special group of patients.

Publication History

Article published online:
28 October 2021