More Is More: Potential Benefits of Characterizing High-Frequency Activity Over Long Durations

Abstract

Variability in the Location of High-Frequency Oscillations During Prolonged Intracranial EEG Recordings Gliske SV, Irwin ZT, Chestek C, et al. Nat Commun. 2018;9(1):2155. doi:10.1038/s41467-018-04549-2. PMID: 29858570. The rate of interictal high-frequency oscillations (HFOs) is a promising biomarker of the seizure onset zone, though little is known about its consistency over hours to days. Here, we test whether the highest HFO-rate channels are consistent across different 10-minute segments of electroencephalography during sleep. An automated HFO detector and blind source separation are applied to nearly 3000 total hours of data from 121 subjects, including 12 control subjects without epilepsy. Although interictal HFOs are significantly correlated with the seizure onset zone, the precise localization is consistent in only 22% of patients. The remaining patients have one intermittent source (16%), different sources varying over time (45%), or insufficient HFOs (17%). Multiple HFO networks are found in patients with both one and multiple seizure foci. These results indicate that robust HFO interpretation requires prolonged analysis in context with other clinical data, rather than isolated review of short data segments.