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Ann Neurol. 2017 Aug;82(2):299-310. doi: 10.1002/ana.25006.

Very high-frequency oscillations: Novel biomarkers of the epileptogenic zone.

Author information

1
Brno Epilepsy Center, Department of Neurology, St Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czech Republic.
2
Central European Institute of Technology, Masaryk University, Brno, Czech Republic.
3
Institute of Scientific Instruments, Czech Academy of Sciences, Brno, Czech Republic.
4
International Clinical Research Center, St Anne's University Hospital, Brno, Czech Republic.
5
Brno Epilepsy Center, Department of Neurosurgery, St Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czech Republic.
6
Mayo Systems Electrophysiology Laboratory, Departments of Neurology and Physiology & Biomedical Engineering, Mayo Clinic, Rochester, MN.

Abstract

OBJECTIVE:

In the present study, we aimed to investigate depth electroencephalographic (EEG) recordings in a large cohort of patients with drug-resistant epilepsy and to focus on interictal very high-frequency oscillations (VHFOs) between 500Hz and 2kHz. We hypothesized that interictal VHFOs are more specific biomarkers for epileptogenic zone compared to traditional HFOs.

METHODS:

Forty patients with focal epilepsy who underwent presurgical stereo-EEG (SEEG) were included in the study. SEEG data were recorded with a sampling rate of 25kHz, and a 30-minute resting period was analyzed for each patient. Ten patients met selected criteria for analyses of correlations with surgical outcome: detection of interictal ripples (Rs), fast ripples (FRs), and VHFOs; resective surgery; and at least 1 year of postoperative follow-up. Using power envelope computation and visual inspection of power distribution matrixes, electrode contacts with HFOs and VHFOs were detected and analyzed.

RESULTS:

Interictal very fast ripples (VFRs; 500-1,000Hz) were detected in 23 of 40 patients and ultrafast ripples (UFRs; 1,000-2,000Hz) in almost half of investigated subjects (n = 19). VFRs and UFRs were observed only in patients with temporal lobe epilepsy and were recorded exclusively from mesiotemporal structures. The UFRs were more spatially restricted in the brain than lower-frequency HFOs. When compared to R oscillations, significantly better outcomes were observed in patients with a higher percentage of removed contacts containing FRs, VFRs, and UFRs.

INTERPRETATION:

Interictal VHFOs are relatively frequent abnormal phenomena in patients with epilepsy, and appear to be more specific biomarkers for epileptogenic zone when compared to traditional HFOs. Ann Neurol 2017;82:299-310.

PMID:
28779553
DOI:
10.1002/ana.25006
[Indexed for MEDLINE]

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