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Clin Neurophysiol. 2016 Jan;127(1):129-142. doi: 10.1016/j.clinph.2015.04.053. Epub 2015 Apr 17.

The identification of distinct high-frequency oscillations during spikes delineates the seizure onset zone better than high-frequency spectral power changes.

Author information

1
Department of Neuropediatrics and Muscular Diseases, University Medical Center Freiburg, Germany.
2
Medical Physics, University Medical Center Freiburg, Germany.
3
Montreal Neurological Institute, McGill University, Canada.
4
Department of Child Neurology, Okayama University Hospital, Kita-ku, Okayama, Japan.

Abstract

OBJECTIVE:

Interictal high-frequency oscillations (HFOs, 80-500Hz) can predict the seizure onset zone (SOZ), but visual detection of HFOs is time consuming. Time-frequency analysis can reveal large high-frequency (HF) power changes (80-500Hz) associated with inter-ictal spikes. The present study determines how well the rate of HFOs and spike-related HF power changes were co-localized with SOZ.

METHODS:

We analyzed 583 channels (68 in the SOZ) sampled from 14 patients who underwent intracranial EEG recording. We determined if the rate of visually-marked HFOs and spike-related HF power changes differed between SOZ and non-SOZ.

RESULTS:

Significantly higher rates of HFOs were found in SOZ. The degree of spike-related HF power augmentation failed to differ between SOZ and non-SOZ, whereas that of post-spike HF power attenuation was significantly more severe in SOZ compared to in non-SOZ. Regions showing HFOs and large spike-related HF-changes showed a partial overlap in distribution in 7/14 patients.

CONCLUSIONS:

Strong HF augmentation during spikes and high HFO rates occurred over different brain locations. The rate of HFOs showed the best performance in identifying SOZ. Post-spike HF power attenuation may represent increased inhibition in these channels and should be investigated further.

SIGNIFICANCE:

Strong HF power changes during spikes and HFOs per se seem to reflect distinct phenomena.

KEYWORDS:

Epilepsy surgery; Fast ripple; Ripple; Seizure onset zone; Spikes

PMID:
25998203
DOI:
10.1016/j.clinph.2015.04.053
[Indexed for MEDLINE]

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