FULL-LENGTH ORIGINAL RESEARCH
Focal resection of fast ripples on extraoperative intracranial EEG improves seizure outcome in pediatric epilepsy
Article first published online: 29 JUL 2011
Wiley Periodicals, Inc. © 2011 International League Against Epilepsy
Volume 52, Issue 10, pages 1802–1811, October 2011
How to Cite
Akiyama, T., McCoy, B., Go, C. Y., Ochi, A., Elliott, I. M., Akiyama, M., Donner, E. J., Weiss, S. K., Snead, O. C., Rutka, J. T., Drake, J. M. and Otsubo, H. (2011), Focal resection of fast ripples on extraoperative intracranial EEG improves seizure outcome in pediatric epilepsy. Epilepsia, 52: 1802–1811. doi: 10.1111/j.1528-1167.2011.03199.x
- Issue published online: 5 OCT 2011
- Article first published online: 29 JUL 2011
- Accepted June 13, 2011; Early View publication July 29, 2011
- Epileptogenic zone;
- Computerized analysis;
- Seizure onset zone;
- High-frequency oscillations
Purpose: High-frequency oscillations (HFOs), termed ripples at 80–200 Hz and fast ripples (FRs) at >200/250 Hz, recorded by intracranial electroencephalography (EEG), may be a valuable surrogate marker for the localization of the epileptogenic zone. We evaluated the relationship of the resection of focal brain regions containing high-rate interictal HFOs and the seizure-onset zone (SOZ) determined by visual EEG analysis with the postsurgical seizure outcome, using extraoperative intracranial EEG monitoring in pediatric patients and automated HFO detection.
Methods: We retrospectively analyzed 28 pediatric epilepsy patients who underwent extraoperative intracranial video-EEG monitoring prior to focal resection. Utilizing the automated analysis, we identified interictal HFOs during 20 min of sleep EEG and determined the brain regions containing high-rate HFOs. We investigated spatial relationships between regions with high-rate HFOs and SOZs. We compared the size of these regions, the surgical resection, and the amount of the regions with high-rate HFOs/SOZs within the resection area with seizure outcome.
Key Findings: Ten patients were completely seizure-free and 18 were not at 2 years after surgery. The brain regions with high-rate ripples were larger than those with high-rate FRs (p = 0.0011) with partial overlap. More complete resection of the regions with high-rate FRs significantly correlated with a better seizure outcome (p = 0.046). More complete resection of the regions with high-rate ripples tended to improve seizure outcome (p = 0.091); however, the resection of SOZ did not influence seizure outcome (p = 0.18). The size of surgical resection was not associated with seizure outcome (p = 0.22–0.39).
Significance: The interictal high-rate FRs are a possible surrogate marker of the epileptogenic zone. Interictal ripples are not as specific a marker of the epileptogenic zone as interictal FRs. Resection of the brain regions with high-rate interictal FRs in addition to the SOZ may achieve a better seizure outcome.