High Frequency Oscillations in the Ripple Band (80–250 Hz) in Scalp EEG: Higher Density of Electrodes Allows for Better Localization of the Seizure Onset Zone
- 136 Downloads
High frequency oscillations (HFO) are known as markers of epileptic areas in intracranial EEG and possibly scalp EEG. We compared distributions of HFO in the ripple band (80–250 Hz) in intracranial and scalp EEG with either a conventional 10–20-montage (10–20-EEG) or a high density recording using 128 electrodes (HD-EEG). HFO were visually identified, in all intracranial EEG channels (80–500 Hz) and all channels of the 10–20-EEG (scalp EEG 80–250 Hz). For the HD-EEG, HFO were analyzed in regions of interest using areas with HFO as seen on the 10–20-EEG as well as areas in the clinically-defined seizure onset zone (SOZ). 13 patients were included in the study, of whom 12 showed HFO in the ripple band. In 8 patients HD-EEG revealed additional regions of ripples compared to the 10–20-EEG. With HD-EEG, areas of highest ripple rates were corresponding between scalp and intracranial EEG in 7 patients (58%) and 8 (67%) patients showed highest ripple rates over the SOZ. In contrast, with 10–20-EEG only 2 patients (17%) had corresponding areas of highest ripple rates and only 3 patients (23%) showed highest ripple rates over the SOZ. HD-EEG proved to be better to identify scalp HFO in the ripple band compared to standard 10–20-EEG. Moreover, ripples in 10–20-EEG seem to lead to false localization of epileptic areas. In contrast ripples detected with HD-EEG were located over the seizure onset zone and maybe a promising tool to localize epileptic tissue in the future.
KeywordsRefractory epilepsy High frequency oscillations Epilepsy surgery Spikes Seizure onset
High frequency oscillation
Magnet resonance tomography
Region of interest
Seizure onset zone
JJ was supported by a Grant of the German Research Foundation (JA1725/2-1).
Compliance with Ethical Standards
Conflict of interest
None of the authors have potential conflict of interest to be disclosed.
- Dümpelmann M, Jacobs J, Kerber K, Schulze-Bonhage A (2012) Automatic 80-250Hz “ripple” high frequency oscillation detection in invasive subdural grid and strip recordings in epilepsy by a radial basis function neural network. Clin Neurophysiol Off J Int Fed Clin Neurophysiol 123:1721–1731. https://doi.org/10.1016/j.clinph.2012.02.072 CrossRefGoogle Scholar
- Engel JJ, Van Ness PC, Rasmussen TB, Ojemann LM (1993) Outcome with respect to epileptic seizures. In: Engel J Jr (ed) Surgical treatment of the epilepsies, 2nd edn. Raven Press, New York, pp 609–621Google Scholar
- Jacobs J, Vogt C, LeVan P et al (2016) The identification of distinct high-frequency oscillations during spikes delineates the seizure onset zone better than high-frequency spectral power changes. Clin Neurophysiol 127:129–142. https://doi.org/10.1016/j.clinph.2015.04.053 CrossRefPubMedGoogle Scholar
- Lu Y, Yang L, Worrell GA, He B (2012) Seizure source imaging by means of FINE spatio-temporal dipole localization and directed transfer function in partial epilepsy patients. Clin Neurophysiol Off J Int Fed Clin Neurophysiol 123:1275–1283. https://doi.org/10.1016/j.clinph.2011.11.007 CrossRefGoogle Scholar
- Michel CM, Lantz G, Spinelli L et al (2004) 128-channel EEG source imaging in epilepsy: clinical yield and localization precision. J Clin Neurophysiol Off Publ Am Electroencephalogr Soc 21:71–83Google Scholar
- Rechtschaffen A, Kahles A (1968) A manual of standardized terminology, techniques and scoring system of sleep stages in human subjects. Brain Information Service/Brain Research Institute, University of California, Los AngelesGoogle Scholar
- Zschocke S, Hansen H-C (eds) (2011) Klinische Elektroenzephalographie, 3rd edn. Springer, New YorkGoogle Scholar