LOCALIZATION OF ICTAL ONSET WITH DC-EEG
Abstract number :
C.05
Submission category :
Year :
2003
Submission ID :
1611
Source :
www.aesnet.org
Presentation date :
12/6/2003 12:00:00 AM
Published date :
Dec 1, 2003, 06:00 AM
Authors :
Sampsa Vanhatalo, John W. Miller, Mark D. Holmes, Michael Scherg, Juha Voipio, Kai Kaila Regional Epilepsy Center, Dept. Neurology, University of Washington, Seattle, WA; Department of Biosciences, University of Helsinki, Helsinki, Finland; MEGIS Software
Epileptic seizures involve EEG signals that are much below the conventional EEG bandwidth ([gt]0.5Hz). We developed a genuine DC-EEG technique for bedside recordings to asses the utility of slow ictal EEG responses (DC shifts) in determining the localization of seizure origin.
Over forty patients with focal epilepsy were examined using DC-EEG at bedside for up to several days during video-EEG recording for preoperative evaluation. Ictal slow EEG signals were analysed both visually and by using 3D-source localization tools.
We observed scalp negative DC shifts with amplitudes typically of up to several hundreds of microvolts at the vertex with a mastoid reference during seizures. 3D source localization demonstrated a focal onset of the DC shifts. Slow EEG signals enabled the identification of the site of seizure origin even in cases (eg. mesial temporal lobe onset) where standard scalp EEG yielded equivocal results.
Full-Bandwidth EEG recording with DC-EEG is feasible in a clinical environment (bedside recordings). Localization of the slow EEG components can provide valuable information about the site of onset of focal seizures, which is of particular relevance for presurgical evaluation.
References:
Vanhatalo S, Holmes MD, Tallgren P, Voipio J, Kaila K, Miller JW. Very slow EEG responses lateralize temporal lobe seizures: An evaluation of non-invasive DC-EEG. Neurology, 2003; 60:1098-1102.
Lagerlund TD, Gross RA. DC-EEG recording: A paradigm shift in seizure localization?, Neurology 60:1062-63, 2003[italic]. Editorial[/italic][figure1]
[Supported by: The Academy of Finland, Finnish Cultural Foundation, Arvo and Lea Ylppö Foundation, and the Regional Epilepsy Center, University of Washington. ]
