Nature Medicine
4, 1173 - 1176 (1998)
doi:10.1038/2667
Epileptic seizures can be anticipated by non-linear analysisJ. Martinerie1, C. Adam1, 2, M. Le Van Quyen1, M. Baulac1, 2, S. Clemenceau1, 2, B. Renault1
& F.J. Varela11
Laboratoire de Neurosciences Cognitives et Imagerie
Cérébrale (CNRS UPR 640), Hôpital de la Salpêtrière
, 47 Bld. de l'Hôpital, 75651 Paris cedex
13, Paris , France
2
Unité d'Epileptologie, Hôpital de la Salpétrière
, 47 Bld. de l'Hôpital, 75651 Paris cedex
13, France
Correspondence should be addressed to J. Martinerie Epileptic seizures are a principal brain dysfunction with important public
health implications, as they affect 0.8% of humans. Many of these patients
(20%) are resistant to treatment with drugs1. The ability to
anticipate the onset of seizures in such cases would permit clinical interventions.
The view of chronic focal epilepsy now is that abnormally discharging neurons
act as pacemakers to recruit and entrain other normal neurons by loss of inhibition
and synchronization into a critical mass2. Thus, pre-ictal changes
should be detectable during the stages of recruitment. Traditional signal
analyses, such as the count of focal spike density3, the frequency
coherence4 or spectral analyses are not reliable predictors.
Non-linear indicators may undergo consistent changes around seizure onset5,
6,
7. Our objective was to follow the transition into seizure by
reconstructing intracranial recordings in implanted patients as trajectories
in a phase space and then introduce non-linear indicators to characterize
them8,
9. These indicators take into account the extended spatio−temporal
nature of the epileptic recruitment processes10 and the corresponding
physiological events governed by short-term causalities in the time series.
We demonstrate that in most cases (17 of 19), seizure onset could be anticipated
well in advance (between 2−6 minutes beforehand), and that all subjects
seemed to share a similar 'route' towards seizure.
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