Ictal time-irreversible intracranial EEG signals as markers of the epileptogenic zone

Schindler, Kaspar Anton; Rummel, Christian; Andrzejak, Ralph G; Goodfellow, Marc; Zubler, Frédéric Alexis Rudolf; Abela, Eugenio; Wiest, Roland; Pollo, Claudio; Steimer, Andreas; Gast, Heidemarie (2016). Ictal time-irreversible intracranial EEG signals as markers of the epileptogenic zone. Clinical neurophysiology, 127(9), pp. 3051-3058. Elsevier 10.1016/j.clinph.2016.07.001

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OBJECTIVE To show that time-irreversible EEG signals recorded with intracranial electrodes during seizures can serve as markers of the epileptogenic zone. METHODS We use the recently developed method of mapping time series into directed horizontal graphs (dHVG). Each node of the dHVG represents a time point in the original intracranial EEG (iEEG) signal. Statistically significant differences between the distributions of the nodes' number of input and output connections are used to detect time-irreversible iEEG signals. RESULTS In 31 of 32 seizure recordings we found time-irreversible iEEG signals. The maximally time-irreversible signals always occurred during seizures, with highest probability in the middle of the first seizure half. These signals spanned a large range of frequencies and amplitudes but were all characterized by saw-tooth like shaped components. Brain regions removed from patients who became post-surgically seizure-free generated significantly larger time-irreversibilities than regions removed from patients who still had seizures after surgery. CONCLUSIONS Our results corroborate that ictal time-irreversible iEEG signals can indeed serve as markers of the epileptogenic zone and can be efficiently detected and quantified in a time-resolved manner by dHVG based methods. SIGNIFICANCE Ictal time-irreversible EEG signals can help to improve pre-surgical evaluation in patients suffering from pharmaco-resistant epilepsies.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurology
04 Faculty of Medicine > Department of Head Organs and Neurology (DKNS) > Clinic of Neurosurgery
04 Faculty of Medicine > Department of Radiology, Neuroradiology and Nuclear Medicine (DRNN) > Institute of Diagnostic and Interventional Neuroradiology

UniBE Contributor:

Schindler, Kaspar Anton; Rummel, Christian; Zubler, Frédéric Alexis Rudolf; Abela, Eugenio; Wiest, Roland; Pollo, Claudio; Steimer, Andreas and Gast, Heidemarie

Subjects:

600 Technology > 610 Medicine & health

ISSN:

1388-2457

Publisher:

Elsevier

Language:

English

Submitter:

Martin Zbinden

Date Deposited:

13 Sep 2016 13:58

Last Modified:

17 Sep 2016 17:28

Publisher DOI:

10.1016/j.clinph.2016.07.001

PubMed ID:

27472540

Uncontrolled Keywords:

Complex networks; Pre-surgical evaluation; Quantitative EEG; Seizure dynamics; Symbolic analysis

BORIS DOI:

10.7892/boris.87515

URI:

https://boris.unibe.ch/id/eprint/87515

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