Title: Ictal-onset localization through connectivity analysis of intracranial EEG signals in patients with refractory epilepsy
Authors: van Mierlo, P. # ×
Carrette, E. #
Hallez, Hans
Raedt, R. #
Meurs, A. #
Vandenberghe, S. #
Van Roost, D. #
Boon, P. #
Staelens, S. #
Vonck, K. #
Issue Date: Aug-2013
Publisher: Wiley-Blackwell Publishing, Inc.
Series Title: Epilepsia vol:54 issue:8 pages:1409-1418
Abstract: Purpose: Fifteen percent to 25% of patients with refractory
epilepsy require invasive video–electroencephalography
(EEG) monitoring (IVEM) to precisely delineate the
ictal-onset zone. This delineation based on the recorded
intracranial EEG (iEEG) signals occurs visually by the epileptologist
and is therefore prone to human mistakes.
The purpose of this study is to investigate whether effective
connectivity analysis of intracranially recorded EEG
during seizures provides an objective method to localize
the ictal-onset zone.
Methods: In this study data were analyzed from eight
patients who underwent IVEM at Ghent University
Hospital in Belgium. All patients had a focal ictal onset
and were seizure-free following resective surgery. The
effective connectivity pattern was calculated during
the first 20 s of ictal rhythmic iEEG activity. The outdegree,
which is reflective of the number of outgoing
connections, was calculated for each electrode contact
for every single seizure during these 20 s. The seizure
specific out-degrees were summed per patient to
obtain the total out-degree. The electrode contact
with the highest total out-degree was considered indicative
of localization of the ictal-onset zone. This result
was compared to the conclusion of the visual analysis
of the epileptologist and the resected brain region segmented
from postoperative magnetic resonance imaging
Key findings: In all eight patients the electrode contact
with the highest total out-degree was among the contacts
identified by the epileptologist as the ictal onset. This contact,
that we named “the driver,” always laid within the
resected brain region. Furthermore, the patient-specific
connectivity patterns were consistent over the majority
of seizures.
Significance: In this study we demonstrated the feasibility
of correctly localizing the ictal-onset zone from iEEG
recordings by using effective connectivity analysis during
the first 20 s of ictal rhythmic iEEG activity.
ISSN: 0013-9580
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Technologiecluster Computerwetenschappen
Computer Science Technology TC, Technology Campus Ostend
× corresponding author
# (joint) last author

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