Page 152 - MEGIN Book Of Abstracts - 2023

clusters. MEG may provide supporting information for Abnormal phase-amplitude coupling characterizes
guiding SEEG electrode implantation and improve the the interictal state in epilepsy (2022)
long-term outcomes of epilepsy surgery. In this study,
we evaluated the accuracy of MEG in determining the Fujita, Yuya; Yanagisawa, Takufumi; Fukuma, Ryohei;
SOZ. Ura, Natsuko; Oshino, Satoru; Kishima, Haruhiko

METHODS We retrospectively analyzed patients with Osaka University Hospital Epilepsy Center, Suita, Osaka
refractory epilepsy who underwent MEG examina- 567-0872, Japan; Osaka University Institute for Advanced Co-
tion and SEEG implantation before resective epilepsy Creation Studies, Suita 565-0871, Japan
surgery in the Shanghai Ruijin Hospital. The SEEG plan
was designed according to the dipole clusters and the ABSTRACT Objective.Diagnosing epilepsy still requires
resections were operated according to the SEEG record- visual interpretation of electroencephalography (EEG)
ings. We investigated the relationships of the pattern and magnetoencephalography (MEG) by specialists,
of MEG dipole clusters and SEEG sampling to the final which prevents quantification and standardization
resective surgery prognosis. of diagnosis. Previous studies proposed automated
diagnosis by combining various features from EEG and
RESULTS We included 42 patients with a postopera- MEG, such as relative power (Power) and functional
tive follow-up of at least 2 years (mean 34.1 months). connectivity (FC). However, the usefulness of interictal
Eighteen (42%) patients who showed concordant phase-amplitude coupling (PAC) in diagnosing epilepsy
localization between MEG and SEEG evaluation had a is still unknown. We hypothesized that resting-state
higher probability of seizure-free outcome (p=0.046, PAC would be different for patients with epilepsy in
χ[2]=4.835, odds ratio=5.00, 95% CI=1.12-22.30). the interictal state and for healthy participants such
Complete sampling of MEG dipole clusters by SEEG that it would improve discrimination between the
electrodes was found in 23 (54%) patients, who had groups.Approach.We obtained resting-state MEG and
higher probability of seizure-free outcome that those magnetic resonance imaging (MRI) in 90 patients with
with incomplete sampling (p<0.001, odds ratio=16.67, epilepsy during their preoperative evaluation and in
95% CI=3.11-89.28). MEG results showing a single, tight 90 healthy participants. We used the cortical currents
cluster or stable orientation were associated to better estimated from MEG and MRI to calculate Power in
seizure outcomes after resective surgery. theδ(1-3 Hz),θ(4-7 Hz),α(8-13 Hz),β(13-30 Hz), lowγ(35-
55 Hz), and highγ(65-90 Hz) bands and FC in theθband.
CONCLUSION MEG dipole cluster helps SEEG implanta- PAC was evaluated using the synchronization index
tion in localizing the SOZ for better long-term epilepsy (SI) for eight frequency band pairs: the phases ofδ, θ,
surgery outcome. The MEG results can play a role as α, andβand the amplitudes of low and highγ. First, we
prognostic predictors of epilepsy surgery. compared the mean SI values for the patients with
epilepsy and the healthy participants. Then, using fea-
Keywords: Engel classification, Epilepsy surgery, Magne- tures such as PAC, Power, FC, and features extracted by
toencephalography (MEG), Seizure onset zone, Stereo- deep learning (DL) individually or combined, we tested
electroencephalography (SEEG) whether PAC improves discrimination accuracy for
the two groups.Main results.The mean SI values were
Seizure (2022), Vol. 97 (35390641) (0 citations) significantly different for the patients with epilepsy and
the healthy participants. The SI value difference was
highest forθ/lowγin the temporal lobe. Discrimination
accuracy was the highest, at 90%, using the combina-
tion of PAC and DL.Significance.Abnormal PAC charac-
terized the patients with epilepsy in the interictal state

 ontents  Index 131
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