Page 144 - MEGIN Book Of Abstracts - 2023

Hiroshima University Hospital, 1-2-3 Kasumi, Minami-ku, Wearable OPM-MEG: A changing landscape for
Hiroshima City 734-0037, Japan; Department of Neurosur- epilepsy (2022)
gery, Graduate School of Biomedical and Health Sciences,
Hiroshima University, 1-2-3 Kasumi, Minami-ku, Hiroshima Pedersen, Mangor; Abbott, David F; Jackson, Graeme D
City 734-0037, Japan. Electronic address: iidak@hiroshima-u.
ac.jp Department of Psychology and Neuroscience, Auckland
University of Technology, Auckland, New Zealand; Depart-
OBJECTIVE Gradient magnetic field topography ment of Medicine, Austin Health and Florey Department of
(GMFT) illustrates the magnetic field gradients of epi- Neuroscience and Mental Health, University of Melbourne,
leptic spike or polyspikes (S/PS) activities on a volume- Melbourne, Victoria, Australia
rendered brain surface. The purpose is to characterize
cortical activation in juvenile myoclonic epilepsy (JME). ABSTRACT Magnetoencephalography with optically
pumped magnometers (OPM-MEG) is an emerging and
METHODS We compared interictal S/PS activities in 10 novel, cost-effective wearable system that can simul-
patients with JME to five patients with Lennox-Gastaut taneously record neuronal activity with high temporal
syndrome (LGS). We defined areas with gradients resolution ("when" neuronal activity occurs) and spatial
exceeding 300fT/cm as activated zones (AZs) on GMFT. resolution ("where" neuronal activity occurs). This
We defined the hemisphere where an AZ initially ap- paper will first outline recent methodological advances
peared as the "preceding hemisphere". We localized the in OPM-MEG compared to conventional superconduct-
foci where AZs arose and evaluated their spatiotempo- ing quantum interference device (SQUID)-MEG before
ral changes. discussing how OPM-MEG can become a valuable and
noninvasive clinical support tool in epilepsy surgery
RESULTS In JME, the localization of S/PS in the preced- evaluation. Although OPM-MEG and SQUID-MEG share
ing hemisphere was frontal in 18 activities (28%), pari- similar data features, OPM-MEG is a wearable design
etal in 10 (15%), and frontal/parietal in 33 (51%), and in that fits children and adults, and it is also robust to
the contralateral hemisphere it was frontal in 14 (32%), head motion within a magnetically shielded room.
parietal in 6 (14%), and frontal/parietal in 19 (43%). In This means that OPM-MEG can potentially extend the
LGS, AZs arose in every lobe of the brain. The median application of MEG into the neurobiology of severe
interhemispheric time difference was 7 ms (range: 0-20) childhood epilepsies with intellectual disabilities (e.g.,
in JME, which was significantly shorter than the 19 ms epileptic encephalopathies) without sedation. It is
(1-50) observed among patients with LGS (p < 0.0001). worth noting that most OPM-MEG sensors are heated,
which may become an issue with large OPM sensor
CONCLUSIONS AZs are localized within the bilateral arrays (OPM-MEG currently has fewer sensors than
frontal and parietal regions. AZs arose serially from foci SQUID-MEG). Future implementation of triaxial sensors
with small time differences. may alleviate the need for large OPM sensor arrays.
OPM-MEG designs allowing both awake and sleep
SIGNIFICANCE These results are consistent with re- recording are essential for potential long-term epilepsy
gional network involvement in JME. monitoring.

Keywords: Gradient magnetic field topography, Juvenile Keywords: EEG, MEG, MRI, OPM-MEG, brain surgery,
myoclonic epilepsy, Magnetoencephalography, Regional epilepsy
network involvement, Working memory network
Epilepsia (2022), Vol. 63, No. 11 (35841260) (2 citations)
Clinical neurophysiology: official journal of the
International Federation of Clinical Neurophysiology
(2022), Vol. 141 (35853311) (1 citation)

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