Noninvasive localization of epileptogenic zones with ictal high-frequency neuromagnetic signals.
OBJECTIVE
Recent reports suggest that high-frequency epileptic activity is highly localized to epileptogenic zones. The goal of the present study was to investigate the potential usefulness of noninvasive localization of high-frequency epileptic activity for epilepsy surgery.


METHODS
Data obtained in 4 patients, who had seizures during routine magnetoencephalography (MEG) tests, were retrospectively studied. The MEG data were digitized at 4000 Hz, and 3D MR images were obtained. The magnetic sources were volumetrically localized with wavelet-based beamformer. The MEG results were subsequently compared with clinical data.


RESULTS
The 4 patients had 1-4 high-frequency neuromagnetic components (110-910 Hz) in ictal and interictal activities. The loci of high-frequency activities were concordant with intracranial recordings therein 3 patients, who underwent presurgical evaluation. The loci of high-frequency ictal activities were in line with semiology and neuroimaging in all 4 of the patients. High-frequency epileptic activity was highly localized to the epileptogenic zones.


CONCLUSIONS
High-frequency epileptic activity can be volumetrically localized with MEG. Source analysis of high-frequency neuromagnetic signals has the potential to determine epileptogenic zones noninvasively and preoperatively for epilepsy surgery.
Xiang
Jing
J
MEG Center, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45220, USA. Jing.xiang@cchmc.org
Wang
Yingying
Y
Chen
Yangmei
Y
Liu
Yang
Y
Kotecha
Rupesh
R
Huo
Xiaolin
X
Rose
Douglas F
DF
Fujiwara
Hisako
H
Hemasilpin
Nat
N
Lee
Ki
K
Mangano
Francesco T
FT
Jones
Blaise
B
DeGrauw
Ton
T
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping / Q000379:methods; D002648:Child; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000175:diagnosis / Q000601:surgery*; D017029:Epilepsy, Complex Partial / Q000175:diagnosis / Q000601:surgery*; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis / Q000601:surgery*; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D015225:Magnetoencephalography / Q000379:methods*; D008297:Male; D012189:Retrospective Studies; D012815:Signal Processing, Computer-Assisted; D014741:Video Recording