Gradient magnetic-field topography reflecting cortical activities of neocortical epilepsy spikes.
OBJECTIVE
To compare and validate the gradient magnetic-field topography (GMFT) method of current source localization for understanding epileptic zones against equivalent current dipole (ECD) and intracranial video-EEG (IVEEG) data in patients with intractable neocortical epilepsy.


METHODS
We used retrospective data from eight patients to determine GMFT at onset (O) and peak (P) of interictal magnetoencephalography (MEG) spikes and mapped GMFT(O) and GMFT(P) locations and distributions using 12 zones in unilateral hemisphere. We compared GMFT with ECD, ictal onset zones (IOZ) and interictal zones on IVEEG, and seizure outcomes.


RESULTS
We projected GMFT(Os) and (Ps) for all spikes on volume-rendered brain surfaces. We localized ECDs for 6-61% of spikes (mean, 28.4%). GMFT(Ps) (mean, 10.3 zones) extended over more zones than GMFT(Os) (6.3 zones) for each spike (p<0.01). The ECD distributions (2.3 zones) were almost equal to the zones of IOZ and surgical areas. GMFT(O) localizations distributed much more extensively than IOZs and surgical areas in three patients with residual seizures comparing with those in five seizure-free patiens.


CONCLUSIONS
We validate the potential of GMFT to study the distribution of MEG spikes. GMFT has an advantage in analyzing the cortical activity and propagation from MEG spikes in neocortical epilepsy.
Shirozu
Hiroshi
H
Department of Neurosurgery, Hiroshima University, Hiroshima, Japan.
Iida
Koji
K
Hashizume
Akira
A
Hanaya
Ryosuke
R
Kiura
Yoshihiro
Y
Kurisu
Kaoru
K
Arita
Kazunori
K
Otsubo
Hiroshi
H
D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D002648:Child; D004569:Electroencephalography / Q000379:methods; D004827:Epilepsy / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D015225:Magnetoencephalography; D008297:Male; D009493:Neurosurgery / Q000379:methods; D012189:Retrospective Studies; D016896:Treatment Outcome; D014741:Video Recording / Q000379:methods; D055815:Young Adult