Surgical implications of neuromagnetic spike localization in temporal lobe epilepsy.
OBJECTIVE
To investigate the clinical usefulness of magnetoencephalography (MEG) as a guide to the surgical treatment of temporal lobe epilepsy (TLE).


METHODS
Preoperative spike localization by MEG was compared with seizure outcome and postoperative spike localization at 12 months after resective surgery in 16 patients with TLE. Spike localization was classified into anterior temporal (AT) and non-AT localization in 11 patients without neocortical lesion treated with anterior temporal lobectomy (ATL); and lesion and lobar localization in five patients with neocortical lesion treated with lesionectomy (n = 3) or lesionectomy with medial temporal resection (n = 2).


RESULTS
All five patients with AT localization became seizure free and spike free after surgery. Among the six patients with non-AT localization, two became seizure free and spike free, two became seizure free with residual spikes, one had residual seizures but no spikes, and one had both residual seizures and spikes. All three patients with lesion localization and two with lobar localization had favorable seizure outcome and became spike free after surgery.


CONCLUSIONS
MEG spike localization can identify neocortical sources remote from the presumed epileptogenic area. Favorable seizure outcome can be expected in patients with AT localization after ATL and patients with lesion localization after lesionectomy. In contrast, non-AT localization indicates either nonmedial TLE or spike propagation to the posterior and extratemporal neocortex. Similarly, lobar localization indicates spike propagation from an epileptogenic lesion or extensive epileptogenicity. Patients with non-AT localization or lobar localization should undergo intensive evaluations, such as intracranial EEG, for improved seizure outcome.
Iwasaki
Masaki
M
Department of Neurosurgery, Tohoku University Graduate School of Medicine, 1-1 Seiryo-machi, Aoba-ku, Sendai 980-8574, Japan. iwa@nsg.med.tohoku.ac.jp
Nakasato
Nobukazu
N
Shamoto
Hiroshi
H
Nagamatsu
Ken-ichi
K
Kanno
Akitake
A
Hatanaka
Keisaku
K
Yoshimoto
Takashi
T
D000200:Action Potentials; D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000175:diagnosis* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D019579:Neocortex / Q000473:pathology; D011184:Postoperative Period; D016896:Treatment Outcome