Postoperative multichannel magnetoencephalography in patients with recurrent seizures after epilepsy surgery.
OBJECTIVE
Assessment of usefulness of magnetoencephalography (MEG) as a novel non-invasive technique in the diagnostic evaluation of patients with recurrent seizures after unsuccessful epilepsy surgery.


METHODS
Seventeen patients in whom epilepsy surgery had failed underwent reevaluation by means of MEG in addition to standard presurgical investigations (EEG, MRI, SPECT, and neuropsychologic testing).


RESULTS
Source analysis of interictal epileptic MEG discharges revealed dipole localizations immediately adjacent to the borders of previous resection in 10 of 17 patients. Standard non-invasive presurgical evaluation suggested epileptogenicity over the general area of previous resection in all patients, but did not provide any detailed spatial localizing data. Invasive EEG recordings confirmed the MEG focus localization in all of 5 patients who were selected for reoperation. Second operation at the site of previous resection achieved complete seizure control in 3 and cessation of tonic-clonic seizures in 1 of these patients.


CONCLUSIONS
MEG may provide useful information in the diagnostic reevaluation of postoperative epileptic patients in whom skull and dura defects produce a "breach effect" which alters non-invasive and invasive EEG.
Department of Neurology, University of Erlangen-Nuernberg, Erlangen, Germany.
K
K
Kirchberger
C
C
Hummel
H
H
Stefan
D000328:Adult; D001931:Brain Mapping / Q000295:instrumentation; D003952:Diagnostic Imaging; D004827:Epilepsy / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography / Q000295:instrumentation*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000175:diagnosis / Q000209:etiology*; D012008:Recurrence; D012640:Seizures / Q000175:diagnosis / Q000209:etiology*; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*; D017211:Treatment Failure