The value of multichannel MEG and EEG in the presurgical evaluation of 70 epilepsy patients.
OBJECTIVE
To evaluate the sensitivity of a simultaneous whole-head 306-channel magnetoencephalography (MEG)/70-electrode EEG recording to detect interictal epileptiform activity (IED) in a prospective, consecutive cohort of patients with medically refractory epilepsy that were considered candidates for epilepsy surgery.


METHODS
Seventy patients were prospectively evaluated by simultaneously recorded MEG/EEG. All patients were surgical candidates or were considered for invasive EEG monitoring and had undergone an extensive presurgical evaluation at a tertiary epilepsy center. MEG and EEG raw traces were analysed individually by two independent reviewers.


RESULTS
MEG data could not be evaluated due to excessive magnetic artefacts in three patients (4%). In the remaining 67 patients, the overall sensitivity to detect IED was 72% (48/67 patients) for MEG and 61% for EEG (41/67 patients) analysing the raw data. In 13% (9/67 patients), MEG-only IED were recorded, whereas in 3% (2/67 patients) EEG-only IED were recorded. The combined sensitivity was 75% (50/67 patients).


CONCLUSIONS
Three hundred and six-channel MEG has a similarly high sensitivity to record IED as EEG and appears to be complementary. In one-third of the EEG-negative patients, MEG can be expected to record IED, especially in the case of lateral neocortical epilepsy and/or cortical dysplasia.
Knake
S
S
Athinoula A. Martinos Center for Biomedical Imaging, Department of Radiology, Massachusetts General Hospital, Charlestown, MA 02129, USA. knake@staff.uni-marburg.de
Halgren
E
E
Shiraishi
H
H
Hara
K
K
Hamer
H M
HM
Grant
P E
PE
Carr
V A
VA
Foxe
D
D
Camposano
S
S
Busa
E
E
Witzel
T
T
Hämäläinen
M S
MS
Ahlfors
S P
SP
Bromfield
E B
EB
Black
P M
PM
Bourgeois
B F
BF
Cole
A J
AJ
Cosgrove
G R
GR
Dworetzky
B A
BA
Madsen
J R
JR
Larsson
P G
PG
Schomer
D L
DL
Thiele
E A
EA
Dale
A M
AM
Rosen
B R
BR
Stufflebeam
S M
SM
D000293:Adolescent; D000328:Adult; D002648:Child; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D008875:Middle Aged; D011300:Preoperative Care; D011446:Prospective Studies; D012680:Sensitivity and Specificity