Focal ictal beta discharge on scalp EEG predicts excellent outcome of frontal lobe epilepsy surgery.
OBJECTIVE
To determine whether a focal beta-frequency discharge at seizure onset on scalp EEG predicts outcome of frontal lobe epilepsy (FLE) surgery.


METHODS
We identified 54 consecutive patients with intractable FLE who underwent epilepsy surgery between December 1987 and December 1996. A blind review of EEGs and magnetic resonance images (MRIs) was performed. Lesional epilepsy is defined as presence of an underlying structural abnormality on MRI.


RESULTS
Overall, 28 (52%) patients were seizure free, with a mean follow-up of 46.5 months. Presence of a focal beta-frequency discharge at seizure onset on scalp EEG predicted seizure-free outcome in lesional (p = 0.02) and non-lesional (p = 0.01) epilepsy patients. At least 90% of patients who had either lesional or non-lesional epilepsy were seizure free if scalp EEG revealed a focal beta discharge at ictal onset. Moreover, logistic regression analysis showed that focal ictal beta pattern and completeness of lesion resection were independently predictive of seizure-free outcome. Ictal onset with lateralized EEG activity of any kind and postresection electrocorticographic spikes did not predict surgical outcome (p > 0.05).


CONCLUSIONS
Only about 25% of FLE surgical patients have a focal beta-frequency discharge at seizure onset on scalp EEG. However, its presence is highly predictive of excellent postsurgical seizure control in either lesional or non-lesional FLE surgical patients.
Worrell
Gregory A
GA
Section of Electroencephalography, Mayo Clinic, Rochester, Minnesota 55905, USA.
So
Elson L
EL
Kazemi
John
J
O'Brien
Terence J
TJ
Mosewich
Russell K
RK
Cascino
Gregory D
GD
Meyer
Frederic B
FB
Marsh
W Richard
WR
D002648:Child; D004569:Electroencephalography; D017034:Epilepsy, Frontal Lobe / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery*; D005260:Female; D005544:Forecasting; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011237:Predictive Value of Tests; D012535:Scalp; D016896:Treatment Outcome