Postoperative EEG and seizure outcome in temporal lobe epilepsy surgery.
OBJECTIVE
To assess the prognostic value of scalp electroencephalogram (EEG) after epilepsy surgery, we investigated whether postoperative EEG abnormalities (interictal epileptiform discharges, IED; interictal slow activity, ISA) were associated with seizure outcome and other patient characteristics after resective surgery in patients with temporal lobe epilepsy (TLE).


METHODS
Sixty-two patients with medically refractory TLE who underwent surgery were studied. Patients were categorized according to etiology (mesiotemporal sclerosis vs. tumors/cortical dysplasias); extent of surgical resection (extensive vs. limited); and amount of preoperative IED on wake EEG (oligospikers, <1 IED/h, vs. spikers). Patients were also classified as seizure-free (SF) or having persistent seizures/auras (not-SF) during follow up visits 1 month and 1 year after surgery. Preoperative 60-min interictal EEGs were evaluated for IED and ISA, and compared to postoperative wake EEGs.


RESULTS
Seizures/auras persisted in 16/62 (25.8%) patients at 1 month and in 8/62 (12.9%) at 1 year follow up. ISA was not significantly related to outcome. Of 42 patients with EEG negative for IED at 1 month, 4 were not-SF; at 1 year, one of 44 such patients was not-SF. IED was significantly associated with seizure/aura persistence in patients categorized as mesiotemporal sclerosis and with extensive surgery. Oligospikers and spikers on preoperative EEG showed no differences in the postoperative seizure outcome, excellent in both cases; moreover, the presence of postoperative IEDs indicated auras/seizures persistence apart from the preoperative EEG spike frequency.


CONCLUSIONS
Our study showed that the presence of IED of postoperatve EEG strongly indicates seizure/aura persistence. Therefore, serial EEGs should be included in postoperative follow up schedules as a crucial tool in evaluating seizure outcome.
Di Gennaro
Giancarlo
G
Epilepsy Surgery Unit, Department of Neurosciences, IRCCS NEUROMED, via Atinense, 18, 86077 Pozzilli (IS), Italy. gdigennaro@neuromed.it
Quarato
Pier Paolo
PP
Sebastiano
Fabio
F
Esposito
Vincenzo
V
Onorati
Paolo
P
Mascia
Addolorata
A
Romanelli
Pantaleo
P
Grammaldo
Liliana G
LG
Falco
Carolina
C
Scoppetta
Ciriaco
C
Eusebi
Fabrizio
F
Manfredi
Mario
M
Cantore
Giampaolo
G
D000293:Adolescent; D000328:Adult; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology* / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D011184:Postoperative Period; D011300:Preoperative Care; D016896:Treatment Outcome