Can intraoperative electrocorticography patterns predict surgical outcome in patients with temporal lobe epilepsy secondary to unilateral mesial temporal sclerosis?
BACKGROUND
Intraoperative electrocorticography (ECoG) can be performed in cases of temporal lobe epilepsy due to hippocampal sclerosis (TLE-HS). However, its significance and correlation with surgical outcome are still controversial.


OBJECTIVE
To analyze the electrophysiological characteristics of temporal lobe structures during ECoG of patients with TLE-HS, with emphasis on the comparison between pre- and post-resection recordings and surgical outcome.


METHODS
Seventeen patients with refractory TLE-HS submitted to corticoamigdalohipocampectomy were included in the study. Clinical variables included age at the onset, duration of epilepsy and seizure outcome. The post-operative follow-up ranged from 24 to 36 months. According to outcome subjects were divided in two subgroups: (A) individuals free of seizures (Engel 1A), and (B) individuals not-free of seizures (Engel 1B-IV). Four patterns of ECoG findings were identified: isolated discharges; high frequency spikes (HFS); continuous discharges; combination of isolated discharges and HFS. According to predominant topography ECoG was classified as mediobasal, lateral (or neocortical), mediobasal and lateral.


RESULTS
The progressive removal of the temporal pole and the hippocampus was associated with significant decrease of neocortical spikes. No correlation between clinical variables and seizure outcome was observed. Patients who only had isolated spikes on intraoperative ECoG presented a statistical trend for excellent surgical control. Patients who presented temporal pole blurring on MRI also had better post-surgical seizure outcome.


CONCLUSIONS
This study showed that out of diverse clinical and laboratory variables, only isolated discharges on intraoperative ECoG and temporal pole blurring on MRI predicted excellent post-surgical seizure outcome. However, other studies with larger number of patients are still necessary to confirm these findings.
Oliveira
Pedro A L
PA
Department of Neurology and Neurosurgery, Division of Neurology, Federal University of São Paulo, São Paulo, Brazil.
Garzon
Eliana
E
Caboclo
Luís O S F
LO
Sousa
Patrícia S
PS
Carrete
Henrique
H
Centeno
Ricardo S
RS
Costa
José M P
JM
Machado
Hélio R
HR
Yacubian
Elza M T
EM
Bianchin
Marino M
MM
Sakamoto
Américo C
AC
D000328:Adult; D038481:Anterior Temporal Lobectomy; D004569:Electroencephalography; D004833:Epilepsy, Temporal Lobe / Q000503:physiopathology* / Q000601:surgery; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D012598:Sclerosis; D013702:Temporal Lobe / Q000503:physiopathology*; D016896:Treatment Outcome