Postoperative Electroencephalogram and Seizure Outcome after Temporal Lobectomy in Mesial Temporal Lobe Epilepsy

ABSTRACT

BACKGROUND: The significance of the postoperative electroencephalogram (EEG) is not yet fully understood. We investigated whether the postoperative EEG is predictive of persistent seizures over time. METHODS: The postoperative 115 EEGs were retrospectively reviewed in 65 patients with mesial temporal lobe epilepsy who underwent temporal lobectomy. The EEGs were divided into 3 groups including the total EEGs, EEGs taken around 1 year after surgery, and EEGs taken around 2 years after surgery. The postoperative EEGs were studied with respect to persistent seizures at one point in time as well as over time. RESULTS: 1) Overall, spikes predicted persistent or recurrent seizures in 1 year after EEG was recorded (p<0.01) but not in 2 years (p=0.075). The subset of EEGs around 2 years after surgery was predictive of good outcome over time whereas EEGs around 1 year after surgery were not. 2) Overall, the presence of spikes were correlated with seizures at the time when the EEGs were recorded (p=0.000). The subset of EEGs around 2 years after surgery were associated with recurrence of seizures (p<0.05) whereas EEGs around 1 year after surgery were not. CONCLUSIONS: EEGs can be predictive of persistent or recurrent seizures at one point in time as well as over time. Their prognostic value, however, depends on the time interval after surgery to be recorded. EEGs around 2 years after surgery are superior in reflecting surgical outcome than EEGs around 1 year after surgery.