Does intraoperative electrocorticography alter seizure outcomes after temporal lobe epilepsy surgery?

OBJECTIVE

Surgery is the treatment of choice in drug-resistant temporal lobe epilepsy (TLE). The estimated seizure freedom after anterior temporal lobectomy and amygdalo-hippocampectomy (ATL-AH) is 70%-80%. Accurate identification of the epileptogenic zone by prompt presurgical evaluation reduces surgical failures. Our study aims to assess the utility of intraoperative electrocorticography (iECoG) in improving seizure outcomes following ATL-AH.

METHODS

We enrolled patients with drug-resistant TLE who underwent ATL-AH from January 2009 to December 2018. They were followed up at 3 months, 12 months and annually for assessment of seizure recurrence. Post-resection ECoG findings were classified into (1) no/rare residual epileptiform discharges and (2) less than 50% reduction in discharges. Post-operative outcome was deemed "good" if seizure-free and aura-free during the entire period of post-operative follow-up and "poor" if there is a recurrence of auras and/or seizures.

RESULTS

Among the 684 patients enrolled, 566 had "good" outcomes and 118 had "poor" outcomes. Resection was ECoG-guided in 545 patients. Less than 50% reduction in spikes on post-resection ECoG was found in 133 patients. There was no significant difference in seizure outcomes based on ECoG guidance (p = 0.65) or clearance of spikes on post-resection ECoG (p = 0.13). iECoG was not done in 139 (20.3%) patients due to technical glitches during the procedure or due to affordability issues.

SIGNIFICANCE: Utility of iECoG in tailoring resection margins is limited and it does not predict seizure outcome after ATL-AH. In centers where ATL-AH is ECoG-guided, it is advisable to abandon this time-consuming procedure.