(1002) Surgical outcomes in patients with refractory temporal lobe epilepsy: the significance of intracranial investigations vs direct anterior temporal lobectomy

Rationale: Surgical outcomes in patients with temporal lobe epilepsy (TLE) following intracranial monitoring - stereotactic electroencephalography (sEEG) and subdural/depth electrodes (SDE/DE) - have not been extensively compared to the practice of direct anterior temporal lobectomy without prior intracranial monitoring (dATL). The goal of this study was to determine the relationship between intracranial monitoring status and surgical outcomes in a homogenous TLE patient cohort treated with standard ATL.

Methods: We performed a retrospective analysis 85 patients with focal refractory TLE who underwent ATL following: a) intracranial monitoring via craniotomy and SDE/DE, b) intracranial monitoring via sEEG, or c) no intracranial monitoring.

Results: At one-year and most recent follow-up, there was no significant difference between the surgical groups in terms of both Engel Class I and combined Engel Class I/II outcomes. The probability of seizure freedom in the long term followed the same profile for all surgical approaches. In patients with MRI-visible temporal lesions, dATL patients performed better overall than those who had intracranial monitoring (sEEG or SDE/DE). In the non-lesional group, the proportion of patients who had intracranial monitoring prior to ATL was comparable to those who had dATL. The surgical hypothesis was shown to play a key role in decision making, as patients with a unilateral TLE (uTLE) hypothesis had better outcomes with dATL, and those with a TLE plus (TLE+) hypothesis did equally well with either of the intracranial monitoring approaches. sEEG provided favorable outcomes for difficult-to-treat patients with a diagnosis of bilateral or poorly lateralized TLE (bTLE).

Conclusions: Our study highlights the value and role of current intracranial monitoring approaches in surgical outcomes of patients with TLE following ATL, and in particular provides an insight in the hypothesis-driven link between the manifestations of the TLE syndrome and optimal strategy to attain seizure freedom.

Funding: Please list any funding that was received in support of this abstract.: Dr Elisaveta Sokolov carried out this work supported by a competitive grant from the HCA International Foundation.