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Keywords:

  • Outcome;
  • Temporal lobectomy;
  • Levetiracetam;
  • Epilepsy surgery

Summary

Purpose:  To study the prognostic implications of antiepileptic drug (AED) use on seizure freedom following temporal lobe resections for intractable epilepsy.

Methods:  Seizure outcome implications of epilepsy characteristics and AED use were studied in patients who underwent temporal lobectomy patients at the Cleveland Clinic between September 1995 and December 2006. Survival analysis and multivariate regression with Cox proportional hazard modeling were used. Complete seizure freedom was defined as a favorable outcome.

Key Findings:  Records of 312 patients were analyzed (mean ± standard deviation follow-up 3.5 ± 1.7 years). The estimated probability of complete seizure freedom was 69% at 12 months (95% confidence interval [CI] 66–72%), and 48% at 36 months (95% CI 45–52%). The mean number of AEDs used per patient at the time of surgery was 1.78 (range 1–4), dropping to 1.02 at last follow-up (range 0–4). Following multivariate analysis, a lower preoperative seizure frequency and perioperative use of levetiracetam predicted a favorable outcome (risk ratio [RR] 0.62, 95% CI 0.43–0.89, and RR = 0.57, 95% CI 0.39–0.83, respectively), whereas nonspecific pathology (RR 1.71, 95% CI 1.15–2.47) and a higher number of AEDs used at the time of surgery correlated with higher rates of seizure recurrence (whole-model log-rank test p-value < 0.0001). Better outcomes within the levetiracetam group were seen despite a higher proportion of several poor prognostic indicators within this patient group, and started as early as 4 months after surgery, gradually increasing to a 15–20% survival advantage by 5 years. No similar outcome correlations were identified with another AED.

Significance:  AED use may be a potential new modifiable seizure-outcome predictor after temporal lobectomy. This possible prognostic indicator is discussed in light of proposed seizure recurrence mechanisms.