Timing of antiepileptic drug withdrawal in adult epilepsy patients after neocortical surgical resection: a critically appraised topic.

Background: The ideal efficacy outcome after surgery for medically refractory epilepsy is seizure freedom without need for antiepileptic drug (AED) therapy but the appropriate timing of AED withdrawal and other prognostic factors remain unclear.

Objective: To critically evaluate current evidence regarding factors that influence the risk of seizure relapse after tapering AEDs in adult postepilepsy surgery patients.

Methods: The objective was addressed through the development of a structured, critically appraised topic. This included a clinical scenario, structured question, literature search strategy, critical appraisal, results, evidence summary, commentary, and bottom-line conclusions. Participants included consultant and resident neurologists, a medical librarian, clinical epidemiologists, and a content expert in the field of epilepsy.

Results: A structured literature search led to selection and appraisal of a retrospective cohort study. Of 147 patients who underwent AED tapering after epilepsy surgery, 61 (41.5%) ended up seizure-free off AEDs, 47 (32%) were seizure-free with AED continuation, and 39 (26.5%) continued to have seizures while on AEDs. Risk factors associated with seizure recurrence included: less time to AED reduction [<9 mo vs. ≥9 mo; P<0.001; hazard ratio (HR)=2.83; 95% confidence interval (CI)=1.62-4.94), seizure recurrence before AED reduction (P=0.002; HR=2.43; 95% CI=1.37-4.31], normal preoperative magnetic resonance imaging (P=0.01; HR=1.96; 95% CI=1.15-3.34), and longer epilepsy duration (>11 y vs. ≤11 y; P=0.02; HR=1.75; 95% CI=1.09-2.81). Cortical location of the epileptic focus was not associated with taper success.

Conclusion: In adults who have undergone neocortical resection surgery for medically refractory epilepsy, longer time from surgery to beginning AED taper (eg, greater than 9 months) is associated with a greater proportion of patients maintaining seizure freedom. Other risk factors associated with lower rate of seizure freedom after AED taper include longer duration of epilepsy, normal preoperative magnetic resonance imaging, and occurrence of postoperative seizures before initiation of AED withdrawal, but not cortical location of the epilepsy focus.