WASHINGTON, DC—Late discontinuation of antiepileptic drugs (AEDs) following epilepsy surgery is associated with a lower rate of seizure recurrence, compared with early AED discontinuation, according to research presented at the 67th Annual Meeting of the American Epilepsy Society. The postsurgical timing of AED withdrawal may not influence the achievement of seizure freedom, however.
Although most patients with epilepsy become seizure-free after surgery, neurologists have no standard criteria for the timing of AED withdrawal following the procedure. In addition, the long-term effect of postoperative AED withdrawal is unclear.
Researchers at the Cleveland Clinic investigated the implications of AED withdrawal following surgery for drug-resistant temporal lobe epilepsy (TLE). The team reviewed data for all patients who underwent temporal lobectomy for drug-resistant TLE in their clinic from 1996 to 2011 and had at least six months of postoperative follow-up. Follow-up lasted as long as 16.7 years. The investigators noted patients’ clinical and imaging information; histopathological profiles; and dates of initiation, reduction, and termination of AEDs. Predictors of postoperative seizure outcome were defined using survival analyses and Cox-proportional hazard modeling.
More than 600 patients met the study criteria, including a patient cohort for whom medication was withdrawn and a second cohort for whom medication remained unchanged after surgery. The investigators used the latter group used as the control group. The researchers assessed the long-term recurrence of seizures following early and late withdrawal of AEDs postsurgery and compared those results with seizure recurrence when AEDs remained unchanged following surgery.
The number of AEDs per patient at the time of surgery ranged from 1 to 5, and the number of AEDs at last follow-up ranged from 0 to 5. At last follow-up, approximately 38% of patients had made no change in their baseline AEDs, about 21% of patients had stopped their AEDs, and approximately 42% had reduced their AEDs. The investigators found no relationship between AED management and the side of resection, MRI findings, baseline seizure-frequency, and presence or absence of convulsions. AEDs were more likely to be stopped in patients with tumors.
By the last follow-up, 55% of patients had seizure recurrence. Multivariate modeling indicated that higher baseline seizure frequency and history of generalization predicted seizure recurrence. For patients who stopped their AEDs, the mean timing of earliest AED change was shorter in patients with recurrent seizures (1.04 years), compared with patients who were seizure-free (1.44 years).
When the researchers analyzed patients who were seizure-free for at least six months postsurgery and compared seizure outcomes in the group with AED withdrawal to the cohort where AEDs were unchanged, they found no difference in long-term rates of seizure-freedom, regardless of etiology. The results of the large, retrospective, controlled cohort study need to be further evaluated in a well-designed, prospective, randomized trial, said the investigators.
—Erik Greb