Prognostic implications of persistent interictal epileptiform discharges on antiseizure medication withdrawal in patients with epilepsy in five-year remission

Abstract

PurposeWhether patients with epilepsy in long-term remission and interictal epileptiform discharges (IEDs) can stop antiseizure medication (ASM) remains a challenging topic even though multiple studies have investigated ASM withdrawal. This study aimed to estimate seizure relapse and its risk factors in patients with epilepsy in five-year remission and persistent IEDs. MethodsPatients with epilepsy and persistent IEDs were prospectively recruited from the Affiliated Nanjing Brain Hospital of Nanjing Medical University from Dec.1, 2010 to Dec.30, 2019. All enrolled patients achieved seizure remission for over five years and were divided into the ASM withdrawal and continuous treatment groups according to their personal preference. Seizure outcomes and 24 h video electroencephalogram findings were obtained through clinical visits or telephone interviews every three months until March 31, 2021. The cumulative recurrence rate and its diversity between the ASM withdrawal and continuous treatment groups were tested using Kaplan–Meier analysis. Multivariate Cox regression analysis was performed to explore the independent predictors for seizure recurrence. Relapsed patients were further monitored for their seizure control and prognosis. ResultsA total of 83 patients with epilepsy in five-year remission and persistent IEDs were enrolled in this study, including 41 (49.4%) in the ASM withdrawal group and 42 (50.6%) in the continuous ASM treatment group. During the follow-up with a median time of 36.8 months (range from 18.7 to 104.6 months), the seizure relapse in off-medication patients (43.9%, 18/41) was higher than that in on-medication patients (21.4%, 9/42; P = 0.031). In the multivariate analysis model, independent predictors for seizure recurrence were structural-metabolic epilepsy or unknown cause (HR = 6.185, 95% CI 1.166–32.805) and multiple seizure types (HR = 2.807, 95% CI 1.051–7.502). ASM withdrawal was not found to be an independent risk factor for seizure recurrence. Of 27 patients with seizure recurrence, 25 were given reinstitution or continuous ASM therapy, whereas two chose sustained observation without medication. At the end of the follow-up, 70.4% (19/27) of recurrence patients were completely free from seizures for at least one year again, and only one patient developed refractory epilepsy. ConclusionFor patients with epilepsy in five-year remission and persistent IEDs, drug withdrawal may be a rational choice after the individualized assessment of benefits and risks. Furthermore, the independent risk factors for the seizure relapse were structural-metabolic epilepsy or an unknown cause, and multiple seizure types. Finally, patients with epilepsy relapsing after ASM withdrawal could achieve seizure remission again after ASM retreatment.