Abstracts

Long-term video EEG monitoring plays a critical role in the diagnosis and presurgical evaluation of epilepsy. Withdrawal of antiseizure medications (ASMs) may increase the likelihood of seizure capture during the EEG monitoring, but it also carries a risk for adverse events such as status epilepticus, fall, and trauma. Therefore, the optimal tapering rate must be individualized. This study aimed to compare seizure detection rates and safety between patients undergoing rapid versus slow taper of ASMs using time-to-event analysis.

We retrospectively analyzed patients with focal epilepsy who underwent long-term video EEG monitoring for diagnostic purpose or presurgical evaluation at the University of Tokyo Hospital between April 2018 and March 2024. We excluded the following patients: those who underwent the monitoring without tapering ASMs or those who had no seizures detected during the monitoring. Standard safety measures were applied to all patients. Patients were divided into two groups based on the tapering strategy: rapid taper group, in which at least one ASM was tapered by ≥50% on day 1; and slow taper group, in which at least one ASM was tapered by < 50%. The day until first seizure detection was recorded and the log-rank test was used to assess statistical differences. Kaplan-Meier survival curves were constructed, Cox proportional hazards modeling was employed to estimate the hazard ratio (HR) of seizure detection associated with tapering strategy. Occurrence of focal to bilateral tonic-clonic seizures (FBTCS) and adverse events (i.e. status epilepticus and falls) were also collected to evaluate safety.