Abstracts

Rationale: To determine the duration until the first epileptic seizure is recorded in pediatric epilepsy patients referred for a pre-surgical evaluation in the epilepsy monitoring unit (EMU) and to determine predictors of time to first seizure in the EMU. Methods: We retrospectively reviewed medical records for all consecutive epilepsy admissions to the EMU at Children s Hospital Boston from October 2009 to May 2011. Only patients undergoing non-invasive pre-surgical evaluation were included. Time from admission to first epileptic seizure, baseline seizure frequency reported by the patient or caregiver at the time of admission, additional demographic data, EEG results, and MRI results were reviewed. Medications are typically reduced by 50% within 2 days and stopped by 3 days if no seizures occured. Time to seizure onset was calculated in days, starting from noon of the day of admission to noon of the next day being counted as day 1. Patients were dichotomized into patients with less than six seizures per month or more than six seizures per month. Statistical analysis was performed using Student t-test. Results: Seventy-six patients (57% male) were identified. Two patients did not experience an epileptic seizure during monitoring and were excluded from the time to seizure onset analysis. Median patient age was 11 years (range 0.25-21). Time to first seizure ranged from one to six days. Time to first epileptic seizure was not related to gender, lesional MRI, or abnormal neurological exam. Seventy-four patients had at least one epileptic seizure captured within six days of monitoring. Patients who presented with fewer than 6 seizures per month at baseline required longer monitoring until the first epileptic seizure was recorded (2.65 days) than patients with 6 or more seizures per month (1.95 days; p-value< 0.05). Conclusions: Most children admitted to the EMU for pre-surgical monitoring will have at least one epileptic seizure within three days of monitoring. Children with six or more seizures per month tend to have earlier seizure occurrence in the EMU. Children with infrequent seizures can still have their first seizure in the EMU within a reasonable time period.