Abstracts

Rationale: The use of inpatient video EEG (vEEG) monitoring is an essential part of the pre-surgical work up for patients with medically intractable, focal epilepsy. The diagnostic value of repeating non-diagnostic vEEG has been well established. However, when epilepsy surgery is not pursued immediately, the validity of the scalp vEEG evaluation is unknown after a prolonged period of time has passed. In this study, we evaluated patients who had repeat video-EEG monitoring years after an initial diagnostic study to determine whether the results significantly changed. Methods: We completed a retrospective chart-review of consecutive patients who underwent multiple admissions for the surgical evaluation and were readmitted for vEEG between January 2005 and December 2011. In order to be included in analysis, patients needed to have been diagnosed with focal epilepsy at the end of a first vEEG session with recorded seizures and lateralized seizure onset. Patients then had to undergo a repeat admission 2 years or more later. Patients admitted for ictal SPECT were excluded. Results: Twelve patients were identified (mean age at first monitoring: 34.5 years; 3 male, 9 female). The mean time between monitoring admissions was 5.4 years (2.0 years - 17.9 years). Eight patients (67%) had no change in localization of seizure onset between admissions. Four (33%) patients had a change in localization despite a lack of described change in seizure semiology. One of the 4 patients (25%) had improved localization with the second admission, while 2 (50%) showed more diffuse involvement with seizures and 1 (25%) had bilateral independent seizures. Eight of 12 patients (67%) underwent subsequent resective surgery. Conclusions: Repeat video-EEG monitoring is a necessary tool in the evaluation for resective epilepsy surgery and may need to be repeated if surgery is not performed within 2 years following initial testing. In this sample, 33% of patients had a significant change between 2 consecutive scalp vEEG monitoring sessions, raising concerns regarding potential surgical candidacy.