Abstracts

Short-term video-EEG monitoring (SVEM) and long-term video-EEG monitoring (LVEM) are extremely helpful in the diagnosis of intractable seizures ([italic]JNNP[/italic] 2004 75:771-2; [italic]Epilepsia[/italic] 2004 45:928-32; [italic]Epilepsia[/italic] 2004 45:1150-3). However, there is little information regarding their usefulness when performed in conjunction with routine EEG (REEG), or serially in the same cohort of patients. Retrospective analysis of data from all the patients with intractable seizures evaluated at the University of Louisville Comprehensive Epilepsy Center over a 2-year period (October 2002-2004) was performed. Patients underwent either SVEM (4-hour duration) or LVEM (1-8 day/s duration). At the beginning of each SVEM and during the first day of each LVEM, a 20-min segment of EEG with video was acquired as baseline recording using appropriate activation procedures (hyperventilation, photic stimulation, and sleep when possible); this baseline segment was designated REEG since its protocol was similar to the routine outpatient EEG performed in our center. In those patients who underwent both SVEM and LVEM (at different dates), the baseline segment obtained at the time of SVEM was considered as REEG. In patients suspected of psychogenic nonepileptic seizures, suggestion was used for induction. Interpretation for each REEG, SVEM and LVEM was categorized into one or more of the following: partial epilepsy (PE), generalized epilepsy (GE), and nonepileptic seizures (NES); the designation, non-diagnostic (ND), was used when none of the above categories was applicable. NES comprised of psychogenic seizures and all other paroxysmal attacks. There were 336 patients (223 females, 66%) in the age range of 11 to 86 years (mean 38 years). As shown in the table, the diagnostic yield was highest (78%) for LVEM, lowest for REEG (14%) and intermediate for SVEM (44%). Eighteen patients underwent LVEM after an earlier SVEM. In 15 of these, the interpretation was non-diagnostic after SVEM; in 8 of these 15 patients (53%), definitive diagnosis was established at the conclusion of LVEM, with NES being the most predominant category in 6 (40%) patients. Eight patients (5%) were considered for VNS implantation after SVEM while 37 patients (18%) were evaluated for epilepsy surgery after LVEM. In the evaluation of intractable seizures, routine EEG is not helpful and LVEM provides the highest diagnostic yield. With SVEM, there are 7-fold and 2.5-fold increases in the diagnostic yield of nonepileptic seizures and generalized epilepsy respectively. In a given cohort of patients, LVEM after a non-diagnostic SVEM is most likely to establish the diagnosis of nonepileptic seizures.[table1]