Abstracts

Adjunctive treatment with VNS has been approved for patients 12 yrs and older with refractory epilepsy since1997. Case series have reported outcomes in mixed adult and pediatric populations, but few have concentrated on children.Our project was designed to examine outcome variables specifically in children. The objectives were to determine the difference in outcome with VNS therapy within 5 years of seizure onset versus 5 years after seizure onset. To determine the difference in antiepileptic drug usage before and after VNS therapy in both groups. Patients who were [lt]18 yrs of age at the time of implantation of the VNS device at VCU between November 1998 and December 2003 were included in a retrospective chart review. Data collected included sex,ethnicity,age and time interval between seizure onset and implantation,diagnoses,EEG and MRI findings,percentage seizure reduction at 3,6,9,12,18,24,36,48,72 months after implantation,type and number of AEDs used before and after.The patients were divided into two groups, Group A with implantation [lt]5 yrs after seizure onset and Group B [gt] 5yrs after seizure onset. 22 patients satisfied inclusion criteria,12 males,10 females; 20 Caucasians,2 African Americans. In Group A, 9 patients and in Group B, 13 patients were included. Overall seizure reduction in Group A was 52% versus 46% in Group B. Regression analysis was performed to compare seizure reduction over time and among the two groups.A statistically significant reduction over time was noted adjusting for both groups (p[lt]0.003). However, no statistically significant difference was noted when the groups were compared to each other for seizure reduction. Number of AEDs used before VNS were 3.7 in Group A and 2.5 after,and in Group B, 4.0 before and 2.7 after. An ANOVA model was used to compare the means for the two groups at each time point for AED usage.Pre and post means for both groups were statistically significant (p[lt]0.004).The interaction effect comparing both groups at each time point was not statistically significant. Statistically significant seizure reduction over time was noted in both groups. Better outcome was noted in the early implantation group, however this was not statistically significant. A stastically significant decrease in AED usage was noted in both groups. Recent studies have shown only minimal benefit in seizure reduction with usage of third or subsequent AEDs in refractory epilepsy after failure of an appropriate trial of initial two AEDs. Should earlier adjunctive therapy with VNS be considered? More prospective studies are needed to answer this question.