Abstracts

Rationale: Vagus Nerve Stimulation (VNS) has been approved by FDA for treatment of intractable epilepsy in children over 12 years of age. However, it is often used in younger children with intractable seizures because few other therapeutic options currently exist. There is little data on the efficacy of VNS therapy in the pre-adolescent patient cohort. The aim of our study was to assess the long-term efficacy of VNS therapy in young children. We hypothesized that their seizure reduction with VNS therapy would be at least as good as that reported for patients over 12 years of age in EO1-EO5 landmark trials. Methods: We retrospectively reviewed medical records of intractable epilepsy patients who were under 12 years of age at the time of VNS implantation. We included all such patients who underwent VNS implantation surgery at the University of Chicago during the time period from 1/1/2002 to 5/19/2009 and who had a minimum of 6 months of follow-up after VNS implantation. Outcome was quantified as percent seizure decrease from baseline. Statistical analysis of the data was done to determine if any of the parameters significantly influenced the outcome. Results: Out of 42 patients studied, 28 (66%) had at least 50% decrease in seizure frequency, one half of patients had 75% decrease in seizure frequency, and 3 (7%) became seizure-free. Most of seizure reduction was achieved within the first 6 months of VNS therapy. Of note, there was a trend for further improvement in seizure reduction over 5 years of follow-up. Aside from seizure reduction, 69% of patients reported lasting improvements in mood and alertness. Complication rate was 4.7% and events included cough, gag, hypopnea and a delayed surgical site infection. Subgroup analysis showed that the following parameters did not significantly influence the outcome (p>0.05): age at VNS implantation, duration of epilepsy prior to VNS implantation, EEG focality, and etiology of epilepsy. Conclusions: Vagus Nerve Stimulation is an important adjunctive therapy for pre-adolescent children with intractable epilepsy. The 66% VNS response rate of our patients compares favorably to the widely sited VNS response rate of 50% for older children and adults with intractable epilepsy. Moreover, our cohort demonstrated a lasting benefit of VNS therapy over five years, including seizure reduction and improvements in mood and alertness. Based on our data, VNS therapy in pre-adolescent children with intractable epilepsy is effective and safe. Larger scale studies are needed to evaluate potential predictors of greatest VNS response in this vulnerable group of children.