Abstracts

Rationale: Epilepsy is a common neurological disorder of childhood that affects 1% of children. 30% of children with epilepsy do not respond to medication. Vagal nerve stimulation (VNS) is a potential alternative treatment for these patients when resective surgery is not an option. However, VNS is currently not FDA approved to treat epilepsy in children ages 3 or younger, and there is little evidence available to guide the use of VNS for young children. The objectives of the present study were 1) to examine the efficacy of VNS for reducing seizure frequency and antiepileptic drugs (AEDs) in young children and 2) to compare long-term VNS efficacy for children who receive the device at ages 0-3 vs. at ages 4-6. Methods: We conducted a 10-year retrospective analysis of VNS implantations at UPMC Children’s Hospital of Pittsburgh. Relevant data were collected within 12 months of VNS implantation and again after VNS implantation at 6 months, 12 months, 24 months, and latest follow-up. Patients were included in demographic and seizure characterization analysis if they had drug-resistant epilepsy with VNS implantation at age 6 or earlier. Patients were excluded from primary outcome analysis (>50% seizure reduction and seizure freedom) if their VNS was removed or permanently turned off within 12 months of initial implantation or if there was no recorded 24-month follow-up. Results: This analysis included 99 patients ages 0-3 (n=40) and ages 4-6 (n=59) at first VNS implantation. 86 patients followed up for >4 years. There were no significant differences between age at VNS implant (0-3 vs. 4-6) and etiology of seizures or most seizure semiologies (see Table 1). 9.1% of patients (n=9) experienced minor complications from VNS surgery (vocal changes, hoarseness, or vocal cord paresis). 8.1% of patients (n=8) experienced major complications; this included 5.1% of patients (n=5) who developed deep infections requiring VNS removal. Patients took an average of 3.01 + 1.29 AEDs prior to VNS and an average of 3.84 + 1.68 AEDs at their latest follow-up. There was no significant difference between age at VNS and quantity of AEDs taken before or after implantation. At the latest follow-up, only 21% of patients took fewer AEDs than before VNS therapy; 53% of patients took more AEDs after VNS therapy. 4 patients were excluded from subsequent outcome analysis due to lack of 24-month follow up with VNS. 48%, 56%, 62%, and 57% responded (achieved >50% seizure reduction) to therapy at 6 months, 1 year, 2 years, and >4 years after VNS implantation, respectively. Until 24 months, patients who received VNS by age 3 achieved >50% seizure reduction at similar rates to those who received VNS after age 3. However, children ages 4-6 at VNS implantation were significantly more likely to have >50% seizure reduction (p=0.011) and to achieve seizure freedom (p=0.026) >4 years after surgery than those who received VNS at ages 0-3. Conclusions: This study corroborates evidence that VNS may be an effective treatment for drug-resistant epilepsy in children. 24 months after VNS, 0-3 year old patients do achieve >50% seizure reduction at similar rates to older children. However, fewer very young children (ages 0-3) maintain >50% seizure reduction after 4 years when compared to older children (ages 4-6). Response rates to VNS modestly diminish in both age groups after 4 years, though these findings may reflect disease progression rather than lack of VNS effectiveness. In the long term, VNS does not seem to allow most young patients to reduce their AEDs. Funding: No funding