Abstracts

Rationale: Vagus nerve stimulation (VNS) was approved by the Japan Ministry of Health, Labor and Welfare in 2010. There is no real limitation in epilepsy syndromes and patients’ age. VNS therapy has become gradually popular as a palliative treatment option for intractable epilepsy in Japan, especially in patients who are not considered to be suitable candidates for intracranial epilepsy surgery (IES). The object of this study was to assess the efficacy of VNS therapy for intractable epilepsy in a consecutive series of pediatric patients who underwent implantation aged 10 years old and younger.Methods: In this retrospective review of medical records or telephone interviews for 23 pediatric patients who underwent VNS implantation for intractable epilepsy from February 2011 through February 2015 in our hospital, there were 10 girls and 13 boys ranging from 1 to 10 years at the time of implantation (mean: 6 y-o). Two patients were excluded because the seizure reduction could be from antiepileptic drugs and the other had a device removal due to surgical site infection. The outcome of VNS therapy was evaluated using the McHugh (MH) outcome classification.Results: The populations were constituted of symptomatic generalized epilepsy (SGE, n=14) and symptomatic localization-related epilepsy (SLRE, n=7). Compared to the pre-treatment baseline, a more than 80% reduction in seizure frequency (MH class 1) was achieved in 8 patients (38%), a 50-79% seizure reduction (MH class 2) in 6 patients (29%). In patients with SGE, 5 patients achieved MH class 1 (36%), and 3 patients got MH class 2 (21%). In the patients with SLRE, MH class 1 was in 3 patients (43%), MH class 2 in 3 patients (43%). A period of follow-up was also an important factor. In 9 patients followed up for more than 2 years, MH class 1 was seen in 4 patients (44%), MH class 2 was in 1 patient (11%). On the other hand, patients less than 2 years after the implantation showed MH class 1 in 4 patients (33%), MH class 2 in 5 (42%).Conclusions: VNS therapy is an effective treatment option as palliation for pediatric patients with intractable epilepsy. In this study, a more than 50% reduction in seizure frequency was seen in 67% of the patients. A more than 80% reduction was achieved in 44% patients followed up for more than 2 years. VNS is also safe in terms of adverse effects, which usually improve year by year. Then VNS is recommended even for the pediatric population as an alternative and palliative option, unless patients are good candidates for IES.