Treatment Outcomes of Vagus Nerve Stimulation in Lennox-Gastaut Syndrome

Abstract

Lennox-Gastaut syndrome (LGS) is one of the most severe epileptic encephalopathies and frequently patients with this syndrome respond poorly to antiepileptic drugs. The aim of this study was to evaluate the treatment outcomes of vagus nerve stimulation (VNS) in LGS patients with drug-resistant epilepsy. Methods: We analyzed the clinical files, collected over 5 years, of children with LGS who received VNS treatment. Results: Seven children were included in this study (four males, three females; mean age of VNS insertion 12.4±3.5 years). All the patients had generalized tonic seizures and there were various other seizure types including myoclonic seizures, atonic seizures, and atypical absence seizures. Although two patients had normal imaging, five patients had abnormalities on imaging, including pachygyria, cortical dysplasia, kernicterus, and a chromosomal anomaly. Comparing the baseline seizure frequency to the frequency after the VNS surgery, the seizure frequency at the last follow-up showed a decrease of 57.2% (0% to 100%) on average (P=0.028) and one patient achieved seizure free status. Only two children were given additional antiepileptic drugs with the aim of managing their seizures. There was no mortality or complications related to the VNS therapy except one case requiring intensive care unit admission due to pneumonia. Comparing the results before and after VNS surgery, the VNS therapy also had a tendency to have a positive effect on quality of life (P=0.066). Conclusion: In LGS patients with drug resistant epilepsy who are not candidates for a corpus callosotomy or resective surgery, VNS could be an effective, low-risk adjunct therapy for decreasing seizure frequency.