Abstracts

Rationale: Lennox-Gastaut Syndrome (LGS) is a rare epileptogenic disorder that arises in childhood and includes multiple seizure types, slow spike-and-wave complexes on EEG and cognitive impairment. LGS usually persists through adulthood and has a poor prognosis, despite extensive pharmacological treatment. When medications fail, patients can proceed to one of two palliative surgeries, vagus nerve stimulation (VNS) or corpus callosotomy (CC). Although VNS is a lower risk procedure, its relative efficacy compared with CC is not well understood.Methods: A systematic search of Pubmed and Ovidsp was performed to find articles that met inclusion criteria, which include 1) prospective or retrospective study, 2) at least one patient diagnosed with Lennox-Gastaut syndrome, 3) concrete measure of seizure frequency reduction, either in numbers or ranges, after VNS and/ or CC. Relevant demographic and clinical data were gathered. Seizure reduction rates were divided into seizure subtypes and categorized as 100%, >75%, and >50%. Characteristics of patient groups (VNS vs. CC) were compared using chi-square tests for categorical variables and t-test for continuous measures. Pooled proportions with 95% Confidence Interval (95% CI) of seizure outcomes were estimated for total seizures and seizure subtypes using random effects methods. The differences between two pooled proportions were tested by evaluating the overlap of the 95% CI. P values less than 0.05 were considered significant.Results: 17 VNS and 9 CC studies were included (Table 1). CC had a significantly better outcome than VNS (Table 2) for >50% atonic seizure reduction (p<0.05) and for >75% atonic seizure reduction (p<0.05). Although there was also a large mean difference between CC and VNS for patients who became 100% free of atonic seizures (48.0% CC vs. 22.8% VNS), this was not found to be significant in the analysis. All other seizure types, as well as total number of seizures, showed no statistically significant difference between VNS and CC. Conclusions: CC may be more beneficial for LGS patients whose predominant disabling seizure type is atonic. For all other seizure types, VNS offers comparable rates to CC without the risks of intracranial surgery.