Abstracts

Rationale: To compare the outcome with respect to: age of implant, aethiology and duration of epilepsy. Methods: 135 drug resistant epileptic patients, excluded from ablative surgery, were submitted to vagal nerve stimulation (1995- 2007). Aetiology: 57 cryptogenic, 78 symptomatic; age of implant: (0-6yr) 18; (7-12y) 32; (13-18y) 31; 54 (more than 18y). Epilepsy type: Lennox-Gastaut 18; Pseudo-Lennox 33; Partial 84. Duration of epilepsy ranged from 3 months to 57 years. Clinical outcome was determined by comparing the seizure frequency after stimulation at 3-6-12-18-24-36 months with the previous 3 months. “Responders” were the patients experiencing a seizure frequency reduction of 50% or more. Statistical analysis: Wilcoxon test, MANOVA, Multivariable Regression Model, Logistic Multivariable Regression Model. Results: The seizure frequency reduction was significant in the group as a whole between baseline and the first follow-up (Wilcoxon test). The percentage of responder increases with time (McNemar test p=0,04). Univariate analysis showed a significant effect of the age of implant on seizure frequency reduction: adult patient had worst clinical outcome than children (p<0,001) and adolescents (p=0,08). Lennox-Gastaut had significant better outcome than partial epilepsy. Lesser duration of epilepsy had positive influence on outcome. Multivariate analysis confirmed age of implant to be the strongest factor influencing prognosis. Furthermore positive is the association between lesional aetiology and young age. Conclusions: the best responder could be a young lesional epileptic patient; after 3 years follow-up the percentage of responders is still in progress.