Abstracts

Rationale: Since 1997, VNS has been an approved add-on therapy for intractable epilepsy. Only a few studies have demonstrated long term seizure outcomes, and there are no studies that have assessed psychosocial outcomes in adults. The aim of our study was to determine psychosocial and seizure outcomes for up to 15 years on VNS therapy.Methods: Following IRB approval, patients who had VNS implantation at our institution for intractable epilepsy from 1998 to 2013 were identified. Demographics, age at epilepsy onset and VNS implantation, seizure frequency and number of antiepileptic drugs (AEDs) before and after VNS implantation were collected. Phone surveys were conducted from May to November 2014 to determine the patients’ current seizure frequency. Psychosocial metrics including driving, employment status, use of antidepressants and satisfaction rate, were assess in those >=18 years old at the time of VNS without developmental delay. Outcomes were based on modified Engel’s classification (I: seizure free/rare simple partial seizures; II: >90% seizure reduction (SR), III: 50-90% SR, IV:<50% SR) (class I,II,II = favorable outcomes).Results: A total of 207 patients underwent VNS implantation, 15 of whom were deceased at the time of the phone survey and 40 had incomplete data for medical abstraction. Of the 152, 90 (59%) were contacted and completed the survey. Of these, 51% were male, with mean age of epilepsy onset 9.4 years (range birth to 60 y). Of the 80 patients with seizure frequency information, 16 (20%) had a modified Engel class I outcome, 14 (18%) had class II, 24 (30%) had class III and 26 (33%) had class IV. 80% said having VNS was worthwhile. Among the 90 patients, 43 patients were >=18 y old without developmental delay in whom psychosocial outcomes were further analyzed. There was a decrease in the number of patients driving (31% vs 14%, p=0.052) and working (44% vs 35%, p=0.285), and an increase in the number of patients using anti-depressant medication (14% vs 28%, p=0.057) at the time of survey compared to before VNS. In this subset, patients with favorable outcomes (60%) were taking significantly fewer AEDs at the time of survey compared to patients with unfavorable outcomes (median 3 vs 4, p=0.045). The associations of favorable outcomes with the psychosocial outcomes of driving, employment and anti-depressant use were not significant. Although, 77% of this subset said VNS was worthwhile.Conclusions: Our study shows that VNS is a well-tolerated long term adjunctive therapy for intractable epilepsy leading to favorable (>50%) seizure reduction in 2/3rd of the patients, and seizure freedom in 20% of patients This is the first study to demonstrate that although there is no statistical difference in the psychosocial metrics before and after VNS implantation in those with either favorable or unfavorable seizure outcomes, the great majority of patients (80%) expressed satisfaction with VNS therapy. Much of this could be due to the very intractable nature of epilepsy in these patients who perhaps express contentment with relative improvement in their seizure frequency.