Abstracts

Rationale: Vagus nerve stimulation (VNS) is an established treatment for intractable epilepsy. However, there is limited data on the very long-term outcome of patients who have undergone VNS. Methods: We retrospectively reviewed the case notes of consecutive patients who underwent VNS for intractable epilepsy at King’s College Hospital from April 2004 to December 2007. Results: 153 patients underwent VNS for intractable epilepsy during this period. Records were available for 140. The median age at surgery was 20 (range 5-63, 65 were <=18 years). The median follow-up period was 10 years (range 0-13, 77 had >=10 year follow-up). The median age of onset of epilepsy was 5 years (range 0-41). The median time from epilepsy onset to VNS implantation was 14 years (range 3-52). The mean number of AEDs before VNS and at last follow-up was unchanged at 3. The number of monthly seizures at last follow-up improved in 61 patients (44%), including 10 (7%) who were seizure free and 36 (26%) who had >50% reduction in seizures. Seizures worsened in 11 (8%) and did not change in 50 (36%). The change in seizure frequency could not be determined in 18 patients (13%). Adverse events occurred in 26 patients (19%) and included cough (10 patients), dysphonia (6), infection (4), lead failure (4), haematoma (1), dysphagia (1), confusion (1). 65 patients (46%) had battery changes, including 3 who required 2 battery changes over the follow-up period. The median duration to first battery change was 7 years. The VNS was not being used at last follow-up in 40 patients (29%). The reasons for this were lack of efficacy (18), improvement in seizures (4), awaiting battery change (3), had DBS (3), adverse effects (3), lead failure (3), infection (2), cosmetic reasons (1), had callosotomy (1), not known (2). 14 patients died, of which one was attributed to SUDEP. The median age at implantation for these patients was 20 years (range 9-63) and the median follow-up was 3.5 years (range 0-12). Conclusions: These results suggest that treatment with VNS remains a useful adjunct for intractable epilepsy and may contribute to seizure reduction in a significant number of patients for whom there is no other alternative treatment. There remains a substantial number in whom VNS is not effective, which underscores the importance of preoperative counselling. Funding: None