Abstracts

RATIONALE: Vagal nerve stimulation is a new non-pharmacological therapy for patients with refractory epilepsy. The treatment is based on animal experiments demonstrating that intermittent stimulation of the vagal nerve could prevent or reduce the frequency and/or duration of seizures. METHODS: At the National Hospital in Norway, a total of 47 therapy resistant patients have had a vagal nerve stimulator implanted since June 1993. We have used the Neuro-Cybernetic Prosthesis system from Cyberonics. The mean age of the population was 34.4 years (12-70 years). All had a long standing epilepsy with frequent seizures, 36 had daily seizures. The majority had localisation related epilepsy. Mean follow-up time was 2.7 years (0.4-6.5 years). RESULTS: 16 patients (34%) responded to the treatment with >50% reduction in seizure frequency. One patient became seizure free. 20 patients (43%) had no reduction in seizure frequency. 24 patients (51%) benefited from extra stimulation triggered by the magnet. The stimulation seemed to affect several types of seizures, most often a reduction in frequency of secondary generalized tonic-clonic seizures was noted. Hoarseness, coughing and a tingling sensation in the throat were the most frequently reported side effects, occuring during stimulation. The patients tended to habituate to these side effects. In 14 patients (30%) the device has been explanted, mostly due to lack of efficacy. CONCLUSIONS: Considering the fact that this patient group belong to the most refractory part of the epilepsy population, the results are regarded as promising. However, the role of vagal nerve stimulation in the future treatment of epilepsy is still not settled. Several questions remain unanswered, e.g. what are the exact mechanisms of action behind the seizure reducing effect, and which patients are most suitable for this treatment?