gms | German Medical Science

The application of vagus nerve stimulation (VNS) for medically intractable epilepsy has already become a widely accepted treatment option for this clinical entity. However, long-term efficacy still remains controversial. In our study, we analysed 21 patients with a follow-up period up to 6 years.

Since 1998 the VNS has been established at our institutions. From this time we operated on more than 40 patients with refractory epilepsy. The implantation of VN-stimulators (Cyberonics VNS) was done via the standard approach. The presented data include 21 patients (10 female, 11 male; average age 37.5 years) with a minimum follow-up of 24 months ranging from 27 to 71 months (mean 52.1). Patients with a history of medically intractable partial seizures who would not benefit from resective surgery or Lennox-Gastaut syndrome, and patients in whom previous epileptic surgery had failed were included. Seizure reduction, side effects, administration of antiepileptic drugs and surgical complications were analysed.

Clinically significant seizure reduction was defined as ≥50 % reduction of seizures (responders). Ten patients were non-responders. An overall seizure reduction of 70.5 % was noticed in the responder group (n=11). Nine patients reported a reduction of seizure frequency between 50 and 87%. Two responders with a symptomatic focal epilepsy have been seizure free. After implantation of the VN-stimulator, 3 patients developed a transient laryngeal nerve paresis with hoarseness and another 3 patients reported breathing difficulties. After changing the stimulation parameters these symptoms improved. In one patient, an infection occurred. The stimulator was explanted and re-implantation was done after 3 months. A battery and stimulator change in 3 patients of the responder group was necessary after 55 to 65 months. Despite a seizure reduction in the responder group, the administration of combined antiepileptic drugs did increase from 2.4 to 3.1. In the non-responder group, 3 stimulators were explanted and 2 turned off as a result of failed therapy.

Our long-term results show that a subgroup of patients (52%) with medically intractable epilepsy achieved a seizure reduction of 50% and more over a long period. This effect means a higher quality of life for these patients and their relatives. However, the patients must realise that this therapeutic option is not a substitute for medication.