Authors' objectives:

The objective of the report was to assess the use of VNS for the treatment of patients with refractory epilepsy.

Authors' results and conclusions: In 2001, a Canadian agency published a review on the use of VNS in subjects with refractory epilepsy. They identified 5 non-controlled trials (between 15 and 454 patients), who showed a reduction in the frequency of seizures under prolonged stimulation (27% to 45% of patients had a 50% decrease or higher). As regards its use in children, the authors found 5 case series reports with 20-30% reduction in the frequency of seizures at 3 months and 40-50% between 18 and 24 months after initiation of therapy. The rate of adverse events in a larger study (60 patients) was about 10%, being generally mild, although a patient died due to aspiration pneumonia considered secondary to VNS. As regards its use in patients with generalized epilepsy, a case series report including 24 patients showed a 46% decrease in the frequency of seizures within 3 months of VNS initiation (p=0.004). In 2002, a systematic review comparing the use of VNS with high and low intensity level schemes in patients with refractory epilepsy was published. Two double-blind, randomized studies with a total of 312 patients were included. The Odds Ratio (OR) of achieving a 50% reduction or greater in the frequency of seizures was 1.93, favouring high intensity stimulation (95% CI from 1.11 to 3.35). No differences were found in withdrawal rate when comparing both modalities, even though patients with high intensity stimulation presented more hoarseness and dyspnea. Great Britain s health technology assessment agency performed a bibliographic review in 2004 on the use of VNS in pediatric population, concluding that the evidence on safety and efficacy of the intervention seems adequate to support its use in refractory epilepsy cases. Recently, a review about clinical guidelines for the treatment of patients with epilepsy has been published. A guide from the American Academy of Neurology only described the use of VNS. It states that its use is recommended in patients with refractory epilepsy, for whom surgical treatment is not a choice.

Authors' recommendations: Although VNS can lessen the number of seizures in some patients, there is no evidence to indicate that this would reflect a reduction in associated morbidity and mortality or significant quality of life improvement. The evidence to date must be cautiously considered, since, in general, it comes from studies of poor methodological quality and with no control group. Special care must be exercised in less studied subpopulations such as patients with generalized epilepsy. At present, no criteria have been identified to select those patients with higher chances of benefiting from VNS. As general guideline, it is recommended to confirm epilepsy diagnosis first as well as adequate compliance to pharmacological treatment, duly documenting failure. When treating a patient with refractory epilepsy, different therapeutic alternatives can be considered, including surgical treatment (which can be curative up to 60-70% of patients with temporal epilepsy) or pharmacological treatment with new drugs. In those patients in whom surgery is not a viable option, the decision to use VNS should be based on frequency and type of seizures, severity of the episodes, toxicity to antiepileptic drugs and the expected overall impact of these factors on the patient s quality of life.

Authors' methods: Overview

Project Status: Completed

URL for project: http://www.iecs.org.ar/

Year Published: 2006

English language abstract: An English language summary is available

Publication Type: Not Assigned

Country: Argentina

Organisation Name: Institute for Clinical Effectiveness and Health Policy

Contact Address: Dr. Emilio Ravignani 2024, Buenos Aires - Argentina, C1414 CABA

Contact Name: info@iecs.org.ar

Contact Email: info@iecs.org.ar

Copyright: Institute for Clinical Effectiveness and Health Policy (IECS)