Five clinical studies of VNS Therapy involving 454 patients have been conducted. There were 2 double-blind, randomised, controlled studies (E03 and E05), which provided the foundation for VNS Therapy approval by the FDA. Based on these studies, efficacy and safety of VNS Therapy was demonstrated.

A unique feature of VNS Therapy is its ability to improve seizure control over time. The long-term impact of VNS Therapy was assessed in an open-label, long-term study of 454 epilepsy patients using data from all 5 VNS Therapy controlled, clinical trials. The study compared the percentage of patients with seizure reductions of ³ 50% over a 3-year period. The percentage of patients with ³ 50% seizure reduction was 43% at 2 and 3 years.¹
 

Results of a multicentre study, comparing a group of patients who were treated with VNS Therapy earlier in the course of their epilepsy with a group treated with VNS Therapy later in the course, showed that earlier use of VNS Therapy significantly improved seizure control. Of the patients in the early group treated within 5 years after onset or having tried 4 or fewer AEDs, 15% reported no seizures with VNS Therapy at 3 months compared with 4.4% of those in the control group.²

In addition, one patient in five reported no seizures with a loss of consciousness, and one in three with complex partial seizures reported complete control of the complex partial seizures at 3 months with earlier use of VNS Therapy.²

A randomised, controlled prospective phase 4 study using VNS Therapy versus medical therapy earlier in the course of epilepsy versus later is ongoing in paediatric patients in Europe. For more information on this study click here. (under construction)

In summary, VNS Therapy has clinically proven to reduce the number and intensity of seizures and, in some cases (4%), to completely eliminate seizures without systemic interaction.
 

¹Morris GL et al. Neurology. 1999; 53:1731-1735.
²Renfroe JB et al. Neurology. 2002; 59 (suppl.4):S26-S30.

For more information on the VNS Therapy for pharmacoresistant epilepsy please contact us or visit the Cyberonics website.