Vagus Nerve Stimulator: Evolving Trends

Introduction: Over three decades ago, it was found that intermittent electrical stimulation from the vagus nerve produces inhibition of neural processes, which can alter brain activity and terminate seizures. This paved way for the concept of vagal nerve stimulator (VNS). We describe the evolution of the VNS and its use in different fields of medicine with a review of literature.

Methods: PubMed and EMBASE search was performed for “VNS” and its use in refractory seizure management, depression, obesity, and neurogenesis.

Results: VNS has been in vogue since 1990 and has proven to reduce the intensity and frequency of seizure by 50% for the management of refractory seizures. Apart from this, VNS has shown to promote neurogenesis in the dentate gyrus of rat hippocampus after 48 hours of stimulation of the vagus nerve. Improvement has been observed in nonpsychotic major depression from a randomized trial conducted in 2005.¹ The same concept has been used to alter behavior and cognition in rodents and good improvement has been observed. Recent studies have proven that VNS is effective in obesity management in patients with depression. Migraines, fibromyalgia, and tinnitus are also known to respond to VNS.

Conclusion: VNS has gained significant popularity with promising results in epilepsy surgery and treatment-resistant depression. The spectrum of its use has also extended to other fields of medicine and there is still a viable scope for its utility in the future.

References

1 Rush AJ, Marangell LB, Sackeim HA, et al. Vagus nerve stimulation (VNS) for treatment-resistant depression: a randomized, controlled acute phase trial. Biol Psychiatry 2005