COMMENTARY

Vagus Nerve Stimulation for Children With Epilepsy

Epilepsy Notes

Andrew N. Wilner, MD

Disclosures

November 11, 2013

In This Article

The Vagus Nerve Stimulator

The first vagus nerve stimulator (VNS) was implanted in 1988.[1] Since then, more than 70,000 have been implanted for epilepsy worldwide.[2]

The VNS consists of a generator, typically implanted in the chest, and an electrode surgically fastened to the left vagus nerve. In addition, an external handheld magnet may be used if the patient senses an aura or to stop a seizure already in progress.

US Food and Drug Administration Approval

In 1997, VNS received US Food and Drug Administration (FDA) approval for the adjunctive treatment of refractory seizures in patients older than 12 years.[3] In 2005, the VNS was approved for the treatment of chronic or recurrent depression in patients older than 18 years.

VNS may also have a beneficial effect on mood in patients with epilepsy in addition to its antiepileptic effect.[1] The mechanism of action of VNS is uncertain, but may be related to metabolic activation of brain stem, limbic, or thalamic structures.[4]

To date, the VNS is the only FDA-approved medical device for the treatment of epilepsy. However, other approaches, such as deep-brain stimulation of the anterior nucleus of the thalamus, responsive neurostimulation, trigeminal nerve stimulation, and transcranial magnetic stimulation, are in development.

Phase 3 Trials for Epilepsy

A randomized, multicenter, clinical trial (Study E03) of 114 patients with partial seizures demonstrated a mean seizure reduction of 31% and a 50% seizure reduction in 39% of patients.[5] A second randomized trial (Study E05) of 254 patients with intractable partial seizures demonstrated an average reduction in seizure frequency of 28% in the high-stimulation group vs a 15% reduction in the low-stimulation (pseudo-placebo) group (P = .04).[4] These results are modest, but similar to those obtained with new antiepileptic drugs in phase 3 trials. Unlike antiepileptic drugs, VNS efficacy appears to improve over time.[3]

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