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New understanding of how VNS treats epilepsy

10 December, 2001

A new study presented indicates that seizure control improves in patients with epilepsy when Vagus Nerve Stimulation (VNS) increases blood flow in the thalamic areas of the brain.

In people with epilepsy, VNS involves inserting an implant under the skin of the upper chest and vagal nerve area of the neck. Nerve fibres in the vagal nerve carry information from the body’s organs to the brain, which are believed to be involved in producing seizures. It is suggested that stimulation of the vagal nerve may be able to disrupt epileptic activity.

VNS causes activation of synaptic activities at multiple sites in the brainstem and both cerebral hemispheres. The results of the study confirm earlier evidence that showed that altered thalamic processing contributes to the anti-seizure effects of VNS.

"The study results are significant because they show that if patients respond to VNS therapy in the short-term they will continue to respond favorably over the long-term,” said Dr Thomas R. Henry, of the Neurology Department of Emory University . "In addition, these results also suggest ... long-term seizure control - something that has not been possible up until now.”

The study involved 11 patients with partial epilepsy who were uncontrolled with anti-epileptic medication and who had complex partial and general tonic clonic seizures. During one year of VNS, seizure control improved in most patients, with a reduction of up to 91 per cent.

"Our study shows that VNS may benefit other blood functions," stated Henry. "Blood flow activations in frontal cortex and subcortical sites may alter attention, memory and mood. These activations may not serve to control seizures but might benefit depression and memory impairment."