Vagus Nerve Stimulator (VNS)

The vagus nerve stimulator (VNS) is a surgically implanted device that intermittently stimulates the left vagus nerve. Why this decreases seizure frequency is not well understood. It is a palliative, not curative, procedure that has been performed in adults and in some children with intractable complex partial seizures or generalized tonic seizures who were not candidates for definitive surgical cure for various reasons. The VNS has been placed in children younger than 3 years [Zamponi: 2008], but most of the experience is in older children. It is generally well-tolerated and safe, with a response in children similar to adults. There is a median reduction of seizure frequency of about a third at 1 year that increases to over 40% at 18 months. Several months may go by before there is any change, followed by a slow but steady improvement in seizure frequency. Sixty to ninety percent of children in one study showed a reduction in seizure frequency. [Zamponi: 2008]

Complications that occur with VNS use include failure of the device to work and infections, both in about 3%, and stimulus-associated hoarseness and swallowing problems. [Smyth: 2003] Sleep-related breathing problems have also been described. [Hsieh: 2008]