The U.S. Food and Drug Administration has just approved its first implantable vagus nerve stimulation device, the Vivistim System. The device has been shown to double the rate of functional improvement of the upper extremity following ischemic stroke, potentially ushering in a new era in stroke care.
“People who have lost mobility in their hands and arms due to ischemic stroke are often limited in their treatment options for regaining motor function” Dr. Christopher M. Loftus said in a FDA press release. “Today’s approval of the Vivistim Paired VNS System offers the first stroke rehabilitation option using vagus nerve stimulation. Used alongside rehabilitative exercise, this device may offer benefit to those who have lost function in their upper limbs due to ischemic stroke.”
The effectiveness of this device was shown in a pre-FDA-approval research study published in April 2020 in The Lancet. The randomized, triple-blind, sham-controlled trial of 106 subjects was conducted at nearly 20 medical centers across the United States and the U.K.
Subjects in this study were at least nine months post-acute ischemic stroke and still exhibiting moderate to severe upper extremity weakness. All participants had a device surgically implanted, with half receiving direct vagus nerve stimulation and the other half receiving sham stimulation.
“Most participants were uncertain or incorrect regarding their treatment allocation,” wrote the authors, suggesting that the participants were well blinded.
Both groups underwent standard physical therapy rehabilitation three times a week for six weeks followed by a home exercise program. Primarily using Fugl-Meyer Assessment-Upper Extremity (FMA-UE) scores, the authors found that the treatment group improved at twice the rate of the sham group. Half of this group also showed continued improvement after 90 days.
This improvement is likely due to the neuroplasticity augmentation that results from stimulating the vagus nerve — something that has been confirmed by numerous other studies.
Because of this known effect, vagus nerve stimulation itself (both invasive and non-invasive) has been used to treat other conditions, including epilepsy and certain headache disorders.
While the FDA states that the new Vivistim System is only approved for use during rehabilitation of the upper extremity following ischemic stroke, its trial success and FDA approval have sparked a much broader conversation.
The authors of an editorial published in the British Journal of Neurosurgery wrote: “There may also be a role for this therapy in recovery from other brain injuries — congenital or acquired; ischaemic, haemorrhagic, traumatic or inflammatory.”
Added another commentator in The Lancet: “With the advent of nerve stimulating therapies [like this] … an exciting potential new era in the management of stroke has started.”