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Improving Long-Term Mobility After Stroke with Vagus Nerve Stimulation

Keck Medicine of USC has performed the world’s first VNS implantation for a stroke recovery patient outside of a clinical trial, offering new hope for others whose rehab has plateaued.

Vagus nerve stimulation (VNS) has been used as a treatment for epilepsy for almost 30 years. In 2005, it also received Food and Drug Administration approval for use in response to severe depression.

Now, the results of a clinical trial published in The Lancet in 2021 suggest that VNS may also prove effective for stroke rehabilitation — and doctors at Keck Medicine of USC have already begun to use it for that purpose.

For stroke survivors, who often endure lingering disabilities resulting from their strokes, this means that surgical intervention may finally become an option in their recovery.

Among the 795,000 people who have strokes every year in the United States, roughly 80% experience loss of arm function. Stroke recovery patients, prior to this clinical trial, relied solely on task-specific rehabilitation practices to regain function of their upper extremities.

“This idea of improving upon rehabilitation has been, in some ways, the holy grail of people working in stroke rehabilitation,” said Charles Liu, MD, PhD, director of the USC Neurorestoration Center, who coauthored the study and served as its lead neurosurgeon.

The Clinical Trial

The 108 participants in the randomized, triple-blind study had all continued to experience moderate-to-severe arm weakness at least nine months after their strokes — a point close to the one-year mark, which is when recovery often begins to plateau.

Fifty-three of the participants received VNS in tandem with their rehabilitation, while 55 received a sham intervention in a control group.

The results were significant: Participants who received VNS in addition to the rehabilitation regained two to three times more upper-extremity motor function than those in the control group.

Following these positive results, VNS received FDA approval for use in stroke survivors. Soon afterwards, in May 2022, Dr. Liu and fellow Keck Medicine neurosurgeon Jonathan Russin, MD, performed the world’s first VNS implantation procedure for a stroke recovery patient outside of a clinical trial.

That patient, a 60-year-old California woman, began a regimen of occupational therapy directed at improving the functioning of her left hand, which remained impaired five years after her stroke.

According to Dr. Liu and Dr. Russin, many patients in her position would have previously met the limit of their recovery.

“Before, there was nothing that we could offer to chronic stroke patients from a surgical intervention standpoint,” Dr. Russin said. “Now, there is.”

What is Vagus Nerve Stimulation?

The implantation of a VNS device requires a 45-minute procedure. Neurosurgeons place a matchbox-sized pulse generator between the skin and muscle of the patient’s left pectoral area, the same area where a pacemaker would sit.

The generator then connects to a set of leads, or coils, that wrap around the vagus nerve in the patient’s neck. This nerve, known as the “wandering” nerve in Latin, conducts much of the nervous system’s autonomic function.

Occupational therapists — or even patients — can activate the device while the patient performs rehabilitative tasks targeted at their injured extremities.

The clinical trial’s results suggest that the pairing of electrical stimulation with occupational therapy “changes the state of the nervous system,” Dr. Liu said, “and by changing the system, what the system is able to do is also changed.”

According to Dr. Liu, this development of a new intervention for stroke-induced neurological injuries represents “potentially the beginning of a brave new world of neurorestoration.”