A small, preliminary study indicates that vagus nerve stimulation (VNS) combined with rehabilitation is safe and feasible for stroke patients, opening the door for further research.
“This ‘first in humans’ study appears to demonstrate improvement in the recovery that stroke patients make. This was a small study and there is more work to be done, but this is an exciting result,” study author Michael Kilgard, PhD, of the University of Texas in Dallas, said in a statement.
Upper limb weakness is present in stroke patients approximately 85% of the time, however current treatment is limited to intensive rehabilitation. Animal studies have shown that VNS — which releases norepinephrine and acetylcholine, both linked to cortical network reorganization — paired with movement improves motor cortex plasticity and forelimb function, suggesting that the therapy may be beneficial for stroke-related hemiparesis.
In the current study, Jesse Dawson, MD, of the Institute of Cardiovascular and Medical Sciences at Queen Elizabeth University Hospital in Glasgow, United Kingdom, and colleagues hypothesized that combining upper-limb rehabilitation with VNS would lead to better functional recovery in patients with ischemic stroke. The researchers conducted a randomized controlled pilot study to test the feasibility and safety of VNS in patients with upper-limb weakness after stroke.
Participants included 20 patients with a history of ischemic stroke and moderate to severe upper-limb weakness. Patients were randomized to receive rehabilitation alone (n=11) or VNS with rehabilitation (n=9). The VNS group demonstrated a mean change in Fugl–Meyer Assessment-Upper Extremity (FMA-UE) scores of +8.7 compared to +3.0 in the rehabilitation group (between-group difference 5.7, 95%CI: -0.4-11.8, P=0.064). However, in the per protocol analysis the change in FMA-UE was significantly different between groups with +9.6 in the VNS group versus +3.0 in the rehabilitation group (between-group difference 6.5, 95% CI: 0.4-12.6, P=0.038). Within the VNS group, 6 participants (66.7%) demonstrated meaningful clinical response compared with 4 participants (36.4%) in the rehabilitation-only group (P=0.17).
Eight participants in the VNS group reported a total of 22 adverse events, including 2 serious events and no serious device-related events. Adverse events related to the device, including nausea and taste disturbance were mild. One patient reported dysphagia and transient vocal cord palsy after device implantation.
“This study demonstrates that vagus nerve stimulation appears to improve the recovery that stroke patients make,” Dr. Kilgard said. “VNS is triggered on successful movements to solidify gains that are made during physical therapy.”
A double-blind, placebo-controlled, multisite study out of the University of Texas Dallas and University of Texas Southwestern Medical Center is currently underway to further test the effects of VNS and rehabilitation in stroke patients.
The study was funded by MicroTransponder, Inc
Dawson J, Pierce D, Dixit A, et al. Safety, Feasibility, and Efficacy of Vagus Nerve Stimulation Paired With Upper-Limb Rehabilitation After Ischemic Stroke. Stroke. 2015; doi:10.1161/STROKEAHA.115.010477.