Can a nerve-stimulation device improve arm function after a stroke?

This study looked at vagus nerve stimulation (VNS) as a treatment for arm weakness after stroke. It found that VNS combined with standard rehabilitation improved arm function significantly more than standard rehab alone.

After a stroke, some nerves do not work as they should. This means that the muscles that those nerves stimulate do not work properly either, leading to weakness in the arms or legs. Rehabilitation is used on these muscles so that the nerves can learn to stimulate them again. It has been suggested that vagus nerve stimulation (VNS) may help this process by helping the nerves to work in a different way. 

Vagus nerve stimulation (VNS) is a procedure in which a device is inserted into the upper chest to stimulate the vagus nerve. This procedure is sometimes used in the treatment of epilepsy to re-train the nerves that are not working properly. However it is not clear if VNS combined with standard rehabilitation helps improve muscle weakness in the arm after a stroke.

108 patients with arm weakness after a stroke were involved in this study. 53 were treated with VNS and rehabilitation, 55 were treated with rehabilitation and a fake VNS procedure. Treatment was done in 3 sessions per week for 6 weeks. Arm function was measured using the Fugl-Meyer Assessment of the upper extremity (FMA-UE). The FMA-UE is a self-reported questionnaire marked out of 66 points.

After 6 weeks, the FMA-UE score of the VNS group increased by an average of 5 points, compared to an increase of 2.4 points in the rehab-only group. After 3 months, significantly more patients in the VNS group (47%) had meaningful improvements in arm function compared to the rehab-only group (24%).

Side effects were reported similarly in both groups. Only one serious side effect occurred due to the surgery in the fake therapy group (paresis of the vocal cords) which resolved after 5 weeks. 

This study showed that VNS in combination with rehabilitation may be an effective treatment for arm weakness after a stroke.

This study followed patients for a total of 3 months. It will be important to learn if the effects of VNS are long-lasting. Longer-term studies are needed. This study was funded by MicroTransponder, the manufacturer of the VNS device.