Objectives: Approximately 40% of stroke survivors have severe impairments that reduce quality of life and require special care. Severe impairment cases have been historically underrepresented in stroke research. Peripheral nerve stimulation (PNS) is a neuromodulation technique that applies transcutaneous electrical currents to upregulate neuroplasticity. It has been demonstrated in previous studies that PNS delivered before motor therapy can improve motor function in patients with severe post-stroke motor deficits. It is possible that PNS during therapy could result in further benefits due to decreased membrane thresholds associated with motor neuron activity during voluntary muscle contraction. The objective of this study was to determine if PNS delivered during motor therapy would yield greater improvements compared to PNS delivered before motor therapy and sham PNS.
Design: Ten participants with chronic stroke and severe motor deficit were enrolled after obtaining informed consent. Chronic was defined as occurring more than 12 months from stroke. Severe motor deficit was defined as Fugl-Meyer Assessment (FMA) score between 7 and 34. Participants were randomly assigned into one of the three groups: (1) sham PNS during motor therapy, (2) active PNS before motor therapy, or (3) active PNS during motor therapy. FMA was the primary outcome measure and was collected by a therapist not involved with interventions.
Results: Mean changes in FMA were 2.8, 5.7, and 9.7 for sham PNS, active PNS before motor therapy and active PNS during motor therapy, respectively. Active PNS during therapy led to greater improvement in motor function compared to active PNS before therapy (p=0.01) as well as sham PNS (p=0.0006).
Conclusions: Our study provided initial evidence that active PNS during motor therapy may yield greater functional motor recovery in participants with chronic and severe motor deficits. Our findings need to be corroborated in future studies with a larger sample size.
Lumy Sawaki– Associate Professor / Director of Neurorehabilitation Research Program, University of Kentucky, Department of Physical Medicine & Rehabilitation
Elizabeth Powell– Biomedical Research Associate, University of Kentucky
Joseph Mallory– Resident Physician, University of Kentucky