Corticomotor Excitability Effects of Peripheral Nerve Electrical Stimulation to the Paretic Arm in Stroke

This study aimed to examine the corticomotor excitability changes after peripheral nerve electrical stimulation (PNS) on the stroke-impaired arm.

This randomized cross-over study included 32 subjects with chronic stroke. They received a 1-hr PNS or placebo PNS by random order to the ulnar and radial nerves of the paretic arm in separate sessions. The primary outcome was excitability of the corticospinal projections for the contralateral first dorsal interosseous hand muscle in terms of slope of the recruitment curve, peak motor-evoked potential amplitude, and duration of the cortical silent period, measured with transcranial magnetic stimulation on both cerebral hemispheres. Seventeen of the subjects were measured for their paretic hand dexterity (using Purdue Pegboard Test) and pinch strength as secondary outcomes.

Peripheral nerve electrical stimulation, but not placebo PNS, increased recruitment curve slope and peak motor-evoked potential amplitude in both the lesioned and nonlesioned hemispheres and lengthened the cortical silent period duration in the nonlesioned hemisphere. Peripheral nerve electrical stimulation significantly improved hand dexterity scores compared with placebo PNS. Pinch strength was not changed by the interventions.

A 1-hr PNS alone to the paretic arm could increase corticomotor excitability in both hemispheres, together with hand dexterity improvement in people presented with mild-to-moderate motor impairment in the paretic upper limb after stroke.

Complete the self-assessment activity and evaluation online at http://www.physiatry.org/JournalCME CME OBJECTIVES: Upon completion of this article, the readers should be able to: (1) Understand the effects of a stroke on the corticomotor excitability of the lesioned and intact hemisphere; (2) Describe the effect of peripheral nerve electrical stimulation on the lesioned and intact hemisphere corticomotor excitability following stroke; and (3) Understand the effect of peripheral nerve electrical stimulation on dexterity of the paretic hand following stroke.

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