Increased Pinch Strength in Acute and Subacute Stroke Patients After Simultaneous Median and Ulnar Sensory Stimulation

Background. Peripheral nerve stimulation may induce cortical adaptations as it improves pinch strength in chronic stroke patients immediately after stimulation. Objective. Test the effects of peripheral sensory stimulation on pinch strength in patients with acute and subacute stroke. Methods. Stroke patients (N = 20) who had onset less than 6 months previously and could voluntarily pinch the thumb to the index finger participated in a randomized, single-blinded, controlled study. Ten patients received 2 hours of simultaneous electrical stimulation over the median and ulnar nerves at the wrist to the level of appreciating paresthesias (peripheral sensory stimulation group). Ten control patients received stimulation to the level of perception (sham-control group). Pinch strength of the thumb pad to tip and to lateral side of the index finger of the paretic hand and the Action Research Arm test were tested before and immediately after the stimulation. Results. Lateral and tip pinch strength were significantly increased in both groups (P<.05). Mean +/- SD of increased lateral pinch strength of peripheral sensory stimulation and sham-control groups were 1.24 +/- 0.54 pounds and 0.20 +/- 0.28 pounds, respectively. Mean +/- SD of increased tip pinch strength of peripheral sensory stimulation and sham-control groups were 1.00 +/- 0.72 pounds and 0.37 +/- 0.36 pounds, respectively. Increase pinch strength of the peripheral sensory stimulation group was greater than the sham-control group, with significant difference (P<.05). The Action Research Arm test was not significantly changed after stimulation in both groups (P>.05). Conclusion. Peripheral sensory stimulation of the paretic hand may increase pinch strength of acute and subacute stroke patients immediately after stimulation.