Background:The combination of motor imagery (MI) and afferent input with electrical
stimulation (ES) enhances the excitability of the corticospinal tract
compared with motor imagery alone or electrical stimulation alone. However,
its therapeutic effect is unknown in patients with hemiparetic stroke. We
performed a preliminary examination of the therapeutic effects of MI + ES on
upper extremity (UE) motor function in patients with chronic stroke.Methods:A total of 10 patients with chronic stroke demonstrating severe hemiparesis
participated. The imagined task was extension of the affected finger.
Peripheral nerve electrical stimulation was applied to the radial nerve at
the spiral groove. MI + ES intervention was conducted for 10 days. UE motor
function as assessed with the Fugl–Meyer assessment UE motor score (FMA-UE),
the amount of the affected UE use in daily life as assessed with a Motor
Activity Log (MAL-AOU), and the degree of hypertonia in flexor muscles as
assessed with the Modified Ashworth Scale (MAS) were evaluated before and
after intervention. To assess the change in spinal neural circuits,
reciprocal inhibition between forearm extensor and flexor muscles with the H
reflex conditioning-test paradigm at interstimulus intervals (ISIs) of 0,
20, and 100 ms were measured before and after intervention.Results:UE motor function, the amount of the affected UE use, and muscle hypertonia
in flexor muscles were significantly improved after MI + ES intervention
(FMA-UE: p < 0.01, MAL-AOU: p <
0.01, MAS: p = 0.02). Neurophysiologically, the
intervention induced restoration of reciprocal inhibition from the forearm
extensor to the flexor muscles (ISI at 0 ms: p = 0.03, ISI
at 20 ms: p = 0.03, ISI at 100 ms: p =
0.01).Conclusion:MI + ES intervention was effective for improving UE motor function in
patients with severe paralysis.