Abstract
Background.
In monkey, reticulospinal connections to hand and forearm muscles are
spontaneously strengthened following corticospinal lesions, likely
contributing to recovery of function. In healthy humans, pairing
auditory clicks with electrical stimulation of a muscle induces plastic
changes in motor pathways (probably including the reticulospinal tract),
with features reminiscent of spike-timing dependent plasticity. In this
study, we tested whether pairing clicks with muscle stimulation could
improve hand function in chronic stroke survivors.
Methods.
Clicks were delivered via a miniature earpiece; transcutaneous
electrical stimuli at motor threshold targeted forearm extensor muscles.
A wearable electronic device (WD) allowed patients to receive
stimulation at home while performing normal daily activities. A total of
95 patients >6 months poststroke were randomized to 3 groups: WD
with shock paired 12 ms before click; WD with clicks and shocks
delivered independently; standard care. Those allocated to the device
used it for at least 4 h/d, every day for 4 weeks. Upper-limb function
was assessed at baseline and weeks 2, 4, and 8 using the Action Research
Arm Test (ARAT), which has 4 subdomains (Grasp, Grip, Pinch, and
Gross). Results.
Severity across the 3 groups was comparable at
baseline. Only the paired stimulation group showed significant
improvement in total ARAT (median baseline: 7.5; week 8: 11.5; P = .019) and the Grasp subscore (median baseline: 1; week 8: 4; P = .004).
Conclusion.
A wearable device delivering paired clicks and shocks over 4 weeks can
produce a small but significant improvement in upper-limb function in
stroke survivors.
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