A Novel Wearable Device for Motor Recovery of Hand Function in Chronic Stroke Survivors

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.

Evidence for Subcortical Plasticity after Paired Stimulation from a Wearable Device

“…The similar results are thus encouraging, as they suggest that there is no benefit to using the more unpleasant stimulation. In our recent clinical trial of this device in stroke patients over a four week period (Choudhury et al, 2020), patients who chose to wear the device for longer each day showed greater functional gains. This suggests that greater plastic changes can be generated by longer periods of paired stimulation.…”

“…Potentiation or depression occurred depending on stimulus timing, consistent with STDP at the level of the brainstem. Applying this protocol in stroke survivors produced a small but significant improvement in upper limb function (Choudhury et al, 2020).…”

“…The wearable device (Figure 1B) was the same as used in our previous work (Choudhury et al, 2020). It comprised a plastic box containing an electrical stimulator and audio amplifier, powered by an internal battery which could be recharged via a standard microUSB port.…”

Effectiveness of home-based upper limb rehabilitation in stroke survivors: A systematic review and meta-analysis

“…Eighteen studies ( 8 , 9 , 34 , 35 , 37 – 43 , 45 – 48 , 50 , 53 , 55 ) used technology-assisted home-based upper limb interventions in their experimental groups to examine the treatment effects on hemiplegic upper limb recovery. In these studies, the technology-assisted interventions used were interactive video games (on devices such as Wii, iPad, Kinect), virtual reality, electrical stimulation (including transcranial stimulation), robotics, telerehabilitation, and wearable devices.…”

Plastic changes in primate motor cortex following paired peripheral nerve stimulation

“…Stimulation of the motor point of two muscles (19)(20)(21)(22), of two peripheral nerves (23)(24)(25)(26), or of the motor point of a muscle paired with a click (27) can all generate plastic changes in motor output. We recently developed a portable device capable of delivering such stimuli while a subject engages in their usual daily activities and showed that this could induce plastic changes in healthy individuals (27)(28)(29) and in stroke patients (30). This opens up the possibility of taking plasticity protocols outside the laboratory, where large numbers of stimuli can be delivered to generate clinically significant effects.…”