Effect of the combination of motor imagery and electrical stimulation on upper extremity motor function in patients with chronic stroke: preliminary results

Abstract

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.

Why brain-controlled neuroprosthetics matter: mechanisms underlying electrical stimulation of muscles and nerves in rehabilitation

“…Similar acute effects were shown using combined motor imagery and electrical stimulation of the lower-limbs [ 137 ]. Preliminary results with chronic stroke patients also suggest that applying electrical stimulation in combination with motor imagery over the course of 10 days may possibly improve upper-limb function after the intervention cessation [ 106 ]. Tasks involving motor imagery and/or action observation can produce reliable and muscle-specific excitability of corticospinal responses in the upper-limbs (e.g., [ 39 , 138 ]).…”

Motor imagery on upper extremity function for persons with stroke: a systematic review and meta-analysis

“…This review was conducted to determine the effects of motor imagery on the recovery of upper limb function in persons affected by stroke. Several studies have reported that the effectiveness of motor imagery training as well as motor imagery with brain-computer interface and motor imagery triggered electrical stimulation on upper extremity function in activities of daily living and functional activities for stroke survivors [14,22,[27][28][29]. They provided several therapeutic types to be conducted with motor imagery to improve upper limb function.…”

“…Motor imagery of movement is an active, cognitive process used to investigate the content and structure of covert processes that precede the execution of action, and so the training protocol will provide a relatively lower level of mo-tor function or acute stage of the disease following stroke [33][34][35]. When paired with conventional therapeutic interventions, motor imagery training can be as effective as pure conventional therapeutic interventions for recovery following stroke [8,14,27,35]. The results of this review also showed that motor imagery training with other therapeutic interventions based on motor function could exhibit positive effects on upper limb function following stroke.…”

“…Several studies have been conducted on motor imagery training to improve the paretic upper limb function and independent daily activities for persons with stroke [4,6,8,9]. Motor imagery training has been provided in a variety of ways, including motor imagery only, motor imagery with repetitive task-oriented approaches, motor imagery with electrical stimulation, and motor imagery with brain-computer interface in order to overcome the limitations following a stroke event [4,[10][11][12][13][14].…”

Table_1.docx

“…This study was a secondary analysis of data from previous randomized, controlled trials or clinical trials (23)(24)(25)(26). Outlines of each study, including ethical approval and clinical trial registration numbers, are provided as Supplementary Material.…”