Specifications of an electromyogram-driven neuromuscular stimulator for upper limb functional recovery.

An electromyogram (EMG)-driven neuromuscular stimulator for upper limb functional recovery (Muraoka et al., 1998) can stimulate target muscles in proportion to the amount of voluntary EMG of the identical target muscles. Furthermore, it can facilitate the contraction of paralyzed muscles by electrical stimulation at subthreshold intensity level. Although it has been suggested that to use the stimulator for as long a time as possible might be needed for more effective treatment, the utilization time was limited by the size of the stimulator, which involved a laptop personal computer. To use in daily life, the device was improved to be a smaller size of 95×65×40 mm (including batteries) which was equivalent to a mobile phone (in 2002). The stimulator was called the Integrated Volitional-control Electrical Stimulator (IVES). IVES has already been manufactured and its use has spread in Japan since 2008. Nowadays, therapy using IVES is an effective therapy to improve the motor function of the upper limb in post-stroke patients with hemiparesis. However, the signal processing and internal structure of IVES has not yet been reported. In this study the device specification of IVES is described, especially its electrical circuits and signal processing that detect voluntary EMG and stimulate from the same electrodes. IVES uses two DIACs for detecting voluntary EMG from stimulating electrodes. The DIACs switch passively between the stimulation circuit and the EMG amplifier circuit. Furthermore, the signal processing of the time-shifted difference of the 2-cycle EMG signal following identical stimulation pulses eliminates stimulation artifacts and evoked potentials, and extracts voluntary EMG.

The effects of electromyography-controlled functional electrical stimulation on upper extremity function and cortical perfusion in stroke patients.

OBJECTIVE: The relation was investigated between hemiparetic arm function improvement and brain cortical perfusion (BCP) change during voluntary muscle contraction (VOL), EMG-controlled FES (EMG-FES) and simple electrical muscle stimulation (ES) before and after EMG-FES therapy in chronic stroke patients. METHODS: Sixteen chronic stroke patients with moderate residual hemiparesis underwent 5 months of task-orientated EMG-FES therapy of the paretic arm once or twice a week. Before and after treatment, arm function was clinically evaluated and BCP during VOL, ES and EMG-FES were assessed using multi-channel near-infrared spectroscopy. RESULTS: BCP in the ipsilesional sensory-motor cortex (SMC) was greater during EMG-FES than during VOL or ES; therefore, EMG-FES caused a shift in the dominant BCP from the contralesional to ipsilesional SMC. After EMG-FES therapy, arm function improved in most patients, with some individual variability, and there was significant improvement in Fugl-Meyer (FM) score and maximal grip strength (GS). Clinical improvement was accompanied by an increase in ipsilesional SMC activation during VOL and EMG-FES condition. CONCLUSION: The EMG-FES may have more influence on ipsilesional BCP than VOL or ES alone. SIGNIFICANCE: The sensory motor integration during EMG-FES therapy might facilitate BCP of the ipsilesional SMC and result in functional improvement of hemiparetic upper extremity.

Real-time changes in corticospinal excitability during voluntary contraction with concurrent electrical stimulation.

While previous studies have assessed changes in corticospinal excitability following voluntary contraction coupled with electrical stimulation (ES), we sought to examine, for the first time in the field, real-time changes in corticospinal excitability. We monitored motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation and recorded the MEPs using a mechanomyogram, which is less susceptible to electrical artifacts. We assessed the MEPs at each level of muscle contraction of wrist flexion (0%, 5%, or 20% of maximum voluntary contraction) during voluntary wrist flexion (flexor carpi radialis (FCR) voluntary contraction), either with or without simultaneous low-frequency (10 Hz) ES of the median nerve that innervates the FCR. The stimulus intensity corresponded to 1.2 × perception threshold. In the FCR, voluntary contraction with median nerve stimulation significantly increased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.01). In addition, corticospinal excitability was significantly modulated by the level of FCR voluntary contraction. In contrast, in the extensor carpi radialis (ECR), FCR voluntary contraction with median nerve stimulation significantly decreased corticospinal excitability compared with FCR voluntary contraction without median nerve stimulation (p<0.05). Thus, median nerve stimulation during FCR voluntary contraction induces reciprocal changes in cortical excitability in agonist and antagonist muscles. Finally we also showed that even mental imagery of FCR voluntary contraction with median nerve stimulation induced the same reciprocal changes in cortical excitability in agonist and antagonist muscles. Our results support the use of voluntary contraction coupled with ES in neurorehabilitation therapy for patients.

Immediate effects of electrical stimulation combined with passive locomotion-like movement on gait velocity and spasticity in persons with hemiparetic stroke: a randomized controlled study.

OBJECTIVE: Research to examine the immediate effects of electrical stimulation combined with passive locomotion-like movement on gait velocity and spasticity. DESIGN: A single-masked, randomized controlled trial design. SUBJECTS: Twenty-seven stroke inpatients in subacute phase (ischemic n = 16, hemorrhagic n = 11). INTERVENTIONS: A novel approach using electrical stimulation combined with passive locomotion-like movement. MAIN MEASURES: We assessed the maximum gait speed and modified Ashworth scale before and 20 minutes after the interventions. RESULTS: The gait velocity of the electrical stimulation combined with passive locomotion-like movement group showed the increase form 0.68 ± 0.28 (mean ± SD, unit: m) to 0.76 ± 0.32 after the intervention. Both the electrical stimulation group and passive locomotion-like movement group also showed increases after the interventions (from 0.76 ± 0.37 to 0.79 ± 0.40, from 0.74 ± 0.35 to 0.77 ± 0.36, respectively). The gait velocity of the electrical stimulation combined with passive locomotion-like movement group differed significantly from those of the other groups (electrical stimulation combined with passive locomotion-like movement versus electrical stimulation: P = 0.049, electrical stimulation combined with passive locomotion-like movement versus passive locomotion-like movement: P = 0.025). Although there was no statistically significant difference in the modified Ashworth scale among the three groups, six of the nine subjects (66.6%) in the electrical stimulation combined with passive locomotion-like movement group showed improvement in the modified Ashworth scale score, while only three of the nine subjects (33.3%) in the electrical stimulation group and two of the nine subjects (22.2%) improved in the passive locomotion-like movement group. CONCLUSION: These findings suggest electrical stimulation combined with passive locomotion-like movement could improve gait velocity in stroke patients.

Effects of integrated volitional control electrical stimulation (IVES) on upper extremity function in chronic stroke.

We evaluated the efficacy of a novel electromyogram (EMG)-controlled electrical stimulation system, called the integrated volitional control electrical stimulator (IVES), on the recovery of upper extremity motor functions in patients with chronic hemiparetic stroke. Ten participants in the chronic stage (more than 12 months post-stroke with partial paralysis of their wrist and fingers) received treatment with IVES to the extensor carpi radialis and extensor digitorum communis 6 h/day for 5 days. Before and after the intervention, participants were assessed using upper-extremity Fugl-Meyer motor assessment (FMA), the active range of motion (A-ROM), the nine-hole peg test (NHPT), and surface EMG recordings. The upper extremity FMA showed a statistically significant increase from 50.8 ± 5.8 to 56.8 ± 6.2 after the intervention (P < 0.01). The A-ROM of wrist extension was also significantly improved from 36.0° ± 15.4° to 45.0° ± 15.5° (P < 0.01). The NHPT significantly decreased from 85.3 ± 52.0 to 63.3 ± 29.7 (P = 0.04). EMG measurements demonstrated statistically significant improvements in the coactivation ratios for the wrist flexor and extensor muscles after the intervention. This study suggested that 5 days of IVES treatment yields a noticeable improvement in upper extremity motor functions in patients with chronic hemiparetic stroke.

Motor improvement and corticospinal modulation induced by hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy in patients with chronic stroke.

BACKGROUND AND OBJECTIVE: We devised a therapeutic approach to facilitate the use of the hemiparetic upper extremity (UE) in daily life by combining integrated volitional control electrical stimulation with a wrist splint, called hybrid assistive neuromuscular dynamic stimulation (HANDS). METHODS: Twenty patients with chronic hemiparetic stroke (median 17.5 months) had moderate to severe UE weakness. Before and immediately after completing 3 weeks of training in 40-minute sessions, 5 days per week over 3 weeks and wearing the system for 8 hours each day, clinical measures of motor impairment, spasticity, and UE functional scores, as well as neurophysiological measures including electromyography activity, reciprocal inhibition, and intracortical inhibition were assessed. A follow-up clinical assessment was performed 3 months later. RESULTS: UE motor function, spasticity, and functional scores improved after the intervention. Neurophysiologically, the intervention induced restoration of presynaptic and long loop inhibitory connections as well as disynaptic reciprocal inhibition. Paired pulse transcranial magnetic stimulation study indicated disinhibition of the short intracortical inhibition in the affected hemisphere. The follow-up assessment showed that improved UE functions were maintained at 3 months. CONCLUSION: The combination of hand splint and volitional and electrically induced muscle contraction can induce corticospinal plasticity and may offer a promising option for the management of the paretic UE in patients with stroke. A larger sample size with randomized controls is needed to demonstrate effectiveness.

Effects of transcutaneous electrical stimulation combined with locomotion-like movement in the treatment of post-stroke gait disorder: a single-case study. Short report.

PURPOSE: This study was designed to examine the effects of electrical stimulation combined with locomotion-like movement (ES/LM) for improving gait disorder in a stroke patient. METHOD: A four-phase ABAB single-subject design with five therapy sessions per phase was employed. In the intervention phases, transcutaneous electrical stimulation was applied to the tibialis anterior (at the end of the hip extension phase and in the initial hip flexion phase) and the soleus (in the initial hip extension phase) during passive hip flexion and extension. To assess improvement, the soleus H-reflex and the ambulatory function were measured (gait velocity and step length). RESULTS: Application of ES/LM resulted in a decrease of the soleus H-reflex and significant increase of gait velocity and step length. CONCLUSION: These findings suggest that ES/LM is a feasible treatment method for impaired ambulatory function in stroke patients at the subacute stage after the event.

Hybrid power-assisted functional electrical stimulation to improve hemiparetic upper-extremity function.

OBJECTIVE: The effect on spastic hemiparesis of a hybrid therapy consisting of functional electrical stimulation and block therapy was examined. DESIGN: Sixteen consecutively enrolled stroke patients who had spastic upper-extremity impairments more than 1 yr after stroke were recruited for this nonblinded randomized controlled trial. Patients underwent hybrid functional electrical stimulation therapy on their extensor carpi radialis longus and brevis, extensor digitorum communis, and extensor indicis proprius muscles once or twice a week for 4 mos after motor point blocks at the spastic finger flexor muscles. Surface electrodes picked up the electromyography signal and stimulated those muscles in proportion to the integrated electromyography signal obtained by the functional electrical stimulation device. The root mean square of the extensor carpi radialis longus and extensor digitorum communis maximum voluntary electromyography, active range of motion of wrist extension, finger extension, Modified Ashworth Scale, and two clinical tests were examined before and after training. RESULTS: Root mean square, active range of motion, Modified Ashworth Scale, and two clinical tests showed marked improvement in all patients as compared with the control subjects. CONCLUSIONS: The hybrid therapy was effective for patients with chronic spastic hemiparesis. Proprioceptional sensory feedback may have an important role in power-assisted functional electrical stimulation therapy.

Development of an EMG recording device from stimulation electrodes for functional electrical stimulation.

A device that records voluntary EMG from a pair of surface stimulation electrodes has been developed for functional electrical stimulation (FES). The device can apply to a small muscle on which it is difficult to locate both the stimulation electrodes and recording electrodes. The device utilizes photo-MOS relays to disconnect the stimulator when it is not active, to ground the electrodes after delivering the stimulation pulses, and to drop the gain of the EMG amplifier during the stimulus period. The device is able to detect the voluntary EMG of a small muscle from the stimulation electrodes for the EMG-controlled FES system.