Satoaki Chida

Functional electrical stimulation

Percutaneous intramuscular electrodes and a portable multichannel system were used to restore the function of paralyzed upper and lower extremities in spinal cord injuries and hemiplegic patients. The hybrid functional electrical stimulation (FEC) using percutaneous intramuscular electrodes provides practical ambulation for paraplegics. FES was more effective than the flexor hinge splint in increasing the grasping power (GP) of tetraplegic patients, and a stronger and stable GP which was not affected by wrist position make FES practical for improving the activities of daily living. A tilt sensor, which was put on the thigh, could be used to measure a gait cycle. This study suggests that putting a tilt sensor on a hemiplegic patients thigh improves the FES procedure and may help to restore gait in these patients. We conclude that percutaneous intramuscular FES is useful for spinal cord injuries and hemiplegic patients.

Evaluation of utility of the “Arm-Balancer” arm support system

As modern society becomes increasingly more elderly, developing specialized equipment to help assist this growing population in everyday tasks becomes more and more important. Here we have developed a passive gravity balanced arm support system called the “Arm-Balancer”. It was designed to assist the arm motion of elderly people with disabilities. The objective of this study is to determine the utility of the “Arm-Balancer”. We will evaluate the effect of this device on the arm muscle tension of the user. The “Arm-Balancer” is supported by a gas spring to eliminate gravity and may be attached to a chair, a bed or used on the floor when attached to the “Tatami Mat” seat. The “Arm-Balancer” consists of a two-segment exoskeleton designed for the users upper arm and forearm. The links are made from stainless steel rods whose lengths are designed to parallel the lengths of the users upper arm and forearm. The upper arm segment is telescopic so the length can be adjusted to the size of the users. Driving the evaluation we determined that the “Arm Balancer” had an assistive force of 10N to the arm and 5N to the wrist. Some elderly people with disabilities were receptive to the “Arm Balancer” while others were ambivalent.

The impact of high-frequency magnetic stimulation of peripheral nerves: muscle hardness, venous blood flow, and motor function of upper extremity in healthy subjects

The purpose of this study was to investigate the impact of high-frequency peripheral nerve magnetic stimulation on the upper limb function. Twenty-five healthy adults (16 men and 9 women) participated in this study. The radial nerve of the non-dominant hand was stimulated by high-frequency magnetic stimulation device. A total of 600 impulses were applied at a frequency of 20 Hz and intensity of 1.2 resting motor threshold (rMT). At three time points (before, immediately after, and 15 min after stimulation), muscle hardness of the extensor digitorum muscle on the stimulated side was measured using a mechanical tissue hardness meter and a shear wave imaging device, cephalic venous blood flow on the stimulated side was measured using an ultrasound system, and the Box and Block test (BBT) was performed. Mechanical tissue hardness results did not show any significant differences between before, immediately after, and 15 min after stimulation. Measurements via shear wave imaging showed that muscle hardness significantly decreased both immediately and 15 min after stimulation compared to before stimulation (P < 0.05). Peripheral venous blood flow and BBT score significantly increased both immediately and 15 min after stimulation compared to before stimulation (P < 0.01). High-frequency peripheral nerve magnetic stimulation can achieve effects similar to electrical stimulation in a less invasive manner, and may therefore become an important element in next-generation rehabilitation.

Measurement of Immediate Effect by Therapeutic Electrical Stimulation Using a New Desktop Rehabilitation Robot

Objective: More frequent use of robot technology in the field of rehabilitation is driving the need for smaller, less cumbersome devices. The objectives of the present study were to evaluate and compare quantitatively the upper limb function of chronic stroke patients before and after therapeutic electrical stimulation using a newly developed rehabilitation robot. Methods: Five stroke patients (3 men, 2 women; mean age: 66.4 ± 9.6 years; time since stroke: 36.0 ± 52.9 months) in the sub-acute and chronic phase of stroke-induced hemiplegia (induced by cerebral hemorrhage in four and by cerebral infarction in one; Brunnstrom stages III-V) participated in the study. None of them had any secondary motor neuron dysfunction or unstable disease control. Before and after 15 min of therapeutic electrical stimulation for repeated finger flexion and extension, participants performed reaching movements while moving the rehabilitation robot with their affected hand. Assessment parameters included Maximum swerve, Average speed, and smoothness of movements, as calculated by Jerk cost X (right-left direction) and Jerk cost Y (forward-backward direction). Results: All patients were able to use the rehabilitation robot to perform the reaching movements. Clear differences were observed before and after therapeutic electrical stimulation for Maximum swerve and Average speed in the X direction, and there was a tendency for Jerk cost X to differ before and after therapeutic electrical stimulation. In contrast, there were no significant differences in either Jerk cost Y or Average speed in the Y direction before and after the stimulation. Conclusion: The immediate effects of therapeutic electrical stimulation in chronic stroke patients can be quantified using our newly developed rehabilitation robot. Successful quantification of the effects of therapeutic electrical stimulation in stroke patients using smaller robotic systems could revolutionize the rehabilitation of these and other patients suffering from motor dysfunction or paralysis.

Postcontraction hyperemia after electrical stimulation: potential utility in rehabilitation of patients with upper extremity paralysis.

The purpose of this study was to compare postcontraction hyperemia after electrical stimulation between patients with upper extremity paralysis caused by upper motor neuron diseases and healthy controls. Thirteen healthy controls and eleven patients with upper extremity paralysis were enrolled. The blood flow in the basilic vein was measured by ultrasound before the electrical stimulation of the biceps brachii muscle and 30 s after the stimulation. The stimulation was performed at 10 mA and at a frequency of 70 Hz for 20 s. The mean blood flow in the healthy control group and in upper extremity paralysis group before the electrical stimulation was 60 ± 20 mL/min (mean ± SD) and 48 ± 25 mL/min, respectively. After the stimulation, blood flow in both groups increased to 117 ± 23 mL/min and 81 ± 41 mL/min, respectively. We show that it is possible to measure postcontraction hyperemia using an ultrasound system. In addition, blood flow in both groups increased after the electrical stimulation because of postcontraction hyperemia. These findings suggest that evaluating post contraction hyperemia in patients with upper extremity paralysis can assess rehabilitation effects.

Optimum Stimulation Frequency of High-Frequency Repetitive TranscranialMagnetic Stimulation for Upper-Limb Function in Healthy Subjects

Objective: Because rTMS requires the subject’s head to be immobilized and the subject to maintain the same posture throughout stimulation, stimulation of long duration may induce discomfort. If changing the stimulation parameters can allow the duration of rTMS to be shortened, physical discomfort may decrease. The purpose of this study was to identify the most beneficial stimulation parameters for high-frequency rTMS in terms of the effect on upper-limb function in healthy subjects. Materials and Methods: Forty right-handed healthy volunteers were divided into four groups: three real rTMS groups (5, 10, and 20 Hz rTMS) and one sham group. In the real rTMS groups, 600 impulses were applied at a frequency of 5, 10, or 20 Hz and an intensity of 90% of resting motor threshold. Performance on a peg-board task, tapping task, and grip strength were measured before stimulation, immediately after stimulation, and 20 min after stimulation. Results: All real rTMS groups showed a significant increase in performance on the peg-board task and tapping task after rTMS. There was no significant increase in grip strength in any group. Conclusions: 10-Hz rTMS may improve upper-limb function with a shorter duration of stimulation than rTMS at 5 or 20 Hz. 10-Hz rTMS had the shortest stimulation time, and is recommended as beneficial setting to use with a little discomfort. These results can be used when deciding rTMS stimulation frequency.