Masayoshi Ichie

Orderly stimulation of skeletal muscle motor units with tripolar nerve cuff electrode

An electrical nerve stimulation technique, using a single tripolar electrode, was shown to be capable of recruiting motor units according to their size, while allowing simultaneous but independent control of firing rate in the active units. Test paradigms consisting of established fundamental physiological concepts of soleus-gastrocnemius architecture, motor units conduction velocity, firing rate behavior of motor units of different sizes, and their susceptibility to fatigue were used to validate the technique and demonstrate its utility as a basic and applied research tool.<<ETX>>

Effect of low-voltage electrical stimulation on angiogenic growth factors in ischaemic rat skeletal muscle.

1 Low‐voltage electrical stimulation (LVES) in skeletal muscle at a level far below the threshold of muscle contraction has been reported to promote local angiogenesis. However, the mechanism underlying the promotion of local angiogenesis by LVES has not been fully elucidated. In the present study, we evaluated whether angiogenic factors, such as vascular endotherial growth factor (VEGF), hepatocyte growth factor (HGF) and fibroblast growth factor (FGF), as well as other disadvantageous factors, such as inflammation (interleukin (IL)‐6) and hypoxia (hypoxia‐inducible factor (HIF)‐1α), contribute to the local angiogenesis produced by LVES. 2 We completely excised bilateral femoral arteries of male Sprague‐Dawley rats. After the operation, electrodes were implanted onto the centre of the fascia of the bilateral tibialis anterior (TA) muscles, tunnelled subcutaneously and exteriorized at the level of the scapulae. The right TA muscles of rats were stimulated continuously at a stimulus frequency of 50 Hz, with a 0.1 V stimulus strength and no interval, for 5 days. The left TA muscles served as controls. 3 We found that both VEGF and HGF protein were significantly increased by LVES in stimulated muscles compared with control. The VEGF level of the LVES group was 89.10 ± 17.19 ng/g, whereas that of the control group was 65.07 ± 12.88 ng/g, as determined by ELISA (P < 0.05). The HGF level of the LVES and control groups was 8.52 ± 1.96 and 5.80 ± 2.14 ng/g, respectively (P < 0.05). In contrast, there was no difference in FGF, IL‐6 and HIF‐1α between the LVES and control groups. 4 These results suggest that LVES in a hindlimb ischaemia model of rats increases not only VEGF, but also HGF, production, which may be the main mechanism responsible for the angiogenesis produced by LVES.

Electromyogram analysis and electrical stimulation control of paralysed wrist and hand

Restoring paralysed hand functions with functional electrical stimulation (FES) essentially requires control of joint angles in their functional positions as well as control of speed and power for grasping. In this study, standard FES patterns were created from the electromyogram (EMG) analysis of 15 healthy subjects in order to restore hand and wrist joint functions in C4 and C5 quadriplegics. Stimulating the hand muscles with the standard patterns produced both wrist joint fixation in a functional position and grasping movement similar to that of healthy subjects. To control the joint angle, certain stimulation voltages were read at the same memory address. Similarly, motion speed was adjusted by changing the reading speed at the stimulation data memory address. Since stimulation patterns created from the EMG analysis of healthy subjects restored the hand and wrist joint functions in C4 and C5 quadriplegics, this method was found to be successful in allowing some normal daily activity for quadriplegics.

Effects and indications of sacral surface therapeutic electrical stimulation in refractory urinary incontinence

Objective: To describe the effects and indications of sacral surface therapeutic electrical stimulation (SS-TES) for refractory urinary incontinence. Design: Evaluation before and after therapy. Setting: On clinical site and at nursing home. Subjects: Seven neurogenic bladder, five unstable bladder and six nocturia cases were investigated. Twelve were outpatients and six were residents. Interventions: Surface electrodes were placed at the posterior sacral foramens of S2 and S4. Stimulation conditions were duration 0.3 ms, frequency 20 Hz and maximum intensity. The stimulation was continued for 15 min twice daily for over one month. Main outcome measures: Therapeutic effects were evaluated on the basis of voiding charts as subjective findings and urodynamic study as objective findings before and after therapy. Results: Subjective findings showed incontinence frequency significantly decreased from 2.39±1.4 times/day before therapy to 1.39±2.0 times/day after therapy (p≤0.01); 55.5% of patients were improved or greatly improved. Objective findings showed that maximum vesical capacity (MVC) significantly increased from 208.29±94.5 ml before therapy to 282.19±66.8 ml (p≤0.001). Uninhibited contraction significantly decreased from 40.4±31.4 cmH2O before therapy to 25.79±23.9 cmH2O (p≤0.01); 44% of patients were improved or greatly improved. This therapy was effective in particular for cases whose MVC was small before applying SS-TES. Conclusion: SS-TES was effective in some patients with refractory urinary incontinence.

Stimulus adjustment protocol for FES-induced standing in paraplegia using percutaneous intramuscular electrodes

The desirable upright posture for standing via functional electrical stimulation (FES) is defined based on simulation results using a link model in the sagittal plane. The criterion for the posture selection is the minimization of the sum of the squared joint flexion moments caused by gravity. The stimulus intensities are adjusted systematically to attain the defined upright posture. Controlled standing was achieved in a Th7 and a Th8-level spinal-cord-injured paraplegic individuals without joint contracture, by using the stimulus adjustment protocol. A practical standing without any bracing devices was obtained, with the vertical upper extremity support of less than four percent of the body weight, and with single-hand-support attainable. The maximal durations of standing were 30 minutes in both cases.

FES powered locomotion of paraplegics fitted with the LSU reciprocating gait orthoses (RGO)

Summary form only given, as follows. The LSU reciprocating gait orthoses (RGO) was fitted to a large population of paraplegics, allowing independent upright posture, balance and stability, execution of the swing phase in one leg simultaneously with push off of the contralateral leg, and unassisted ability to walk over moderate distances. A four-channel reciprocal muscle stimulator was applied to a group of paraplegics with the objective of improving the gait pattern and reducing the metabolic energy consumption. After six weeks of functional electrical stimulation (FES) exercise to the quadriceps and hamstring muscles, analysis shows that locomotion with the FES-RGO system reduces the patients pulse rate by 11-17 pulses/minute, as well as improving the gait pattern by reduction of posterior pelvic tilt, floor clearance and postural balance. Subjective patient remarks strongly support the added value of the reciprocal FES stimulator. One C-5 paraplegic, who was unable to walk with the aid of the RGO alone, managed to become ambulatory once the FES stimulator was applied.<<ETX>>

Development Of An FES System Controlled By EMG Signals

This paper describes about control strategy of an FES system controlled by EMG signals. Partially detected EMGs just before the stimulating pulses were used for eliminating the influence of the stimulus from the EMG during motion. Parameters for providing stable FES control w ere investigated in the forearm muscles of healthy subjects. The system operation for controlling hand movement was tested by using the EMGs from the wrist muscles as control signals in 3 healthy subjects and a C6/7 quadriplegic.

Studies on control commands for FES in the paralyzed extremities

A description of commands for controlling the paralyzed upper extremities by functional electrical stimulation (FES) is given. Respiration was used for restoration of totally paralyzed upper limbs in C4 quadriplegic patients. The paralyzed hand in C6-7 quadriplegics was volitionally controlled by wrist movements of the patient. EMG control of the paralyzed upper limbs is also described.<<ETX>>

Current Status and Future Prospects for Upper and Lower Extremity Motor System Neuroprostheses

This paper reviews the current state of the art and identifies the major challenges facing the future development and clinical application of neuroprostheses to provide limb movement. It gives insight into the current status of functional electrical stimulation (FES) for motor control, identifies problems, and proposes possible directions of development in cervical cord injury, thoracic spinal cord injury, and stroke. For upper extremity function, existing clinical applications are covered, major problems are identified, and possible future trends are highlighted. The discussion on lower extremity applications describes current and possible future solutions of the major impediments to the development of FES systems for individuals with paraplegia after spinal cord injury and surface and implantable setups for stroke survivors with hemiplegia. Particular attention is given to sensor issues and requirements for walking with FES after stroke.

Control Of Shoulder Movement By FES(1) - EMG Analysis

EMG analysis of shoulder movement was performed in normal volunteers. Muscle activities of the shoulder girdle were simultaneously detected during shoulder motion. These muscles co-contracted with well coordinated manner and the results might be basically utilized for creating stimulation data of shoulder motion of cervical cord injury and stroke patients in our FES system. INTROOUCTlON We have tried to restore motor function of the paralyzed upper extremities in the C4 quadriplegic and hemiplegic patients by FES. In this trial it has been possible to restore the upper limb function for some activities of daily living by controlling movements of the elbow, wrist and fingers in this system. However, control of the shoulder is essential for the precise and well coordinated control of the total upper limb in three dimensional space. Therefore, EMG analysis of the muscles relating to shoulder movement might be essential as previously reportedIll, The purpose of this paper is to describe the further analyses of the spatio-temporal contraction pattern of muscles of the shoulder girdle by means of EMG and motion analyzers in order to make the precise stimulation pattern for control of shoulder movements by FES.