Mineyoshi Sato

Restoration and analysis of standing-up in complete paraplegia utilizing functional electrical stimulation

OBJECTIVE Restoration of stand-up motion in patients with complete paraplegia utilizing multichannel functional electrical stimulation, and analysis of the restored motion. DESIGN Nonrandomized control trial. SETTING General community, a referral center, institutional practice, and ambulatory care: PATIENTS Twelve volunteer samples were used for the collection of normal data. Two complete paraplegics received treatment for the restoration of stand-up motion. MAIN OUTCOME MEASURES The electromyogram, joint angle, and floor reaction force were investigated during standing-up with arms crossed in front of the chest, and hands-assisted standing-up using parallel bars. The maximum knee joint torque during standing-up without hands-assists was calculated using a three-segment link model. Standing-up motion in complete paraplegics was restored, and then analyzed using the three-dimensional floor reaction force and the hip, knee, and ankle angles. RESULTS Main muscles used to stand up were the quadriceps, tibialis anterior, and paraspinal muscles. Hands-assists reduced the muscle activity and the vertical floor reaction force. Peak muscle activity was less during hands-assisted standing-up, except for the rectus femoris and the iliopsoas muscle. The maximum knee joint torque during standing-up was 1.6Nm/kg for both knees. Two complete paraplegics were able to stand up smoothly from a wheelchair based on stimulation data obtained from normal subjects. The characteristic pattern during standing-up was knee flexion preceding extension. CONCLUSION Stand-up motion was restored utilizing electromyogram data and knee joint torque data from normal subjects.

Clinical experience of functional electrical stimulation in complete paraplegia.

Percutaneous intramuscular electrodes and a portable multichannel system were used to restore the function of the paralyzed lower extremities in six patients with complete paraplegia. The total number of inserted electrodes was 168. All of the patients could stand, two could walk in parallel bars, and two could walk with a walker. The rate of breakage of electrodes was only 0.6% in our series. There were 10 (6.0%) superficial infections, and 10 (6.0%) movement of electrodes which required reimplantation. The results suggest that the ultrafine intramuscular electrode is practical for long term use with paraplegic patients. Although the system can be used for paraplegic patients during the activities of daily living, it will be necessary to develop a closed-loop controller to reduce the amount of stimulation to the extensor muscles and extend the endurance of upright activity to reduce fatigue.

Changes in muscle force following therapeutic electrical stimulation in patients with complete paraplegia

Changes in muscle force following therapeutic electrical stimulation (TES) in 5 patients with complete paraplegia were evaluated by computed tomography, Cybex II, a strain-gauge transducer, and manual muscle testing. The stimulation parameters included a frequency of 20 Hz, a pulse width of 0.2 ms, and an output voltage of —15 V. The cross-sectional areas of muscles, the muscle torques, and the muscle forces increased after TES, though the increased ratio differed in each muscle. The reasons why it differed are as follows: (1) The possibility of peripheral nerve injury; (2) The different patterns of nerve distribution in the muscles; (3) Implantation techniques; and (4) The possibility of breakage, movement, or changes in the impedance of electrodes. This study demonstrates that TES increases muscle force during electrical stimulation in paralyzed muscle, but that an initial TES-induced muscle force greater than a poor-minus level on manual muscle testing is necessary for practical use. TES treatment should be started as soon as possible after the onset of paralysis, in order to maintain muscle quality.

An electrical knee lock system for functional electrical stimulation

An electrical knee lock system that can be combined with functional electrical stimulation was designed for paraplegic patients. This knee system unlocks the knee electrically and allows knee flexion during the swing phase of the gait. When the knee is extended by electrical stimulation of the knee extensors, the knee is automatically locked by the weight of the locking bar, and the stimulation of the knee extensors is stopped. Since the knee extensors are stimulated for only a short period, muscle fatigue of the knee extensors seldom occurs. We applied this system to a T8 completely paraplegic patient. Standing-up, standing, walking, and sitting-down motions were all restored by our hybrid system. No electrical stimulation was necessary during standing, and the knee extensors were stimulated during only a small percentage of the 1-gait cycle.

Development of FES-Rowing Machine

As per present social needs, assisting machines are very much needed for persons of advanced age. We analyzed and developed a fitness apparatus suitable for meeting the requirement of elderly people. The proposed apparatus consists of a rowing machine and Functional Electrical Stimulation (FES), that can be used to exercise every muscle of a person of advanced age. The rowing mechanism was actually developed to train rowers and can train the legs and upper body parts most effectively. Move over FES can assist the exercise of the legs by using surface electrical stimulation. An experiment was conducted and the results prove that the developed apparatus can train the muscles of the person of advanced age effectively and can compensate exercise shortage.

Electrophysiologic evaluation of denervated muscles in incomplete paraplegia using macro electromyography

OBJECTIVE To evaluate denervated muscles in persons with incomplete paraplegia due to thoracolumbar spinal injury (TLSI) using macro electromyography in determining indications for functional electrical stimulation (FES). DESIGN A randomized clinical trial and a criterion standard. SETTING A department of orthopedic surgery in a university hospital. PATIENTS AND OTHER PARTICIPANTS Eighteen patients with incomplete paraplegia, including 11 with TSLI, and 50 healthy adults. INTERVENTION Area and amplitude of macro motor unit potential (macro MUP) were measured at the tibialis anterior, the vastus lateralis, and the vastus medialis. The normal limits of macro MUP parameters were defined based on values from healthy subjects. Abnormal denervated muscles were detected by macro EMG and conventional EMG in paralytic patients. The correlation between macro MUP parameter values and muscle forces of the tibialis anterior and quadriceps femoris induced by electrical stimulation was analyzed. MAIN OUTCOME MEASURES The number of abnormal muscles, parameter values, and muscle force induced by electrical stimulation. RESULTS Abnormal muscles were found only in the TLSI patients and 13 abnormal muscles were detected by macro EMG only. The abnormal muscles defined by macro EMG showed insufficient contraction induced by electrical stimulation. The increase of parameter value negatively correlated with the muscle force (tibialis anterior area r=-.797, amplitude r=-.866; quadriceps area r=-.866, amplitude r=-.893; p < .001). CONCLUSIONS These results suggest that macro EMG is useful in detecting denervated muscles, in determining indications for FES, and in predicting FES effects before implantation of electrodes.

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.

Lattice specific heat of AlCu alloy by solid-solutioning under pressure

Abstract The lattice dynamics and thermal properties of AlCu alloy by solid-solutioning under pressure are studied using our previous microscopic electronic theory. The phonon frequencies of the band and local modes and the lattice specific heat at constant volume are presented theoretically for the Al1−xCux system. The band and local mode frequencies increase with the solubility of Cu, and the specific heat decreases except at low temperatures. The Debye temperature for the Al1−xCux, Al1−xSix and Al1−xGex systems is estimated from the specific heat at low temperatures and from the average elastic velocity. The Debye temperature decreases with the solubility of Cu, and even stronger with the extended solubility of Si and Ge.

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.