Yasunobu Handa

A multichannel FES system for the restoration of motor functions in high spinal cord injury patients: a respiration-controlled system for multijoint upper extremity

A multichannel functional electrical stimulation (FES) system for the restoration of quadriplegic upper extremity function is described. The system is composed of a personal computer, peripheral electronic circuits, CRT display and respiratory sensors for volitional control by the patient, and percutaneous electrodes. In this system, versatile volitional control is realized by controlling the memory allocation of the stored stimulation data by voluntary respiratory signals, and sophisticated fine control of the fingers, wrists, and elbow is realized by creating multichannel stimulation data from recorded myoelectric activities of normal subjects during movements of the upper limb.<<ETX>>

Development of percutaneous intramuscular electrode for multichannel FES system

A percutaneous intramuscular electrode developed for controlling paralyzed extremities by functional electrical stimulation (FES) is discussed. The electrode was made of a Teflon-coated 19-strand rope wound from ultrafine SUS 316L stainless steel wires and was helically coiled for high flexibility. Because of low percentages of electrode failure in the body, stable and reliable FES was achieved for a long time.<<ETX>>

EMG-angle relationship of the hamstring muscles during maximum knee flexion

The aim of the present study was to investigate the EMG-joint angle relationship during voluntary contraction with maximum effort and the differences in activity among three hamstring muscles during knee flexion. Ten healthy subjects performed maximum voluntary isometric and isokinetic knee flexion. The isometric tests were performed for 5 s at knee angles of 60 and 90 degrees. The isokinetic test, which consisted of knee flexion from 0 to 120 degrees in the prone position, was performed at an angular velocity of 30 degrees /s (0.523 rad/s). The knee flexion torque was measured using a KIN-COM isokinetic dynamometer. The individual EMG activity of the hamstrings, i.e. the semitendinosus, semimembranosus, long head of the biceps femoris and short head of the biceps femoris muscles, was detected using a bipolar fine wire electrode. With isometric testing, the knee flexion torque at 60 degrees knee flexion was greater than that at 90 degrees. The mean peak isokinetic torque occurred from 15 to 30 degrees knee flexion angle and then the torque decreased as the knee angle increased (p<0.01). The EMG activity of the hamstring muscles varied with the change in knee flexion angle except for the short head of the biceps femoris muscle under isometric condition. With isometric contraction, the integrated EMGs of the semitendinosus and semimembranosus muscles at a knee flexion angle of 60 degrees were significantly lower than that at 90 degrees. During maximum isokinetic contraction, the integrated EMGs of the semitendinosus, semimembranosus and short head of the biceps femoris muscles increased significantly as the knee angle increased from 0 to 105 degrees of knee flexion (p<0.05). On the other hand, the integrated EMG of the long head of the biceps femoris muscle at a knee angle of 60 degrees was significantly greater than that at 90 degrees knee flexion with isometric testing (p<0.01). During maximum isokinetic contraction, the integrated EMG was the greatest at a knee angle between 15 and 30 degrees, and then significantly decreased as the knee angle increased from 30 to 120 degrees (p<0.01). These results demonstrate that the EMG activity of hamstring muscles during maximum isometric and isokinetic knee flexion varies with change in muscle length or joint angle, and that the activity of the long head of the biceps femoris muscle differs considerably from the other three heads of hamstrings.

Relationship between EMG signals and force in human vastus lateralis muscle using multiple bipolar wire electrodes.

This paper describes the relationship between knee extension force and EMG signals detected by multiple bipolar wire electrodes inserted into the human vastus lateralis muscle under isometric conditions. Six healthy male volunteers participated in this study. Eight pairs of bipolar wire electrodes were inserted into the right vastus lateralis muscle and the EMG data were simultaneously detected and analyzed. The EMG raw data and individual force-IEMG relations were influenced by the location of the electrode inserted into the muscle. The force and IEMG relationship averaged across subjects detected from the eight electrodes, however, showed almost the same linear correlation in spite of different electrode locations. No linear correlation was observed between MdF and the knee extension force. This result suggests that, if all of the muscle fibers participate in the same action at the same time, the averaged normalized IEMG from any places using wire electrodes could reflect the total activities of that muscle even if the muscle is large.

Reduction in subluxation and improved muscle function of the hemiplegic shoulder joint after therapeutic electrical stimulation

Seventeen hemiplegic patients with chronic shoulder subluxation secondary to a cerebrovascular accident (CVA) were divided into three groups, two of which were subjected to 6 weeks of therapeutic electrical stimulation (TES) for 15 minutes twice a day, in order to assess the effectiveness of the treatment in reducing subluxation, and in improving shoulder abduction function. The third group was used as a control (C group). After 6 weeks of electrical stimulation of the supraspinatus (S group) and deltoid (D group), a significant (p<0.05) reduction in subluxation was observed in both groups when compared to the C group. The maximal force of shoulder abduction showed a tendency to increase in the S group (p<0.10). A significant increase in maximal force was also observed in the D group. In most of the TES-treated muscles, the interference pattern of EMG at maximum voluntary contraction increased. The amplitude of the EMG activity of the stimulated muscle also increased. Thus, we concluded that electrical stimulation therapy of the supraspinatus and the deltoid muscle is an effective treatment modality for shoulder subluxation and shoulder abduction function in hemiplegic patients.

An approach to a muscle model with a stimulus frequency-force relationship for FES applications

A simplified model of electrically stimulated muscle for use in applications of functional electrical stimulation (FES) is discussed in this paper. The muscle model was required to have both stimulus frequency and stimulus intensity (amplitude/width) inputs. The stimulus frequency versus force relationship of rabbit muscle was modeled first with a small number of model parameters that could be identified by simple experiments in a short time. The model identified was found to be applicable to human muscles. The frequency-force relationships of electrically stimulated fast and slow type muscles were also predicted by the model. The frequency-force model and a simplified model of muscle activation dynamics were used to construct a muscle model that described the summation of muscle contraction. The use of this model decreased the time burden on patients during parameter identification at the clinical site. The clinical applicability of these new model descriptions was suggested through computer simulations.

Localization of mRNAs for novel, atypical as well as conventional protein kinase C (PKC) isoforms in the brain of developing and mature rats

Using in situ hybridization histochemistry, the localization of mRNAs for 10 isoforms of protein kinase C (PKC) in the rat brain was studied at embryonic and postnatal stages. In the embryonic brain, the gene expression was positive only for PKCɛ, μ, λ, and ζ with the former three more evident: The expression for PKCμ and λ in the ventricular germinal zone and that for PKCɛ, ζ, and λ in the mantle zone. In the postnatal brain, the expression for PKCδ, η and θ was detected differentially in a few circumscribed loci such as the thalamus, the habenula, the septum, and the cerebellar granule cells, whereas that for the other isoforms was seen widely in various loci of the gray matter with different intensity. The expression in the cerebellar external granule cell layer was positive only for PKCβ (βI and βII), μ, and λ with that for PKCβ confined to its inner zone. There is a general tendency for all PKC isoforms that the expression levels reach at peaks in early postnatal brain and decreases more or less in adult specimens. This is the first report on the spatio-temporal heterogeneity in the gene expression for the whole members of PKC family in the brain throughout development, especially at embryonic days.

Rotational action of the supraspinatus muscle on the shoulder joint

The shoulder joint allows three-dimensional movement. In order to analyze the function of the muscles which act on the shoulder joint, three-dimensional movements, including rotation, must be considered. Among muscles participating in the shoulder joint movement, the supraspinatus muscle is known to have abduction and stabilization effects on the shoulder joint. However, the rotational function of the supraspinatus muscle has not been identified, because few studies have been reported on it. This study investigates the rotating function of the supraspinatus muscle using electrical stimulation, magnetic resonance imaging (MRI) and anatomical examination. Electrical stimulation was applied selectively to the supraspinatus muscle of healthy subjects using percutaneous wire electrodes. The electrical stimulation was given at different positions of the shoulder joint. It was found that the electrically induced rotational movements changed their direction depending on the position of the shoulder joint. When the humerus was relatively in internal rotation, internal rotation resulted. When it was in external rotation, external rotation occurred. Regarding the abduction angle of the shoulder joint, external rotation was induced with an increase in the abduction angle, whereas internal rotation occurred when the abduction angle was decreased. By the dissection of cadavers and MRI examination, it was indicated that the relation between the running direction of the supraspinatus muscle and the center of rotation of the humeral head was dependent on the position of the shoulder joint. Those findings supported the results of electrical stimulation of the supraspinatus muscle at various shoulder positions. These results indicate that the bi-directional rotating function of the supraspinatus muscle is characterized by an anatomical relationship between the running direction of the supraspinatus muscle and the center of rotation of the humeral head.

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.