Toshiki Matsunaga

Muscle fatigue from intermittent stimulation with low and high frequency electrical pulses

OBJECTIVE To evaluate muscle fatigue resulting from intermittent low frequency and high frequency stimulation for the application of closed-loop control in functional electrical stimulation (FES). DESIGN Nonrandomized trial. SETTING General community, a referral center, institutional practice, and ambulatory care. PATIENTS Twenty healthy nondisabled men volunteered for the normal muscle group. Four paraplegic men with implanted percutaneous intramuscular electrodes for FES volunteered for the paralyzed muscle group. INTERVENTION The stimulation frequency was set at low (20 Hz) or high (100 Hz). Stimulation was administered in 4-second bursts at the start of 60-second, 120-second, and 240-second periods (duty cycles of 1/15, 1/30, and 1/60, respectively). MAIN OUTCOME MEASUREMENTS Knee extensor torques were measured during intermittent electrical stimulation. A strength decrement index (SDI) was used to assess muscle fatigue. Actual knee extensor torques in the paraplegic men were also measured with an isokinetic dynamometer. RESULTS Muscle fatigue was significantly greater at 20 Hz than at 100 Hz for both the nondisabled and the paraplegic subjects (p < .0001). Muscle fatigue at the 1/15 cycle was significantly reduced (p < .01). CONCLUSIONS Muscle fatigue was greater at the lower frequency (20 Hz) than at the higher frequency (100 Hz) during intermittent electrical stimulation, suggesting that intermittent high frequency stimulation may be valuable in the development of closed-loop control strategies for FES.

Clinical use of percutaneous intramuscular electrodes for functional electrical stimulation

OBJECTIVE To evaluate the clinical use of the percutaneous intramuscular electrode in functional electrical stimulation (FES). DESIGN Randomized and controlled study. SETTING A referral center and institutional practice providing outpatient care. PATIENTS Seventeen patients (12 men, 5 women) who had implanted percutaneous intramuscular electrodes for more than 1 year were examined. The average follow-up time after implantation of electrodes was 2.2 years (range, 1yr to 4yr 10mo). Overall, there were 327 electrodes (83 upper extremities and 244 lower extremities). INTERVENTION The indwelling electrode was composed of helically coiled Teflon-coated rope stranded from 19 hard drawn wires of SUS 316L stainless steel (SES 114). MAIN OUTCOME MEASURES The rates of breakage, movement, and infection, and the number of electrodes that needed reimplantation were evaluated. RESULTS Only one electrode broke (0.3%) in the iliopsoas muscle at 12 weeks after implantation. Eight electrodes (2.4%) were removed because of loss of sufficient contraction force caused by movement of the electrodes. Movements occurred at 9 weeks in 6 electrodes and at 5 months in two. The failure rate of electrodes in the lower extremities was 3.7%. No failures occurred in the upper extremities. Ten electrodes (3.1%) required reimplantation. Although ten superficial infections (3.1%) were seen around the site of electrode insertion, no removals of electrode were needed. All electrodes in one patient were removed, however, because of generalized methicillin-resistant Staphylococcus aureus infection complicated with renal disease. Electrodes were reimplanted after improvement of the infection. CONCLUSIONS The ultrafine percutaneous intramuscular electrode was considered practical for long-term FES use.

Clinical application of peroneal nerve stimulator system using percutaneous intramuscular electrodes for correction of foot drop in hemiplegic patients.

Objective.  To assess the orthotic effect of a functional electrical stimulation device (Akita Heel Sensor System; AHSS) in the treatment of hemiplegic gait with foot drop.

Electrical Stimulation Using Implantable Radiofrequency Microstimulators to Relieve Pain Associated With Shoulder Subluxation in Chronic Hemiplegic Stroke

Objective.  To evaluate the ability to relieve shoulder pain by implanting ceramic‐case versions of radiofrequency microstimulators (RFM) in paralyzed shoulder muscles.

Hybrid Control of Powered Orthosis and Functional Neuromuscular Stimulation for Restoring Gait

The restoration of motor functions of patients with spinal cord injury (SCI) is one of important subjects for study. For this purpose, methods of functional neuromuscular stimulation (FNS) have been investigated in medical science and practice during these three decades. However, we have not achieved complete restoration of motor functions in SCI patients. On the other hand, we have achieved useful devices in human-scaled transportation by using power assist technology. Thus, applying power assist technology to the problem of restoring motor functions is one of possible solutions and sounds practical. In this paper, we propose a new hybrid system to combine power assist technology and FNS for restoring motor functions of lower extremity in SCI patients. Both powered orthosis and FNS are used to generate and control the joints moments of lower extremity in the proposed hybrid system. The main role of powered orthosis Vs is to compensate the joints moments generated by FNS and to enhance the controllability of FNS with the actuators. The proposed hybrid control system has been experimentally evaluated in gait motions by measuring the angle trajectories and generated moments around the knee and hip joints in the cases when only actuators are used and both FNS and actuators of the orthosis are used. The results prove that the control method for the hybrid system is useful to restore motor functions of lower extremity in SCI patients.

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.

Hybrid functional electrical stimulation for energy-efficient restoration of standing-up motion

OBJECTIVE To find the most energy-efficient standing-up motion for quadriceps and to restore that motion in a person with complete paraplegia by using hybrid functional electrical stimulation. DESIGN Nonrandomized control trial. SETTING A referral center and institutional practice providing outpatient care. PARTICIPANTS Twenty-nine volunteer samples were used to collect normal data. One patient with complete paraplegia received treatment for the restoration of standing-up motion. MAIN OUTCOME MEASUREMENTS Joint angles and ground reaction forces were investigated during the standing-up motion with arms crossed in front of the chest with an ankle-foot orthosis set at various angles. The electromyogram (EMG) was performed during the standing-up motion with and without the orthosis. The energy costs of quadriceps during the standing-up motion were calculated using a mathematical model. Standing-up motion in a person with complete paraplegia was restored and then analyzed by measuring the vertical ground reaction force and the hip and knee angles. RESULTS Quadriceps energy cost was lowest (p < .05) in subjects wearing the ankle-foot orthosis set at neutral with a flat sole line. In the integrated EMG the peak value of rectus femoris contraction was larger with the orthosis than without it (p < .05). A patient with complete paraplegia was able to stand up smoothly from a wheelchair based on stimulation patterns obtained from healthy subjects. CONCLUSIONS Energy-efficient standing-up motion in a patient with complete paraplegia was restored when the patient used an ankle-foot orthosis set at neutral with a flat sole line.

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.

Impact of pulmonary rehabilitation on postoperative complications in patients with lung cancer and chronic obstructive pulmonary disease

Given the extent of the surgical indications for pulmonary lobectomy in breathless patients, preoperative care and evaluation of pulmonary function are increasingly necessary. The aim of this study was to assess the contribution of preoperative pulmonary rehabilitation (PR) for reducing the incidence of postoperative pulmonary complications in non‐small cell lung cancer (NSCLC) patients with chronic obstructive pulmonary disease (COPD).