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

An electrical nerve stimulation technique, using 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 employed to validate the technique and demonstrate its utility as a basic and applied research tool.

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.

Electrical stimulation of pelvic floor musculature by percutaneous implantable electrodes: a case report.

A forty-year-old man with reflex urinary incontinence due to spinal cord injury was treated with electrical stimulation of the pelvic floor musculature. In this case we employed percutaneous implantable electrodes and an external pulse regulator. After 4 weeks of stimulation incontinence was improved and urodynamically maximum cystometric capacity increased from 220 ml to 350 ml. Our method is easy and not invasive. This technique can be an alternative for the electrical stimulation for urinary incontinence.

Functional anatomical studies of the elbow movements. I. Electromyographic (EMG) analysis.

Activities of the elbow flexors and extensors during the movement of the elbow flexion and extension were analyzed in six normal human volunteers by electromyography (EMG). In the flexors, the majority of the muscles showed EMG activities during both the flexion and extension phases, although patterns and amplitudes of EMG activities varied from individual to individual. The biceps brachii always became less active when the forearm was in pronation. In the extensors, increase of EMG activities was observed at the period of the maximum elbow extension in the majority of cases, while no EMG activity was shown throughout the movement in some cases. During the elbow movement except at the maximum extension, the triceps brachii was almost inactive and some of their three heads, in particular the long head, often showed no EMG activity. In contrast, the anconeus was usually active, sometimes showing strong EMG activity.

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.

Method for studying muscle properties under orderly stimulated motor units with tripolar nerve cuff electrode.

An electrical nerve stimulation technique, using 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, firing rate behaviour of motor units of different sizes, and their susceptibility to fatigue were employed to validate the technique and demonstrate its utility as a basic and applied research tool.

Control of thumb movements: EMG analysis of the thumb and its application to functional electrical stimulation for a paralyzed hand.

This paper describes the control of thumb movements by functional electrical stimulation (FES). In order to determine stimulation data of thumb muscles, activities of nine thumb muscles and the palmaris longus were analyzed in normal subjects by averaging their EMGs. In this analysis, it was found that well coordinated contractions of these thumb muscles were required for finer movements and precise positioning of the thumb. Based upon this analysis, several standard stimulation data for the thumb muscles were programmed and stored into a computer-controlled FES system. Input of the threshold and maximum stimulating voltages for individual thumb muscles of normal subjects to the system enabled automatic creation of stimulation data for each subject. The thumb movements of the normal subjects induced by these data were very smooth and their trajectories were reproducible. In addition, precise thumb positioning and joint stability were easily obtained. These standard stimulation data for the thumb muscles were also applied to FES control of a C4 quadriplegic. The controllability of the thumb movements was improved and the reliability of hand tasks achieved by FES was increased.

Functional electrical stimulation (FES) systems for restoration of motor function of paralyzed muscles--versatile systems and a portable system.

Multichannel functional electrical stimulation (FES) systems were developed to restore the motor functions of the paralyzed muscles, i.e. two kinds of versatile systems for laboratory use and a practical portable system were developed. The first microcomputer-based FES system was composed of an 8 bit microcomputer (PC-8801mkII) with a voice recognition board and 30 stimulation outputs, in which the voice commands were used for selecting a motion pattern, and for executing (start), (hold), (restart) and (stop) commands. In combination with the voice commands, a proportional control command detected from a head angle sensor was used for volitional control of motion. The second microcomputer-based FES system was composed of a 16 bit microcomputer (PC-9801 UV or compatible) with flexible control capabilities (e.g. respiratory sensors) for volitional control and with 64 stimulation outputs. An originally designed practical portable FES system was 89 x 145 x 31 mm in dimension and 380 g in weight. This paper describes the system configurations, the control methods of these FES systems and three examples of the clinical applications of the FES systems.

Study on the elbow movement produced by functional electrical stimulation (FES).

Functional electrical stimulation (FES)-induced movements of the upper extremity using the electromyography (EMG)-based stimulation data, which were created on the basis of EMG analysis of elbow flexion and extension in a normal human subject, were examined. As a result of the FES to the elbow flexors and extensors in another normal subject, smooth and reproducible elbow flexion and extension were controlled. This result seems to indicate not only an advantage of EMG-based stimulation data in the FES but also a great potential of FES as a new technique for the functional anatomy of the human extremities.