The use of electromyographic (EMG) pattern analysis to provide upper-motor-neuron paraplegics with patient-responsive control of FES (functional electrical stimulation) for the purpose of walker-supported walking is discussed. The system described uses above-lesion surface EMG signals to activate standing and walking functions in a patient-responsive manner. This system was been experimentally applied to paraplegics since early 1982. Below-lesion response-EMG control from the stimulated sites was added in 1987 to regulate stimuli levels in the face of fatigue. Although transcutaneous FES alone is being used the system is applicable in principle to implantable FES systems. >

EMG pattern analysis for patient-responsive control of FES in paraplegics for walker-supported walking

Changes in tissue health were monitored in a group of spinal cord injury (SCI) individuals with the use of an implanted neuromuscular electrical stimulation (NMES) system to provide standing and to facilitate standing transfers. Tissue health was evaluated through monitoring tissue oxygen levels in the ischial region along with measuring interface pressures at the seating support interface. Baseline assessments were done at study enrollment and repeated on completion of a conditioning exercise program. Serial assessments of tissue health were performed on eight NMES implant recipients. Unloaded tissue oxygen levels in the ischial region tended to increase after following the NMES exercise program for 8 weeks. Concurrently, pressure distributions at the seating support interface tended to change such that although the total pressure acting at the interface did not change, ischial region pressures showed a significant decrease. These changes indicate that chronic use of NMES has a quantifiable benefit on tissue health.

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Effects of regular use of neuromuscular electrical stimulation on tissue health.

Publisher Summary
The purpose of a biomaterial is to replace a part or a function of the body in a safe, reliable, economic, and physiologically acceptable manner. To achieve that function, a biomaterial must be in contact with living tissues resulting in an interface between living and non-living substances. It is the long-term stability of this interface that predicates the success or failure of a biomaterial and devices fabricated from biomaterials. This chapter examines the physiological and materials variables that can influence the stability of a biomaterial interface. It reviews in vitro and in vivo tests that are useful in understanding interfacial behavior. It discusses some of the interfacial responses of implants in the cardiovascular, neural, neuromuscular, orthopedic, ophthalmic, otolaryngeal, and dental areas. A general theory of biomaterials interfacial behavior is proposed and the evidence has been weighted.

Biomaterials—The Interfacial Problem

attitude, 80, 82, 84, 344 Acetylcholine, 100, 219, 220, 222, 223, 227, 228, 229, 230 inhibitory effects of, 227 on neurons in normal somatosensory cortex, 223 Aerobic exercise, 279, 290

Brain Injury and Recovery

We report about the results on positioning of the ankle joint of a hemiplegic patient and of normal experimental subjects, using functional electrical stimulation (FES) of antagonistic muscle groups and position feedback. Such a controller is intended to be used as the execution level of a multilevel orthotic system. The synthesis of the controller has been made with the aid of the components of an analog hybrid computer. Experimental results show that the static and dynamic properties of regulated movements are not essentially inferior to the properties of voluntary movements. There are stated technological problems that will have to be solved before the controller can be clinically applied for rehabilitation purposes. At the present state of the art, the poor technology of FES, the unsolved problem of fatigue with FES muscles, size, price, and bad cosmetic effect prevent the position controller from being clinically applicable.

Closed-Loop Positioning of Hemiplegic Patient's Joint by Means of Functional Electrical Stimulation

Publisher Summary This chapter provides the classification, motor system, and implanted systems of functional electrical stimulation of extremities (FESE). Originally, functional electrical stimulation was intended only to provoke functional movements during activities of daily living in patients with paralyzed extremities. One of the most important problems in FESE is the reduction of torque due to fatigue. Some recent work can be found in Peckham, but much more work has to be done before any final conclusion regarding the mechanism of fatigue and optimum stimulation current could be made. The most widely used device applying FESE is the electronic peroneal brace. For upper extremities, Gracanin and Marincek described a Functional Electronic Radial Brace for patients who lost voluntary control of extension of the wrist and fingers. In spite of the work described in this chapter, which shows definite sound trends of progress, there are still major problem areas where much more research has to be done before more sophisticated orthotic systems would be available for patients.

L. Vodovnik

Papers

Functional Electrical Stimulation of Extremities