Functional Electrical Stimulation with Surface Electrodes

The review investigates the objective evidences of benefits derived from surface functional electrical stimulation (FES) of lower and upper extremities for people after incomplete spinal cord injury (SCI) and stroke. FES can offer noticeable benefits in walking ability. It can be efficiently combined with treadmill and body weight support. Voluntary muscle strength and endurance gain can be achieved through FES assisted gait training together with increased gait velocity in absence of electrical stimulator. Cyclic FES, FES augmented by biofeedback, and FES used in various daily activities can result in substantial improvements of the voluntary control of upper extremities. I. INTRODUCTION UNCTIONAL electrical stimulation (FES) is a rehabilitative technology that uses electrical currents applied to the peripheral nerves. When a stimulating current, consisting from a series of rectangular monophasic or biphasic (symmetrical or asymmetrical) electric pulses, is applied to the electrodes placed on the skin overlaying sensory-motor nerve structures, an electric field is established between two electrodes and ions will create a current in the tissue. The ionic flow across the nerve influences the transmembrane potential and can generate an action potential. The action potential propagates along the nerve causing contraction of a paralyzed muscle. In this way FES provides restoration of walking or arm movements in a person with complete or incomplete spinal cord injury, stroke or other lesions to the upper motor neuron (1). Surface stimulation electrode is a terminal through which electrical current passes into the underlying tissue (2). At the electrode-tissue interface a conversion occurs between the current of electrons driven through the wires coupled to the stimulator and the current of ions in the tissue. An electrode is usually made of metal. However, it may be made of a nonmetal, commonly carbon. The design criteria