Testing of electrical trancutaneous stimulators for suppressing pain.

As so many students of bioelectrical phenomenona frequently remind us, it was Luigi Galvani who first reported his experiments in applying electrical currents to contract the muscles of frogs and sheep . Numerous attempts have since been undertaken to utilize that phenomenon for a variety of therapeutic purposes, many of them quite successful . One of the most notable is the heart pacemaker. Electricity interacts with our neuromuscular system in three ways . It may affect the afferent nerves, or efferent nerves, or act directly on the muscles as shown by Galvani . Stimulation of the afferent nerves can introduce signals that are transmitted to the posterior root of the spinal cord and then to the brain, inducing sensations that may overpower other signals or stimulate a reflex arc . Electrical stimulation of the efferent nerves may initiate many physiological changes . We shall confine ourselves to afferent pain phenomena and the influence of electrical stimulation on them. Pain is Nature's way of telling us that something is wrong . It functions like an early warning signal that is transmitted via the spinal cord, (where it may trigger a reflex arc) to the brain, where it is analyzed and referred. This signal may originate from a damaged area in the body or from an area apparently far from the source . If it is electrically interfered with, at least to some extent, the pain is either reduced or disappears . The electrical stimulus is often described by patients as producing a sensation of buzzing, tingling, vibrating, or numbing. Alleviation of intractable pain is, of course, an important treatment modality . The VA Prosthetics Center therefore undertook a program to study the effectiveness of several commercially available electrical trans-