By Kenneth R. Morareidge, Ph.D., Physiology Consultant
Copyright, 1989, All Rights Reserved
The potential of microcurrent therapy in health care has only recently attracted serious attention. Like many biological phenomena, knowledge of the very existence of small currents in the body had to wait on the development of technology sophisticated and sensitive enough to study them. The application of microcurrents to human tissue is remarkably effective in speeding the wound healing process. Numerous clinical studies have confirmed the effectiveness of very small currents in accelerating the healing process in non-union bone fractures and bone transplants. The use of microcurrent in such applications has become a standard procedure among orthopedic surgeons and physical therapists.
However, the effects of microcurrent therapy on the other types of injuries are just beginning to be explored on a systematic basis. Several clinical studies have reported the acceleration of healing of soft tissue injuries. Even more recent is the use of microcurrent therapy by physical therapists, athletic trainers, and other body workers. The available technology now allows great freedom in experimenting with microcurrent generators.
What is microcurrent? Normal household current is measured in amperes (amps). Microcurrent is measured in MicroAmps, millionths of an ampere. Current levels that seem to be most effective in helping tissue heal range from 20 to 500 MicroAmps. But many questions remain about these currents. How do they work in the body? Can they ever be dangerous? what are the long term effects of their use? In addition, there are questions of liability and licensing which legislators have yet to deal with.
Most of the published research on soft tissue injury and the effects of microcurrents have described the accelerated healing of ulcers in the skin, and associated suppression of bacterial growth (1,2,3,4). A skin ulcer is an injury that is visible and easy to assess. One can follow the rate of healing by measuring the size of the ulcer, and bacterial samples are easy to obtain with a swab. Observations of this type of injury can be at least provisionally extended to deeper tissue. For example, if microcurrents increase the rate of collagen formation in skin (3), there is a good chance that they also do it in ligaments and tendons. Also there is evidence of connective tissue cell multiplication, the formation of new collagen, in injured tendons (5) and increased strength in healed tendons of experimental animals (6) as a result of the application of microcurrent.
One report describes the accelerated healing of ligament injuries in members of a Canadian Olympic Team. The team physician routinely used microcurrent therapy in treating the athletes (7). Other studies have shown that microcurrents reduce pain with far fewer treatments than would be expected with conventional physical therapy (8,9).
There is even a study that indicates that microcurrents helped weight lifters increase strength more rapidly, and that these effects extended beyond the time treatment stopped (10).
Much of what we know about electrical currents in the body comes form the work of Robert Becker, who spent many years studying regeneration in the salamander and other animals (11). Microcurrents were first seen at amputation sites and in conjunction with other injuries, and were called "currents of injury," or "stump currents."
These electrical currents at injury sites were associated with the animals' ability to regenerate damaged or lost limbs. The greater the current density, the more complete the regeneration. This helped explain the differences between various types of animals in their regeneration abilities. Many animals, especially young ones can regenerate lost limbs or portions thereof. The champion of all land animals at this do-it-yourself replacement is the salamander. It also turns out that the salamander has the greatest injury current density of any land animal.
Becker's most astonishing discovery was that under the influence of an appropriately applied direct current certain cells are capable of de-differentiation. He found that mature, fully differentiated cells are able to retrogress to an embryonic form, with the ability to redifferentiate into whatever cell types are needed for complete regeneration. The group of undifferentiated cells that forms thusly at the stump of an amputated limb is called the bastema. The currents of injury that have been measured at amputation stumps in humans and animals appear to be related to the nerves supplying the area, and to the formation of the bastema.
The entire body is a low-level, direct current generator, a battery whose positive pole is along the spine and whose negative pole is the periphery. But how are these currents conducted through the body? The most obvious possibility is the nervous system and its support structure. Cells of the nervous system are known to generate electrical energy. Nerve signals are, after all, electrical or electrochemical events that transmit signals over large distances in the body.
But these signals are just that-signals, not actual currents. Furthermore, the voltages generated by the nervous system and by muscle are much larger than those we see at injury sites.
The nervous system is not comprised solely of neurons. There is a vastly greater network of cells that supports and nurtures the neurons. Generally there are glial cells in the central nervous system and Schwann cells in the peripheral nerves. All neuron cells bodies reside in the brain and spinal cord. Only their axons and dendrites extend outward, forming the peripheral nerves that connect every part of the body with the CNS. Becker has likened these neurons cell bodies and glia support structure to "Hairy raisins embedded in a pudding." These glia cells are electrical conductors that do not transmit discrete signals like neurons, but rather carry very small direct currents. These currents have a profound effect, either directly or by the magnetic fields they generate, not only on the neurons which they surround, but also on other cells.
Another possible conductor of electricity is the circulatory system, especially the capillaries. Nordenstrom (12) has indicated that in an area of injury a positive charge builds up, which would serve as a sing for the negative current flowing from the core of the body to the periphery. Concentration of the injury current is further enhanced by the ability of the circulatory system (capillaries) to conduct current. This happens when the normally ion-impermeable walls of the capillaries become less so. Forcing an increased current flow through the capillaries to the point of injury. Nordenstrom has had some very positive results in causing lung tumors to regress by using electrical currents.
Then there is that biological will-o-the-wisp, the meridian. The functional existence of meridians is a basic tenet of Chinese medicine. Their physical existence has been demonstrated by the use of radioactive tracers injected at acupuncture points. The tracers indeed distributed along the meridians (13, 14). However, the anatomical nature of the meridians remains in dispute. The Korean investigative results have not been reproduced. Such channels must be very thin and delicate, scarcely distinguishable from the surrounding connective tissue. It is quite possible that the flow of fluid or electricity is necessary to keep these channels open, and if collapsed, they become virtually invisible. The actual function of meridians remains a subject of speculation. They contain large amounts of DNA and a number of hormones. including adrenaline. They apparently are among the earliest structures to form in the embryo and may act as guides for the formation and later maintenance of other vessels and organs.
All of these mechanisms may be involved. This may explain why chronically tight muscles and connective tissue suffer damage. This m