Doctors are tapping the potential of the body’s electricity
Doctors are tapping the potential of the body’s electricity
In 1974, British pediatrician Cynthia Illingworth stunned the medical establishment with the discovery that children under 10 could regenerate the last digit of severed fingers and toes, complete with nails. How this happens is still a mystery but scientists now theorize the answer could lie in a minute electric current the body produces when injured. This, they believe, triggers the slashed nerve to regenerate. As the nerve grows, the surrounding tissue and bone return, and the digit reforms intact. If the electricity theory holds, regeneration for adults may be possible.
As futuristic as such speculation may sound, regeneration is but one possibility in a burgeoning field: electric medicine. By tapping the body’s own electric currents or introducing imperceptible currents into the tissues, doctors can successfully diagnose disease, reduce pain and treat patients suffering
from epilepsy or multiple sclerosis.
For almost a century, scientists have been familiar with the complex array of electrical connections in the nervous system. But until the development of the heart pacemaker in the 1950s, crude medical technology prevented these insights from application to treatment. However, with the development of lowcurrent micro-circuitry for the space program and other fields, new generations of electrical devices and techniques have filtered down to laboratories and hospitals around the world and offer hope for many patients, especially those whose conditions can’t be completely controlled with surgery or drugs.
The side effects of electricity are almost nil (burning the tissues with too much current is very unlikely in the hands of a trained technician). As a
result, research and treatment are speeding along simultaneously. So far, scientists have discovered that different types of body cells produce and respond to specific strengths of electricity. One of the researchers’ primary aims is to hook into these natural potentials to discover just the right amount of current or strength of field to affect a particular tissue or condition. “We’re talking about ‘codes’ for bones to turn on or nerves to start growing. These are very subtle^phenomena,” says University of Toronto physician Bruce Pomeranz, who is working on pinning down the mysteries of regeneration.
He has already observed that whereas one microamp of current speeds up nerve growth, 10 microamps have no effect, that a negative electrical field excites growth and a positive field inhibits it, and even that different frequencies of current trigger cells to release different chemicals. After working with “literally hundreds of
rats,” Pomeranz has succeeded in finding the right current—one microamp—to speed up the regeneration of the main nerve in the leg. “The next step will be to get fingers in adults to regenerate,” he says.
Cerebral palsy—a disorder in which muscles become spastic, joints may lock, and movement is difficult, sometimes impossible, to control—is one area in which treatment with electricity has proved successful. Since the mid’70s, some neurosurgeons have been implanting tiny electrodes in the brains or on the spinal cords of patients severely handicapped by cerebral palsy in an attempt to stimulate the neurons that control muscle tone and co-ordination. Says Dr. Harold Hoffman, a pediatric neurosurgeon at Toronto’s Hospital for Sick Children: “We’ve seen improvement and a couple of the children
started walking after we’d implanted the stimulators.” But, he cautions, the work has been done on growing children who have had extensive physiotherapy and might have improved anyway.
One reason many physicians have suspended judgment on the new electric treatment for cerebral palsy, believes Dr. Adrian Upton, a neurologist at McMaster University in Hamilton, Ont., is that “in a lot of the early work with surface and deep-brain stimulators, people just switched them on,” sometimes with no apparent improvement in patients’ muscle control. “There’s potential benefit for any patient with these devices, but you have to adjust the current from the stimulator to fit each individual,” adds Upton, who has devised a method of biocalibration that does just that.
Whereas the brain implants are generally employed only for very severe cases of cerebral palsy, a nonsurgical project beginning this month at the Ontario Crippled Children’s Centre in Toronto aims at improving muscle co-ordination in children who are able to walk either unaided or wearing a brace. Based in part on previous work to correct scoliosis (curvature of the spine) by means of an externally applied current,
the new cerebral palsy project will use currents from electrodes strapped to the children’s legs to force the muscle opposite the spastic one to contract. This will in turn stretch and condition the spastic muscle. The main hope of the Toronto project, says research associate Stephen Naumann, is “to teach the brain a normal walk via the peripheral nerves.”
Further along than the cerebral palsy work is another area of electric medicine aimed at patients who cannot be helped by conventional means: those with bone fractures that refuse to mend. Despite repeated casts, bone grafts and orthopedic hardware, all but five per cent of such “nonunion fractures” continue to produce fibrocartilage (a form of scar tissue) instead of bone at the break. In the past, amputation has sometimes been the only solution. But during the past seven years, orthopedic surgeons have been reporting successful healing in 80 to 85 per cent of their patients through very mild electrical stimulation applied directly to the fractured bone.
Dr. William deHaas of the University of Calgary has developed a method of applying the electricity by mounting magnetic coils on the patient’s cast. The resulting pulsed electromagnetic field, he hypothesizes, “may set up an environment that signals to the bone that it has been injured, encouraging the fibrocartilage to become bone.” In addition, deHaas reports that colleagues in Calgary have been using the same field of electricity to heal ligaments and tendons in rabbits.
In healing bone and treating cerebral palsy, tiny amounts of electricity are pumped into the body. But another, now well-established area of electric medicine makes use of the body’s own natural electrical currents to control artificial limbs. The principle is deceptively
simple: the amputee merely thinks of moving his or her arm. Electrodes on the skin of the stump pick up the weak electrical signals in the muscle remnants. Amplifiers then magnify the signal, tripping a circuit that powers the artificial hand or arm. Headed by electrical engineer Bob Scott, a team at the University of New Brunswick has designed a circuitry system for patients with such severe amputations or birth defects that only a fragment of one muscle remains—an advance that offers a fuller life to patients like fiveyear-old Kevin Roscoe, who was born with part of his arm missing.
This winter, Scott is starting a pilot project for toddlers, using a newly designed forearm and hand that is smaller, lighter and incorporates yet another
advance—“smarter circuitry” that can distinguish between purposeful and random movements, thus remedying a major problem with very young children: the batteries in their prostheses run down by noon. “If children can be fitted with a prosthesis at age 2 or younger, when they are learning muscle co-ordination in their other arm,” says Scott, “the results are incomparably better. They grow up to become functionally two-handed.”
Meanwhile, in Edmonton, neurophysiologist Richard Stein and electric technologist Dean Charles are currently working on a system for patients whose skin is so damaged by burns that electrodes can’t pick up the muscle signals. Stein’s intriguing solution is to surgically implant electrodes and a radio transmitter “to get at signals deep within the body,” which in turn close up the tissues around them. Movement is controlled by a receiver in the prosthesis, which picks up the muscle sig-
nais across the skin with the aid of FM radio waves.
Venturing even further into the realm of the miraculous is the work of neurosurgeon John Girvin of the University of Western Ontario. By using skin as a receptor for speech sounds, Girvin and Dr. Larry Marks of Yale University plan eventually to give the deaf a new sense of hearing. And by means of a TV camera mounted perhaps in the eye socket and electrode receptors surgically implanted in the brain, Girvin and engineer William Dobelle of Columbia University hope to give the blind “enough sight to get around in the world,” says Girvin. Both projects are still very experimental and he estimates that at least a decade of research will be needed to determine
if the techniques are feasible.
It remains to be seen whether such ideas will ultimately become reality or merely curious tangents in medical history. Despite swift advances in spaceage electronics, the major stumbling block in electric medicine may be the technology, for in comparison to the complexities of the human nervous system, the tiny instruments are still primitive. While an average neuron has 20,000 to 50,000 connections, a microchip transistor has only three. Nevertheless, the successes achieved so far in treating cerebral palsy, in healing nonunion bone fractures, and in developing sophisticated electric prostheses should fire other physicians and scientists with hope. “Trying to predict the future of electric medicine may be a little like trying to predict the future of the motor car back in the early 1900s,” comments Upton. “A lot of people just never believed that the car would become an everyday means of transportation.”
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