The trouble with doctors, says the exasperated mother, is that they only believe what they've been taught.

Louise McKnew might have been a doctor--she was pre-med in college--but with one thing and another she never got her degree. Now, degree or not, and like it or not, she's an expert on spinal-cord injuries. At any given moment she knows where the most promising research is being done, who is doing it, what the chances are of imminent breakthrough. Her son, 22, is confined to a wheelchair, and has been for over four years, the result of a broken neck from an automobile accident when he was a senior at St. Albans.

McKnew, who lives in Chevy Chase, Md., believes that the breakthroughs are close, but because neurologists and neurosurgeons have been taught that spinal-cord injury is "hopeless, permanent, irreversible forever," the breakthroughs, she fears, may stay stuck in the laboratories.

She is determined that they shall not.

Dr. Alan I. Faden, neurologist, brain-research pioneer, is not certain that Louise McKnew is entirely wrong.

"When I was trained," says Faden, "which was not too terribly long ago, he is 37 , the standard gospel in neurologic circles was that spinal injury is generally untreatable since the central nervous system, once damaged, is damaged permanently and does not have regenerative capabilities," or so the doctrine went.

"So, what happens," he says, "is that most physicians come out of training programs being totally nihilistic when it comes to the effects of either spinal injury or brain injury . . .

"That is very important, because it sets the tone for everything that follows. Until you can change that attitude among the individuals who see spinal-injured patients, you're not going to go very far."

Faden's work for the past five years has involved the shattering of myths about shattered spines. Chief of the Neurobiology research unit, and professor in the Department of Neurology of the Uniformed Services University of the Health Sciences in Bethesda, he is on the leading edge of one of the breakthroughs, one which may eventually prevent much of the paralysis that follows neck or back or certain brain injuries.

How long "eventually" will be depends at least in part on the mind set of the people--neurologists, emergency medical personnel, drug companies, therapists--who will be involved.

Faden's work grows out of a new understanding of the brain and the substances secreted by the cells of the body's central nervous system. These substances, called neurotransmitters, carry messages from various parts of the brain to activate, inhibit or somehow change one or more of the infinitely complex and interrelated body functions. Some of these substances have more than one function, it turns out, and it appears that in something like an injured spinal cord, they may--for reasons not well understood--actually do harm as well as good.

For example, when there is a serious injury to the neck or spinal cord the brain secretes an enormous amount of the neurotransmitter painkiller, Beta-endorphin. Not only does it probably alleviate the pain, but it drops blood pressure, possibly to levels that produce the condition known as shock. Beta-endorphin also somehow sets into motion the biochemical activities that are usually the real cause of post-injury paralysis. (Only when the spinal cord is completely severed is paralysis inevitable.)

Faden is a pioneer in the now burgeoning research on the brain's mysterious chemicals. His own work has centered on the use of a substance for which he co-discovered a new use, Naloxone--a drug that blocks the action of opiates as well as the neurotransmitter Beta-endorphin.

Even more recently, Faden's work has focused on a substance called TRH, Thyrotropin-Releasing Hormone (a natural substance) which seems to work even better than Naloxone (a synthetic chemical compound) in reversing shock and in preventing paralysis in injured experimental animals. At the same time, it leaves unimpeded the pain-relieving function of endorphins and any outside painkilling drugs.

Basically the work involves surgically traumatizing the spinal cords of cats and then treating them with the substance. (The animal laboratory, run by a highly respected veterinarian, is regarded by animal protectionists as a model of what animal facilities should be.)

In any case, video tapes of the post-surgery animals dramatically attest to the effectiveness of TRH, as earlier studies had with Naloxone. Cats so treated recovered almost 100 percent. Untreated cats, or those given control substances, even steroids, were left with disabilities. In fact, trying to "blind" the doctors to which cats were receiving control preparations was almost impossible because the differences were so spectacular.

Small tests using Naloxone on human subjects are already underway in a few major shock-trauma centers around the country, and some other emergency personnel have hinted to Faden that the drug, available for use in heroin overdoses, is also being used, quietly, in some spinal-cord injury and shock situations. (Faden sees this unauthorized use as potentially dangerous--an improper or incorrectly administered dose could postpone approval for years or, on the other hand, too low a dose might give the false impression that the treatment wasn't effective.)

But it is TRH that appears to have the greatest potential. The results of the animal research were published last fall in the New England Journal of Medicine. Now Faden and others are working out an appropriate dose for humans. He hopes that the actual controlled studies on people will begin in a matter of months.

Meanwhile, as a result of her son's injury, Louise McKnew has become active in the National Spinal Cord Injury Association, one of several organizations designed to promote research and therapy for paraplegics and quadriplegics, the former usually paralyzed from the waist down and the latter from the neck down.

Alan Faden's work, in itself, will not help McKnew's son, who is now, she says, Yale University's first wheelchair-bound undergraduate student. The usefulness of Naloxone or TRH is limited to the all-important acute stage during the first few hours after the injury when it can prevent the diminished blood flow and other chemical changes that lead to paralysis.

But McKnew acts as a kind of international clearinghouse for researchers in the field, making sure they are all kept aware of promising work on nerve regeneration, and central nervous-system transplants, research that could hold eventual promise for those whose injuries have resulted in chronic paralysis.

Lobbying Congress for research programs and funds, raising money from private sources, but especially educating the public--and many doctors--still bound to the old ways of thinking, have become a way of life for Louise McKnew.

There are, she notes, some 500,000 spinal-cord injured people in the country and the number increases by about 20,000 a year. Half are from automobile accidents and most of the rest are sports-related. About 80 percent of the cases are young men age 15 to 25.

"These kids are routinely choked on the words 'hopeless' and 'forever,' " says McKnew. "But now there's a real challenge to dogma and myth . . ."