Pain: Search for Understanding and Relief

VIRTUALLY every man has experienced pain and therefore knows just how it feels. But he cannot tell anybody else what it is really like. Pain cannot even be precisely defined. Lay and medical dictionaries alike offer essentially circular definitions of it as hurt, distress or suffering--pain is pain. Half the medical textbooks say little about it, except for extreme and uncommon forms, and doctors learn correspondingly little about it in medical school. The great British physiologist Sir Charles Sherrington described pain as "the psychical adjunct of an imperative protective reflex." More simply, pain is what the victim perceives in his mind after he has touched a hot stove--and reflexively pulled back his hand to guard against further burn damage.

Pattern of Responses. It is only since World War II that the investigation of pain has been pursued as energetically as the search for disease-causing microbes. One of the difficulties that must be understood, says University of Wisconsin Psychologist Richard A. Sternbach, is that pain is not a "thing," and certainly not a single, simple thing, but an abstract concept used by observers to describe three different things: "1) A personal, private sensation of hurt; 2) a harmful stimulus, which signals current or impending tissue damage; and 3) a pattern of responses, which operates to protect the organism from harm." Sternbach concedes that his use of "hurt" in the first part of his redefinition is circular, but insists that the important consideration is the total.

How a pain researcher views this pattern depends mainly on his specialty, Sternbach told a pain symposium last month at the City of Hope Medical Center in Duarte, Calif. Each investigator, he said, is "locked in" to thinking of pain in his own terms. Thus the psychologist views it as a basic, elementary sensation like sight or hearing. To the psychiatrist, it is an affect or emotion, like depression or anxiety; to the analyst, the product of an internal psychic conflict; to the neurologist or neurosurgeon, a pattern of neurophysiological activity. The biologist emphasizes its survival value. The existential philosopher, Frederik J. J. Buytendijk, regards pain as a potentially character-building phenomenon that unites an individual with the rest of humanity in its existential suffering.

Specialists in these related sciences have begun to seek a common language to describe the many varieties of pain, to chart its pathways from the burned finger or the stubbed toe to the brain, to assess its total impact, and to find better ways of relieving it. Mind doctors and body doctors are at last recognizing that in their evolving concern with pain they are really talking about the same thing in different terms. Increasingly, they realize that even the most obviously real and physical pain, as from a burn or a fracture, is processed in the mind. By the application of psychotherapeutic techniques, notably hypnosis, they are teaching patients to control their reactions to such pain.

Thick and Thin. First, researchers must answer a basic question: how is pain felt? As long ago as 1826, Johannes Peter Mueller promulgated the "law of specific nerve energies." He suggested that stimulation of specific pain receptors in the skin, like those for heat or pressure, sends impulses along specific nerve fibers to equally specific parts of the spinal cord and brain. This concept has since been called the "direct telephone-line system." The latest research shows that the system is by no means so simple as direct dialing. It is full of crossovers and redundancies, creating the effects of multiple conference calls and party lines.

Even the slightest, sharpest pinprick or the pulling of a single hair activates not one nerve fiber but many. Any one fiber, it appears, may be sensitive to more than one kind of painful stimulus. The fibers are not all alike but fall into two main classes, some that are microscopically thin and others that are relatively thick. The fine-fiber circuits can actuate the heavy-fiber circuits, which may reinforce or prolong the sensation of pain. So charting the pathways of pain--from the surface pinprick through the relays of the nervous system to parts of the brain where it is perceived and interpreted, perhaps with emotional overtones--is more complex than wiring a computer.

As neurophysiologists now see it, when a man gets a shot of penicillin in the buttock, the stab sends an impulse along the nerve fibers to the fourth lumbar vertebra (see diagram). Then the impulse travels upward and soon crosses over to the opposite side of the spinal cord for its journey toward the brain. Along the way it triggers an automatic reflex that causes the man to flinch and tighten his gluteal muscle. After the impulse reaches the thalamus, a major (and evolutionally ancient) junction box at the base of the brain, where it is perceived as pain, it proceeds to the cortex. Only in this, the newest and most advanced part of the brain, is the entire painful sensation fully processed and interpreted.

How it is interpreted depends as much on the pained as on the pain. For in most everyday situations, the emotional component is more significant than the underlying sensation. A man getting a penicillin shot knows that "it's for his own good" and accepts the little stab without protest. A four-year-old who cannot grasp this concept will probably scream. The adult will almost certainly make some vocal protest if he is taken unawares, and he may do so at the first touch of the dentist's drill if he has been expecting it to hurt. Both surprise and fearful anticipation are elements in reactions to pain.

It's All Real. Some people who evince little or no vocal or visible reaction when they are obviously hurt say they have a high threshold for pain. Many more, who do not try to suppress their feelings, admit to having a low threshold. There is no physiological evidence of any differences in the pain sensors and therefore in the basic pain sensations in these two groups. Whatever differences there are apparently exist entirely in the emotional reactions. These also vary with cultural attitudes. The stoicism of the American Indian and the Chinese is proverbial, although ethnic variations in sensitivity have not been proved. Descendants of "old American" families make a greater effort to suppress their reactions to pain than other cultural groups, such as Italians, among whom an outcry is socially acceptable. For yet others, the "wailing wall" psychology provides a rationale: the vocal protest is supposed to ease the pain. Many a man will groan aloud to alleviate cramping pains in his belly, though he may remain silent under other kinds of pain.

The one personality trait, regardless of culture, that most consistently accompanies exaggerated sensitivity to pain, says Sternbach, is neurotic anxiety. This is not the anxiety associated with a specific situation, such as an impending operation, but the persistent, seemingly baseless anxiety that often has its roots in the unconscious. From many observations, Sternbach concludes: "The quiet, brooding, anxious and resentful individual is the one who is most likely to have symptoms of pain and is least able to tolerate them." By contrast, victims of the more crippling emotional illnesses, the psychoses, are far less likely to complain of pain.

If pain exists without letup, says Neurosurgeon Benjamin L. Crue of the City of Hope, the chances are 10 to 1 that it is neurotic or at least psychogenic. "Organic pain doesn't work that way," says Crue. "It comes and goes, with a few exceptions such as some cases of cancer. Nearly all the rest of the pain that patients call 'constant' or 'unremitting' is psychological." This is not to say that such pain is not "real." Most medical authorities now agree with Sternbach, who says: "Excluding the malingerer, who by definition is a deliberate faker, all pain is real." It does no good for a doctor to say "It's all in your mind." The important thing for the pain-relieving physician to do is to determine the source of the pain, whether in mind or body, or even in the amputee's "phantom limb," and then select the most effective treatment.

Stay the Knife. Technically, the total suppression of pain comes only with anesthesia, which cannot be prolonged. The lighter state of analgesia, or relief of pain without loss of consciousness, is far more difficult to achieve. For cancer patients with intractable pain of indisputably physical origin, neurosurgeons have devised a number of radical operations. One of the commonest, for pain anywhere below the neck, is cordotomy--literally, cutting the spinal cord--a remedy that is less drastic than it sounds. In the standard operation, the cord is exposed and a small cut is made in the nerve bundles controlling the pain-afflicted area. The so-called cut may actually be a tiny electrical burn. Crue and his colleagues have just reported a refinement, in which small electrodes are implanted through the skin and left in place, so that the treatment can be repeated if pain recurs. Other neurosurgical procedures involve cutting the roots of nerves at the spine to relieve cancer pain in the lower end of the backbone, and cutting or chemically killing the trigeminal nerve in the face to halt the agonizing stabs of tic douloureux, the most agonizing form of neuralgia.

Many neurosurgeons would stay the knife if they could, and are joining with pharmacologists to develop better ways of relieving pain with drugs. As many as 65% of tic douloureux victims can be treated effectively, says Crue, with drugs originally designed to control epileptic seizures. For the relief of severe pain of virtually every kind, morphine and its synthetic analogues remain the most potent drugs known,* but all are highly addicting and need to be taken in stepped-up doses to maintain a constant level of analgesia. Supposedly nonaddicting substitutes are exultantly reported almost every year by research chemists, and are found just as regularly to be addicting in proportion to their effectiveness. Aspirin remains the most widely useful and, for most patients, the safest of analgesics, despite its limited potency.

The newest and most significant advances in relief and control of pain have come through the side door, from psychiatry. Three in number, they involve the use of psychotropic drugs, the application of standard psychotherapeutic techniques, and hypnosis. First of the drugs to find favor was chlorpromazine (Thorazine), used to reduce the severe anxiety of patients with advanced cancer. Serendipitously, it was found that when their anxiety was lessened, so was their perception of pain --though not necessarily the underlying sensation. Many a patient said: "Doctor, I still feel the pain, but it doesn't bother me so much."

As psychologists and psychiatrists probed further into the emotional components of pain, they realized that if anxiety is dominant for some patients, depression is for others. So doctors have now begun prescribing such mood-elevating drugs as imipramine (Tofranil), amitryptiline (Elavil) and a related compound, Triavil. Patients being treated with these drugs are able to function normally in everyday activities, and are allowed to drive cars. As with the tranquilizers, it is mainly the perception of pain that is altered, although some grateful patients report that their pain has actually been eliminated. Standard psychotherapy, both on a one-to-one doctor-patient basis and in groups, has also proved highly effective in relieving patients' perception of pain and their reactions to it. Presumably it does so by allaying their anxiety or lifting them out of depression.

Filter the Hurt. The newest and most striking psychiatric approach to the relief of pain is through hypnosis. In recent years, medical hypnotism has gained acceptance, and a leading exponent is Manhattan's Dr. Herbert Spiegel. What he teaches his patients, says Spiegel, is the art of handling pain so that it cannot tyrannize over them: "The patient learns to superimpose a feeling of numbness over the pain area, and to filter the hurt out of it. He does this through a focused awareness, like being absorbed in a task." In the days before medical hypnotism, a man might have focused his awareness away from his broken leg by biting his finger or his lip. Now, says Spiegel, about 80% of people can be hypnotized; only 20% may go into a deep trance, but for the others the lighter trance state is sufficient to reduce the perception of pain.

With hypnosis, many victims of incurable cancer can have their morphine dosage reduced by two-thirds, if not eliminated. Clearly, in these cases and in other disabling, recurrent pains such as migraine, the signals received and transmitted by the nerve fibers are not altered. What is changed is the mental perception and processing of pain.

It is upon these mental aspects of pain that medical researchers must concentrate, since there is no prospect that its sensory bases can be modified. Along with the pioneering in psychotherapy there goes an intensified search for more potent and safer analgesic drugs. For it is now clear that even such renowned pain killers as morphine exert their beneficent effects largely by allaying anxiety and thus altering the overall reaction to pain.

* With the exception of herion, which no U.S. physician may legally posses or prescribe, although it is still used in Britain and some other countries.

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