Chapter Sixteen

A SENSE of PROTECTION

IN A LITHOGRAPH by nineteenth-century printmaker Honoré-Victorin Daumier, a distinguished gentleman in a white waistcoat is sitting on a high-backed Victorian sofa. Perhaps I should say contorting, not sitting, for pain has doubled him up. His legs bend under him and his back arches downward, nearly forming a fetal position. Four sets of leering little devils perch beside him, half of them playing tug-of-war with cables looped around the man’s midsection and half sundering his abdomen with a huge, jagged-tooth saw. The man’s face expresses absolute agony.

Daumier added a title to his drawing: La colique, the pain of colic. Like most viewers, I find it difficult to view the print without a wince, mirroring the poor man’s anguish. Who has not felt at least a twinge from a muscular spasm caused by intestinal blockage or distension?

Pain is the hallmark of mortality. We plunge into the world through a woman’s stretched and torn tissues, our first response a cry of fear or grief or both. Years later we exit the world, often in one last paroxysm of pain. Between those two events we live out our days, with pain always lurking at the door. The word itself derives from poena, the Latin word for punishment, a dark hint that the demons working the saw are more than imaginary.

Ironically, I have spent my medical career among people whose faces also bear the signs of punishment and anguish, but for the opposite reason. Leprosy patients suffer because they feel no pain. They long for the demons who would alert them to impending danger.

My fascination with pain began, I suppose, in my childhood. As we traveled the mountains of South India, my parents would bring along a few pairs of dental forceps. I interrupted my play to stand by, with wide eyes and a racing heart, as my mother or father extracted teeth—without anesthetic. I would watch my tiny mother wriggle her pointed forceps up between the gum and tooth, seeking a firm grip so the crown of the tooth would not break off when she yanked. She hung on fiercely to those forceps while the patient’s own thrashing motions worked the tooth loose. The patients cried out, danced around wildly, and spit up blood. Still, even after seeing those reactions, onlookers lined up for treatment. Ridding themselves of toothache warranted the cost.

Occasionally in villages on the plains we would also see the impressive fakirs, religious men who demonstrated their conquest of pain. Some would push a thin, stiletto-type blade through their cheek, tongue, and out the other cheek, then withdraw the blade without bleeding. Others strung themselves high in the air by pulling on ropes that passed through a metal ring at the top of a pole and ended in meat-hooks stuck into the flesh of their backs. Showing no signs of pain, they dangled like spiders above an admiring crowd. Still others garishly decorated themselves with scores of oranges attached to large safety pins, which they jabbed into their skin. They laughed and merrily danced down the streets on stilts, jiggling the oranges in time with music.

On my return to India as an orthopedic surgeon, I encountered the full spectrum of human misery. Unaccountably, I found myself drawn to those who never came to the hospital, the deformed beggars who lined the entrances to temples, railway stations, and most public buildings. I saw clawed hands with missing fingers, ulcerated feet, paralyzed thumbs, and every conceivable kind of orthopedic defect, and I learned that no orthopedist had ever treated them or their fifteen million fellow sufferers worldwide. Because of the stigma attached to leprosy, few hospitals would admit them.

I have been studying pain ever since because leprosy destroys the nerves that carry pain, making the body devastatingly vulnerable to injury. I even came to appreciate those fanciful creatures who wielded the cables and saws in Daumier’s lithograph. Are they truly demons? Without their apparent torments, would the gentleman attend to his colic?

The Body’s Hotline

As I write, nerve cells are informing my brain that my strained back needs attention. The nerve endings of pain receptor cells detect pressure or inflammation, translate that sensation into a chemical and electrical code, and send those messages to the brain, which in turn weighs their significance and dictates a response.

Pain messages travel along a hotline, insisting on priority. They can preoccupy the brain, in the process drowning out all pleasurable sensations. The entire body responds. The muscles in my aching back contract, which intensifies pain by squeezing nerves. My blood flow changes: blood pressure reacts to pain just as it reacts to anxiety and fear. I may go pale or flush or even faint. Pain may upset my digestion, causing a spasm that brings on the feeling of nausea.

At another level, pain may dominate me psychologically. I may become cranky, complaining to my colleagues and family. Perhaps I’ll cancel an overseas trip to give my back extra rest, which in turn leads to further complications: guilt from letting people down or depression about my inability to work.

Amazingly, the sensation that evokes such a powerful response in every part of my body and mind soon fades into oblivion. Think back to your worst experience of pain and try to remember what it felt like. You cannot. You can summon up sharp recollections from other senses, such as the face of a childhood friend or the tune of the national anthem or even a memory of taste or smell piquant enough to prompt salivation. Yet the sense of tyrannical pain has somehow vanished. You have forgotten.

Dominating, subjective, and ephemeral, pain offers a research target as elusive as the quark. What is pain? When is it really there—and where?

As a medical student in England I had the rare privilege of studying under Sir Thomas Lewis, a pioneer in the study of pain. I remember those days well because Sir Thomas used his students as guinea pigs in his research. One gets an unforgettable perspective on pain by recording sensations while being pinched or pricked. Often Lewis subjected himself to the same tests, lest he misinterpret the students’ accounts. He collected his findings into a book, Pain, that became a classic, a model of beautiful language as well as medical research.

We allowed blood pressure cuffs to be inflated around a metal grater that pressed into our arms, endured drippings of hot sealing wax, and dutifully performed isometric exercises while a tourniquet cut off our blood supply. One wicked contraption shot electrical voltage through the fillings of a tooth. Some volunteers submersed their hands in ice water, then hot water. We had cheeks and hands pricked simultaneously to determine which pain extinguishes the other. We heard bells rung and stories read aloud, and we repeated sequences of numbers in forward and reverse order, all to measure how distraction modifies the sensation of pain.

These exhaustive methods yielded a few basic measurements. At what point does it start hurting (pain threshold)? Do you ever grow accustomed to the heat or pressure (adaptation to pain)? Where does it hurt (distribution of pain)? At what point can’t you endure it any more (pain tolerance)? Subjects also had to describe each pain verbally and distinguish degrees of pain (as many as twenty-one were reported).

We students came away with slight lesions, blisters, and pinpricks, as well as a diploma that exempted us from further victimization. The professors came away with graphs mapping out sensitivities on every square centimeter of the body. Such experiments have proceeded unabated for more than a century for one reason: the nervous system is incredibly complex. Each tiny swatch of the body has a different perception of pain.

I need not reproduce the charts here, for instinctively everyone knows the principles of pain distribution. A single speck of dust flies into your eye. You react immediately: your eye tears up, and you squint it shut and dab at the eyelid to remove the speck. Such a speck can immobilize even a superbly conditioned athlete like a baseball pitcher; the pain is so great that he cannot continue pitching until the speck is removed. The same speck on the pitcher’s arm would go wholly unnoticed. Indeed, thousands of dirt particles will accumulate there in the course of the game. Why the disparity in sensitivity?

The eye has certain rigid requirements of structure. Unlike the ear, its well-guarded sensory neighbor, the eye must lie exposed on the surface, in a direct line with light waves. The eye must also be transparent, which severely limits a blood supply, for opaque blood vessels would block vision. Any intrusion represents danger since the blood-starved eye cannot easily repair itself. Therefore a well-designed pain system makes the eye extraordinarily sensitive to the slightest pressure or pain, and its hair-trigger response trips the blink reflex.

Every bodily part has a unique sensitivity to both pain and pressure, determined by function. The face, especially in the area of the lips and nose, is acutely sensitive to both. Feet, subject to a day’s stomping, are better protected by tough skin and thus mercifully insensitive. Fingertips present an unusual case. Constant use requires them to be sensitive to pressure and temperature but relatively pain resistant: carpenters would be rare if the gripping fingers fired off pain signals to the brain at every stroke of a hammer. In the body’s torso, protecting vital organs becomes the main concern. Thus a light tap on the foot goes unnoticed, on the groin is felt as painful, and on the eye causes agony.

As I study pain in the human body, I marvel again at the Creator’s wisdom. I might prefer that the lining of the trachea were even more sensitive to irritants, causing more pain and coughing and so making lung-destroying tobacco smoke intolerable. But could humans even endure a hypersensitive trachea in a dust storm or in our modern polluted environment?

I think again of the eye and its split-second response. Wearers of contact lenses might wish for less sensitivity in the eye, but the sensitivity benefits the great majority of people and their need to preserve vision. Each part of the body responds to the appropriate danger that might interfere with it and thus affect the whole body.

When I began to see patients, I encountered the phenomenon of referred pain. The economical body assigns pain sensors to alert us to the most common threats. The intestine warns of distention, though not cutting or burning; the secluded brain has few pain receptors. If a part of the body faces an unexpected danger, the body borrows pain sensations from other regions. An injured spleen may seek help from faraway pain receptors in the tip of the left shoulder, and a kidney stone may be felt anywhere along a band from the groin to the lower back.

Referred pain makes proper diagnosis of a heart attack a tricky problem for a young doctor. “It’s a burning sensation in my neck,” one patient reports. “No, it feels like my arm is being squeezed,” says another. In a sense, the spinal cord is playing a trick on the brain. A warning system located in the spinal cord or lower brain detects a cardiac problem and instructs unrelated skin and muscle cells to act as if they are in serious jeopardy, as a favor to their wordless neighbor. Remarkably, the borrowed area—say, the left arm—may even feel tender to the touch. The left arm puts on an acting performance in order to seize the attention of a victim who would otherwise not attend to a vulnerable heart.

I learned to see pain as a kind of language, the most effective language in mobilizing the body’s response to potential harm.

Ongoing Conversation

Daily, pain contributes to our quality of life, even in such a common activity as walking. A leprosy patient, with perfectly normal skin tissue on the soles of his feet, may return from a walk with foot ulcers. A healthy person who takes exactly the same walk will develop no blisters or ulcers. Why? A file cabinet in my office contains a box of photographic slides that illustrate the reason. The stress of walking causes an increase in blood supply and mild inflammation, which we can measure through a thermograph machine that displays heat in various colors.

The slides of color-coded feet show that the way a healthy person puts feet to the ground changes radically from the first mile to the fifth mile. Perhaps at the beginning your great toe absorbs most of the stress; by the end of the walk your lateral toes and the lateral border of your foot will take over. Later the toe and heel will come down together. When you begin a really long hike, you will start off heel-toe, heel-toe. But when you return, you’ll be lifting your foot and setting it down as one unit—all these adjustments having been made subconsciously.

You do not make those shifts because of muscular fatigue. Rather, pain cells in your toes, heels, arches, and lateral bones have intermittently informed the brain, “Ease up a little. I need some rest.” You stride along oblivious since your brain assigns these functions to a subliminal control system that constantly monitors pain and pressure in every part of your body. A leprosy patient, having lost this incessant hum of intercellular conversation, will walk five miles without changing gait or shifting weight. The same pressure strikes the same cells with unrelenting force. In the slides of my patients, the favored portions of the foot show a white-hot color, a visual warning of potential ulcers.

As I sit and write these words, the pain cells in my hips and legs are periodically asking me to shift my weight a bit, and I reflexively obey by changing position and crossing and uncrossing my legs. Pain employs a tonal range of conversation. It whispers to us in the early stages of risk; subconsciously, we feel a slight discomfort and toss and turn in bed. (A paraplegic person lives in constant fear of bedsores because he or she can no longer hear those whispers.) It speaks to us as hazard increases: a hand grows tender and sore after a long stint at raking leaves. And pain shouts at us when the danger becomes severe: blisters, ulcers, and tissue damage force us to pay attention.

A limp amplifies the body’s response to pain. Out of orthopedic habit, I tend to stare impolitely at people who limp. What they may view as an embarrassing malfunction, I view as a wonderful adaptation. A limper’s body is compensating for damage to one leg by redirecting weight and pressure to the other, healthy leg. Every normal person limps occasionally. Sadly, leprosy patients do not limp, and their injured legs never get the rest needed for healing.

When the body’s pain-monitoring system breaks down, the inability to sense pain can cause permanent damage. Perhaps you step on a loose stone or curb. As your ankle begins to twist, the lateral ligaments of the ankle endure a terrific strain. Detecting the strain, nerve cells order the body to take all weight off the damaged leg, and its thigh and calf muscles will become momentarily flaccid. If your other, undamaged leg has lifted off the ground to take a step, you will now have no support and will lurch to the ground. (A step, says the anatomist, is a stumble caught in time.) Your body opts for falling rather than forcing the ankle to take on weight in its twisted position. You get up feeling a fool and hoping no one was watching, but in reality you have just achieved a beautifully coordinated maneuver that saved you from a badly sprained ankle or worse.

I cannot erase from my mind the memory of watching a leprosy patient sprain his ankle without falling. He stepped on a loose stone, turned his ankle completely over so that the sole of his foot pointed inward, and walked on without a limp. Lacking the protection of pain, he did not even glance at the foot he had just irreparably damaged by rupturing the left lateral ligament! Despite his therapist’s warnings, in subsequent days he kept turning his ankle again and again until eventually, due to more complications, he had to have that leg amputated.

Pain, so often viewed as an enemy, is actually the sensation most dedicated to keeping us healthy. If I had the power to choose one gift for my leprosy patients, I would choose the gift of pain.