The Sixth Sense

Dr. Oliver Sacks is a British-trained neurologist who now practices in New York, where he is professor of clinical neurology at the Albert Einstein College of Medicine. With his earlier book, Awakenings (1973), which described the remarkable effect of a new drug, LDopa, on cases of postencephalitic parkinsonism, Dr. Sacks established himself as a writer who could describe physical illnesses clearly to lay readers, who could both imagine and communicate what it is like to suffer neurological diseases that undermine the bodily ground of our being, and who felt no inhibitions about reporting his own amazement, fascination, compassion, and optimism when confronted by patients with rare, extraordinary, and tragic disorders.

Then came A Leg To Stand On (1984), in which Dr. Sacks described how he himself had suffered damage to the nerves of one of his legs, as a result of which he lost all idea that that leg was any part of himself and experienced it (temporarily) as an external encumbrance of which he had no subjective awareness. Both these books—as well as Migraine (1973, revised 1985), which was apparently written primarily for migraine sufferers—are inspired by a specific philosophy of medicine, the idea that “it is insufficient to consider disease in purely mechanical or chemical terms,” as contemporary medicine mostly does, but “that it must be considered equally in biological or metaphysical terms, i.e., in terms of organization and design.” In other words, it is not enough to regard the body as a machine which can go wrong and be repaired or tinkered with by medical mechanics, but it must also be regarded as the residence, the ground, indeed part of the person, the soul.

It follows from this philosophy that case histories, and perhaps particularly neurological case histories, cannot just be objective accounts of the signs, symptoms, and lesions observed and inferred by the physician, but must also include accounts of the patient’s subjective experience of his illness, including his experiences of changes in his perception of his self-perceiving self. As Dr. Sacks puts it in his preface to his present volume of clinical tales:

There is no “subject” in a narrow case history; modern case histories allude to the subject in a cursory phrase (“a trisomic albino female of 21”), which could as well apply to a rat as a human being. To restore the human subject at the centre—the suffering, afflicted, fighting, human subject—we must deepen a case history to a narrative or tale; only then do we have a “who” as well as a “what,” a real person, a patient, in relation to disease—in relation to the physical.

The patient’s essential being is very relevant in the higher reaches of neurology, and in psychology; for here the patient’s personhood is essentially involved, and the study of disease and identity cannot be disjoined. Such disorders, and their depiction and study, indeed entail a new discipline, which we may call the “neurology of identity,” for it deals with the neural foundations of the self, the age-old problem of mind and brain. It is possible that there must, of necessity, be a gulf, a gulf of category, between the psychical and the physical; but studies and stories pertaining simultaneously and inseparably to both—and it is these which especially fascinate me, and which (on the whole) I present here—may none the less serve to bring them nearer, to bring us to the very intersection of mechanism and life, to the relation of physiological processes to biography.

Dr. Sacks’s aim in The Man Who Mistook His Wife For a Hat is, then, to tell stories or tales about his encounters with patients, in order to demonstrate that it is possible to be objective and subjective at the same time, that the gulf between the psychical and the physical can after a fashion be bridged, and that disorders of the nervous system (mostly, fortunately, very rare ones) can eliminate or, less frequently, exaggerate aspects of the sense of identity which those of us who have intact nervous systems take entirely for granted.

For instance, in health we assume without question that when we see a familiar thing or person we will be able to recognize it or him, and it is only in rare moments of reflection that we appreciate that there is, indeed, something remarkable about the fact that we effortlessly convert visual sensations into images that we recognize, that have meaning for us. However, Dr. P., the subject of Dr. Sacks’s title story, who had a lesion in the visual cortex, could no longer effortlessly convert sensations into recognizable objects. When shown a glove, he described it as “a continuous surface infolded on itself. It appears to have five outpouchings,” and only when, by accident(!), he got it on did he exclaim, “My God, it’s a glove!” And when at the end of his consultation he sought to put on his hat, he instead seized his wife’s head and tried to put it on his own. “His wife looked as if she was used to such things,” and later gave Dr. Sacks a coherent account of how her husband coped with the everyday details of living.

He does everything singing to himself. But if he is interrupted and loses the thread, he comes to a complete stop, doesn’t know his clothes—or his own body. He sings all the time—eating songs, dressing songs, bathing songs, everything. He can’t do anything unless he makes it a song.

Dr. P. was a doctor of music, not of medicine, and in ways that are vividly described by Dr. Sacks he had learned to use melody, sound, and rhythm as an integrating guide that gave meaning to his actions.

But perhaps a clearer example of the dependence of the sense of identity on an intact nervous system is that of Christina, in the clinical tale “The Disembodied Lady.” In health we always know where our bodies are and what position or posture we are in, and we know this without having to look and see where we, our trunk, our head, our limbs, are. The knowledge is just part of our (often only) subliminal self-awareness. It is, however, dependent on a specific sense, the proprioceptive sense, which was discovered in the 1890s by the British neurologist, Charles Sherrington, who called it “our secret sense, our sixth sense” and named it proprioception because of its indispensability for our sense of ourselves. Nerve endings in all the movable parts of our body (muscles, tendons, joints) send a continuous but unconscious flow of information about their position, posture, and tone which keeps us in touch with our bodies. And, although we are readily able to imagine that we might go blind or deaf or lose our sense of taste or smell, it is hard to imagine that we might lose all sense of our bodilyness, of owning our own bodies.

Yet this is what happened to Christina who, while in the hospital for routine surgery, developed an acute infection of her nerves (a polyneuritis) which selectively and permanently destroyed her proprioceptive nerve fibers. As a result she became and remains disembodied, lacking all instinctive sense of her body, its position, its solidity, and has had to learn how to use vision to monitor her posture and her movements. And although she has, it seems, been remarkably successful in doing so, she still feels that her body is “dead, not-real, not-hers—she cannot appropriate it to herself.” As she herself says: “I feel my body is blind and deaf to itself…it has no sense of itself.”

But I must not tell Dr. Sacks’s tales for him. To do so would be to take away the sense of surprise and shock on which so many of them depend. It is enough for me to say that readers of The Man Who Mistook His Wife For a Hat will meet a gallery of patients who have suffered a major neurological disaster which has left them lacking some essential quality of being that the healthy take for granted or, more rarely, possessing some gift that seems bizarre rather than enviable: a middle-aged ex-sailor who believed himself to be nineteen and for whom time had stopped in 1945; a man who found a severed human leg in his bed which is really his own, unsevered leg; a man who tilted like the Leaning Tower of Pisa until, at his own suggestion, he was supplied with a spirit level attached to his glasses; a ward full of brain-damaged patients who all found President Reagan talking on television hilariously funny; a ninety-year-old woman whom tertiary syphilis, contracted seventy years previously, rendered frisky and skittish; a young man high on amphetamines who dreamed he was a dog and for the next three weeks lived in a doggy, olfactory world; mentally defective twins who amused each other by swapping six-figure prime numbers—and many others.

Some of these tales sound tall and Munchhauseny, but in fact they have been chosen to exemplify precisely how damage to specific parts of the nervous system can deplete, distort, or exaggerate those functions on which the sense of identity depends—and to show how, despite massive damage to the brain, the self continues to exist and assert itself. As one reads them one comes to appreciate why Dr. Sacks chose as his epigraph William Osler’s remark that “to talk of diseases is a sort of Arabian Nights entertainment.”

Readers of these tales will learn a lot about Dr. Sacks too. He clearly has no inhibitions about using his own flamboyant behavior and appearance—one of his patients likened him to an archimandrite priest—as a diagnostic and therapeutic tool. In doing so he is continuing or perhaps reviving an ancient tradition among physicians, which was particularly common among neurologists in the days before medicine became applied technology. He is a born storyteller who has no qualms about affecting surprise and endowing himself with the gift of total recall for the sake of liveliness of presentation. And he has a number of abiding preoccupations—not only with identity, but also with the role played by music, religious ceremonies, and nature, particularly in gardens, in helping patients (and, by implication, all of us) to maintain integration and to achieve what Osler called Aequanimitas. One hopes that he will develop this theme further in a later book.

He has heroes too, both his “suffering, afflicted, fighting” patients and his forerunners in neurology: Hughlings Jackson, Charles Sherrington, Henry Head, Kurt Goldstein, and A.R. Luria, who are, I think, better known and less forgotten than Sacks assumes. Finally, it must be said that, despite the liveliness of Sack’s writing, parts of this book will be heavy going for nonmedical readers. Unexplained anatomical and physiological terms abound but there is no glossary of technical terms and no index.