Proprioception, to a considerable extent, can compensate for defects in the inner ears. Thus patients who have been surgically deprived of their labyrinths (as is sometimes done to relieve the intolerable, crippling vertigo of severe Meniere’s disease), while at first unable to stand upright or take a single step, may learn to employ and to enhance their proprioception quite wonderfully; in particular, to use the sensors in the vast latissimus dorsi muscles of the back—the greatest, most mobile muscular expanse in the body—as an accessory and novel balance organ, a pair of vast, winglike proprioceptors. As the patients become practised, as this becomes second-nature, they are able to stand and walk—not perfectly, but with safety, assurance, and ease.
Purdon Martin was endlessly thoughtful and ingenious in designing a variety of mechanisms and methods that made it possible for even severely disabled Parkinsonians to achieve an artificial normality of gait and posture—lines painted on the floor, counterweights in the belt, loudly ticking pacemakers—to set the cadence for walking. In this he always learned from his patients (to whom, indeed, his great book is dedicated). He was a deeply human pioneer, and in his medicine understanding and collaborating were centraclass="underline" patient and physician were coequals, on the same level, each learning from and helping the other and between them arriving at new insights and treatment. But he had not, to my knowledge, devised a prosthesis for the correction of impaired tilting and higher vestibular reflexes, the problem that afflicted Mr MacGregor.
‘So that’s it, is it?’ asked Mr MacGregor. ‘I can’t use the spirit level inside my head. I can’t use my ears, but I can use my eyes. Quizzically, experimentally, he tilted his head to one side: “Things look the same now—the world doesn’t tilt.”’ Then he asked for a mirror, and I had a long one wheeled before him. ‘Now I see myself tilting,’ he said. ‘Now I can straighten up—maybe I could stay straight. . . But I can’t live among mirrors, or carry one round with me.’
He thought again deeply, frowning in concentration—then suddenly his face cleared, and lit up with a smile. ‘I’ve got it!’ he exclaimed. ‘Yeah, Doc, I’ve got it! I don’t need a mirror—I just need a level. I can’t use the spirit levels inside my head, but why couldn’t I use levels outside my head—levels I could see, I could use with my eyes?’ He took off his glasses, fingering them thoughtfully, his smile slowly broadening.
‘Here, for example, in the rim of my glasses . . . This could tell me, tell my eyes, if I was tilting. I’d keep an eye on it at first; it would be a real strain. But then it might become second-nature, automatic. Okay, Doc, so what do you think?’
‘I think it’s a brilliant idea, Mr MacGregor. Let’s give it a try.’
The principle was clear, the mechanics a bit tricky. We first experimented with a sort of pendulum, a weighted thread hung from the rims, but this was too close to the eyes, and scarcely seen at all. Then, with the help of our optometrist and workshop, we made a clip extending two nose-lengths forward from the bridge of the spectacles, with a miniature horizontal level fixed to each side. We fiddled with various designs, all tested and modified by Mr MacGregor. In a couple of weeks we had completed a prototype, a pair of somewhat Heath Robinsonish spirit spectacles: ‘The world’s first pair!’ said Mr MacGregor, in glee and triumph. He donned them. They looked a bit cumbersome and odd, but scarcely more so than the bulky hearing-aid spectacles that were coming in at the time. And now a strange sight was to be seen in our Home—Mr MacGregor in the spirit spectacles he had invented and made, his gaze intensely fixed, like a steersman eyeing the binnacle of his ship. This worked, in a fashion—at least he stopped tilting: but it was a continuous, exhausting exercise. And then, over the ensuing weeks, it got easier and easier; keeping an eye on his ‘instruments’ became unconscious, like keeping an eye on the instrument panel of one’s car while being free to think, chat, and do other things.
Mr MacGregor’s spectacles became the rage of St. Dunstan’s. We had several other patients with Parkinsonism who also suffered from impairment of tilting reactions and postural reflexes—a problem not only hazardous but also notoriously resistant to treatment. Soon a second patient, then a third, were wearing Mr MacGregor’s spirit spectacles, and now, like him, could walk upright, on the level.
8. Eyes Right!
Mrs S., an intelligent woman in her sixties, has suffered a massive stroke, affecting the deeper and back portions of her right cerebral hemisphere. She has perfectly preserved intelligence—and humour.
She sometimes complains to the nurses that tney have not put dessert or coffee on her tray. When they say, ‘But, Mrs S., it is right there, on the left’, she seems not to understand what they say, and does not look to the left. If her head is gently turned, so that the dessert comes into sight, in the preserved right half of her visual field, she says, ‘Oh, there is it—it wasn’t there before’. She has totally lost the idea of ‘left’, with regard to both the world and her own body. Sometimes she complains that her portions are too small, but this is because she only eats from the right half of the plate—it does not occur to her that it has a left half as well. Sometimes, she will put on lipstick, and make up the right half of her face, leaving the left half completely neglected: it is almost impossible to treat these things, because her attention cannot be drawn to them (‘hemi-inattention’—see Battersby 1956) and she has no conception that they are wrong. She knows it intellectually, and can understand, and laugh; but it is impossible for her to know it directly.
Knowing it intellectually, knowing it inferentially, she has worked out strategies for dealing with her imperception. She cannot look left, directly, she cannot turn left, so what she does is to turn right—and right through a circle. Thus she requested, and was given, a rotating wheelchair. And now if she cannot find something which she knows should be there, she swivels to the right, through a circle, until it comes into view. She finds this signally successful if she cannot find her coffee or dessert. If her portions seem too small, she will swivel to the right, keeping her eyes to the right, until the previously missed half now comes into view; she will eat this, or rather half of this, and feel less hungry than before. But if she is still hungry, or if she thinks on the matter, and realises that she may have perceived only half of the missing half, she will make a second rotation till the remaining quarter comes into view, and, in turn, bisect this yet again. This usually suffices—after all, she has now eaten seven-eighths of the portion—but she may, if she is feeling particularly hungry or obsessive, make a third turn, and secure another sixteenth of her portion (leaving, of course, the remaining sixteenth, the left sixteenth, on her plate). ‘It’s absurd,’ she says. ‘I feel like Zeno’s arrow—I never get there. It may look funny, but under the circumstances what else can I do?’