My Year Off (5 page)

In my case, after the immediate crisis was over, I was prescribed a modest daily 75-mg dose of aspirin to thin the blood and then, after some months, a very mild dose of Pravastatin to reduce my (slightly elevated) cholesterol
level. Actually, the relationship of cholesterol to stroke is unclear. Many doctors will say that modest elevations in cholesterol are probably not as important as they can be in heart disease. None the less, cholesterol is associated with the degeneration of the blood vessel wall in the disease known as atherosclerosis (hardening of the arteries) in which cholesterol plaques in the blood vessel wall tend to clot, thus blocking off the blood vessel. Cholesterol is only one of many potential causes of stroke, but in a subject in which there are so many imponderables, it has the advantage that it can be both measured and treated. It’s for this reason that, in an illness that has so many mysteries, it attracts rather more than its fair share of attention.

Whatever the cause of stroke, almost any preventive measure is worth taking. The plain fact is that, in Britain and North America, someone will have a stroke approximately every five minutes. The onset of stroke is usually sudden and it is this suddenness that is one of its chief characteristics, as the word itself implies. The most common symptom of stroke is a weakness or paralysis of the arm or leg on one side of the body. This is known as ‘hemiplegia’. My hemiplegia affected my entire left side, from my left cheek and tongue to my left hand to my left foot, while internally my left lung was also weakened, so that I was often short of the breath required for sustaining speech.

‘Cerebral haemorrhages’, about 15 per cent of all strokes, as I came to learn, are usually the direct result of the rupture of one of the tiny arteries deep inside the brain, an organ patterned in all directions by a network of tiny blood vessels as fine and feathery as the skeleton of a leaf. If, as I did later in my convalescence, you visit the Royal College of Surgeons in Lincoln’s Inn Fields,
you can study the beautifully intricate network, a filigree tracery, of arteries that supply the brain, in any number of fascinating three-dimensional models on display there.

The brain, detached from its sheltering skull and stored in formaldehyde, looks a bit like a peeled walnut. In a living body exposed brain tissue has the appearance of cold porridge, the ‘grey matter’ of English slang. It’s this rather unpromising material that contains the core of who we are. As Stephen Pinker puts it in
How The Mind Works
, ‘The brain’s special status comes from a special thing that the brain does, which makes us see, think, feel, choose and act.’ When the brain is damaged, for example, in its visual areas, the patient is unable to recognize the world in which he or she finds himself. For such people, their world, as Pinker puts it, ‘is like handwriting they cannot decipher. They copy a bird faithfully but identify it as a tree stump. A cigarette lighter is a mystery until it is lit.’

The remaining 85 per cent of strokes are caused by the partial or complete blockage of an artery, either by the local narrowing and eventual blockage of an artery caused by clotting, or by the sudden arrival of a clot from elsewhere in the body (i.e. from an artery in the neck, or from a chamber in the heart) and thereby resulting in the cutting off of the blood supply — and the death of brain cells — to an organ as dependent on the blood supply as the heart and lungs are on oxygen. The main cause of arterial blockage is the deposit of fatty substances in the wall of the blood vessel. This results in stenosis (narrowing); occlusion (blockage); or embolism (the formation of a blood clot on the damaged arterial wall). This ‘cerebrovascular disease’ is often linked to the degeneration of arteries elsewhere in the
body, especially the heart. The main causes of arterial wall damage leading to narrowing and blockage are, first, high blood pressure and second, the accumulation of fat in the vessel wall. Of these, high blood pressure is far more important. This goes some way to explaining why, as a patient during these months, I found virtually every member of the medical profession I met for the first time wanting to take my blood pressure.

If the causes of my stroke were obscure, the effects were clear enough, and occupied a great deal of my attention. In the months after my stroke, I became fascinated by the workings of the brain and used to meet regularly with a subtle and delightful Irish neuro scientist, Professor Ray Dolan of the Wellcome Department of Cognitive Neurology, at the Institute for Neurology in Queen Square, who gave me a series of informal seminars in the mechanics of the brain, so far as they are known today. Within the field of neuroscience, the Institute is a state-of-the-art organization researching a subject that is still very much in infancy. Waiting one day in the high-tech minimalist foyer of the Wellcome building, I was amused to note a beguilingly frank advertisement for a forthcoming seminar: ‘The functional organization of working memory processes within the lateral frontal cortex — do we know anything yet?’

Dolan explained that the brain consumes 25 per cent of the energy production of the body. ‘It is as if the body is a slave to the brain,’ he told me. ‘The extraordinary thing about the brain is that while the body has obviously adapted to our physical environment, the brain has adapted to a psychological or social environment that has been, we assume, a major shaper of the brain and of how it is structured.’

This is an allusion to one of the big debates within
the field of contemporary neurology: to what extent has the brain evolved and developed according to Darwinian theory? The most famous protagonist of Darwinian theory as applied to psychological development (opposed by the science writer Stephen Jay Gould) is Stephen Pinker. In an interview Professor Pinker told me: ‘After having argued that language was some kind of distinct part of the human mind, the natural question was: so what are the other parts?’ The central idea of
How The Mind Works
can be stated in a sentence: ‘The mind,’ says Pinker, ‘is a system of organs of computation, designed by natural selection to solve the kinds of problems our ancestors faced in their foraging way of life, in particular, understanding and outmanoeuvring objects, animals, plants and other people.’ In other words, ‘the mind is what the brain does’. Or, as he says, ‘To put it crudely, the brain is like a computer that evolved.’

One of the most important recent developments in neurology is the recognition that the brain is rather more plastic (i.e. adaptable) in its functions than was once thought. The Victorian images of the brain that we’ve inherited were derived from railway systems, or the telephone switchboard, and suggested a rigid framework. Nowadays, the emphasis is on the adaptability of the brain to meet particular needs. Damage in one area will result, neurologists believe, in compensatory activity elsewhere. According to one Nobel prizewinning neuroscientist, Gerald Maurice Edelman, ‘The brain is a selective system, more like evolution than computation.’ Despite the extraordinary efforts now being devoted to neurological investigation, as the medical historian Roy Porter puts it, ‘Neurological conditions remain amongst the most intractable.’ Which brings us back to the brain’s place in our bodies.

A great deal of the body’s energy is devoted to the brain (and vice versa). Most of that energy comes from the breaking down of glucose into carbon dioxide and water, a biochemical process that requires a high level of oxygen. Unlike the body’s muscles, the brain is unable to store glucose in reserve; it depends instead on a constant supply from arterial blood, and the same is true of the necessary oxygen. When the brain is deprived by a stroke of oxygen or glucose, it begins to suffocate almost immediately. Irreversible brain damage will occur within fifteen to thirty minutes of the initial deprivation, unless blood flow resumes.

The brain is the miracle of the human frame, and aptly its biggest mystery. In recent years, neurological inquiry has become, with the study of genetics, the leading edge of medical research. The use of radioactive or fluorescent tracers and newly developed techniques of micro-electrode neurophysiology have brought the study of the brain centre-stage in the theatre of medicine. For the first time, researchers like Ray Dolan are making new discoveries about the organization of language and memory, and the way in which emotions interact with cognition, and how cognitive functions are composed of innumerable sub-processes.

When I asked Dolan how easy it would be to replace the brain with a computer, he replied: ‘You would need an awful lot of chips. There are twenty billion neurons in the brain and each of those neurons makes on average ten thousand connections.’ He went on to describe ‘the extraordinary computational power of the living brain to represent so much, to be able to remember so much and its almost limitless memory capacity’. To put it another way, if you were somehow able to link up all the laptop computers of a city like London, you would be
only just beginning to equal the capacity of one ordinary brain.

I also met with Dolan’s vivacious colleague at the Institute, Richard Frackowiak, who crisply described the brain as ‘an organ in a box with a hole at the bottom where the brain stem is situated’. A cerebral haemorrhage, he said, ‘squashes the brain. The pressure rises because the skull is absolutely rigid. In the worst possible case, the brain is actually squeezed out — that’s called “coning”. The pressure pushes it down through the hole at the bottom. But that is exremely rare and happens only in the more severe kind of stroke. You can get everything from fifteen minutes’ paralysis of the hand to a profound coma, from triviality to something fatal.’ Most people, in fact, die from other complications, notably cardio-respiratory difficulties. So how, I asked him, does a stroke kill you?

‘Well,’ Frackowiak replied, ‘it squashes the parts of the brain that deal with your heart rate and your breathing. It’s the same as being hanged, really. You die because your heart stops and you stop breathing.’ He went on, ‘There are many other ways you can die with a stroke. Lying in bed, you can get a raging pneumonia and die simply because your lungs fill up with fluid and you can’t breathe, can’t get oxygen in. And then there are many potential medical complications that can occur.’

We talked about the brain’s resilience to stroke. ‘The brain,’ said Frackowiak, ‘is uniquely adaptable, but it’s not like the liver. You can cut out seven-eighths of the liver and it’ll regenerate. So it’s not as resilient as the heart or the liver, and that’s why it’s stuck in a rigid box [the skull] and covered with fluid to absorb shock. It is beautifully designed. It is extraordinary. It weighs only
1.4 kilograms and yet it defines our whole personality, and our interaction with the world.’

The brain and the spinal cord, or central nervous system, is located at the core of our very being; this is the epicentre of the earthquake in the life of a man or a woman that is constituted by a stroke.

In the West, about three-quarters of acute stroke cases occur, as we have seen, in people aged sixty-five or more. But this means that 25 per cent of all strokes will occur in people under that age; another estimate says that a fifth of all strokes occur in people under the age of forty. So, while stroke is
perceived
as an old person’s illness, the statistical reality is that large numbers of younger people today are having to come to terms with a sudden and devastating affliction of which they know little or nothing. In Britain, about two hundred young, ‘socio-economically active people’ (as the jargon has it) are affected by stroke
every week
. The general public is almost completely unaware of this staggering statistic.

The remoteness of the affliction perhaps explains our general ignorance of it, except, perhaps as the mysteriously devastating illness that fells our elderly relatives. I suppose the first time I must have become conscious of ‘stroke’ was when, as a child, I read
Treasure Island
. The opening chapters of Robert Louis Stevenson’s masterpiece are among the most compellingly urgent ever written, and the moment when the mysterious sea captain (‘the brown old seaman, with the sabre cut’) fights Black Dog and collapses on the floor of the Admiral Benbow always seemed to me especially gripping:

Such was the treatment for stroke in the fiction of my childhood, and I suspect that memories of this passage, and others like it, formed the bulk of my adult knowledge of stroke, too.

Regardless of age, the physical and psychological damage is the same. The cost to society in economic terms is staggering: in the USA and Britain, respectively, $30 billion and £2. 8 billion each year. About one third of those afflicted by stroke between the ages of thirty-five and sixty-five are disqualified from work by disability. The majority of stroke-survivors will have a paralysed arm, and many will be unable to walk normally. Between 50 and 75 per cent will have some form of permanent disability.

The heartbreaking nature of such disability is vividly evoked by Sheila Hale who, writing in the
London Review of Books
in March 1998, poignantly evoked the post-stroke experience of her brilliant historian husband John: ‘The sociable stranger with the donnish manner would like to know who you are and what interests you. He
will listen attentively and respond enthusiastically. Whether you speak English, Italian, French or German, you will have no doubt that he follows your meaning. The trouble is that however hard you try you will not be able to understand a single word he is saying … It is more than five years since my husband, a Renaissance historian, lost his language following a stroke.’