快猫短视频

IT COULD happen to you. A knock on the door in the dead of night. A sober-faced police officer saying, 鈥淚鈥檓 sorry, but there鈥檚 been an accident.鈥� A surreal rush to the hospital, where your loved one lies in a coma, somewhere between being and nothingness.

Months pass without the patient regaining consciousness. The doctors tell you that your loved one has slipped into a so-called 鈥減ersistent vegetative state鈥�: eyes open, breathing without assistance, but totally unresponsive to you or anything else in the room. Some vegetative patients eventually return to awareness, while others can linger for decades-in one case, up to 37 years. What would you do?

Would you resign yourself to a lifetime of tube feeding and bedside vigils? Or would you give up hope and allow the doctors to pull out the feeding tubes? Few choices could ever be as excruciating-especially because people sometimes do wake after years of showing little or no awareness.

In 1989, for example, a fatal crush at the Hillsborough football stadium in Sheffield left two men, Tony Bland and Andrew Devine, in persistent vegetative states. Four years later, the House of Lords ruled that Bland鈥檚 doctors could stop artificially giving him food and water, because he was unlikely ever to regain awareness. But in 1997, newspapers reported that Devine had 鈥渨oken up鈥�, and questions were raised about whether Bland鈥檚 doctors had given up too soon. And last Christmas Eve, newspapers called it a miracle when Patricia White Bull, a 42-year-old Native American woman, 鈥渟napped back into consciousness鈥� after 16 years in a coma-like state.

Such 鈥渕iracles鈥� get wide press coverage, leaving other families in agonies over when-or whether-to allow a vegetative patient to die. 鈥淚f you鈥檙e looking for guidance, you want to know why they are the way they are, what we can do about it, and what is the probability that they鈥檒l get better,鈥� says Nicholas Schiff, a neuroscientist at Cornell University in Ithaca, New York. Until recently, scientists had no good answers to these questions. But now researchers have found a way to use brain scans to predict-albeit imperfectly-who will improve and who won鈥檛. This may help ease the minds of families wondering whether their loved one is still trapped somewhere inside the body. But the persistent vegetative state is a profoundly disturbing condition, and people forced to confront it in a family member often respond very differently from how they would have predicted.

The first problem in dealing with this mysterious condition, which afflicts 25 000 Americans and perhaps 1000 Britons, is identifying it in the first place. Unlike comatose patients, whose eyes are closed in a constant, sleep-like state, people in a vegetative state have daily cycles of wakefulness during which their eyes open. They may even laugh, grimace or move their limbs, while appearing oblivious to their surroundings.

So might some patients actually be awake, yet unable to signal their thoughts to the people around them? That鈥檚 what happened to Peter Buckingham. Six weeks after a car accident, Buckingham gradually began to regain consciousness. He had a vague sense of who he was, but he felt confused and unaware of the passing of time-and, worst of all, he couldn鈥檛 respond to his family members when he recognised them. 鈥淚 suppose you could liken it to a dream state,鈥� he says now. Fortunately, Buckingham continued to improve, and after a further six weeks he began to regain the ability to communicate. But other patients may remain in this 鈥渓ocked-in鈥� state indefinitely, raising the possibility that doctors may unwittingly cut off food and water to a conscious person.

To avoid this horror, doctors look carefully for any signs of awareness. They watch to see if the patient can track moving objects or people with their eyes. They make sudden loud noises in the hope of provoking a response, and ask the patient to make simple movements such as closing their eyes or moving an arm. But if the patient is blind and deaf, or paralysed either by brain damage or by seizures of the joints that develop when people are left immobile, 鈥渢he clues that we鈥檙e usually looking for are not there鈥�, says Keith Andrews of the Royal Hospital for Neurodisability in London.

Locked in

Andrews made headlines a few years ago when he and his colleagues looked at 40 patients referred to his clinic from 1992 to 1995 with a diagnosis of persistent vegetative state. They found that 17 patients, more than 40 per cent, did have some awareness. Most were blind, or nearly so, but others had simply never been propped up in positions that allowed them to use slight gestures such as shrugging a shoulder or using a buzzer for communication (British Medical Journal, vol 313, p 13). One man who had been misdiagnosed as being in a persistent vegetative state for seven years had enough awareness to dictate a love letter to his wife. Andrews still believes it鈥檚 possible to recognise vegetative patients accurately, but he acknowledges that his study created a stir. 鈥淎 lot of people have taken it as evidence that you should never withdraw tube feeding.鈥�

Brain scans may be a more reliable way to separate truly unconscious people from 鈥渓ocked-in鈥� patients who are conscious but can鈥檛 communicate. In positron emission tomography (PET), in which radioactive tracers are used to measure the metabolic activity in regions of the brain, scans of people in a persistent vegetative state generally show less than half the normal level of cerebral metabolism. This is similar to levels seen in heavily anaesthetised patients. 鈥淟ocked-in鈥� patients, by contrast, have levels around 75 per cent of normal, says Schiff.

PET scans may prove even more useful in teasing out subtle hints of awareness in vegetative patients-hints that may herald a later wakening to consciousness. David Menon and his colleagues at the University of Cambridge鈥檚 Wolfson Brain Imaging Centre devised a way to detect what they call 鈥渃overt鈥� cognitive processing.

Their first patient was a 26-year-old woman who had suffered brain damage after a fever. Four months after entering hospital, she seemed to be in a vegetative state. The researchers first shone bright lights in her eyes and used a PET scan to watch her brain鈥檚 response. Having verified that she could see, they then showed her photographs of friends and family. The PET scans indicated that these photos stimulated activity in a part of the brain called the fusiform gyrus, which is known to play a role in face recognition. In contrast, scrambled images with the same brightness and colours, but no faces, evoked no such response (The Lancet, vol 352, p 200).

A second patient, injured in a traffic accident, appeared to be blind, so the researchers tested her response to sounds instead. Familiar words stimulated a region of the brain called the superior temporal gyrus-which responds to words in normal volunteers-while white noise modulated to sound a bit like words did not.

These two patients eventually regained some awareness. Two months after the study, for example, the woman whose brain reacted to faces became more responsive and could soon use short sentences such as, 鈥淒on鈥檛 like physiotherapy.鈥� A third patient who had shown no response to faces or words during PET scans did not recover. Menon and his colleagues are planning a larger study that would use functional magnetic resonance imaging (MRI), which does not involve radiation and will allow them to do more scans of each patient.

Sometimes patients can have islands of intact cognitive function without any promise of improvement, cautions Schiff. For example, he and his colleague Fred Plum cared for a patient who had been unconscious for twenty years but who uttered odd expressions such as 鈥渄own, down, down鈥�, or swear words, every few days. Last November, the researchers reported that the language centres of her brain, such as Broca鈥檚 and Wernicke鈥檚 areas, lit up as highly active on PET scans, even though overall she showed the half-normal brain activity typical of patients in a vegetative state (Journal of Cognitive Neuroscience, vol 11, p 650). Until the researchers saw this patient, says Schiff, they wouldn鈥檛 have guessed that such fragments of preserved activity could occur. The existence of these islands of awareness suggests that normal consciousness is made up of modules that are then integrated into a whole, he says.

Another attempt to predict the fate of people in persistent vegetative states came in 1998, when Andreas Kampfl and his colleagues at the University Hospital Innsbruck used MRI scans to examine the head injuries of 80 patients between six and eight weeks after their accidents. At the end of a year, 38 patients had recovered while 42 remained in a persistent vegetative state. The people who recovered had fewer brain lesions, especially in the corpus callosum and dorsolateral brainstem. In fact, by measuring damage in these regions Kampfl was able to separate those who recovered from those who did not with almost 85 per cent accuracy (The Lancet, vol 351, p 1763).

鈥淪o far, we are the first group who described which kind of lesions you have in a vegetative state,鈥� says Kampfl. Even so, he describes MRI as no more than an aid to give families a better idea of what to expect. Physicians should never rely on MRI alone in recommending to withdraw feeding tubes. 鈥淔or me as a clinician, it鈥檚 not good enough,鈥� Kampfl says. 鈥淵ou have to give patients one year.鈥�

To be safe, most doctors do wait a year before considering cutting off food and water. After three months in a vegetative state, people whose brains have been starved of oxygen rarely recover, and people who have suffered a blow to the head rarely recover any awareness after six months (see Diagram). 鈥淚t seemed clearer just to say that the chances of emerging after a year are so small that at the end of the day they鈥檙e minute,鈥� says Andrews. Indeed, one study of more than 200 patients who had been in a vegetative state longer than a year found that only seven ever regained any awareness.

Even if patients do recover from a vegetative state, especially a long one, they usually have serious disabilities. 鈥淭he term recover is wrong. Recover for me means 100 per cent. That will never happen,鈥� says Kampfl. Typically patients might start out by tracking family members with their eyes, but the amount of function they eventually regain varies widely. And the 鈥渕iracles鈥� reported in the papers turn out to be much less abrupt than they鈥檙e often made to sound. White Bull, for example-the woman who woke after 16 years-regained awareness gradually rather than suddenly, say physicians who have investigated the case. Indeed, says Plum, she probably was never in a fully vegetative state at all. And though the newspapers talked about her going shopping and eating pizza, they mentioned only briefly that she would need intensive speech and physical therapy.

Many patients emerging from comas have a similar experience. 鈥淐oming out of coma is a long, confusing process, not an immediate event,鈥� says Buckingham, who still has problems seven years after his accident. He says his recovery has been like waking up as an infant and having to go through an entire life鈥檚 development again. He鈥檚 reached the point where he can resume a relatively normal existence, but he has said that 鈥渢he relearning experience is so traumatic and such an immense task, that I wouldn鈥檛 wish it upon my worst enemy鈥�. He hasn鈥檛 regained everything. 鈥淢emories such as falling in love with my present wife are still memories without emotion,鈥� he says. And people who don鈥檛 know his past often assume he鈥檚 drunk, dull, or slow because of problems with his motor coordination and memory.

Still, Buckingham and White Bull have been luckier than most people who go through prolonged vegetative or coma-like states. Many never regain awareness, or at best recover only a tiny fraction of their former abilities-a prospect that fills most able-bodied people with horror. In a survey of doctors last year, for example, 95 per cent said they would want treatment withdrawn if they were in a persistent vegetative state (Resuscitation, vol 42, p 197).

But people鈥檚 definition of an acceptable quality of life changes when they鈥檙e faced with the actual event in a family member. Five years after the House of Lords ruling on Tony Bland, court approval to stop treatment had been given for only 18 patients in Britain. 鈥淲e thought there鈥檇 be a great flood of people making applications for withdrawal of tube feeding,鈥� says Andrews. But it hasn鈥檛 happened.

Families often show gratitude for any improvement in their relative鈥檚 condition, no matter how insignificant it seems to doctors. In April, Australian newspapers reported that 37-year-old John Thompson had been 鈥渨ritten off for dead鈥� by doctors after a drug overdose, but that his family had petitioned the court to reinstate feeding. Now his family claims that he can smile at them and kiss them.

Nancy Childs of the University of Texas at Austin says that she witnessed a recovery in one teenager who had been vegetative for 15 months after a car accident. The girl鈥檚 mother had refused to even consider stopping treatment, and one day the teenager began to move her eyes and legs on command. Her doctors treated her with stimulants, which have been shown to improve awareness in people who are at least minimally conscious. Eventually she was able to perform simple arithmetic and write 鈥淢om, I love you鈥� using eye blinks (The New England Journal of Medicine, vol 334, p 24). She remained severely disabled and wheelchair-bound. Nevertheless, her mother was overjoyed, and the patient did not seem depressed over her condition.

Until doctors have more options for diagnosing and treating vegetative states with techniques like brain cell transplants to repair injured areas, much of the burden of recovery lies with families and patients, who are alone in a way that very few of us will ever understand. Some patients simply do not have enough brain function to ever recover. Those that do must still find the inner strength to pick up the pieces of their shattered psyche and accept a new life that sometimes makes them feel like a stranger in their own body. 鈥淚t鈥檚 still very hard work every minute,鈥� says Buckingham.