[Paleopsych] NYT: Inside the Injured Brain, Many Kinds of Awareness
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Tue Apr 5 17:59:28 UTC 2005
Inside the Injured Brain, Many Kinds of Awareness
By BENEDICT CAREY
The debate over Terri Schiavo's fate comes at a time when researchers
are deepening their understanding of the unconscious brain.
Neuroscientists now understand at least some of the physiology behind
a wide range of unconscious states, from deep sleep to coma, from
partially conscious conditions to a persistent vegetative state, the
condition diagnosed in Ms. Schiavo.
New research, by laboratories in New York and Europe, has allowed for
much clearer distinctions to be made between the uncounted number of
people who at some time become comatose, the 10,000 to 15,000
Americans who subsist in vegetative states and the estimated 100,000
or more who exist in states of partial consciousness.
This emerging picture should make it easier for doctors to judge which
brain-damaged patients have some hope of recovering awareness, experts
say, and already it is providing clues to the specific brain processes
that sustain conscious awareness.
"Understanding what these processes are will give us a better sense of
how to help the whole range of people living with brain injuries,"
said Dr. Nicholas Schiff, an assistant professor of neurology and
neuroscience at NewYork-Presbyterian/Weill Cornell hospital. "That is
where this field is ultimately headed: toward a better understanding
of what consciousness is."
The most familiar unconscious state is sleep, which in its deepest
phases is characterized by little electrical activity in the brain and
almost complete unresponsiveness. Coma, the most widely known state of
impaired unconsciousness, is in fact a continuum. Doctors rate the
extent to which a comatose person shows pain responses and reactions
to verbal sounds on a scale from 3, for no response, to 13, for
As in sleep, people in comas may move or make sounds and typically
have no memory of either. But they almost always emerge from this
state in two to three weeks, doctors say, when the eyes open
spontaneously. What follows is critical for the person's recovery.
Those who are lucky, or who have less severe injuries, gradually
awaken. "The first thing I remember was telling my ex-boyfriend, who
was at the foot of the bed, to shut up," said Trisha Meili, who fell
into a coma after being beaten and raped in 1990, and wrote about the
experience in the book, "I Am the Central Park Jogger."
In the days after this memory, Ms. Meili said, she slipped in and out
of conscious awareness, "as if my body was taking care of the most
important things first, and leaving my moment to moment awareness for
In fact, researchers say, this is precisely what happens. The
primitive brain stem, which controls sleep-wake cycles as well as
reflexes, asserts itself first, as the eyes open. Ideally, areas of
the cerebral cortex, the seat of conscious thought, soon follow, like
lights flicking on in the upper rooms of a darkened house.
But in some cases - Ms. Schiavo's was one of them - the cortical areas
fail to engage, and the patient's prognosis becomes dire.
Neurologists were all but unanimous in diagnosing the condition of Ms.
Schiavo, whose heart stopped temporarily in 1990, depriving her brain
of oxygen. Brain cells and neural connections wither and die without
oxygen, like marine life in a drained lake, leaving virtually nothing
People with these kinds of injuries - Nancy Cruzan, whose case reached
the Supreme Court in 1990 is an example - almost always remain
unresponsive if they have not regained awareness in the first months
after the injury.
In medical terms, they become persistently vegetative, a diagnosis
first described in 1972 by Dr. Fred Plum of Cornell University and Dr.
Bryan Jennett, a neurosurgeon at Glasgow University in Scotland. In a
sense, the description of the diagnosis began the modern study of
disorders of consciousness. "Before 1972 people talked about permanent
comas, or irrecoverable comas, but we defined a different state
altogether, with the eyes open, some reflex activity, but no sign of
meaningful psychological responsiveness," Dr. Jennett, now a professor
emeritus, said in an interview.
In an exhaustive review of the medical histories of more than 700
persistently vegetative patients, a team of doctors in 1994 reported
that about 15 percent of those who suffered brain damage from oxygen
deprivation, like Ms. Schiavo, recovered some awareness within three
months. After that, however, very few recovered and none did so after
About 52 percent of people with traumatic wounds to the head, often
from car accidents, recovered some awareness in the first year after
the injury, the study found; very few recovered after that. "It's the
difference between taking a blow to the brain, which affects a local
area - and taking this global, whole-brain hit," said Dr. Joseph Fins,
chief of the medical ethics division of NewYork-Presbyterian/Weill
Yet these statistics cannot explain the stories of remarkable recovery
that surfaced during the debate over Ms. Schiavo's fate. There was
Terry Wallis, a mechanic in Arkansas who regained awareness in 2003,
more than 18 years after he fell into unconsciousness from a car
accident; Sarah Scantlin, a Kansas woman who, also a victim of a car
accident, emerged from a similar state after 19 years; and several
others, whose collective human spirit seemed to defy the experts, and
Researchers say these cases can be accounted for by recent studies
that indicate the existence of yet another state of subdued
responsiveness, one that represents a clear break from the vegetative.
For years, doctors who specialize in rehabilitation have known that
some of their severely brain-damaged patients were responsive, at
least once in a while. In their good moments, these patients could
track objects with their eyes. They could follow commands, like
reaching for a glass, or grabbing someone's hand. They were -
intermittently, unpredictably, but unequivocally - responsive.
In 2002, a panel of experts established a new diagnosis on the basis
of exactly these reactions: the minimally conscious state. "It took
years to get some agreement on the definition, and it's only now
getting some acceptance," said Dr. Nancy Childs, at Texas NeuroRehab
Center in Austin, "but we've known for years that there was this other
In a landmark study published in February, a team of neuroscientists
in New York, New Jersey and Washington, led by Dr. Schiff, used
imaging technology to compare the brain activity in two young men who
were deemed to be minimally conscious with the brain activity of seven
healthy men and women. The researchers recorded an audiotape for each
of the nine subjects in which a relative or loved one reminisced,
telling familiar stories or recalling shared experiences.
In each of the brain-damaged patients, the sound of the voice prompted
a pattern of brain activity similar to that of the healthy
participants. The team has since replicated the results in other
minimally conscious patients.
Like an interlocking set of old Christmas lights, blinking on and then
off, the neural connections in minimally conscious patients seem to be
in place, the research suggests. In persistently vegetative brains, by
contrast, the crucial connections are apparently shot: maybe one light
blinks here, another over there, but the full network is dark.
One case, of a 26-year-old English woman named Kate who emerged from a
subdued unconscious state after six months, suggests such patients may
be at times acutely aware of what is happening around them. During
rehabilitation, though unable to communicate, this woman had a visit
from a college friend.
"I have just met an old friend from Uni and it really upset me," the
woman recalled thinking, doctors reported. "I can now see how much I
am missing. She has been married for five years and she has a house
and a life. I just scream as I can't cry, which I would do if I
Recovery from severe brain damage is viewed in this new understanding
as a step-wise progression: people who regain conscious awareness pass
from a coma to a vegetative state to minimal consciousness - and
almost always do so quickly, usually within a month or so of shaking
the coma. Those who regain awareness within hours of emerging from a
coma probably also pass through the same progression, but so swiftly
the changes go unnoticed, some experts say.
"If you look at these cases of recovery closely, you will find that
many of these patients were showing signs of consciousness much
earlier" than is sometimes portrayed in news media accounts, Dr. Fins
of NewYork-Presbyterian said.
Researchers know little about how to draw a person out of a minimally
conscious state, which itself can last a lifetime. In one study of 124
brain-damaged patients, doctors in Philadelphia and New Jersey
reported in March that amantadine, a drug for Parkinson's disease,
appeared to speed recovery in some people. But the evidence was not
definitive and will require confirmation, the authors wrote.
Rehabilitation, such as it is, typically includes life support, if
needed, and regular visits from medical staff, typically to change the
patient's position in bed and to stimulate the senses with bright
lights, noises, sharp smells and tastes, including lemon and
chocolate. "I always tell families that it's time and nature and God
taking care of things, that what we do mostly is monitor the
patients," said Dr. Childs.
Dr. Joseph Giacino, a neuropsychologist at the JFK Johnson
Rehabilitation Institute in Edison, N.J., has been following a group
of brain-damaged patients with both oxygen-deprivation and traumatic
injuries, and finds that the group with traumatic injuries - if they
become minimally conscious - are far more likely to show signs of
recovery than the others. "There is a real separation between these
patients and the others in terms of improvement in the first year,"
Dr. Giacino said.
Ms. Schiavo showed no evidence of having ever entered a minimally
conscious state, either in the early 90's or later, neurologists say.
An EEG of her cerebral cortex showed almost no electrical activity,
said a neurologist who examined her, and a dozen experts interviewed
about her case agreed that an M.R.I. scan would have added no
In Dr. Schiff's study comparing M.R.I. activity of minimally conscious
with normal subjects, the researchers also found a striking
difference. The overall rate of energy consumption was significantly
higher in the normal brains than in the minimally conscious ones. This
difference in idling speed may be crucial to maintaining conscious
awareness, Dr. Schiff and others suggested.
Because signaling between brain cells requires one cell to overwhelm
the other, Dr. Schiff said, a lower idling speed may make the
signaling threshold harder to overcome - effectively damping activity
throughout the brain. "The idea is that maybe if you were to activate
that substrate, you may cross the threshold and generate enough
activity" to produce more awareness, he said.
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