New Coma Scale Detects More Wakefulness in Some Patients
May 31, 2011 (Lisbon, Portugal) — A new scale used in the assessment
of coma allows the detection of more consciousness in patients with
severe brain damage, which may lead to more appropriate resuscitative
care in these patients.
Prof. Steven Laureys, MD
, PhD, head of the Coma Science Group in the
Neurology Department at the University Hospital of Liège in Belgium,
presented the report at the 21st Meeting of the European Neurological
"Worldwide, physicians measure consciousness in severely brain
damaged patients using a coma scale: the Glasgow Coma Scale (GCS), used
since the 70s," Dr. Laureys told Medscape Medical News
. "In our
study, we used another more recent scale called the Full Outline of
scale and showed it to be superior to find
subtle signs of consciousness."
He added that the new scale offers the advantage of being able to be
performed in intubated patients who are on a respirator, which currently
includes most coma patients, and to identify nonverbal signs of
consciousness by assessing visual pursuit (ie, eye tracking); hence,
minimal signs of consciousness (about 10% in his study) are measured
that are not assessed by the classic coma scales.
Also released here is proposed new terminology with respect to coma,
developed by the European
Task Force on Disorders of Consciousness,
which it is hoped will infer less of a dismal prognosis and therefore
may lead to less cessation of treatment in select patients.
New Coma Scale Detects More Wakefulness in Some Patients New Terminology
Patients in a comatose state who are described as being in a
"persistent vegetative state" often have a poor prognosis attributed to
them, and this "has led to cessation of rehabilitation, neglect, and
sometimes the ethically even more problematic decision to deny further
feeding or other life-sustaining measures," Prof. Gustave Moonen, with
the Department of Neurology at the
University of Liege, stated in a
statement from the ENS.
"We find it high time to propose a new, more neutral and descriptive
term. By calling it 'unresponsive wakefulness syndrome' we describe what
we clinically see but do not judge whether there is consciousness or
not," said Dr. Moonen, a member of the European Task Force on Disorders
New proposed terms for consciousness disorders include the following:
- "Unresponsive wakeful" to replace "vegetative state" to indicate
patients who have a functioning wake-sleep rhythm but show no response
to commands and all their movements are reflexive.
- The task force proposes substituting the common term "minimally conscious state" with "minimally responsive state (MRS),"
a term that discerns 2 different stages. In "MRS-minus," patients show
low-level behavioral responses, such as reacting to pain or following
with the eyes. In "MRS-plus" they are additionally able to follow
commands, to verbalize intelligibly, and/or to communicate
- The term "functional locked-in syndrome" has
been coined for patients showing no behavioral response but near-normal
brain activity measurable by such technologies as functional magnetic
resonance imaging, positron emission tomography, electroencephalography,
or evoked potentials. These patients clearly seem to be conscious but
not able to use their bodies to communicate.
"Overall, we hope that this new wording will help to herald a change
in the ethical approach towards patients who need more, not less,
attention by their environment, since they are not able to claim on
their own their right to human contact," Dr. Laureys said. FOUR Score
To assess the new scale, Dr. Laureys and colleagues compared the
FOUR, GCS, and Glasgow Liege Scale (GLS) in 176 intensive care unit
comatose patients who had had acute brain injury within the past month.
Outcomes were evaluated 3 months after injury in 136 patients.
Although the FOUR, GCS, and GLS showed good reliability, 71 patients
were considered in a vegetative/unresponsive state based on the GCS;
however, the FOUR scale identified 8 of these 71 patients as being
minimally conscious based on patients' visual pursuit.
According to the researchers, the FOUR score is a "valid tool with
good interrater reliability that is comparable to the GCS and GLS in
predicting outcome" and has the added advantage of including nonverbal
signs of consciousness, such as visual pursuit.
"Recent studies have shown that patients with severe brain damage who
show little outward signs of perception
or understanding may have a
certain degree of pain experience and awareness," Dr. Laureys said. "New
methods of measuring awareness, such as this simple scale, could help
doctors better treat these patients and give families an indication on
whether their loved one is aware of their presence."
"I fully agree with the intention of Laurey's group to develop this
scale," noted independent commentator Erich Schmutzhard, MD, professor
of neurology and critical care medicine at the Department of Neurology,
NICU Medical University Innsbruck, Austria. "Hopefully, with the new
scale, the number of misdiagnoses
will diminish," he told Medscape Medical News
"At our institution, we use a very similar approach in our daily
routine to assess the natural course of initially comatose patients
developing into unresponsive wakefulness syndrome and then into a
minimally conscious state or, better, a minimally responsive state." He
added that clinically they treat patients, even those who are clearly
profoundly comatose, "as though they can understand us." This means that we're actually tracing
down the elusive phenomenon called consciousness to very specific
The FOUR score
was also recently assessed in a report by Eelco F.M.
Wijdicks, MD, from the Mayo Clinic in Rochester, Minnesota, and
colleagues, published online May 11 in Neurology
In a pooled analysis of previous studies, they examined the specificity
and sensitivity of the FOUR score vs the GCS in predicting outcome
among 381 patients with neurologic injury.
Both scales performed equally well, but very low sum scores on the
FOUR score provided good prediction of in-hospital and 3-month
mortality. "A patient with a FOUR score of 1 or less has an 84% chance
of mortality, while the mortality was only 44% in a FOUR score of 2 or
greater," they write. The differences probably reflect a loss of
brainstem reflexes, a prominent component of the FOUR score scale, they
"The robust predictive value of the FOUR score and low sum scores
provides us with the opportunity to investigate this in a prospective
manner in patients with a catastrophic
neurologic injury who are
deteriorating," Dr. Wijdicks and colleagues conclude. "It also provides
the opportunity to better assess comatose patients in clinical trials." Clues From Sleep and Connectivity
Finally, several other interesting observations by the group from
University Hospital of Liège, Belgium, in collaboration with researchers
from Italy and the United States were also presented here:
- Using high-density EEG, the researchers
examined brain activity during sleep among those in a minimally
conscious and vegetative (now wakeful unresponsive by the new
terminology) states. They found behavioral but no electrophysiologic
sleep-wake patterns among patients in a wakeful unresponsive state but
"near to normal" patterns in patients in a minimally conscious state.
"We suggest that the study of sleep and homeostatic regulation of SWA
[slow wave activity] may provide a complementary tool for the assessment
of brain integrity," in these patients, the researchers, with lead
author M. A. Bruno, conclude.
- The same group also used a combination of
EEG and transcranial magnetic stimulation to assess cortical effective
connectivity in vegetative (wakeful unresponsive) or minimally conscious
states, as well as 2 patients with locked-in syndrome after brain
injury. A key requirement for consciousness is connectivity, that is,
that multiple specialized cortical areas can interact rapidly and
effectively, the study authors note.
"Using high-density EEG measurements we discovered that in a wakeful
unresponsive state, only bottom-up connectivity but never top-down
feedback could be recorded, indicating a breakdown of effective
connectivity," Dr. Laureys
said in a statement from ENS. "On the other
hand, patients in a minimal conscious state or recovering from wakeful
unresponsiveness to MCS or higher states of consciousness showed
near-normal cortico-cortical feedback loops. This means that we’re
actually tracing down the elusive phenomenon called consciousness to
very specific physiological parameters.
"Just as the second half of the 20th century is rightfully called the
era of uncovering the genetic code, the first half of the 21st century
might one day be called the age of cracking the code of consciousness,"
Dr. Laureys concluded. "Being able to correlate consciousness to
specific brain activities, we may expect essential insights into the
criteria for being an individual human
being, as well as into the border
areas between life and death."
21st Meeting of the European Neurological Society (ENS): Oral abstracts 238, 242, and 267. Presented May 30, 2011.
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