High rate of misdiagnosis in patients in an acute vegetative state

Jun 20 2007

New studies underline the importance of extreme caution in any decision to limit the life chances of patients during the acute phase of a vegetative state.

Around a quarter of patients in an acute vegetative state when they are first admitted to hospital have a good chance of recovering a significant proportion of their faculties, and up to a half will regain some level of consciousness, researchers from Belgium found out. Another study shows that around 40% of patients were wrongly diagnosed as in a vegetative state, when they in fact registered the awareness levels of minimal consciousness. Comparing past studies on this issue shows that the level of misdiagnosis has not decreased in the last 15 years. These studies should foster debate about appropriate standards of care for these patients, and about end of life limitations, experts said at the European Neurological Society Meeting in Rhodes (Greece).

The profoundly difficult moral and medical issues associated with patients in a vegetative state have been recently highlighted by the case of Terri Schiavo in the United States. Experts disagreed on the right response to her condition. With her eyes wide open, the characteristic that distinguishes the vegetative state from coma, it was clearly impossible for some of her family members to believe she was unconscious. Doctors addressing the 17th Meeting of the European Neurological Society from June 16 to 20 in Rhodes (Greece) stress however that the vegetative state in a significant proportion of patients admitted to intensive care may be transitory, and that there is a wide range of possible recovery scenarios, depending on the type of brain injury. A complementary study shows that assessment by medical teams of a patient’s actual state of consciousness continues to be surrounded by confusion and false diagnosis, experts reported at the ENS Meeting.

A study presented by Dr Steven Laureys from the Coma Science Group at the University of Liège (Belgium) and his team examined the accuracy of the common perception that a vegetative state is a long term condition. Researchers analyzed data collected over a five year period at the 26 bed intensive care unit at the university hospital.

Up to Half of Patients in An Acute Vegetative State Regain Some Level of Consciousness

Of the just over 5900 patients admitted to the unit, 11% showed some degree of impaired consciousness on admission. Of this group, just over half, 356 patients, were diagnosed as in a vegetative state. Of these patients with serious brain damage, 28% died in the intensive care unit. 15% were classified as still in a vegetative state when they left intensive care. But just over half of those who had originally been considered to be in a vegetative state left the unit having recovered consciousness to some degree. In the best cases, the largest group at 59%, they had recovered to the point where they could obey commands. At the lower end of the scale, a small group (7%) had shown minimal recovery and responded only to pain stimuli. It is an extraordinarily difficult experience for any family to be confronted with a member suffering acute brain injury, alive but with their faculties so damaged that they may seem beyond awareness. The data emerging from this study clearly demonstrate however that around a quarter of patients in an acute vegetative state when they are first admitted to hospital have a good chance of recovering a significant proportion of their faculties, and up to a half will regain some level of consciousness. Chances of recovery are known to depend significantly on the patient’s age, with younger patients usually having a better prognosis.

Patients With Traumatic Injuries Have Better Chance of Recovery

The kind of injury to the brain is also a decisive factor in recovery scenarios. Thus the study undertaken by the Belgian team also analyzed patients according to whether brain damage came from traumatic or non-traumatic injuries. People suffering traumatic brain injuries have a much better chance of some recovery. 70% of those with traumatic injuries were restored to some level of consciousness. People with non-traumatic injuries, such as oxygen deprivation, fared much worse. Only 36% in the study achieved comparable recovery. Likewise, mortality rates differed sharply between the two groups, with 19% of those suffering traumatic injuries dying in hospital, while 48% of patients with non-traumatic brain injuries died.

“Our data show that acute vegetative state is certainly not rare among patients admitted to intensive care”, says Dr Laureys. “What is important to note is that it may be transient and that the prognosis for patients with impaired consciousness depends to a great extent on the nature of the brain damage.” While recovery of consciousness in patients with non-traumatic (compared to traumatic) brain injuries is less assured and mortality is higher, a significant proportion of these patients also recover some consciousness. Dr Laureys: “The study underlines the importance of extreme caution in any decision to limit the life chances of patients during the acute phase of a vegetative state.”

It is general medical practice at the moment to stop treatment after 3 months for non-traumatic patients, and after a year for traumatic patients. Traumatic patients are those who have suffered brain injury typically in a car accident or serious fall. Non-traumatic brain injuries are those associated with oxygen deprivation, for instance when a patient stops breathing after a heart attack. The vegetative state can also be observed after intoxication or after infection of the brain – in such cases predicting outcome is even more challenging. Legal and medical guidelines across the developed world permit stopping medical treatment when it is no longer justified. It is even considered unethical to continue treatment, says Dr Laureys. So there is clearly a huge problem for physicians and families, and most obviously for the patient, when states of consciousness are incorrectly diagnosed.

A combined study carried out by other research teams in Liège and Brussels (Belgium) has examined the accuracy of diagnoses of patients in a vegetative or minimally conscious state. Studies done as long ago as 1993 showed a high rate of false diagnoses. Guidelines have been published since then to try to clarify criteria, with new guidelines for what was defined as a separate category, the minimally conscious state, a condition distinct from coma or the vegetative state. Patients are considered to be in a minimally conscious state if they show deliberate behavior, that is behavior which is the result of some degree of conscious thought processes, and if they exhibit it often enough, even if erratically, that doctors can distinguish their responses from purely reflex actions.

Vegetative State: 40% of Patients Wrongly Diagnosed

“The study showed how very hard it is to disentangle the minimally conscious state from the vegetative state”, says Dr Laureys. “Physicians and family are faced with a patient who cannot communicate. But it is known that a minimally conscious state indicates better chances of recovery, and that these patients can perceive emotion, so their management should be very different.”

For the study reported at the European Neurological Society congress, over a hundred patients were selected, around a third of whom had traumatic injuries. Just under half were studied during the acute stage, that is during the first four weeks after the injury, the rest at the chronic stage, that is patients who had suffered injury at least four weeks previously. These patients had been diagnosed by teams of medical staff as in a vegetative or minimally conscious state, or designated as “unsure” which state. The study employed two skilled researchers to examine patients, classifying them according to the Coma Recovery Scale - Revised which is widely considered a very promising tool in coma assessment. Using the scale, researchers were able to establish that around 40% of patients were wrongly diagnosed as in a vegetative state, when they in fact registered the awareness levels of minimal consciousness. In those patients health workers had diagnosed as in a minimally conscious state, 10% were actually communicating functionally. The results show a strong tendency to underestimate levels of consciousness in brain injury patients. In those cases where medical teams had recorded an unsure diagnosis, around 90% were found to be minimally conscious, using the Coma Recovery Scale-Revised.

Level of Misdiagnosis Has Not Decreased in 15 Years.

The study thus concluded that although medical teams are more aware of the issues surrounding the vegetative state than in the past, and although medical guidelines are available, diagnostic skills remain poor. Comparing past studies on this issue shows that the level of misdiagnosis has not decreased in the last 15 years.

“These studies should foster debate about appropriate standards of care for these patients, and about end of life limitations,” says Dr Laureys whose team are the only non-American participants included in the American Academy of Neurology Committee for the Development of Practice Guidelines for the Vegetative and Minimally Conscious State currently looking at this issue. So far, no court worldwide has agreed that care should be withdrawn from patients classified as minimally conscious.

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