According to a study, the PET scan is the most reliable tool to assess the state of consciousness of patients in a coma. Detecting brain activity radically changes medical care.
Vincent Lambert, this 38-year-old quadriplegic in a state of minimal “plus” consciousness for five years, recently underwent functional imaging exams (Pet scan, Functional MRI). Crucial results that will determine whether or not to continue care. And to answer this question that tears apart doctors and families, “the positron emission tomoscintigraphy (PET scan) is the most reliable tool. “This is undoubtedly what Professor Steven Laureys, famous neurologist from the Coma Science Group (Liège), the last to have carried out a complete medical expertise on Vincent Lambert within his center of excellence in neuroscience. In support of this assertion, the unpublished results of a study published this Wednesday in the scientific journal The Lancet of which this Belgian doctor is the main author.
Bedside tests + PET scan: the most reliable formula
To reach this conclusion, the team of scientists conducted a survey of 126 patients from all over Europe admitted to the Liège University Hospital after severe brain damage. More specifically, these researchers wanted to compare the effectiveness of the different techniques used in clinical practice to detect possible traces of consciousness in these patients who have been discharged from intensive care for several months. In the cohort, there were 81 people diagnosed in “minimal state of consciousness”, 41 in “vegetative state”, and 4 in “locked-in-syndrome” which designates an almost complete paralysis of the organism, despite consciousness and faculties. cognitive intact. The aim of the research was also to see which technique best reduced the risk of misdiagnosis.
Conclusion of the experts, “We must continue to perform consciousness tests at the edge of the patient’s bed using the standardized coma recovery scale. “Because by not using it, we risk missing one in three of the patients considered to be vegetative, but who in reality had signs of consciousness.
Second, the PET scan, which measures the brain’s energy consumption, is an “efficient” and “complementary” tool for looking at how the brain is still active. For a third of the patients, it made it possible to detect signs of brain activity that had not been perceived at the edge of the bed. In addition, this tool allows you to better predict those who have chances of recovering. For example, here, 13 of the 41 non-responding vegetative patients actually had signs of consciousness on neurofunctional imaging. And of those patients for whom the doctors made a mistake when they first diagnosed, 9 experienced recovery. “This tool therefore also makes it possible to reduce uncertainty with regard to the prognosis for recovery”, underlines Professor Laureys in this regard.
Finally, the researchers noted a small disappointment with the functional MRI, which was less “powerful” and “reliable” than the PET scan to detect signs of consciousness. Especially because 4 out of 10 patients moved too much during this examination, despite their condition, says the neurologist.
Listen to it Prof. Steven Laureys, director of the Coma Science Group: “One third of patients have signs that doctors cannot see at the bedside. “
The PET scan: an expensive machine and not always available
Conclusion of the Belgian team, it is important to use these new medical imaging tools for a diagnosis that remains difficult. Professor Laureys also emphasizes that his previous studies had already shown that not using them ran a 40% risk of making the wrong diagnosis.
But then, how can we miss such an effective diagnosis? First of all because these machines have a significant cost. The PET scan is indeed more expensive than the functional MRI. In addition, this tool is widely used for cancer patients for whom the examination is an indication. In these patients, it is used to detect a cancerous tumor and / or metastases, and to monitor their evolution. Consequently, its use to detect states of consciousness therefore remains limited in France, where it is also not reimbursed. “Nevertheless, it seems important to demonstrate the superiority of this technique over others. Because in terms of medical ethics, a diagnostic error is difficult to bear, ”says Professor Laureys. In particular with regard to the future management of these patients in a coma.
Listen to it Prof. Steven Laureys : ” In France, the number of PET scan machines is limited. And they are mainly used for cancer patients… “
A reliable diagnosis to adapt care
Indeed, when a patient ends up in a nursing and care home, the importance of a reliable diagnosis beforehand is crucial. The management of the patient will be totally different for a person in a vegetative state or in a state of minimal consciousness. For the latter, the healthcare teams are indeed considering a long rehabilitation work, the hoped-for goal of which is to restore the patient to some of his motor skills. Besides that, we also address the patient differently if we know that he is aware of his surroundings.
In addition, in 2008, the Coma Science Group team, again led by Steven Laureys, demonstrated for the first time that patients in a minimally conscious state did indeed feel pain. “Our study on pain justified the need to differentiate between the two populations (vegetative state and state of minimal consciousness)”, already specified at the time this neurologist.
Finally, a more reliable diagnosis can also help some reluctant families to opt for the difficult choice of passive euthanasia.
Listen to it Prof. Steven Laureys : ” If you are considered vegetative while you are conscious, it is extremely serious. We must do everything to avoid these scenarios… “
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