The use of PET scans can help distinguish between patients that are in vegetative states and those that have some degree of consciousness and have the potential to improve, according to new research published online in The Lancet.
Steven Laureys, an author of the study and the director of the Coma Science Group at the University of Liège in Belgium, believes that patients in the latter group often are neglected in both a social and a medical sense. "Many of them don't even see a medical doctor or a specialist for years," Laureys told the New York Times. "So I think it's very important to ask the question, are they unconscious?"
According to the Times article, the number of people in the U.S. believed to be minimally conscious is between 100,000 and 300,000, while about 25,000 are in a vegetative state. For the study, Laureys and his colleagues examined 122 patients, 41 of whom had been declared vegetative, and 81 of whom were considered "minimally conscious," meaning they showed signs of awareness and responsiveness.
Initial diagnoses of patients in both groups was made by doctors who performed neurological exams. Then, most patients underwent brain imaging, with PET scans measuring brain activity in regions that are necessary for consciousness. Some patients also underwent functional MRI scans.
The researchers found brain imaging determined that 13 of the 41 vegetative patients actually had minimal consciousness. Furthermore, after one year, the condition of nine of those 13 patients improved. The researchers found that PET was more accurate than function MRI.
"Our findings suggest that PET imaging can reveal cognitive processes that aren't visible through traditional bedside tests, and could substantially complement standard behavioral assessments to identify unresponsive or 'vegetative' patients who have the potential for long-term recovery," Laureys said in an announcement.