Positron emission tomography (PET) scans may be a highly-effective tool to determine whether or not a person in a comatose state will ever regain consciousness.
Steven Laureys, lead researcher from the University of Liège in Belgium, and colleagues tracked 126 patients with brain damage who were in unresponsive state for a year or more. Of these patients, 81 were in a minimally conscious state, 41 were unresponsive and four subjects were classified as suffering from "locked in syndrome." These subjects are fully conscious, but unable to move or respond to stimuli.
Several PET scans were used to detect levels of consciousness in 13 of the subjects. Nine of those regained consciousness in less than a year.
"This really exciting study suggests for the first time that... PET could be used in the future to predict the likelihood that a patient may wake-up a long time after a severe brain injury," Michael Bloomfield, from the Medical Research Council Clinical Sciences Centre in London, told the press.
Functional MRI (fMRI) examinations were also taken of the patients and found to be less effective than PET scans at predicting who would return to consciousness.
"PET correctly predicted outcome in 75 of 102 patients (74%, 64-81), and fMRI in 36 of 65 patients (56%, 43-67)," researchers wrote in the article detailing their findings. A standard bedside test doctors routinely use to predict recovery from long-term comas is only about 60 percent accurate.
Positrons, the anti-matter equivalent of electrons, are used in PET scans to create a three-dimensional map of the inside of human bodies. This technology is normally used to diagnose cancer patients and this study marks the first serious study of the tool to predict recovery from unconsciousness.
Brain scans using PET technology are able to map which areas of the brain are using energy and which are not operating properly.
Ethical questions could surface concerning the rights of patients diagnosed as permanently unresponsive. The medical complex may have to adopt new policies and guidelines to manage patients unlikely to ever wake up.
Lawsuits over the lives of the permanently unresponsive are also likely to occur and could reach the highest levels of the judicial system.
The use of PET scans to predict recovery rates of unresponsive patients was detailed in the journal The Lancet.
