A new test could help identify patients who have the potential to wake up from a coma, a loss of awareness or response to stimuli. Under current procedures, up to 40% of coma patients are misdiagnosed. The new test can predict who will wake up within a year with 94% accuracy.
An international team of researchers have discovered that the amount of glucose (sugar) consumed by the brain can directly predict a person’s future level of awareness. Using a type of position emission tomography (PET) scan, they measured the amount of sugar being metabolized by the brain.
Ron Kupers from the University of Copenhagen and Yale University, a co-author of the study says,
In nearly all cases, whole brain energy turnover directly predicted either the current level of awareness or its subsequent recovery.
The researchers mapped the brains of 131 brain-injured patients who suffered full or partial loss of consciousness. After measuring the metabolism of neurons in the patients, they compared the results as to whether or not the patient awakened within a year. The results revealed that patients with less than 42% of normal brain activity did not regain consciousness in a year. Those who had over 42% of normal brain activity awakened after a year.
Co-author of the study, Johan Stender from the University of Copenhagen says,
The discovery of a clear metabolic boundary between the conscious and unconscious states could imply that the brain undergoes a fundamental state change at a certain level of energy turnover, in a sense that consciousness “ignite” as brain activity reaches a certain threshold.
Unfortunately, researchers were unable to test this hypothesis directly but their findings provide a road map to future research. The goal is to see how brain metabolism changes over time in brain-injured patients.