There have been several protracted and agonizing public debates in recent months about patients in a “vegetative state” and whether they are beyond hope of ever waking up. These disputes took place in the absence of information. Now, however, researchers are finding that brain scans can show whether patients show any signs that they are conscious in their vegetative states.
People with severe brain injuries sometimes appear to wake from a coma but are completely unresponsive, leaving loved ones to wonder if they are aware of anything; have any chance of recovery or are permanently in a vegetative state. A new study has found that positron emission tomography (PET) scans may help answer these agonizing questions.
The researchers, led by Dr. Steven Laureys, the director of the Coma Science Group from the University of Liège in Belgium, and his colleagues studied 122 patients with brain injuries. Forty-one of the patients had been declared vegetative, i.e. awake but with no signs of awareness. Eighty-one other patients were considered to be “minimally conscious,” which meant they intermittently showed signs of awareness and responsiveness. Those patients generally have a better chance of eventual improvement than those who are vegetative, although their recovery may be limited and take a long time.
For both groups of study patients, the initial diagnoses were made by doctors using neurological exams. They performed detailed s using the so-called the coma recovery scale, which is considered to be a reliable assessment. The patients were then given the PET brain imaging tests. The PET scans measured whether there was brain activity in regions needed for consciousness, and those results were subsequently compared with scans from healthy people. Inactivity was interpreted as a vegetative state. Some patients were given an MRI scan as well to measure brain activity while being told to imagine walking around or playing tennis. The brain scans found that one-third of those patients believed to be in a vegetative state had received an incorrect diagnosis and actually did show signs whether they were conscious as some level and could potentially improve.
Published in The Lancet yesterday, the research results showed that 13 of the patients labeled as “behaviorally unresponsive” or vegetative using standard hospital testing showed brain activity consistent with some consciousness using the PET imaging scan. A year later, nine of the 13 were showing “minimally conscious states or better.” The PET scans had served as a better indicator of who would improve than the MRI scans were.
Laureys pointed out that many vegetative patients are neglected by medicine after their diagnosis and do not see a doctor for years. The reports are that in the U.S., more than100,000 people are believed to be minimally conscious, and an additional 25,000 are vegetative.
The study did show that doctors can use brain scan techniques to discern whether critical regions of their brain are functioning in problematic or vegetative patients, even when there are no outward signs that they are conscious. This could also be used in the future to predict whether a patient may “wake-up” a long time. However, the researchers caution that much more research is needed to determine how accurate PET scans might be at doing this before the technique could reliably used.
By Dyanne Weiss