Imaging Tool Helped Predict Recovery from Brain Damage

PET scans helped doctors know who may wake up from vegetative or minimally conscious state

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) The brain remains complex and elusive to clinicians, who still have difficulty determining if or when someone with a severely damaged brain will recover. Now there may be a new tool to help them.

Researchers reported in a new study that an imaging tool known as Positron Emission Tomography (PET) has shown promise in helping doctors predict outcomes for people in vegetative or minimally conscious states.

"Ask your doctor about ways to protect yourself from brain injury."

This study was led by Steven Laureys, PhD, clinical professor of neurology at the University of Liège in Belgium.

The researchers enrolled 126 patients referred to them from all over Europe between January 2008 and June 2012. All of the patients had been clinically assessed and classified as having either unresponsive wakefulness (41 patients), locked-in syndrome (4 patients) or minimally conscious state (81 patients).

Unresponsive wakefulness is also known as the vegetative state in which there is no wakefulness or response to stimuli. In the minimally conscious state, there is some evidence of awareness and response to stimuli. Locked-in syndrome patients are awake and aware but cannot move or talk. They were considered a conscious control group.

The reasons for brain injury included traumatic (such as car accident) and non-traumatic (such as infection) events.

The study's authors noted that the frequency of misdiagnosis among patients in a vegetative state through bedside clinical methods is as high as 40 percent. These authors thought that imaging techniques might prove helpful.

Each patient had a PET scan with imaging agent fluorodeoxyglucose (FDG-PET) and functional MRI (fMRI).

PET scans use radioactive material to map brain activity. In this case, when glucose was injected, the researchers could see what parts of the brain were taking in the glucose. MRI measures brain activity by detecting changes in blood oxygenation and flow through parts of the brain.

Each patient was assessed 12 months after their scans by clinical assessment with the Coma Recovery Scale-Revised test — a scale that divides patients into groups depending on how well they function and that predicts long-term rehabilitation prospects.

The PET scan proved most accurate, especially when it came to predicting how many of the patients would recover. FDG-PET was about 74 percent accurate at predicting the extent of recovery within a year, compared with 56 percent for fMRI.

Twelve of 36 patients who were clinically diagnosed as behaviorally unresponsive and scanned with FDG-PET showed some level of consciousness, and indeed, nine recovered a reasonable level of consciousness within 12 months.

The authors concluded that using all methods together might make for better predictive outcomes for these patients, but that FDG-PET, as a new tool for these patients, was simple and reliable. They noted that, at the present time, many clinicians may not have access to PET scans and MRIs in a specialized unit, as they did.

In a commentary on this study, Jamie Sleigh and Catherine Warnaby of the University of Auckland in New Zealand, wrote that this “work serves as a signpost for future studies. Functional brain imaging is expensive and technically challenging, but it will almost certainly become cheaper and easier. In the future, we will probably look back in amazement at how we were ever able to practice without it."

This study was published April 16 in The Lancet.

The authors declared no conflicts of interest.

Review Date: 
April 15, 2014
Last Updated:
April 18, 2014