Brain network scanning may predict injury's effects

A brain scanning technique known as resting-state functional connectivity (FC) could help clinicians identify and even predict the effects of brain injuries such as strokes, according to neurologists at the Washington University School of Medicine in St. Louis.

Originally developed to study how brain networks let various parts of the brain collaborate, FC also appears to enable scientists to link differences in harm done to brain networks to changes in patient impairment, according to results of a study in the Annals of Neurology March issue.

"Clinicians who treat brain injury need new markers of brain function that can predict the effects of injury, which helps us determine treatment and assess its effects," says Maurizio Corbetta, professor of radiology and neurobiology at Washington University. "This study shows that FC scans are a potentially useful way to get that kind of information."

FC relies on MRI scanners, which require patients to be still as the scanner tracks changes in blood flow to various brain regions. With mental inactivity, blood flow in networked regions tend to rise and fall in relative synchronicity.

Over the course of their study of 23 patients who had recently survived strokes, the researchers came across a surprise finding.

Those with damage to networks that cross both sides of the brain were more impaired than those with damage to networks contained within one side of the brain. So while a stroke that occurs on, say, the left side of the brain might impair control of the right arm, that impairment would be far worse if the damage disrupted network connections over on the right side than if it was contained on the left side.

Neurologists have thought that one side of the brain controls the other, but this study suggests that our brains may house far more complicated connections between networks. This could render resting-state functional connectivity all the more important as it reveals detailed network health and/or damage.

"It's not wrong to say that one side of your brain controls the opposite side of your body, but we're starting to realize that it oversimplifies things," says Alex Carter, the study's lead author and an assistant professor of neurology. "It's starting to seem like proper function requires the two hemispheres to be competing for attention, pushing against each other and thereby achieving some kind of balance."

The group is already planning additional studies of brain injury patients, including long-term studies monitoring patient recuperation via FC.