New Studies Identify Imaging Findings Associated with Persistent Post-Concussion Syndrome
A topic frequently addressed in this blog is the building body of evidence showing that the minority of patients who have long term, sometimes permanent, symptoms following concussion typically experience those symptoms because of injury to the brain, not to achieve some “secondary gain.” Although scientists do not have a clear understanding about why some people are more vulnerable to these injuries, we know as discussed in prior posts, that certain factors can play a role, such as genetics, prior head injuries and a history of migraines. Two recently published studies contribute to our understanding that real pathology likely underlies most persistent symptoms and that this pathology can be identified with advanced neuroimaging techniques.
In one study, published January 24, 2017 in the Journal of Neurotrauma, scientists tracked the resting-state connectivity of patients within the first two weeks of concussion using an imaging technique called “functional MRI” (fMRI). The study revealed telltale patterns of brain activity that were associated with worse behavioral and cognitive tests six months later – different from patterns in healthy control subjects. For example, concussion patients who ended up with persistent symptoms displayed less connectivity in frontal areas of the “default mode network” of the brain, an area particularly active in a resting brain. There was also less connectivity within other networks such as the executive function network, the fronto-parietal network, the dorsal attentional network and the orbitofrontal network.
In the second study, to be published in the April, 2017 issue of the MRI Journal, Wayne State Researchers used two advanced MRI sequences, FLAIR (fluid-attenuated inversion recovery) and SWI (susceptibility weighted imaging) to examine 180 patients with persistent symptoms referred by their personal injury attorneys and 94 asymptomatic age-matched volunteers. Of the 180 patients, 83% were classified as “mild” (concussion.) The researchers found that TBI subjects had a significantly greater number of lesions detected by FLAIR than controls and a significantly greater number of lesions detected by SWI than controls. Nevertheless, this study identified FLAIR or SWI abnormalities in only 38% of the mild TBI subjects after controlling for age-related pathology.
The imaging used in the Wayne State study is known as “anatomical imaging” which does not identify functional changes such as the changes identified in the Journal of Neurotrauma study or metabolic or microstructural changes identified using advanced techniques such as diffusion tensor imaging (discussed in prior posts) and magnetic resonance spectroscopy. It highlights the importance of using a variety of imaging techniques to identify pathology in patients with persistent symptoms.