Progress on Proving Mild Traumatic Brain Injury Using Biomarkers
Concussion, or mild traumatic brain injury (TBI), typically produces no gross pathology, such as hemorrhage or abnormalities, that can be seen on conventional CT scans of the brain. It does cause rapid-onset neurophysiological and neurological dysfunction that in most patients resolves spontaneously over a fairly short period of time. Studies have shown, however, that approximately 15% of individuals with mild TBI develop persistent cognitive dysfunction and other symptoms. Researchers are starting to make progress on proving mild traumatic brain injury using the biomarkers that underlie such symptoms.
We know that mild TBI can be caused either by an impact to the head inducing rotational acceleration of the brain, or rapid rotational acceleration of the head without impact. Mild TBI without impact is commonly seen in restrained drivers during a motor vehicle impact. At a neurophysiological level, these mechanical and inertial forces result in stretching of white matter axons, leading to diffuse axonal injury (Nature Reviews Neurology 9, 201-210 (April 2013) | doi:10.1038/nrneurol.2013.9). This injury triggers a chemical cascade, a pathological process that interrupts axonal transport and produces an accumulation of protein products.
Scientists have been actively engaged in the discovery of biomarkers for TBI in the last decade, research based on our awareness that TBI produces pathological changes in the chemistry of the brain. This research is very exciting because it will likely lead to the use of blood tests to both diagnose traumatic brain injury and to determine the likely severity of the consequences. The “invisible injury” will be made more visible. A number of review articles have captured the pros and cons of various potential markers, typically focused on the proteins that accumulate following injury.
On June 18, 2013, researchers at the University of Rochester Medical Center in upstate New York announced the results of study which produced significant evidence to support the development of an effective blood test.
The study, published in Journal of Neurotrauma, showed that a combination of two protein biomarkers, S100B and ApoA-1, significantly increased the correct diagnosis of mild TBI. The study further showed that one of the biomarkers, S100B, was effective at predicting which patients would likely have abnormal CT scans. This could lead to reduced use of CT scan, since this diagnostic tool only shows abnormalities in a small percentage of TBI cases.
We are seeing more exciting research on diagnosing and proving mild traumatic brain injury, a product of funding that has resulted from heightened awareness of the long-term health consequences of traumatic brain injury.