Traumatic brain injury (TBI) is damage to the brain resulting from external forces, such as rapid acceleration/deceleration, impacts, blast waves, or penetration by a projectile. Brain function is temporarily or permanently impaired and the structural integrity of the brain is damaged.
Veterans and military personnel that have been exposed to explosions may or may not experience symptoms associated with TBI. They may still have damage to the brain’s white matter, according to researchers at Duke Medicine and the U.S. Department of Veterans Affairs.
Those who have experienced recent military conflicts in Iraq and Afghanistan often have a history of exposure to bombs, grenades and other explosive devices. Research published in the Journal of Head Trauma Rehabilitation suggests that a lack of TBI symptoms following an explosion may not accurately reflect the extent of brain injury.
Dr. Rajendra Morey, an associate professor of psychiatry and behavioral sciences at Duke University School of Medicine and a psychiatrist at the Durham Veterans Affairs Medical Center explains “People near an explosion assume that if they don’t have clear symptoms – losing consciousness, blurred vision, headaches – they haven’t had injury to the brain.” The findings were gathered from evaluating U.S. veterans who have served since September 2001 using Diffusion Tensor Imaging (DTI). The DTI can measure microscopic movements of water molecules within the brain to give detailed information about white matter and its integrity. In white matter fibres that are intact, water molecules move in a directional manner. Injured fibres allow the water molecules to diffuse.
White matter moderates information distribution between different grey matter areas of the brain, affecting how the brain perceives, thinks and learns. Injury to white matter can impair cognitive processes and performance.
Neuropsychological testing was used and researchers observed a relationship between the amount of white matter injury and changes in reaction time and the ability to switch between mental tasks. It was found that the extent of injury to white matter between those who exhibited TBI symptoms to those who didn’t have TBI symptoms were relatively similar.
It was noted that the results are of this research are preliminary and further research is required.
Image: Advanced form of MRI called Diffusion Tensor Imaging (DTI) showing white matter fibres
Rajendra, A. Taber, K. et al (2014) ‘White Matter Compromise in Veterans Exposed to Primary Blast Forces’, Journal of Head Trauma Rehabilitation¸ vol. 29, iss. 1