Mary Alexis Iaccarino, MD: Blast Injury and Repetitive Exposure Can Make TBI Complicated

Researchers and doctors are learning more about how blast injuries, especially if repetitive and sustained close together, can affect the brain far more significantly than a singular blow to the head as from football, boxing, or a car crash. When treating veterans and service members, clinicians in the Home Base program start by taking an in-depth TBI history starting from childhood to the present. The more they understand the mechanism, frequency, and interval between any sustained injuries, the more pointed their treatment can be.

Dr. Mary Alexis Iaccarino is director, Clinical TBI and Brain Health Services, Home Base.

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When we think about military-related TBI, what often comes to mind is blast injury, which is this idea that you don’t need to have a direct blow to the head to sustain a concussion or brain injury. We’re only beginning to understand through research how that may be different. What we’re starting to look at is the neuropathology. So, how does the blast wave affect the brain, cortical structures, subcortical structures, differently than maybe a direct contact blow to the head? Like you might see in football or boxing or even something like a motor vehicle accident. This is a really new area of science that’s not as well-understood as we’d like it to be, but we think it’s an important linkage for developing specific treatments for this injury. So, what we’ve learned so far is that - a couple of things. A blast injury is different in how it affects neurons and the brain. We’ve also learned that the repetity [sic] of injury might be an important reason for why people feel as impaired as they do. And so for example if you have one hit to the head, or suffer one perturbation of brain function, like you would around a single blast or let’s say a single blow to the head, and then you have a long period of time to recover, that may not be so bad. What we’re beginning to understand through various animal models and others is that if you have repetitive hits, such as being on the range and setting off 20 or 30 rockets, you likely have a different exposure pattern, different neural inflammation, than say a single hit. And that’s going to become very important, both from a treatment perspective, and then even earlier up the chain from say a prevention perspective. So it’s one, the mechanism; but then two, how frequent and the interval between hits, that’s probably very much going to matter in terms of symptomatology and potentially outcomes. So, when somebody enters our TBI program, we try to do a very in-depth interview on their exposure. We actually start all the way from childhood. Many people enter military service, had plenty of concussions before they got there. For example, they played football throughout middle school and high school, or soccer, or maybe MMA or other sort of martial arts. So, they have some exposure even pre-military service. Then in military service, you know, we always think about combat-related injury, but there’s also training-related injury, and other sorts of exposures. We actually do a full brain injury, or TBI history, starting from birth, really, all the way until the time that they come to see us trying to characterize the different exposures and the different types of injury. So even if they all fit into the bucket of concussion or mild traumatic brain injury, they might be very different in how they were acquired. And we try to understand that now, as we learn more about these injuries, that may change what we do later. BrainLine is powered in part by Wounded Warrior Project to honor and empower post-9/11 injured service members, veterans, and their families.

Posted on BrainLine September 28, 2021. Reviewed September 28, 2021.

About the author: Mary Alexis Iaccarino, MD

Mary Alexis Iaccarino, MD, is a board-certified physiatrist with sub-specialty training in brain injury medicine. Her clinical and research areas of interest include diagnostic and treatment strategies in mild traumatic brain injury including blast and sport-related concussion. Dr. Iaccarino joined the Home Base team in 2016 as a brain injury physiatrist for the Intensive Clinical Program (ICP) and outpatient TBI program. Her goal is to provide comprehensive, evidenced-based brain injury care to veterans through multidisciplinary collaboration with psychology, neuropsychology, physical therapy, psychiatry, and other specialists. She specializes in the treatment of physical, cognitive, and behavioral deficits that occur after brain injury including headaches, pain, dizziness and vision symptoms, sleep difficulties, fatigue, concentration, and memory problems.

Headshot of Dr. Mary Alexis Iaccarino in a salmon button-down shirt