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Blast-Related Traumatic Brain Injury in U.S. Soldiers

Military personnel with mild TBI after exposure to explosions often had cerebral axonal injury, according to diffusion tensor imaging.

Blast-related traumatic brain injury (TBI), common among U.S. military personnel in Iraq and Afghanistan, can be accompanied by pain, behavioral and cognitive deficits, and post-traumatic stress disorder (PTSD). Some people argue that impairments due to mild TBI in combat veterans do not typically persist and that lingering cognitive and behavioral problems are due to PTSD (Journal Watch Neurology Apr 8 2008).

To determine whether blast-related TBI causes axonal injury, researchers studied 63 U.S. male military personnel who had a clinical diagnosis of mild TBI and 21 controls who had been exposed to blasts but did not receive a TBI diagnosis. Patients were scanned with diffusion tensor imaging (DTI), a type of magnetic resonance imaging, within 90 days after injury.

According to DTI, 32% of the TBI group had one site of abnormal white matter, and another 29% had two or more such sites. Indicators of white-matter injury (e.g., anisotropy reduction) were significantly more pronounced in TBI patients than in controls. The most common white-matter injury sites in TBI patients were the middle cerebellar peduncles and orbitofrontal white matter. Follow-up DTI (at 6–12 months) revealed lesion evolution, suggesting that the white-matter injury had been newly acquired.

Comment: This study addresses some thorny issues. First, blast-related mild TBI in combat soldiers is likely to produce residual brain injury. Second, the finding of orbitofrontal injury explains the previously documented impairment of olfaction in such patients (J Rehabil Res Dev 2008; 45:941). Although the present study did not address the relation between mild TBI and PTSD, the presence of orbitofrontal injury suggests a possible connection. PTSD is believed to be associated with altered ventromedial frontal cortex modulation of the amygdala (Nat Neurosci 2008; 11:232). Frontal cortex injury could decrease amygdala inhibition, which might in turn increase the likelihood of developing PTSD in response to a horrendous, life-threatening event. DTI may indeed emerge as a technique that aids in detection of brain injury after these types of TBI.

— Robert L. Ruff, MD, PhD

Dr. Ruff is the Chief of the Neurology Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, and Professor of Neurology and Neurosciences at Case Western Reserve University, Cleveland, OH.

Published in Journal Watch Neurology July 12, 2011

Citation(s):

Mac Donald CL et al. Detection of blast-related traumatic brain injury in U.S. military personnel. N Engl J Med 2011 Jun 2; 364:2091.

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Reader Remarks:

Review and add to remarks on this article

• traumatic brain injury
  john s parker, latrobe area hospital, 13 Jul 2011 7:41 AM EST
  Specialty: Internal Medicine
  Has hyperbaric therapy been used to treat these injured soldiers ? Results ?
• Blast-Related Traumatic Brain Injury
  Leonard F. Koziol, 19 Jul 2011 8:15 PM EST
  Specialty: Neurodvlp Disab Psych/Neuro
  Is is also of interest that one of the most frequent areas of white matter abnormality was the middle cerebellar... [more]
• Blast related TBI in Soldiers
  C. Sheryl Pingel, VAMC, 19 Jul 2011 8:15 PM EST
  Specialty: Psychiatry
  We need to be looking at treatment on site for these injuries.
  
  Have there been ay in the fielld treatment... [more]

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