US Department of Defense
BLAST INJURY RESEARCH
COORDINATING OFFICE
Advancing Blast Injury Research to Protect and Heal Those Who Serve

Five-Year Serial Brain MRI Analysis of Military Members Exposed to Chronic Sub-Concussive Overpressures


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Canadian Special Operations Forces repeatedly exposed to blast overpressure during training and combat develop structural alterations in the brain.

The Canadian Special Operations Forces personnel, like all military members worldwide, are frequently exposed to blast overpressure (BOP) during combat and training. Even with the use of personal protective equipment these individuals remain at risk for traumatic brain injury. Due to the limited understanding of the underlying mechanisms of BOP-induced brain injury, the Canadian Department of National Defense initiated a five-year longitudinal study to track and analyze the effects of BOP exposure on brain structure during operations and training.

A longitudinal MRI and EEG study was conducted on 92 male military members to assess pre- and post-BOP exposure. This study aimed at investigating acute ischemic injury, white matter lesions, hemorrhagic lesions, axonal injury, and other interval changes, including subdural hemorrhages or fluid collection and volumetric changes over time. Over a five-year period, MRI scans were interpreted in a blinded manner by two professional neuroradiologists and one neuroradiology fellow using a customized neuroradiology reporting form. Researchers uncovered significant changes in brain volume, white matter lesions, and the enlargement of perivascular spaces, also called Virchow Robin spaces.

The most concerning issue is whether the findings of decreased brain volume, increased white matter lesions, and the enlargement of Virchow Robin spaces indicate a neurodegenerative process, potentially placing these military members on the spectrum of chronic traumatic encephalopathy.


Soldiers prepare to breach and clear a house during a live-fire exercise
Figure 1. Soldiers prepare to breach and clear a house during a live-fire exercise at the Joint Readiness Training Center 25-02 rotation at Fort Johnson, La., Nov. 4, 2024. (Photo Credit: Army Spc. Isaiah Mount)

References:

Glikstein, R., Melkus, G., Portela de Oliveira, E., Brun-Vergara, M.L., Schwarz, B.A., Ramsay, T., Zhang, T & Skinner C. (2025) Five-Year Serial Brain MRI Analysis of Military Members Exposed to Chronic Sub-Concussive Overpressures. J Magn Reson Imaging. 61(1): 415-423.


Funding:

This study was funded by the Department of National Defense/Government of Canada under Contract: W6399-15-GB43.

Last modified: 31-Jan-2025