(HealthDay News) – Pilots of U-2 high-altitude reconnaissance aircraft with occupational exposure to hypobaria show a significant increase in both the number of and volume of white matter hyperintensities (WMH), according to a study published in the Aug. 20 issue of Neurology.

Stephen McGuire, MD, from the U.S. Air Force School of Aerospace Medicine at the Wright-Patterson Air Force Base in Ohio, and colleagues evaluated 102 U-2 pilots and 91 matched controls using three-dimensional, T2-weighted, high-resolution (1mm isotropic) imaging data.

The researchers found that U-2 pilots demonstrated a significant increase in volume (394%) and number (295%) of WMH. WMH were more uniformly distributed throughout the brain in U-2 pilots compared with the mainly frontal distribution in controls.

“This is consistent with our hypothesized pattern of damage produced by interaction between microemboli and cerebral tissue, leading to thrombosis, coagulation, inflammation, and/or activation of innate immune response, although further studies will be necessary to clarify the pathologic mechanisms responsible,” the authors write.

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