Abstract Details

Title Significantly Increased Subcortical High-Density White Matter Lesion Number and Volume in High-Altitude Pilots Compared to Normative Controls

Topic Neurotoxicology

Presentation(s) S29 - (-)

Poster/Presentation
Number 003

Objective

Background An increased incidence of High-Density White Matter lesions (HWM) on Fluid Attenuated Inversion Recovery (FLAIR) MRI imaging has been previously demonstrated in United States Air Force U-2 pilots whom have experienced a clinical episode of altitude-associated neurologic decompression sickness (NDCS). However some pilots for whom there was no history of a clinical NDCS event were also found to have prominent subcortical HWM changes as well. Our hypothesis was that the entire U-2 pilot population would demonstrate increased subcortical HWM on FLAIR imaging compared to a truly comparable normative population.

Design/Methods Ninety-four U-2 pilots underwent a 3T brain MRI at the UTHSCSA Research Imaging Institute and 67 of a projected 294 normative controls underwent a 3T brain MRI at LAFB. A calibration study demonstrated equivalency of the machines. Quantitative measurement of subcortical FLAIR lesion count and volume was performed as previously described.

Results Data from the pilots and normative controls (respectively): average subcortical HWM number: 8.55±13.44; 3.30±4.28; average subcortical HWM volume: 0.136cm3±0.231; 0.044cm3±0.073. Using the nonparametric Mann-Whitney test to compare these groups, both the subcortical HWM number (p=0.0005) and the subcortical HWM volume (p=0.005) were significantly different.

Conclusions The total number and volume of the subcortical HWM found within the pilots is significantly greater than those within the comparative normative data set. Research to date looking at the pilots does not explain the variability within the pilot population, but this study shows that their exposure to extreme hypobarics has led to statistically significant white matter change even in the absence of clinical symptoms. Research is ongoing to determine if this extreme hypobaric exposure is activating either the thrombotic or inflammatory system, leading to these imaging findings.

Authors/Disclosures
Andrew Y. Robinson, MD PRESENTER	No disclosure on file
Patrick M. Grogan, MD, FAAN (Neurology Associates)	No disclosure on file
	No disclosure on file
	No disclosure on file
	No disclosure on file
Stephen A. McGuire, MD, FAAN	No disclosure on file
Omar Malik, MD	No disclosure on file

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