Prospective Study of White Matter Health for an Altitude Chamber Research Program

Area of Science:

• Aerospace Medicine
• Neuroimaging
• Physiology

Background:

• Hypobaric decompression is linked to brain white matter injury.
• Safety limits for hypobaric research volunteers are unknown.
• Ethical concerns exist regarding volunteer safety in altitude chamber research.

Purpose of the Study:

• To assess the impact of hypobaric research exposure on white matter status.
• To inform safety guidelines for altitude chamber research volunteers.
• To investigate the relationship between decompression stress and white matter hyperintensities (WMH).

Main Methods:

• Prospective study involving Magnetic Resonance Imaging (MRI) before and after a 9-month hypobaric research program.
• Volunteers underwent 3-D, volumetric, fluid attenuated inversion recovery (FLAIR) MRI.
• Analysis of white matter hyperintensities (WMH) volume and count.

Main Results:

• Eleven individuals completed 160 short-duration hypobaric exposures (max 40,000 ft).
• The cohort showed minimal changes in total WMH volume before and after exposures.
• One WMH was present on both entry and exit scans; excess WMH on screening correlated with prior mild traumatic brain injury (MTBI).

Conclusions:

• Brief, infrequent hypobaric exposures with denitrogenation did not promote WMH in this cohort.
• Less intensive decompression stress programs may not require MRI screening.
• A negative history of MTBI predicts a low likelihood of excess WMH in young, healthy subjects.