Brain Magnetic Resonance Imaging Anomalies in U-2 Pilots with Neurological Decompression Sickness

Abstract

P. Brain magnetic resonance imaging anomalies in U-2 pilots with neurological decompression sickness.Aviat Space Environ Med 2013; 84:3-11.Introduction: This was a retrospective observational study of imaging used to evaluate and treat 13 U-2 pilots with neurological decompression sickness (DCS). Magnetic resonance imaging (MRI) and computed tomography (CT) provided data for screening, diagnosis, and determinations of fi tness to fl y after recovery. While small series and case reports described the role of imaging in diving DCS, none addressed radiology ' s role in aviation DCS. Methods: We performed a literature review of altitude DCS radiology studies. We then reviewed radiology images at our institution on U-2 pilots with neurological DCS between January 2002 and August 2010. We retrospectively analyzed MRI data for white matter hyper-intensities (WMHs), defi ned as hyperintense lesions Ն 3 mm on T2 and FLAIR. All studies occurred after hyperbaric oxygen (HBO) treatment. Results: There were 17 pilots who reported 20 neurological DCS incidents. Of these 17 pilots, 13 underwent imaging. Two (15%) demonstrated acute subcortical lesions on MRI, seven (54%) had asymptomatic WMHs, and six (46%) were normal. The clinical significance of the lesions is unknown. Consistent with diving DCS, imaging played no role in acute diagnosis. However, imaging was vital for determining fi tness for return to fl ying. Additionally, CT identifi ed a potentially predisposing sinus condition in one pilot which may enable return to fl ying after treatment. Conclusions: Modern imaging has unique fi ndings for altitude DCS patients. The high incidence of WMHs in this series is a matter of ongoing research to determine potential clinical consequences. Emerging techniques such as functional MRI may play important roles in future aeromedical decisions.

Magnetic Resonance Imaging in Breath-Hold Divers with Cerebral Decompression Sickness

“…In patients with AGE, air gas occludes large arteries and causes territorial infarction. In contrast, MRI has a low sensitivity for the diagnosis of cerebral DCS not only in divers but also in aviators [ 9 ]. A neuropathological examination showed that DCS caused subtle and diffuse changes in the brain with no large areas of necrosis, including grossly dilated empty vessels in the white matter, small areas of focal necrosis in the gray matter, and diffusely distributed areas of vacuolation of the myelin around small blood vessels [ 10 ].…”

Review of NASA's Evidence Reports on Human Health Risks

“…The report carries an impressive bibliography, with more than 230 sources cited. However, the committee concurs with the 2014 DCS Risk Standing Review Panel (Steinberg et al, 2014) that additional literature review areas could strengthen the report: Jersey et al, 2013;McGuire et al, 2013;Pilmanis et al, 2010) • A review of research focusing on human adaptation to hypoxic and high-altitude environments • Work on pre-breathe interruption (Conkin, 2011;Pilmanis et al, 2010) • Work by Buckey and colleagues on DCS instrumentation (Buckey et al, 2005) Please refer to the 2014 DCS Standing Review Panel for detailed citation suggestions (Mahon et al, 2014).…”

Review of NASA's Evidence Reports on Human Health Risks

“…• Work by Thom and colleagues at University of Maryland on micronuclei particles • Work by Flagg and colleagues on pre-breathe interruption • Work by the U.S. Navy at the Navy Experimental Diving Unit and Naval Submarine Research Lab relating to EVA operations and limited resource allocation • Reports on the U.S. Air Force Manned Orbital Laboratory Program focusing on manned long-term low-pressure exposures • Specific research related to U2-pilot DCS (e.g., Jersey et al, 2013;McGuire et al, 2013;Pilmanis et al, 2010) • A review of research focusing on human adaptation to hypoxic and high-altitude environments • Work on pre-breathe interruption (Conkin, 2011;Pilmanis et al, 2010) • Work by Buckey and colleagues on DCS instrumentation (Buckey et al, 2005) Please refer to the 2014 DCS Standing Review Panel for detailed citation suggestions .…”