Intracranial Effects of Microgravity: A Prospective Longitudinal MRI Study
Authors: Christian Otto
Ashot Sargsyan
Larry A Kramer
Robert J Ploutz-Snyder
Karina Marshall-Goebel
Steven S Laurie
Roy F Riascos
Khader M Hasan
Michael B Stenger
Brandon R Macias
Journal: Radiology (2020)
Discipline: CLINICAL MEDICINE
Keywords: Astronauts; long-duration spaceflight; ocular changes; intracranial pressure; microgravity effects
Affiliations: From the Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, McGovern Medical School, 6431 Fannin St, MSB 2.100 Houston, TX 77030 (L.A.K., K.M.H., R.F.R.); Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, Tex (M.B.S.); Kellogg Brown & Root (KBR), Houston, Tex (A.S., S.S.L., K.M., B.R.M.); Department of Teleoncology, Memorial Sloan-Kettering Cancer Center, New York, NY (C.O.); and School of Nursing, University of Michigan, Ann Arbor, Mich (R.J.P.S.).

Abstract:  Background Astronauts on long-duration spaceflight missions may develop changes in ocular structure and function, which can persist for years after the return to normal gravity. Chronic exposure to elevated intracranial pressure during spaceflight is hypothesized to be a contributing factor, however, the etiologic causes remain unknown. Purpose To investigate the intracranial effects of microgravity by measuring combined changes in intracranial volumetric parameters, pituitary morphologic structure, and aqueductal cerebrospinal fluid (CSF) hydrodynamics relative to spaceflight and to establish a comprehensive model of recovery after return to Earth. Materials and Methods This prospective longitudinal MRI study enrolled astronauts with planned long-duration spaceflight. Measures were conducted before spaceflight followed by 1, 30, 90, 180, and 360 days after landing. Intracranial volumetry and aqueductal CSF hydrodynamics (CSF peak-to-peak velocity amplitude and aqueductal stroke volume) were quantified for each phase. Qualitative and quantitative changes in pre- to postflight (day 1) pituitary morphologic structure were determined. Statistical analysis included separate mixed-effects models per dependent variable with repeated observations over time. Results Eleven astronauts (mean age, 45 years ± 5 [standard deviation]; 10 men) showed increased mean volumes in the brain (28 mL; P &lt; .001), white matter (26 mL; P &lt; .001), mean lateral ventricles (2.2 mL; P &lt; .001), and mean summated brain and CSF (33 mL; P &lt; .001) at postflight day 1 with corresponding increases in mean aqueductal stroke volume (14.6 μL; P = .045) and mean CSF peak-to-peak velocity magnitude (2.2 cm/sec; P = .01). Summated mean brain and CSF volumes remained increased at 360 days after spaceflight (28 mL; P &lt; .001). Qualitatively, six of 11 (55%) astronauts developed or showed exacerbated pituitary dome depression compared with baseline. Average midline pituitary height decreased from 5.9 to 5.3 mm (P &lt; .001). Conclusion Long-duration spaceflight was associated with increased pituitary deformation, augmented aqueductal cerebrospinal fluid (CSF) hydrodynamics, and expansion of summated brain and CSF volumes. Summated brain and CSF volumetric expansion persisted up to 1 year into recovery, suggesting permanent alteration. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Lev in this issue. 

Retracted: No

PubPeer comments:
 This article was reviewed on the error bar podcast episode 0: https: theerrorbar.com ?e=0. The review was done in the light of newspaper headlines about the article. The slightly-edited transcript is copied here: headline: SPACE FLIGHT SWELLS THE BRAIN tweet: it may do, but there was no control group, all the reported brain changes could have occurred up to 18 months before the astronauts went into space. perhaps intensive astronaut training programmes increases brain size? description: The Express reports a study from the journal Radiology, in which 11 astronauts brains were measured before and after going into space. Kramer and colleagues found that the astronauts brains increased in volume by 27ml u2013 a single measure of whisky (other spirits are available) - and that this increase remained for at least a year after space flight. first: many congratulations for this work, it s obviously very difficult to study astronauts! evaluation: 1. there was no control group. None. So, it could be ageing, changes in the scanner... 2. the first scan was done, on average, 18 months preflight, while all the remaining scans were done between 3 days and 1 year after returning. space flight itself was an average of about 6 months. so, on average, there was 2 years between the first and second brain scans, but only one year between the 2nd and 6th. 3. ALL the differences are between postu2010flight and preu2010flight. so, another way to frame this story is: Preparing for space flight expands your brain. 4. the error bars in figure 4 do not match the error bars in Table 2. 5. the scientists themselves said that the changes were a bit like those when you lie down. ,