Lumbar Spine Paraspinal Muscle and Intervertebral Disc Height Changes in Astronauts After Long-Duration Spaceflight on the International Space Station. Issue 24 (15th December 2016)

• Record Type: Journal Article
• Authors: Chang, Douglas G.; Healey, Robert M.; Snyder, Alexander J.; Sayson, Jojo V.; Macias, Brandon R.; Coughlin, Dezba G.; Bailey, Jeannie F.; Parazynski, Scott E.; Lotz, Jeffrey C.; Hargens, Alan R.
• Is Part Of: Spine. Volume 41:Issue 24(2016)
• Page Start: 1917
• Page End: 1924
• Publication Date: 2016-12-15
• Subjects: aerospace medicine -- atrophy -- back pain -- immobilization -- intervertebral disc -- magnetic resonance imaging -- muscles -- paraspinal muscles -- spine -- weightlessness; Spine -- Abnormalities -- Periodicals; Spine -- Diseases -- Periodicals; Spine -- Surgery -- Periodicals; 616.73005
• DOI: 10.1097/BRS.0000000000001873
• Languages: English
• ISSNs: 0362-2436

Abstract

Abstract : Study Design: Prospective case series. Objective: Evaluate lumbar paraspinal muscle (PSM) cross-sectional area and intervertebral disc (IVD) height changes induced by a 6-month space mission on the International Space Station. The long-term objective of this project is to promote spine health and prevent spinal injury during space missions and here on Earth. Summary of Background Data: National Aeronautics and Space Administration (NASA) crewmembers have a 4.3 times higher risk of herniated IVDs, compared with the general and military aviator populations. The highest risk occurs during the first year after a mission. Microgravity exposure during long-duration spaceflights results in approximately 5 cm lengthening of body height, spinal pain, and skeletal deconditioning. How the PSMs and IVDs respond during spaceflight is not well described. Methods: Six NASA crewmembers were imaged supine with a 3 Tesla magnetic resonance imaging. Imaging was conducted preflight, immediately postflight, and then 33 to 67 days after landing. Functional cross-sectional area (FCSA) measurements of the PSMs were performed at the L3-4 level. FCSA was measured by grayscale thresholding within the posterior lumbar extensors to isolate lean muscle on T2-weighted scans. IVD heights were measured at the anterior, middle, and posterior sections of all lumbar levels. Repeated measures analysis of variance was used to determine significance at P < 0.05, followed by post-hoc testing. Results: Paraspinal lean muscle mass, as indicated by the FCSA, decreased from 86% of the total PSM cross-sectional area down to 72%, immediately after the mission. Recovery of 68% of the postflight loss occurred during the next 6 weeks, still leaving a significantly lower lean muscle fractional content compared with preflight values. In contrast, lumbar IVD heights were not appreciably different at any time point. Conclusion: The data reveal lumbar spine PSM atrophy after long-duration spaceflight. Some FCSA recovery was seen with 46 days postflight in a terrestrial environment, but it remained incomplete compared with preflight levels. Level of Evidence: 4