Risk of Intervertebral Disc Damage after Prolonged Space Flight (Intervertebral Disc Damage) - 10.18.17

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ISS Science for Everyone

Science Objectives for Everyone
Among many space-related health changes, crewmembers frequently report back pain while in orbit and when they return to Earth, which physicians believe is related to changes in the astronauts’ intervertebral discs. The discs create a cushion between vertebrae in a person’s spine, and changes to their shape and size can affect the spinal column and back. Crewmembers participating in the Intervertebral Disc Damage experiment complete a battery of six tests before, and after spaceflight, so doctors can determine how the discs change, and whether this correlates to the pain those crewmembers experience.
Science Results for Everyone
Space explorers need to maintain their health on long-duration missions beyond low Earth orbit (LEO) in order to perform physical tasks upon arrival to new environments. This study discovered that significant paraspinal muscle mass was lost during a long-duration mission to microgravity and not recovered following return to Earth.  To offset this loss, scientists must develop countermeasures to ensure space explorers are in top physical condition upon arrival to destinations beyond LEO.

The following content was provided by Alan R. Hargens, Ph.D., and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom: N/A

Principal Investigator(s)
Alan R. Hargens, Ph.D., University of California San Diego, San Diego, CA, United States

Jeffrey C. Lotz, University of California, San Francisco, San Francisco, CA, United States
Steve Chiang, M.D., The Methodist Hospital, Houston, TX, United States
Conor O’Neill, M.D., University of California, San Francisco, San Francisco, CA, United States
Douglas Chang, M.D., Ph.D., University of California, San Diego, San Diego, CA, United States
Scott Parazynski, The Methodist Hospital, Houston, TX, United States
Moshe Allon, M.D., Upright MRI of Clear Lake, Nassau Bay, TX, United States
Jojo V. Sayson, PT, DMT, Ola Grimsby Institute, San Diego, CA, United States
Roy Riascos-Castaneda, M.D., University of Texas Medical Branch, Houston, TX, United States

NASA Johnson Space Center, Human Research Program, Houston, TX, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
NASA Research Office - Human Research Program (NASA Research-HRP)

Research Benefits
Earth Benefits, Scientific Discovery, Space Exploration

ISS Expedition Duration
September 2012 - March 2016; September 2016 - February 2018

Expeditions Assigned

Previous Missions
Information Pending

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Experiment Description

Research Overview

  • The proposed measures represent a comprehensive set of tests that evaluate exposure severity, potential injury mechanisms, and pain generator localization. This research expects to aid understanding of spinal pain and deconditioning during prolonged microgravity and of the higher incidence of disc prolapse or herniation during and following re-exposure to 1-G with a long-term view to prevent such spinal deconditioning with exercise or other physiologic countermeasures.
  • After successful completion of the investigation, the PI team will deliver a comprehensive database of microgravity-induced intervertebral disc and vertebral changes (type and magnitude) and a prioritization of these changes as to their deleterious effects and risks for crew member injury based on clinical findings.
  • Importantly, this research has application to back-pain patients on Earth in general and specifically, to patients exposed to long-term bed rest or lack of mobility (spinal-cord injury patients as well as patients suffering lack of exercise, mobility and obesity). This research also applies to abnormal spinal curvature and pain suffered by children wearing heavy backpacks to and from school as well as heavily armed soldiers.


There are two groups of participants. The first group of subjects totals 6, or half of the total study participants. The first group completes the full battery of 6 tests and completes the first stage of post-flight BDC within the R+1 to 7 timeframe. The second group completes one less test than the first group and performs their first stage of post-flight BDC in the R+5 to 10 timeframe. Pre-flight tests occur between L-120 to 60 for both subject groups. Both subject sets complete a second round of post-flight BDC in the R+30 to 60 timeframe. The pre-flight and post-flight BDC tests are described below.
  • MRI (Morphology/Water Content): MRI scans are taken of the lumbar and cervical spine while the subject lies flat on his or her back on a MRI table to measure the spinal bones, discs and muscles. Scans are performed once pre-flight as well as twice post-flight: once on either R+1 (first six subjects) or in the R+5 to 10 (last six subjects) timeframe and again in the R+30 to 60 timeframe.
  • MRS: Magnetic Resonance Spectroscopy measures metabolites in spinal disc tissues of the lumbar spine. Sessions are performed once pre-flight and twice post-flight (on R+1 and R+30 to 60). This test is only completed by the first group of six subjects.
  • Upright MRI (Axial Load): The subject visits the Stand-Up MRI in Clear Lake, Texas. Here, the PI team takes MRI scans in four different conditions: (1) while the subject lies flat on his/her back, (2) while the subject is standing upright with no load on the back, (3) while standing upright but with 10% of the subject’s body weight loaded on the back, and (4) while seated and with the load removed from the back. Scans are performed once pre-flight and once post-flight. The post-flight schedule will vary: either R+3 to 5 (first six subjects) or in the R+5 to 10 (last six subjects) timeframe
  •  Spinal Kinematics: Once pre-flight and once post-flight in the R+3 to 5 (first six subjects) or R+5 to 10 (last six subjects) timeframe, the PI team measures the lumbar spine stiffness and stability using the KineGraph Vertebral Motion Analyzer (VMA). The KineGraph VMA is a system that measures the motion of the bones in the spine using a standard fluoroscope. A fluoroscope is an FDA-approved imaging machine that has been in widespread use for decades, and is used to collect moving video X-ray images of the motion of the spine. In addition to a fluoroscope, the KineGraph VMA also involves the use of a large patient handling device that assists the subject through a series of controlled spine bends while the fluoroscope is collecting images. These large patient handling devices are needed to standardize the bending, so that it is possible to compare the subject’s spinal motion to that of other people. The study consists of taking a series of video X-rays as the subject does different types of spine bending while assisted by the large patient handling devices. The subject bends forward and backward, side-to-side, while standing up, and while lying down. To ensure the subject can comfortably do all of these bends, he or she is asked to perform each of these bends on his or her own before being assisted by the patient handling devices.
  • Biering-Sorenson: The subject performs a strength test of the abdominal and back muscles once pre-flight and once post-flight. Post-flight testing occurs in either the R+3 to 5 (first six subjects) or R+5 to 10 (last six subjects) timeframe.
  • Back Pain Questionnaires: The subject completes two questionnaires once pre-flight and twice post-flight, the latter in either the R+1 to 7 (first six subjects) or R+1 to 10 (last six subjects) timeframe and again in the R+30 to 60 timeframe (all subjects).

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Space Applications
Astronauts report back pain during long-duration microgravity missions and experience an increased likelihood of back injuries, such as herniated discs, after return to Earth. Magnetic resonance imaging, X-rays, bending exercises, and strength tests before and after spaceflight can help identify the suite of changes that can take place in space. Understanding how microgravity changes the structures of a person’s back could help physicians develop exercises or therapies to prevent injury and pain on long-duration space missions, as well as after astronauts return home.

Earth Applications
People with limited mobility, including patients on bed rest or with spinal cord injuries, experience some of the same spinal changes as those seen in microgravity. Understanding the origin of spine degeneration in space is expected to aid physicians on Earth to diagnose and treat spine disorders related to inactivity and, conversely, overloading. The study could also have implications for people with curved-spine disorders such as scoliosis, and for children and soldiers who carry heavy backpacks.

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Operational Requirements and Protocols

Twelve subjects are requested to perform the preflight and postflight baseline data collection for IVD.

This investigation only requires baseline data collection (BDC) both preflight and postflight. No inflight testing will occur.

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Decadal Survey Recommendations

Animal and Human Biology AH2

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Results/More Information

The Intervertebral Disc Damage investigation aims to determine the impact of microgravity on the intervertebral discs of space explorers during and after long-duration stays in microgravity. Researchers found that paraspinal muscle (PSM) mass was significantly lower compared with preflight values following long-duration spaceflight. Also of note, 68% of the muscle mass loss was recovered by postflight day 46; whereas, the lumbar intervertebral disc (IVD) were unchanged following space flight. These results provide insight into back pain and IVD risks, suggesting possible countermeasures targeted to the lumbar PSMs while in-flight and during the preflight and postflight periods.

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Results Publications

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Ground Based Results Publications

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ISS Patents

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Related Publications

    Schlabs T, Rosales-Velderrain A, Ruckstuhl H, Stahn AC, Hargens AR.  Comparison of cardiovascular and biomechanical parameters of supine lower body negative pressure and upright lower body positive pressure to simulate activity in 1/6 G and 3/8 G. Journal of Applied Physiology. 2013 July 15; 115(2): 275-284. DOI: 10.1152/japplphysiol.00990.2012. PMID: 23640597.

    Macias BR, D'Lima DD, Cutuk A, Patil S, Steklov N, Neuschwander TB, Meuche S, Colwell CW, Hargens AR.  Leg intramuscular pressures and in vivo knee forces during lower body positive and negative pressure treadmill exercise. Journal of Applied Physiology. 2012 July; 113(1): 31-38. DOI: 10.1152/japplphysiol.01434.2011. PMID: 22539171.

    Shymon S, Yaszay B, Dwek JR, Proudfoot JA, Donohue M, Hargens AR.  Altered disc compression in children with idiopathic low back pain: an upright magnetic resonance imaging backpack study. Spine. 2014 February 1; 39(3): 243-248. DOI: 10.1097/BRS.0000000000000114. PMID: 24253789.

    Kim SH, Neuschwander TB, Macias BR, Bachman Jr. L, Hargens AR.  Upper extremity hemodynamics and sensation with backpack loads. Applied Ergonomics. 2014 May; 45(3): 608-612. DOI: 10.1016/j.apergo.2013.08.005. PMID: 24075289.

    Rodríguez-Soto AE, Jaworski R, Jensen A, Niederberger B, Hargens AR, Frank LR, Kelly KR, Ward SR.  Effect of load carriage on lumbar spine kinematics. Spine. 2013 June 1; 38(13): E783-791. DOI: 10.1097/BRS.0b013e3182913e9f. PMID: 23524870.

    Hargens AR, Bhattacharya R, Schneider SM.  Space physiology VI: exercise, artificial gravity, and countermeasure development for prolonged space flight. European Journal of Applied Physiology. 2013 September; 113(9): 2183-2192. DOI: 10.1007/s00421-012-2523-5. PMID: 11641383.

    Sayson JV, Lotz JC, Parazynski SE, Hargens AR.  Back pain in space and post-flight spine injury: Mechanisms and countermeasure development. Acta Astronautica. 2013 May; 86: 24-38. DOI: 10.1016/j.actaastro.2012.05.016.

    Laws CJ, Berg-Johansen B, Hargens AR, Lotz JC.  The effect of simulated microgravity on lumbar spine biomechanics: an in vitro study . European Spine Journal. 2015 September 24; 25(9): 2889-2897. DOI: 10.1007/s00586-015-4221-6. PMID: 26403291.

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