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Changes in intervertebral disc cross-sectional area with bed rest and space flight
A D LeBlanc1, H J Evans, V S Schneider
1Department of Medicine, Baylor College of Medicine, Houston, Texas.
Spine
|April 1, 1994
Summary
Bed rest and weightlessness cause intervertebral discs to expand, altering spine mechanics. These disc changes are reversible after short-term spaceflight but may persist after long-duration missions.
Area of Science:
- Spinal biomechanics and adaptation to unloading.
- Intervertebral disc physiology and imaging.
Background:
- Weightlessness and bed rest reduce musculoskeletal loading.
- Unloading leads to intervertebral disc expansion, affecting nutrient diffusion and spinal properties.
Purpose of the Study:
- To quantify lumbar disc expansion during bed rest and spaceflight.
- To understand the adaptive changes in intervertebral discs under reduced mechanical load.
Main Methods:
- Magnetic resonance imaging (MRI) measured intervertebral disc cross-sectional area and T2 relaxation time.
- Measurements were taken in normal volunteers during and after periods of bed rest and weightlessness.
Main Results:
- Bed rest induced disc expansion (up to 22% above baseline) within 4 days, with associated increases in disc T2.
- Disc height increased ~1 mm during bed rest.
- Disc area normalized within days after 5 weeks of bed rest, but remained elevated for 6 weeks after 17 weeks of bed rest; 8 days of weightlessness showed no significant changes 24 hours post-flight.
Conclusions:
- Intervertebral discs undergo significant adaptive expansion in response to weightlessness.
- These disc adaptations are rapidly reversible after short spaceflights.
- Persistent disc changes after long-duration missions may impact astronaut health and performance.