Frontiers in Physiology (Dec 2016)

Intervertebral disc swelling demonstrated by 3D and water content magnetic resonance analyses after a 3-day dry immersion simulating microgravity

  • Loïc Treffel,
  • Karen Mkhitaryan,
  • Stéphane Gellee,
  • Guillemette Gauquelin-Koch,
  • Claude Gharib,
  • Stephane Blanc,
  • Catherine Millet,
  • Catherine Millet

DOI
https://doi.org/10.3389/fphys.2016.00605
Journal volume & issue
Vol. 7

Abstract

Read online

Background Vertebral deconditioning is commonly experienced after space flight andsimulation studies. Disc herniation (DH) is quadrupled after space flight.Purpose The main hypothesis formulated by the authors is that microgravity results inintervertebral disc swelling.Study Design The aim of the study was to identify the morphological changes of the spine andtheir clinical consequences after simulated microgravity by 3-day dry immersion (DI).The experimental protocol was performed on 12 male volunteers using magnetic resonanceimaging and spectroscopy before and after DI.Methods All the experiment was financially supported by CNES (Centre national d’étudesspatiales i.e. French Space Agency).Results We observed an increase in rachis height of 1.5 ± 0.4 cm and a decrease in curvature,particularly for the lumbar region with a decrease of -4 ± 2.5°. We found a significantincrease in intervertebral disc (IVD) volume of +8 ± 9% at T12-L1 and +11 ± 9% at L5-S1.This phenomenon is likely associated with the increase in disc intervertebral water content(IWC), 17 ± 27%. During the 3 days in DI, 92% of the subjects developed back pain in thelumbar region below the diaphragmatic muscle. This clinical observation may be linked to themorphological changes of the spine.Conclusions The morphological changes observed and, specifically, the disc swelling causedby increased IWC may contribute to understanding disc herniation after microgravityexposure. Our results confirmed the efficiency of the 3-day DI model to reproduce quickly theeffects of microgravity on spine morphology. Our findings raise the question of the subjectselection in spatial studies, especially studies about spine morphology and reconditioningprograms after space flight. These results may contribute to a better understanding of themechanisms underlying disc herniation and may serve as the basis to developcountermeasures for astronauts and to prevent IVD herniation and back pain on Earth.

Keywords