title: Intervertebral Disc Swelling Demonstrated by 3D and Water Content Magnetic Resonance Analyses after a 3-Day Dry Immersion Simulating Microgravity.
abstract: Background:Vertebral deconditioning is commonly experienced after space flight and simulation studies. Disc herniation is quadrupled after space flight.Purpose:The main hypothesis formulated by the authors is that microgravity results in intervertebral disc (IVD) swelling.Study Design:The aim of the study was to identify the morphological changes of the spine and their clinical consequences after simulated microgravity by 3-day dry immersion (DI). The experimental protocol was performed on 12 male volunteers using magnetic resonance imaging and spectroscopy before and after DI.Methods:All the experiment was financially supported by CNES (Centre national d'études spatiales i.e., French Space Agency).Results:We observed an increase in spine 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 significant increase in IVD volume of +8 ± 9% at T12-L1and +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 the lumbar region below the diaphragmatic muscle. This clinical observation may be linked to the morphological changes of the spine.Conclusions:The morphological changes observed and, specifically, the disc swelling caused by increased IWC may contribute to understanding disc herniation after microgravity exposure. Our results confirmed the efficiency of the 3-day DI model to reproduce quickly the effects of microgravity on spine morphology. Our findings raise the question of the subject selection in spatial studies, especially studies about spine morphology and reconditioning programs after space flight. These results may contribute to a better understanding of the mechanisms underlying disc herniation and may serve as the basis to develop countermeasures for astronauts and to prevent IVD herniation and back pain on Earth.
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Centre National de la Recherche Scientifique (CNRS) Strasbourg, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Treffel
authors.affiliation: Siemens Healthinners, Service Application Saint-Denis, France.
authors.forename: Karen
authors.initials: K
authors.lastname: Mkhitaryan
authors.affiliation: CHU Toulouse Rangueil Hospital Imaging Service Toulouse, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Gellee
authors.affiliation: French Space Agency, Centre National d'Etudes Spatiales Paris, France.
authors.forename: Guillemette
authors.initials: G
authors.lastname: Gauquelin-Koch
authors.affiliation: Faculté de Médecine et d'Odontologie, Université Claude Bernard Lyon 1 Lyon, France.
authors.forename: Claude
authors.initials: C
authors.lastname: Gharib
authors.affiliation: Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Centre National de la Recherche Scientifique (CNRS) Strasbourg, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Blanc
authors.affiliation: Faculté de Médecine et d'Odontologie, Université Claude Bernard Lyon 1Lyon, France; Service d'Odontologie, Hospices Civils de LyonLyon, France.
authors.forename: Catherine
authors.initials: C
authors.lastname: Millet
keywords: back pain; disc herniation; disc swelling; dry immersion; magnetic resonance imaging/magnetic resonance spectroscopy; microgravity; vertebral deconditioning