Background & Aims
Space flights disrupts the homeostatic balance of many physiological systems that have adapted to function terrestrially. This can produce physiological changes in spine developing acute and chronic pain in passengers. Yet, a comprehensive body of literature exploring physiological spine changes and acute and chronic pain in space passengers (astronauts and animals) is lacking.
The first aim of this study was to summarize the physiological changes experienced by passengers (humans and animals), after space flight.
The second aim was to analyze when the physiological changes and symptoms appear during and after space flight.
The third aim was to analyze relationship between space flight changes and acute and chronic pain after space flight in human and animal model.
Methods
This systematic review was conducted following PRISMA and was pre-registered in PROSPERO (ID 451144). Eligibility criteria were: 1) Randomized Control Trial (RCT), Trials, or longitudinal, study in human and animals 2) published util January 1, 2024, 3) studies with not space flights were excluded (ex: microgravity model in earth) 4) variables must assess either in-flight or post-flight. We conducted a literature search in five databases (i.e. Medline, Embase, Global Health, Web of Science, Scopus, Cochrane library) combining the Key Words: Pain; Space; Low Back Pain; Astronauts; Spine changes; Microgravity; Physiological Changes; Humans; Animals. We extracted information on the study population, space flight characteristics, pain outcomes, spine changes. Risk of Bias were analyzed by SYRCLE in animals’ studies and QUIPS Tool for human studies. CAMARADES tool was used in animals and NIH Tool for humans to assess quality of studies. Finally, we assess level of evidence by GRADE system.
Results
After duplicates were removed, 884 abstracts were screened by two reviewers, finally 12 articles were included in this review. 3 articles were animal models and 9 were human model. 5 articles prove information about physiological changes and 7 about acute and chronic pain after space flight.
By main themes included decreased spinal ROM, paraspinal and abdominal muscle atrophy, changes in IVD swelling pressure and water content, changes in lumbar lordosis, signs of IVD degeneration, and LBP. None of the identified studies directly examined both short-duration adaptations and early in-flight pain. Only one study analyzed the qualitative aspects of pain, using a numerical rating scale.
All the studies indicated a low risk of bias in the ‘Prognostic Factors Measurement’ and ‘Outcome Measurement’ domains. In the article involving animals, evaluated by SYRCLE, the researchers did not randomize the sample and did not blind the evaluator of the variables.
Conclusions
Acute adaptations to spaceflight appear to be related to the phenomena of in-flight pain. In early spaceflight, otolithic unloading may disrupt the vestibular system, and subsequent vestibulospinal reflexes and trunk motor control. These changes, along with disruptions of terrestrial cues of verticality, may alter the way dynamic spinal stability is achieved and contribute to low back pain due to paraspinal muscle fatigue and intersegmental instability. More studies are needed to explore potential implication in long-term period after flights.
References
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Presenting Author
Guillermo Ceniza Bordallo
Poster Authors
GUILLERMO CENIZA BORDALLO
PhD Candidate
University Complutense of Madrid
Lead Author
Eric Zimmermann
1Faculty of Arts, McGill University, Montreal, QC, Canada
Lead Author
Kacper Nibruski
Department of Family Medicine, University of British Columbia, Vancouver, BC, Canada
Lead Author
Marie Vigouroux
Edwards Family Interdisciplinary Center for Complex Pain, Montreal Children's Hospital, Montreal
Lead Author
Topics
- Evidence, Clinical Trials, Systematic Review, Guidelines, and Implementation Science