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Original Investigation
March 26, 2020

Spaceflight-Associated Changes in the Opacification of the Paranasal Sinuses and Mastoid Air Cells in Astronauts

Author Affiliations
  • 1Department of Radiology and Radiological Science, Medical University of South Carolina, Charleston
  • 2Department of Otolaryngology–Head and Neck Surgery, Medical University of South Carolina, Charleston
  • 3Tsukuba Space Center, Japanese Aerospace Exploration Agency, Tsukuba, Japan
JAMA Otolaryngol Head Neck Surg. Published online March 26, 2020. doi:10.1001/jamaoto.2020.0228
Key Points

Question  Are there changes in the opacification of the paranasal sinuses or mastoid air cells associated with symptoms of head congestion and facial fullness frequently experienced by astronauts during spaceflight?

Findings  This cohort study of 35 astronauts found that long-duration (>30 days) spaceflight on the International Space Station, but not short-duration spaceflight on the Space Shuttle, was associated with an increased likelihood for the development of mastoid effusions. No change in the opacification of paranasal sinuses was noted after long-duration or short-duration spaceflight.

Meaning  The development of mastoid effusions during spaceflight might be associated with several Earth-based mechanisms.

Abstract

Importance  Head congestion is one of the most common somatic symptoms experienced by astronauts during spaceflight; however, changes in the opacification of the paranasal sinuses or mastoid air cells in astronauts have not been adequately studied.

Objectives  To quantify preflight to postflight changes in the opacification of the paranasal sinuses and mastoid air cells in Space Shuttle astronauts and International Space Station (ISS) astronauts and to assess whether there are differences between the 2 groups of astronauts.

Design, Setting, and Participants  This cohort study examined preflight and postflight head magnetic resonance images (MRIs) of 35 astronauts who had participated in either a short-duration (≤30 days) Space Shuttle mission or a long-duration (>30 days) ISS mission and had undergone both preflight and postflight MRI. Images were obtained before and after spaceflight. Images were evaluated by 2 neuroradiologists blinded to which mission each astronaut had flown and to which images were preflight or postflight images.

Exposure  Spaceflight on the Space Shuttle or the ISS.

Main Outcomes and Measures  Measured outcomes included preflight to postflight changes in Lund-Mackay scores for the paranasal sinuses and in scores grading mastoid effusions.

Results  Most astronauts in both the Space Shuttle group (n = 17; 15 men; mean [SD] age at launch, 47.7 [3.1] years) and the ISS group (n = 18; 14 men; mean [SD] age at launch, 48.6 [4.7] years) exhibited either no change or a reduction in paranasal sinus opacification as seen on postflight MRI scans (Space Shuttle group: 6 [35.3%] had no sinus opacification before or after spaceflight, 5 [29.4%] had less sinus opacification after spaceflight, 3 [17.6%] had the same amount of sinus opacification before and after spaceflight, and 3 [17.6%] had increased paranasal sinus opacification after spaceflight; ISS group: 8 [44.4%] had no sinus opacification before or after spaceflight, 4 [22.2%] had less sinus opacification after spaceflight, 1 (5.6%) had the same amount of sinus opacification before and after spaceflight, and 5 [27.8%] had scores consistent with increased paranasal sinus opacification after spaceflight). Long-duration spaceflight (ISS group) was associated with an increased risk of mastoid effusion relative to short-duration spaceflight (relative risk, 4.72; 95% CI, 1.2-18.5). Images were obtained a mean (SD) 287.5 (208.6) days (range, 18-627 days) prior to and 6.8 (5.8) days (range, 1-20 days) after spaceflight. Astronauts had undergone either a mean (SD) of 13.6 (1.6) days of spaceflight on the Space Shuttle (17 astronauts) or 164.8 (18.9) days on the ISS (18 astronauts).

Conclusions and Relevance  This study found that exposure to spaceflight conditions on the ISS is associated with an increased likelihood for the formation of mastoid effusions. There was no association between exposure to spaceflight conditions and changes in paranasal sinus opacification. The limitations of this study include lack of information concerning medical history and mission-specific operational experience for individual astronauts. Further studies are indicated to determine the cause and composition of the mastoid effusions.

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