Gravity and Mastoid effusion

Background Asymptomatic mastoid effusions have recently been observed in astronauts returning from long-term spaceflight. In hospitalized patients, mastoid effusion increases the risk for bacterial otitis/mastoiditis. We reasoned that cephalad fluid shifts during strict -6° head down tilt bed-rest (HDT) could reproduce space-flight associated mastoid effusion and that artificial gravity may reverse the response.

Methods The recent "Artificial Gravity Bed-Rest Study" (AGBRESA) tested influences of artificial gravity (AG) during 60 days head down bed rest on a short-arm human centrifuge in healthy subjects. The two intervention groups received daily AG with 30 minutes continuous AG (cAG) or Intermittend AG. A third group acted as a control group with no AG. We assessed cranial magnetic resonance images (MRI) for mastoid effusions one day before HDT, at day 14 and 52 of HDT, and three days after HDT.

Results Among twelve subjects in the first study campaign, none exhibited mastoid effusions before HDT. Five subjects showed mastoid effusions at HDT day 14 (3 cAG, 1 iAG, 1 control). Eleven subjects showed mastoid effusions at HDT day 52 and three days after HDT (3 cAG, 4 iAG, 4 control).

Conclusions Mastoid effusions commonly occur during strict HDT bed-rest. The model can be applied to study the mechanisms and potential countermeasures for space flight-associated mastoid effusions and to test potential countermeasures. Formation of mastoid effusions during HDT is not prevented by daily 30 minutes short-arm intermittent or continuous centrifugation.

Poster-PDF A-1525.pdf

Publication History

Article published online:
13 May 2021