MR-derived cerebral spinal fluid hydrodynamics as a marker and a risk factor for intracranial hypertension in astronauts exposed to microgravity.
OBJECTIVE
To quantify the change in cerebral spinal fluid (CSF) production rate and maximum systolic velocity in astronauts before and after exposure to microgravity and identify any physiologic trend and/or risk factor related to intracranial hypertension.


METHODS
Following Institutional Review Board (IRB) approval, with waiver of informed consent, a retrospective review of 27 astronauts imaged at 3T was done. Qualitative analysis was performed on T2 -weighted axial images through the orbits for degree of flattening of the posterior globe according to the following grades: 0 = none, 1 = mild, 2 = moderate, and 3 = severe. One grade level change postflight was considered significant for exposure to intracranial hypertension. CSF production rate and maximum systolic velocity was calculated from cine phase-contrast magnetic resonance imaging and compared to seven healthy controls.


RESULTS
Fourteen astronauts were studied. The preflight CSF production rate in astronauts was similar to controls (P = 0.83). Six astronauts with significant posterior globe flattening demonstrated a 70% increase in CSF production rate postflight compared to baseline (P = 0.01). There was a significant increase in CSF maximum systolic velocity in the subgroup without posterior globe flattening (P = 0.01).


CONCLUSIONS
The increased postflight CSF production rate in astronauts with positive flattening is compatible with the hypothesis of microgravity-induced intracranial hypertension inferring downregulation in CSF production in microgravity that is upregulated upon return to normal gravity. Increased postflight CSF maximum systolic velocity in astronauts with negative flattening suggests increased craniospinal compliance and a potential negative risk factor to microgravity-induced intracranial hypertension.
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Larry A
LA
Kramer
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Khader M
KM
Hasan
Wyle Integrated Science and Engineering, Houston, Texas, USA.
Ashot E
AE
Sargsyan
Department of Neurology, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Jerry S
JS
Wolinsky
Division of General Internal Medicine, University of Calgary, Calgary, Alberta, Canada.
Douglas R
DR
Hamilton
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Roy F
RF
Riascos
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
William K
WK
Carson
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Jared
J
Heimbigner
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Vipulkumar S
VS
Patel
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Seferino
S
Romo
Universities Space Research Association, Houston, Texas, USA.|Baylor College of Medicine, Section of Emergency Medicine, Houston, Texas, USA.
Christian
C
Otto
D018480:Astronauts; D015415:Biomarkers / Q000134:cerebrospinal fluid; D002555:Cerebrospinal Fluid / Q000166:cytology / Q000502:physiology*; D004311:Double-Blind Method; D006801:Humans; D057446:Hydrodynamics; D019586:Intracranial Hypertension / Q000134:cerebrospinal fluid / Q000209:etiology* / Q000473:pathology*; D007427:Intracranial Pressure; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014893:Weightlessness / Q000009:adverse effects*
D015415:Biomarkers
MRI; cerebral spinal fluid; flow; intracranial hypertension; microgravity; orbits