Kramer Larry A, Hasan Khader M, Sargsyan Ashot E, Wolinsky Jerry S, Hamilton Douglas R, Riascos Roy F, Carson William K, Heimbigner Jared, Patel Vipulkumar S, Romo Seferino, Otto Christian
Department of Diagnostic and Interventional Imaging, University of Texas Health Science Center at Houston, Houston, Texas, USA.
Wyle Integrated Science and Engineering, Houston, Texas, USA.
J Magn Reson Imaging. 2015 Dec;42(6):1560-71. doi: 10.1002/jmri.24923. Epub 2015 Apr 27.
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.
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.
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).
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.
量化宇航员在暴露于微重力环境前后脑脊液（CSF）生成率和最大收缩速度的变化，并确定与颅内高压相关的任何生理趋势和/或风险因素。
经机构审查委员会（IRB）批准并豁免知情同意后，对27名在3T磁场下成像的宇航员进行了回顾性研究。通过眼眶的T2加权轴向图像进行定性分析，根据以下分级评估后极部眼球扁平化程度：0级 = 无，1级 = 轻度，2级 = 中度，3级 = 重度。飞行后分级变化1级被认为是暴露于颅内高压的显著变化。通过电影相位对比磁共振成像计算脑脊液生成率和最大收缩速度，并与7名健康对照者进行比较。
研究了14名宇航员。宇航员飞行前的脑脊液生成率与对照组相似（P = 0.83）。6名后极部眼球显著扁平化的宇航员飞行后脑脊液生成率较基线增加了70%（P = 0.01）。在无后极部眼球扁平化的亚组中，脑脊液最大收缩速度显著增加（P = 0.01）。
眼球扁平化阳性的宇航员飞行后脑脊液生成率增加，这与微重力诱导颅内高压的假说相符，该假说推断微重力环境下脑脊液生成下调，返回正常重力后上调。眼球扁平化阴性的宇航员飞行后脑脊液最大收缩速度增加，提示颅脊髓顺应性增加，这可能是微重力诱导颅内高压的一个潜在负性风险因素。
