Brain Magnetic Resonance Imaging Responses to Nonhypoxic Hypobaric Decompression.

IF 0.9 4区医学 Q4 BIOPHYSICS

Aerospace medicine and human performance Pub Date : 2024-10-01 DOI:10.3357/AMHP.6445.2024

Desmond Connolly, Indran Davagnanam, Marzena Wylezinska-Arridge, Dermot Mallon, Stephen Wastling, Vivienne M Lee

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Abstract

Introduction: The pathophysiological basis of neurological decompression sickness and the association between cerebral subcortical white matter (WM) change and nonhypoxic hypobaria remain poorly understood. Recent study of altitude decompression sickness risk evaluated acute WM responses to intensive hypobaric exposure using brain magnetic resonance imaging.

Methods: Six healthy men (20 to 50 yr) completed 6 h of hyperoxic hypobaria during three same-day altitude chamber decompressions to pressure altitudes ≥ 22,000 ft (6706 m). Research magnetic resonance imaging sequences, conducted on the days preceding and following decompression, evaluated subcortical WM integrity, cerebral blood flow, neuronal integrity (fractional anisotropy), and neurometabolite concentrations.

Results: No subcortical lesions were evident on diffusion weighted imaging and WM fractional anisotropy was unaffected. Mean WM blood flow was upregulated by 20% to over 25 mL · 100 g-1 · min-1. Gray matter flow was unchanged. There were no changes in gray matter or cerebellar neurometabolites. In parietal subcortical WM, levels of γ-aminobutyric acid (GABA) fell from (mean ± SD) 1.68 ± 0.2 to 1.35 ± 0.3 institutional units while glutathione (GSH) fell from 1.71 ± 0.4 to 1.25 ± 0.3 institutional units. Lactate increased postexposure in five subjects.

Conclusions: Postexposure decrements in GABA and GSH imply WM insult with loss of neuroprotection and oxidative stress. An association between decrements in GABA and GSH support a common origin, while GSH decrements also correlate with WM blood flow responses. WM lactate increments are prone to error but suggest dysregulation of subcortical microvascular flow. WM neurometabolite and blood flow indices did not normalize by 24 h postexposure. Connolly D, Davagnanam I, Wylezinska-Arridge M, Mallon D, Wastling S, Lee VM. Brain magnetic resonance imaging responses to nonhypoxic hypobaric decompression. Aerosp Med Hum Perform. 2024; 95(10):733-740.

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脑磁共振成像对非缺氧低压减压的反应

简介人们对神经性减压病的病理生理基础以及大脑皮层下白质（WM）变化与非缺氧性低压病之间的关联仍然知之甚少。最近一项关于高原减压病风险的研究利用脑磁共振成像评估了急性脑白质对高强度低压暴露的反应：方法：6 名健康男性（20 至 50 岁）在 3 次同日高海拔减压舱减压过程中完成了 6 小时的高氧低气压暴露，压力高度≥ 22,000 英尺（6706 米）。减压前后几天进行的磁共振成像研究评估了皮层下 WM 的完整性、脑血流量、神经元完整性（分数各向异性）和神经代谢物浓度：扩散加权成像显示皮层下无明显病变，WM分数各向异性未受影响。平均WM血流量增加了20%，超过25 mL - 100 g-1 - min-1。灰质血流量没有变化。灰质或小脑神经代谢物没有变化。在顶叶皮层下 WM 中，γ-氨基丁酸（GABA）水平从（平均值±标准差）1.68 ± 0.2 降至 1.35 ± 0.3 机构单位，而谷胱甘肽（GSH）则从 1.71 ± 0.4 降至 1.25 ± 0.3 机构单位。有五名受试者在暴露后乳酸增加：结论：暴露后 GABA 和 GSH 的下降意味着 WM 损伤导致神经保护功能丧失和氧化应激。GABA和GSH的下降之间存在关联，这支持了两者的共同起源，而GSH的下降也与WM血流反应相关。WM乳酸增量容易出现误差，但表明皮层下微血管流动失调。暴露后 24 小时，WM 神经代谢物和血流指数仍未恢复正常。Connolly D、Davagnanam I、Wylezinska-Arridge M、Mallon D、Wastling S、Lee VM。脑磁共振成像对非缺氧低压减压的反应。Aerosp Med Hum Perform.2024; 95(10):733-740.

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来源期刊

Aerospace medicine and human performance PUBLIC, ENVIRONMENTAL & OCCUPATIONAL HEALTH -MEDICINE, GENERAL & INTERNAL

CiteScore

1.10

自引率

22.20%

发文量

272

期刊介绍： The peer-reviewed monthly journal, Aerospace Medicine and Human Performance (AMHP), formerly Aviation, Space, and Environmental Medicine, provides contact with physicians, life scientists, bioengineers, and medical specialists working in both basic medical research and in its clinical applications. It is the most used and cited journal in its field. It is distributed to more than 80 nations.