Background: 

It was recently reported that lower intracranial pressure variability (ICPV) is associated with delayed ischemic neurological deficits and unfavorable outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). In this study, we aimed to determine whether lower ICPV also correlated with worse cerebral energy metabolism after aSAH.

Methods: 

A total of 75 aSAH patients treated in the neurointensive care unit at Uppsala University Hospital, Sweden between 2008 and 2018 and with both intracranial pressure and cerebral microdialysis (MD) monitoring during the first 10 days after ictus were included in this retrospective study. ICPV was calculated with a bandpass filter limited to intracranial pressure slow waves with a wavelength of 55 to 15 seconds. Cerebral energy metabolites were measured hourly with MD. The monitoring period was divided into 3 phases; early (days 1 to 3), early vasospasm (days 4 to 6.5), and late vasospasm (days 6.5 to 10).

Results: 

Lower ICPV was associated with lower MD-glucose in the late vasospasm phase, lower MD-pyruvate in the early vasospasm phases, and higher MD-lactate-pyruvate ratio (LPR) in the early and late vasospasm phases. Lower ICPV was associated with poor cerebral substrate supply (LPR >25 and pyruvate <120 µM) rather than mitochondrial failure (LPR >25 and pyruvate >120 µM). There was no association between ICPV and delayed ischemic neurological deficit, but lower ICPV in both vasospasm phases correlated with unfavorable outcomes.

Conclusion: 

Lower ICPV was associated with an increased risk for disturbed cerebral energy metabolism and worse clinical outcomes in aSAH patients, possibly explained by a vasospasm-related decrease in cerebral blood volume dynamics and cerebral ischemia.

中文翻译：

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颅内压变异性：动脉瘤性蛛网膜下腔出血脑缺血和能量代谢功能障碍的新潜在指标？

背景： 

最近有报道称，较低的颅内压变异性 (ICPV) 与迟发性缺血性神经功能缺损和动脉瘤性蛛网膜下腔出血 (aSAH) 患者的不良预后有关。在这项研究中，我们旨在确定较低的 ICPV 是否也与 aSAH 后较差的脑能量代谢相关。

方法： 

本回顾性研究纳入了 2008 年至 2018 年间在瑞典乌普萨拉大学医院神经重症监护病房接受治疗并在发作后前 10 天内接受颅内压和脑微透析 (MD) 监测的 75 名 aSAH患者。ICPV 是用带通滤波器计算的，带通滤波器仅限于波长为 55 至 15 秒的颅内压慢波。每小时用 MD 测量脑能量代谢物。监测期分为3个阶段；早期（第 1 至 3 天）、早期血管痉挛（第 4 至 6.5 天）和晚期血管痉挛（第 6.5 至 10 天）。

结果： 

较低的 ICPV 与晚期血管痉挛阶段较低的 MD-葡萄糖、早期血管痉挛阶段较低的 MD-丙酮酸盐以及早期和晚期血管痉挛阶段较高的 MD-乳酸-丙酮酸盐比率 (LPR) 相关。较低的 ICPV 与脑底物供应不足（LPR >25 和丙酮酸 <120 µM）相关，而不是线粒体衰竭（LPR >25 和丙酮酸 >120 µM）。ICPV 与迟发性缺血性神经功能缺损之间没有关联，但两个血管痉挛阶段的 ICPV 较低与不利结果相关。

结论： 

较低的 ICPV 与脑能量代谢紊乱的风险增加和 aSAH 患者的临床结果较差有关，这可能是由于脑血容量动力学和脑缺血的血管痉挛相关减少所致。