Objectives

In the application of the Monro-Kellie doctrine in spontaneous intracranial hypotension, the brain tissue volume is generally considered as a fixed constant. Traditionally, cerebral venous dilation is thought to compensate for decreased cerebrospinal fluid. However, whether brain tissue volume is invariable has not yet been explored. The objective of this study is to evaluate whether brain tissue volume is fixed or variable in spontaneous intracranial hypotension patients using automatic quantitative methods.

Methods

This retrospective and longitudinal study analyzed spontaneous intracranial hypotension patients between 1 January 2007 and 31 July 2015. Voxel-based morphometry was used to examine brain volume changes during and after the resolution of spontaneous intracranial hypotension. Brain structure volume was analyzed using Statistical Parametric Mapping version 12 and FMRIB Software Library v6.0. Post-treatment neuroimages were used as surrogate baseline measures.

Results

Forty-four patients with spontaneous intracranial hypotension were analyzed (mean [standard deviation] age, 37.8 [8.5] years; 32 female and 12 male). The whole brain tissue volume was decreased during spontaneous intracranial hypotension compared to follow-up (1180.3 [103.5] mL vs. 1190.4 [93.1] mL, difference: −10.1 mL [95% confidence interval: −18.4 to −1.8 mL], p = 0.019). In addition, ventricular cerebrospinal fluid volume was decreased during spontaneous intracranial hypotension compared to follow-up (15.8 [6.1] mL vs. 18.9 [6.9] mL, difference: −3.2 mL [95% confidence interval: −4.5 to −1.8 mL], p < 0.001). Longer anterior epidural cerebrospinal fluid collections, as measured by number of vertebral segments, were associated with greater reduction of ventricular cerebrospinal fluid volume (Pearson’s r = −0.32, p = 0.036).

Conclusion

The current study found the brain tissue volume and ventricular cerebrospinal fluid are decreased in spontaneous intracranial hypotension patients. The change in ventricular cerebrospinal fluid volume, but not brain tissue volume change, was associated with the severity of spinal cerebrospinal fluid leakage. These results challenge the assumption that brain tissue volume is a fixed constant.

中文翻译：

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自发性颅内低血压的脑容量变化：重新审视 Monro-Kellie 学说。

目标

Monro-Kellie学说在自发性颅内低血压的应用中，一般认为脑组织体积是一个固定常数。传统上，脑静脉扩张被认为可以补偿减少的脑脊液。然而，尚未探索脑组织体积是否不变。本研究的目的是使用自动定量方法评估自发性颅内低血压患者的脑组织体积是固定的还是可变的。

方法

这项回顾性和纵向研究分析了 2007 年 1 月 1 日至 2015 年 7 月 31 日之间的自发性颅内低血压患者。基于体素的形态测量法用于检查自发性颅内低血压消退期间和之后的脑容量变化。使用统计参数映射版本 12 和 FMRIB 软件库 v6.0 分析脑结构体积。治疗后的神经影像被用作替代基线测量。

结果

分析了 44 名自发性颅内低血压患者（平均 [标准差] 年龄，37.8 [8.5] 岁；32 名女性和 12 名男性）。与随访相比，自发性颅内低血压期间全脑组织体积减少（1180.3 [103.5] mL 与 1190.4 [93.1] mL，差异：-10.1 mL [95% 置信区间：-18.4 至 -1.8 mL]，p  = 0.019）。此外，与随访相比，自发性颅内低血压期间心室脑脊液量减少（15.8 [6.1] mL vs. 18.9 [6.9] mL，差异：-3.2 mL [95% 置信区间：-4.5 至-1.8 mL] , p < 0.001)。根据椎节数测量，硬膜外脑脊液收集时间越长，心室脑脊液体积减少越多（Pearson's r = -0.32，p  = 0.036）。

结论

目前的研究发现自发性颅内低血压患者的脑组织体积和心室脑脊液减少。脑室脑脊液体积的变化与脑脊液漏的严重程度有关，但与脑组织体积的变化无关。这些结果挑战了脑组织体积是固定常数的假设。