Background

The dementia subtype idiopathic normal pressure hydrocephalus (iNPH) has unknown etiology, but one characteristic is elevated intracranial pressure (ICP) wave amplitudes in those individuals who respond with clinical improvement following cerebrospinal fluid (CSF) diversion. To explore the mechanisms behind altered ICP wave amplitudes, we correlated central aortic blood pressure (BP) and ICP waveform amplitudes (intracranial aortic amplitude correlation) and examined how this correlation relates to ICP wave amplitude levels and systemic hemodynamic parameters.

Methods

The study included 29 patients with probable iNPH who underwent continuous multi-hour measurement of ICP, radial artery BP, and systemic hemodynamic parameters. The radial artery BP waveforms were used to estimate central aortic BP waveforms, and the intracranial aortic amplitude correlation was determined over consecutive 4-min periods.

Results

The average intracranial aortic amplitude correlation was 0.28 ± 0.16 at the group level. In the majority of iNPH patients, the intracranial aortic amplitude correlation was low, while in about 1/5 patients, the correlation was rather high (average Pearson correlation coefficient > 0.4). The degree of correlation was hardly influenced by systemic hemodynamic parameters.

Conclusions

In about 1/5 iNPH patients of this study, the intracranial aortic amplitude correlation (IAAC_AORTIC) was rather high (average Pearson correlation coefficient > 0.4), suggesting that cerebrovascular factors to some extent may affect the ICP wave amplitudes in a subset of patients. However, in 14/19 (74%) iNPH patients with elevated ICP wave amplitudes, the intracranial aortic amplitude correlation was low, indicating that the ICP pulse amplitude in most iNPH patients is independent of central vascular excitation, ergo it is modulated by local cerebrospinal physiology. In support of this assumption, the intracranial aortic amplitude correlation was not related to most systemic hemodynamic variables. An exception was found for a subgroup of the patients with high systemic vascular resistance, where there was a correlation.

中文翻译：

---

特发性正常压力脑积水中搏动性颅内压改变的背后机制：血管搏动和全身血流动力学变量的作用。

背景

痴呆亚型特发性正常压力脑积水（iNPH）的病因不明，但特征之一是那些对脑脊液（CSF）转移后临床改善有反应的个体的颅内压（ICP）波幅升高。为了探讨ICP波振幅改变背后的机制，我们将中心主动脉血压（BP）和ICP波形振幅（颅内主动脉振幅相关性）相关联，并研究了这种相关性与ICP波振幅水平和全身血流动力学参数之间的关系。

方法

该研究纳入了29名可能患有iNPH的患者，这些患者接受了ICP，radial动脉BP和全身血流动力学参数的连续多小时测量。使用动脉BP波形估计中心主动脉BP波形，并在连续的4分钟时间内确定颅内主动脉振幅相关性。

结果

在组水平上，平均颅内主动脉振幅相关性为0.28±0.16。在大多数iNPH患者中，颅内主动脉振幅相关性较低，而在约1/5患者中，相关性较高（平均Pearson相关系数>  0.4）。相关程度几乎不受全身血流动力学参数的影响。

结论

在本研究的约1/5 iNPH患者中，颅内主动脉振幅相关性（IAAC _AORTIC）较高（平均Pearson相关系数 > 0.4），表明脑血管因素在一定程度上可能影响部分患者的ICP波幅值。但是，在14/19（74％）ICP波振幅升高的iNPH患者中，颅内主动脉振幅相关性较低，这表明大多数iNPH患者的ICP脉冲振幅均独立于中央血管兴奋性，因此，它受到局部脑脊髓的调节生理。为支持这一假设，颅内主动脉振幅相关性与大多数全身血流动力学变量无关。在全身血管阻力高的患者亚组中发现一个例外，存在相关性。