Both aging and changes in blood flow velocity between the extracranial (intraspinal) and intracranial regions of cerebral vessels have an impact on brain hydro-hemodynamics. Arterial and venous cerebral blood flows interact with cerebrospinal fluid (CSF) in the both the cranial and spinal systems. Studies suggest that increased blood and CSF flow pulsatility plays an important role in certain neurological diseases. Here, we investigated the changes in blood-CSF flow pulsatility in the cranial and spinal systems with age as well as the impact of the intracranial compartment on flow patterns. Phase-contrast magnetic resonance imaging (PC-MRI) was performed in 16 young and 19 elderly healthy volunteers to measure the flows of CSF and blood. CSF stroke volume (SV), blood SV, and arterial and venous pulsatility indexes (PIs) were assessed at intra- and extracranial levels in both samples. Correlations between ventricular and spinal CSF flow, and between blood and CSF flow during aging were also assessed. There was a significant decrease in arterial cerebral blood flow and intracranial venous cerebral blood flow with aging. We also found a significant increase of intracranial blood SV, spinal CSF SV and arterial/venous pulsatility indexes with aging. In regard to intracranial compartment impact, arterial and venous PIs decreased significantly at intracranial level in elderly volunteers, while young adults exhibited decrease in venous PI only. Intracranial venous PI was paradoxically lower than extracranial venous PI, regardless of age. In both sample groups, spinal CSF SV and aqueductal CSF SV were positively correlated, and so were extracranial blood and spinal CSF SVs. The study demonstrates that aging changes blood flow but preserves blood and CSF interactions. We also showed that many parameters related to blood and CSF flows differ between young and elderly adults.

中文翻译：

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衰老过程中颅外与颅内流体血流动力学的比较：PC-MRI 试点横断面研究

脑血管的颅外（椎管内）和颅内区域之间的老化和血流速度的变化都会对脑流体血流动力学产生影响。动脉和静脉脑血流与颅骨和脊柱系统中的脑脊液 (CSF) 相互作用。研究表明，增加的血液和脑脊液流动脉动在某些神经系统疾病中起着重要作用。在这里，我们研究了颅骨和脊柱系统中血液-CSF 流动脉动随年龄的变化以及颅内隔室对流动模式的影响。对 16 名年轻健康志愿者和 19 名老年健康志愿者进行了相位对比磁共振成像 (PC-MRI)，以测量 CSF 和血液的流量。脑脊液每搏输出量 (SV)、血液 SV、在两个样本的颅内和颅外水平评估动脉和静脉搏动指数 (PI)。还评估了心室和脊髓脑脊液流量之间的相关性，以及衰老过程中血液和脑脊液流量之间的相关性。随着年龄的增长，动脉脑血流量和颅内静脉脑血流量明显减少。我们还发现随着年龄的增长，颅内血 SV、脊髓 CSF SV 和动脉/静脉搏动指数显着增加。在颅内隔室影响方面，老年志愿者在颅内水平的动脉和静脉 PI 显着降低，而年轻人仅表现出静脉 PI 的降低。无论年龄如何，颅内静脉 PI 都低于颅外静脉 PI。在两个样本组中，脊髓CSF SV和导水管CSF SV呈正相关，颅外血和脊髓CSF SV也呈正相关。该研究表明，衰老会改变血流，但会保留血液和脑脊液的相互作用。我们还表明，与血液和脑脊液流量相关的许多参数在年轻人和老年人之间是不同的。