Shapiro K, Fried A
J Neurosurg. 1986 Mar;64(3):390-6. doi: 10.3171/jns.1986.64.3.0390.
The pressure-volume index (PVI) technique of bolus manipulation of cerebrospinal fluid (CSF) was used to measure neural axis volume buffering capacity and resistance to absorption of CSF (Ro) in 20 shunt-dependent hydrocephalic children acutely ill from shunt malfunction. All children had had ventricles that were near normal or subnormal in size when the shunts were functioning. The mean intracranial pressure (ICP, +/- standard deviation (SD] at the time of revision was 10.6 +/- 6.4 mm Hg. The mean measured PVI (+/- standard error of the mean) was 18.4 +/- 1.1 ml compared to the normal PVI of 17.5 +/- 4.4 ml (+/- SD) predicted for these children. According to paired t-tests, these measured values were similar to those predicted on the basis of neural axis volume for each child, indicating that these children had normal neural axis volume buffering capacity. While the study was in progress, abrupt increases of ICP were documented in all children. These waves were observed spontaneously as well as in response to the addition of volume to the neural axis. In each child a specific threshold pressure along the pressure-volume curve corresponded to the appearance of unstable ICP. The threshold pressures at which this occurred corresponded to a mean neural axis compliance of 0.32 +/- 0.07 ml/mm Hg (+/- SD). The Ro varied as a function of ICP. The Ro measured at ICP's below 15 mm Hg ranged from 2 to 7.5 mm Hg/ml/min and rose to 12 to 30 mm Hg/ml/min at pressures in the 20 to 25 mm Hg range. The results of this study indicate that neural axis volume buffering capacity is normal in shunt-dependent children who respond to shunting by reconstitution of the cortical mantle. This study indicates that the proximate cause of their abrupt clinical deterioration is unstable ICP, which occurred at a similar point on the pressure-volume curve of all children studied. The correlation of Ro to ICP suggests that CSF absorption does not increase in these children as ICP rises, resulting in movement along relatively normal pressure-volume curves. The functional implications of these parameters are discussed.
采用推注脑脊液（CSF）的压力 - 容积指数（PVI）技术，对20名因分流装置故障而急性发病的分流依赖性脑积水儿童的神经轴容积缓冲能力和脑脊液吸收阻力（Ro）进行测量。所有儿童在分流装置正常工作时，脑室大小接近正常或低于正常水平。翻修时的平均颅内压（ICP，±标准差[SD]）为10.6±6.4 mmHg。测量得到的平均PVI（±平均标准误差）为18.4±1.1 ml，而根据这些儿童预测的正常PVI为17.5±4.4 ml（±SD）。根据配对t检验，这些测量值与基于每个儿童神经轴容积预测的值相似，表明这些儿童具有正常的神经轴容积缓冲能力。在研究过程中，所有儿童均记录到ICP的突然升高。这些波动在自发情况下以及向神经轴添加容积后均可观察到。在每个儿童中，压力 - 容积曲线上的一个特定阈值压力与不稳定ICP的出现相对应。出现这种情况的阈值压力对应的平均神经轴顺应性为0.32±0.07 ml/mmHg（±SD）。Ro随ICP变化。在ICP低于15 mmHg时测量的Ro范围为2至7.5 mmHg/ml/min，在压力为20至25 mmHg范围内时升至12至30 mmHg/ml/min。本研究结果表明，对于通过重建皮质被膜对分流作出反应的分流依赖性儿童，其神经轴容积缓冲能力正常。本研究表明，他们临床突然恶化的直接原因是不稳定的ICP，这在所有研究儿童的压力 - 容积曲线上的相似点出现。Ro与ICP的相关性表明，随着ICP升高，这些儿童的脑脊液吸收并未增加，导致沿着相对正常的压力 - 容积曲线移动。讨论了这些参数的功能意义。
