Investigation of the optimal shunt properties for the treatment of hydrocephalus

为了评价分流系统在人体内的压力环境，我们测量了仰卧和坐位分流系统的颅内压(ICP)、腹内压(IAP)和静水压力。坐位时IAP的升高和ICP值的降低抵消了虹吸效应。自体脑脊液的容量负荷为3ml会引起颅内压升高，根据压力变化可计算出颅内弹性(连续推注法)。我们用这种方法阐明了大范围颅内压的压力-弹性关系。在正常范围内，可见仰卧位为单谷，坐位为双谷的低弹力区。在高颅内压时，其抬高速度减慢。低弹性环境似乎是分流治疗的目标，因为颅内压在低弹性状态下变得活跃。另外，我们还测量了颅内氧合、氧合b、脱氧Hb和脑氧合。在NPH患者中，颅内压轻度升高导致氧合Hb降低，脑氧合功能降低。这一发现对NPH的发病机制非常重要。这些结果提示，颅内压、颅内弹性和脑氧合似乎是分流治疗的良好指标。

To evaluate the pressure environment of the shunt system in the human body, we measured the intracranial pressure (ICP), intra-abdominal pressure (IAP), and hydrostatic pressure of the shunt system in supine and sitting position. The increase in IAP and decrease in ICP offset the siphoning effect in the sitting position. The preferable ICP is estimated between -15 and -20 mmHg in the sitting position.The volume load of autologos CSF of 3ml causes the increase in ICP and the intracranial elastance can be calculated from the pressure change (serial bolus injection method). We elucidated the pressure-elastance relationship of wide range of ICP using this method. In the normal range of ICP low elastance area with single valley in the supine position and double valleys in the sitting position was seen. In the high ICP its elevation rate was decelerated. The low elastance circumstance is seemed to be the goal of shunt therapy because the ICP becomes actable in the low elastance.We measured intracranial oxygenation, oxy-b, deoxyHb, and brain oxygenation additionally. In the NPH patients, slight increase in ICP caused the decrement of oxyHb and brain oxygenation. This finding is very important for pathogenesis of NPH.These findings suggested that the ICP, intracranial elastance, and brain oxygenation seems to become a good indicator of the shunt therapy.