Yamada Shigeki
Department of Neurosurgery, Shiga University of Medical Science.
No Shinkei Geka. 2021 Mar;49(2):317-327. doi: 10.11477/mf.1436204393.
Hydrocephalus is caused by excessive accumulation of cerebrospinal fluid(CSF)in the ventricles or the skull. Unlike acute hydrocephalus presenting with elevated intracranial pressure, chronic hydrocephalus is called normal-pressure hydrocephalus(NPH). Because the CSF volume increases slowly, the brain compressively deforms without increasing intracranial pressure. NPH should be diagnosed and treated according to the following three categories: idiopathic NPH(iNPH), secondary NPH(sNPH), and congenital NPH(cNPH). The intracranial CSF distribution in iNPH differed from that in sNPH or cNPH. In iNPH, the Sylvian fissure and basal cistern were conspicuously enlarged, whereas the convexity subarachnoid space was severely decreased. CSF distribution in the subarachnoid space specific to iNPH is known as "disproportionately enlarged subarachnoid space hydrocephalus(DESH)," which might be due to direct CSF communication between the lateral ventricles and the basal cistern at the inferior choroidal point of the choroidal fissure. After shunt surgery in a patient with NPH, the lateral ventricles and Sylvian fissure shrank from top to bottom, while the convexity subarachnoid space expanded. In NPH, except for obstructive hydrocephalus, the flow void sign on spin-echo T2-weighted images is usually observed around the aqueduct, which reflects the increased CSF movement.
脑积水是由脑室或颅骨内脑脊液（CSF）过度积聚引起的。与表现为颅内压升高的急性脑积水不同，慢性脑积水被称为正常压力脑积水（NPH）。由于脑脊液量缓慢增加，大脑在不增加颅内压的情况下发生压缩性变形。NPH应根据以下三类进行诊断和治疗：特发性NPH（iNPH）、继发性NPH（sNPH）和先天性NPH（cNPH）。iNPH中的颅内脑脊液分布与sNPH或cNPH中的不同。在iNPH中，大脑外侧裂和基底池明显扩大，而脑凸面蛛网膜下腔严重缩小。iNPH特有的蛛网膜下腔内脑脊液分布被称为“蛛网膜下腔不成比例扩大性脑积水（DESH）”，这可能是由于脉络膜裂下脉络点处侧脑室与基底池之间脑脊液直接相通所致。NPH患者进行分流手术后，侧脑室和大脑外侧裂从上到下缩小，而脑凸面蛛网膜下腔扩大。在NPH中，除梗阻性脑积水外，自旋回波T2加权图像上通常在导水管周围观察到流空信号，这反映了脑脊液运动增加。
