Takagi Kiyoshi, Watahiki Ryota, Machida Toru, Onouchi Kenji, Kato Kazuyoshi, Oshima Marie
Normal Pressure Hydrocephalus Center, Kashiwatanaka Hospital, Kashiwa (Current institute: Normal Pressure Hydrocephalus Center, Nagareyama Central Hospital, Nagareyama), Tsukuba, Japan.
Department of Mechanical and Biofunctional Systems, Institute of Industrial Science, The University of Tokyo, Tsukuba, Japan.
Asian J Neurosurg. 2020 Feb 25;15(1):107-112. doi: 10.4103/ajns.AJNS_354_19. eCollection 2020 Jan-Mar.
The image diagnosis of idiopathic normal-pressure hydrocephalus (iNPH) is based on the ventriculomegaly, whose criterion is an Evans' Index (EI) >0.3. Recently, disproportionately enlarged subarachnoid space hydrocephalus (DESH) has been proposed as a morphological characteristic to iNPH. Several studies cast doubt on the reliability of these criteria in the diagnosis of iNPH. Furthermore, interobserver differences of these criteria have not yet been investigated. The objective of this study was to assess the diagnostic reliability and interobserver variability of EI and DESH.
The preoperative magnetic resonance (MR) images of 84 definite iNPH patients were retrospectively evaluated by a neuroradiologist (NR) and physical therapist (PT). They independently assessed the EI and DESH. The MR images were evaluated preoperatively by a neurosurgeon (NS). The results were showed in mean (standard deviation).
The mean age was 78.4 (6.3) years (male:female = 49:35). The mean EI was 0.33 (0.04), 0.32 (0.04), and 0.31 (0.03) for NS, NR, and PT, respectively ( < 0.0001). The rate of accurate diagnosis of iNPH with EI >0.3 was 74%, 66%, and 61% for NS, NR, and PT, respectively, and there was a moderate level of agreement. By contrast, there was a substantial lower level of accuracy in assessment with DESH for all three evaluators as 50%, 44%, and 27% for NS, NR, and PT, respectively, again with a moderate level of agreement. However, the rates of patients fulfilling both EI >0.3 and DESH were remarkably lower than either of the two parameters individually at a mere 37%, 30%, and 16% for NS, NR, and PT, respectively, with a low level of agreement between the rates.
This study suggests that DESH cannot be a diagnostic criterion for iNPH. If EI >0.3 and DESH were both necessary to diagnose iNPH, then more than 70% of patients would have been misdiagnosed and would have been deprived of the chance of treatment and its benefits. These results request a paradigm shift in the concepts of iNPH.
特发性正常压力脑积水（iNPH）的影像学诊断基于脑室扩大，其标准是Evans指数（EI）>0.3。最近，提出蛛网膜下腔不成比例扩大性脑积水（DESH）作为iNPH的一种形态学特征。几项研究对这些标准在iNPH诊断中的可靠性提出质疑。此外，尚未对这些标准的观察者间差异进行研究。本研究的目的是评估EI和DESH的诊断可靠性及观察者间变异性。
一名神经放射科医生（NR）和一名物理治疗师（PT）对84例确诊的iNPH患者的术前磁共振（MR）图像进行回顾性评估。他们独立评估EI和DESH。术前由一名神经外科医生（NS）对MR图像进行评估。结果以平均值（标准差）表示。
平均年龄为78.4（6.3）岁（男:女 = 49:35）。NS、NR和PT的平均EI分别为0.33（0.04）、0.32（0.04）和0.31（0.03）（<0.0001）。EI>0.3时iNPH的准确诊断率，NS为74%，NR为66%，PT为61%，一致性为中等水平。相比之下，所有三位评估者使用DESH评估的准确率大幅降低，NS为50%，NR为44%，PT为27%，一致性同样为中等水平。然而，同时满足EI>0.3和DESH的患者比例显著低于单独的两个参数，NS为37%，NR为30%，PT为16%，各比例之间的一致性较低。
本研究表明DESH不能作为iNPH的诊断标准。如果EI>0.3和DESH都是诊断iNPH所必需的，那么超过70%的患者会被误诊，从而失去治疗机会及其益处。这些结果要求对iNPH的概念进行范式转变。
