Chiari I型畸形患者后颅窝结构异常与脑脊液流体力学改变的定量对比研究及其在后颅窝减压术后临床转归中的意义

Chiari malformation type I (CMI) is part of a pathological continuum of hindbrain malformations and has been increasingly recognized as being one of the major causes of syringomyelia. Despite decades of research, the exact etiology and pathogenesis of syringomyelia remain virtually obscure. The articles we have published recently revealed that some subtle morphometric characteristics of the posterior cranial fossa (PCF) may be the primary anomaly, leading to the formation or propagation of syrinx. Some recent studies also reported the differences in Cerebrospinal Fluid(CSF) flow patterns at the craniocervical junction between CMI patients with and without syringomyelia.. Therefore, by combining the morphological analysis of PCF with MR Imaging with Advanced Computer Program (Diffusion Tensor Imaging and 4D magnetic resonance phase contrast flow imaging) , this study aims to identify the differences of CSF flow patterns and the microstructural alterations of the spinal cord between CMI patients with and without syringomyelia . Furthermore, through the quantitative correlation between the developmental anomalies of the posterior cranial fossa and the dynamic changes of the CSF pattern and spinal cord injury，we expect to explore its prognostic value for predicting the clinical outcomes in CMI patients with syringomyelia treated by foramen magnum decompression.

Chiari I畸形（Chiari I malformation ,CMI）是导致脊髓空洞的常见病因，其发生机制迄今尚不明确。前期我们发表文章报道：伴和不伴有脊髓空洞的CMI患者其后颅窝形态学存在差异。近期相关研究同样发现伴和不伴有脊髓空洞的CMI患者的脑脊液流体力学特征存在明显不同。因此我们猜测CMI患者潜在的后颅窝形态学细微异常可能对脊髓空洞的发生起到重要作用。本项目拟首先采用弥散张量成像和基于四维磁共振相位对比血流成像技术研究，观察CMI患者枕颈区脊髓神经纤维微细结构及脑脊液流体动力学改变，进一步通过传统功能磁共振成像和功能磁共振技术连接等方法，探讨CMI患者的后颅窝特征与脑脊液流动及脊髓空洞发生发展的相关性，为CMI畸形的康复治疗奠定理论基础。

Chiari I型畸形（Chiari malformation Type I, CMI）是一种由于胚胎期后脑先天性发育不良所致的后颅窝（posterior cranial fossa, PCF）结构拥堵，解剖学上表现为小脑扁桃体等结构疝入上颈椎管内超过枕骨大孔5mm的病理状态。CMI患者脊髓空洞的发生率高达50~76%，其可引起空洞累及脊髓节段持续进展的神经损害。目前尚无很好的指标准确地评估和预测患者脊髓空洞的自然进展和转归。我们的前期研究结果发现，一些细微的后颅窝区域形态学异常可能对脊髓空洞的发生发展起到重要作用。.本研究是一项前瞻性研究，共28例CMI患者及12例年龄、性别匹配的健康志愿者被纳入本研究。通过四维流相位对比磁共振成像技术（4D magnetic resonance phase contrast flow imaging, 4D-PC Flow MRI）对CMI畸形PCF形态学特征、脊髓空洞特征与脑脊液（cerebrospinal fluid, CSF）动力学特征的相关性进行深入研究。.研究结果显示，CMI患者后颅窝斜坡倾斜角（∠α）显著减小，且与脊髓空洞大小呈正相关。所有健康志愿者枕颈交界处CSF流动均呈匀质分布。与之形成鲜明对比的是，几乎所有CMI患者CSF流动均显示出异质性流动特征。在非扩张型脊髓空洞（SS）组中，7（43.8%）例患者出现涡流型流型CSF，10（62.5%）例患者为喷射型流型，另有6（37.5%）例出现不稳定湍流型流型。扩张型脊髓空洞(LS)组中，5（41.7%）例出现涡流型流型，6（50%）例出现喷射型流型，5（41.7%）例出现不稳定湍流型流型。4D flow数据的定量分析结果显示脊髓空洞组患者心脏收缩期\舒张期平均CSF流速峰值均较健康对照组显著减小，且与脊髓空洞大小呈正相关。CSF流动参数与后颅窝形态学参数之间的相关性分析显示斜坡倾斜角（∠α）与CSF流速峰值具有统计学相关性。.本研究证实CMI患者CSF动力学特征存在异常，CSF流动参数与后颅窝形态学参数之间的相关性证实了我们前期有关“后颅窝斜坡低平引起的对枕大孔出口前方所产生的‘闸门效应’，可能是促使CMI患者脊髓损伤形成和发展的重要因素之一”这一假说。进一步明确了CMI患者脊髓空洞的病因和发病机制，为建立新的临床诊断评估方法和手段提供了科学依据。