ChiariI畸形伴脊髓空洞症的MR形态测量研究

MR morphometric study on posterior cranial cavity in Chiari I malformation with syringomyelia

目的:运用MRI对ChiariI畸形伴脊髓空洞的病人进行后颅腔形态学测量,探讨ChiariI畸形伴脊髓空洞的发病机制。方法:选择MRI资料完整,不伴脑积水、肿瘤或外伤所致小脑扁桃体下疝者共114例,年龄3～78岁,平均38.6岁,其中男62例,女52例;其中合并脊髓空洞者共计60例。分别测量枕大孔前后径A,此线上疝出的小脑扁桃体前后径B/小脑扁桃体垂直径C,脊髓空洞长度D及空洞前后径E。测量结果用SPSS10.0统计软件包进行分析,P<0.05认为有统计学差异。结果:A、B、B/A及C在无空洞组和有空洞组间无显著性差异;A、B、B/A与小脑扁桃体下疝程度无相关性,D及E与小脑扁桃体下疝程度呈显著正相关。结论:小脑扁桃体疝入枕大孔平面以下,脑脊液(CSF)不断冲击脊髓中央管,产生“水锤效应(waterhammereffect)”,使中央管不断扩张,甚至浸入周围脊髓实质,形成脊髓空洞。CSF压力的增加和搏动的增强可能导致空洞长度和前后径的不断增加。

Objective： MRI was used to measure the posterior cranial structure in order to find out the pathogenesis of syringomyelia in Chiari I malformation. Methods： The posterior cranial structures were measured on midsagittal MR imaging in 114 patients with the herniation of cerebellar tonsil from 3 -78 years old （the average age was 38.6）, including 62 male and 52 female. There were 60 patients among them with syringomyelia. The anteroposterior diameter（A） of the great occipital foramen, the anteroposterior diameter （B） of the herniated cerebellar tonsil in line A, the vertical diameter （C） of the cerebellar tonsil, the herniated cerebellar tonsil in line A, the vertical diameter（C） of the cerebellar tonsil, the lenght （D） and the anteroposterior diameter（E） of the syringomyelia were measured respectively. SPSS was used for statistical analysis. Results： There was no significant difference in two groups （without and with syringomyelia） in A, B and B/A value. The value of A, B, B/A had no relationship wiht the degree of the herniation of cerebellar tonsil. The value of D and E have the positive correlation with the degree of the herniation of cerebellar tonsil. Conclusion： The herniation of cerebellar tonsil results in continuous impact of the Spinal cord central canal by cranial spinal fluid （CSF）. Subsequently causes the water hammer effect, which dilates the central canal gradually, and finally the syringomyelia occurs. The increase of the CSF pressure and the strengthen of CSF pulsation may caue the gradual enlargement of the lenght and the anteroposterior diameter of the syringomyelia.