Chiari畸形Ⅰ型患者小脑扁桃体下疝程度及脊髓空洞形态与后颅窝容积的相关性

Correlation between posterior fossa volume and the severity of cerebellar tonsillar descent/MR imaging of syringomyeliain patients with Chiari malformation

中文关键词:  Chiari畸形  后颅窝容积  小脑扁桃体下疝  磁共振成像  脊髓空洞症  线性距离

英文关键词:Chiari Malformation  Posterior fossa volume  Cerebellar tonsillar descent  Magnetic resonance imaging  Syringomyelia  Morphometric analysis

中文摘要:

  【摘要】 目的：分析Chiari畸形Ⅰ型（Chiari malformation type Ⅰ， CMⅠ）患者小脑扁桃体下疝程度及脊髓空洞形态与后颅窝线性容积的关系，探讨影响小脑扁桃体下疝程度的后颅窝解剖学因素。方法：2003年6月~2011年6月在我科接受治疗并符合入选标准的CMⅠ患者共59例，男34例，女25例，年龄16~20岁，平均17.9岁，Risser征5级，均有完整MRI资料（包括头枕部及全脊髓矢状面扫描图像）；均无颅内占位性病变、颅骨破坏、后颅窝手术史或获得性Chiari畸形。均伴有不同形态的脊髓空洞，55例（93.2%）伴有不同程度的脊柱侧凸畸形。在MRI T1加权像正中矢状位扫描层面上评估患者的小脑扁桃体下疝程度和脊髓空洞类型；测量后颅窝斜坡长度、枕骨大孔前后径、枕骨鳞部长度、后颅窝矢状径、后颅窝高径和斜坡倾斜角。将CMⅠ患者按照小脑扁桃体下疝严重程度分为三度：Ⅰ度，小脑扁桃体下缘超过枕骨大孔水平5mm但没有到达C1后弓上缘；Ⅱ度，小脑扁桃体下缘尾向移位超过C1后弓上缘但未超过C1后弓下缘；Ⅲ度，小脑扁桃体下缘尾向移位超过C1后弓下缘。依据脊髓空洞类型分为膨胀型、念珠型、细长型和局限型四组。比较不同组间后颅窝线性容积的差异，并对相关指标进行相关性分析。结果：Ⅰ度扁桃体下疝CMⅠ患者的后颅窝斜坡长度明显大于Ⅱ、Ⅲ度扁桃体下疝CMⅠ患者（P＜0.05），Ⅲ度扁桃体下疝患者的斜坡倾斜角较Ⅰ、Ⅱ度患者明显减小（P＜0.05），其余指标三组间无显著性差异；CMⅠ患者的斜坡倾斜角与小脑扁桃体下疝程度之间存在显著性负相关关系（r=-0.626，P=0.005）。膨胀型脊髓空洞患者的斜坡倾斜角显著小于其他类型的脊髓空洞患者（P＜0.05），其余指标各类型之间无显著性差异。结论：后颅窝斜坡短平可能是促使CMⅠ患者小脑扁桃体下疝加重的重要因素之一，同时对CMⅠ患者的脊髓空洞的形成和发展也存在影响。

英文摘要:

  【Abstract】 Objectives: To compare the posterior fossa volume among patients and magnetic resonance imaging of syringomyelia with various degrees of cerebellar tonsillar descent, and to explore the potential anatomical factors of cerebellar tonsillar descent. Methods: A total of 59 patients with Chiari malformation type Ⅰ(CMⅠ) treated in our center from June 2003 to June 2011 was recruited. On mid-sagittal magnetic resonance images, the degree of tonsillar descent, configuration of syrinx, clivus length, anteroposterior diameter of the foramen magnum, supraocciput length, anteroposterior diameter of the posterior fossa, osteal posterior fossa height and clivus gradient were measured. Morphometric analysis was conducted among patients with different degrees of cerebellar tonsillar descent and with various patterns of syrinx configuration, respectively. Results: There were no significant differences in the results of anteroposterior diameter of the foramen magnum, supraocciput length, anteroposterior diameter of the posterior fossa and osteal posterior fossa height among patients with various degrees of tonsillar descent(P>0.05) and with various patterns of syrinx configuration(P>0.05). The clivus length in patients with grade Ⅰ tonsillar discent was significantly longer than that in patients with grade Ⅱ or Ⅲ tonsillar descent(P＜0.05). The clivus gradient in patients with grade　Ⅲ tonsillar discent was significantly smaller than that in patients with grade Ⅰ or Ⅱ tonsillar descent(P＜0.05). The analytic results showed that the result of clivus gradient had remarkable negative correlation with the degree of tonsillar descent(r=-0.626, P=0.005). Patients with distending syrinx had a larger clivus gradient in comparison with those with other types of syrinx(P＜0.05). Conclusions: A shorter and flatter clivus can increase the risk of aggravation of tonsillar descent and has an effect on the progression of syrinx.