成人Chiari畸形Ⅰ型后颅窝线性容积特征与小脑扁桃体下疝程度和脊髓空洞的相关性分析

Morphometric analysis of posterior fossa in adult Chiari malformation type Ⅰ and its correlation with syringomyelia and the extent of cerebellar tonsillar displacement

中文关键词:  成人Chiari畸形  后颅窝线性容积  影像学分析  脊髓空洞

英文关键词:Adult Chiari malformation type Ⅰ  Posterior fossa volume  Morphometric analysis  Syringomyelia

中文摘要:

  【摘要】 目的：探讨成人Chiari畸形Ⅰ型（Chiari malformation type Ⅰ，CMⅠ）患者后颅窝线性容积特征及其与脊髓空洞和小脑扁桃体下疝程度之间的相关性。方法：收集2010年6月~2014年6月在我院接受治疗的CMⅠ患者，入选标准为：（1）年龄＞30岁；（2）经头颈部MRI确诊为CMⅠ伴或不伴脊髓空洞；所有入选患者均排除颅内占位性病变、颅骨破坏、后颅窝手术史或获得性Chiari畸形。选取年龄匹配的正常成人作为对照组，测量两组头颅正中矢状位MRI中斜坡长度、枕骨大孔横径、枕上长度、后颅窝矢状径、后颅窝高径和后颅窝斜坡倾斜角α等指标，并将两组按性别分组后比较后颅窝线性容积差异。同时根据小脑扁桃体下疝程度及是否伴发脊髓空洞进行分组，分析后颅窝线性容积特征与小脑扁桃体下疝程度及脊髓空洞的关系。结果：共纳入CMⅠ患者37例，男18例，女19例；年龄38.5±5.5岁（31～56岁）。正常对照组41例，男19例，女22例；年龄36.4±6.3岁（33～58岁），成人CMⅠ患者后颅窝斜坡长度、枕上长度、后颅窝矢状径、后颅窝高径及斜坡倾斜角分别为35.9±4.2mm、38.2±5.8mm、77.4±6.1mm、28.2±3.9mm和47.4°±6.4°，均明显小于正常对照组（43.3±2.9mm、43.5±5.6mm、82.5±4.5mm、35.4±3.4mm、58.6°±5.7°，P＜0.05）；伴脊髓空洞的成人CMⅠ组患者斜坡倾斜角（45.8°±7.6°）较单纯CMⅠ组（49.7°±5.1°）显著减小；Ⅱ度扁桃体下疝CMⅠ患者的后颅窝斜坡长度（31.4±3.6mm）及倾斜角（42.3°±5.4°）明显小于Ⅰ度扁桃体下疝CMⅠ患者（36.2±3.8mm、48.1°±5.2°；P＜0.05），余指标未见明显差异。结论：成人CMⅠ患者的后颅窝容积明显减少，但与脊髓空洞和扁桃体下疝程度之间无显著相关性；CMⅠ患者斜坡发育不良与脊髓空洞的形成以及小脑扁桃体下疝程度存在一定相关性。

英文摘要:

  【Abstract】 Objectives: To determine the characteristics of the posterior fossa linear volume in adult patients with Chiari malformation type Ⅰ(CMⅠ) and its association with the extent of cerebellar tonsillar displacement and syringomyelia. Methods: A retrospective radiographic study was performed on adult patients with CMⅠ who were treated in our hospital between June 2010 and June 2014. The inclusion criteria were as followings: (1)age more than 30 years old; (2)the diagnosis of CMⅠ in each patient was confirmed by a combined head and cervical spine MRI; (3)patients with skull fracture or other diseases which can lead to secondary CMⅠ were excluded. Age-matched healthy adults were recruited as control group. The length of clivus, the anteroposterior diameter of foramen magnum, the length of supraocciput, the anteroposterior diameter of posterior fossa, the posterior fossa height and the clivus angle were measured on the mid-sagittal MRI images to compare the posterior fossa volme between adults CMⅠ patients and controls. Then a further analysis was performed to determine the association between the posterior fossa volum in adult CMⅠ patients and the severity of cerebellar tonsillar displacement as well as the syringomyelia. Results: 37 CMⅠ patients (18 males and 19 females) with a mean age of 38.5±5.5(31-56) years old were recruited in this study. 41 healthy adults(19 males and 22 females) were recruited as the control group with a mean age of 36.4±6.3(33-58) years old. The length of clivus, the length of supraocciput, the anteroposterior diameter of posterior fossa, the posterior fossa height and the clivus angle of CMⅠ patients were 35.9±4.2mm, 38.2±5.8mm, 77.4±6.1mm, 28.2±3.9mm and 47.4°±6.4° respectively, which differed significantly with the indexes in the control group(43.92±2.9mm, 43.5±5.6mm, 82.5±4.5mm, 35.4±3.4mm and 58.6°±5.7°, P＜0.05). The clivus angle was significantly smaller in CMⅠ patients with syingomyelia than that in those without syingomyelia(45.8°±7.6° vs. 49.7°±5.1°, P＜0.05). The length and angle of clivus were significantly smaller in CMⅠ patients with Ⅱ grade tonsillar descent(31.4±3.6mm and 42.3°±5.4°) than those in grade Ⅰ patients(36.2±3.8mm and 48.1°±5.2°, P＜0.05). Conclusions: The bony component of posterior fossa decreases in adult CMⅠ patients, but it is not correlated to the presence of syringomyelia or the severity of cerebellar tonsillar denscent. Maldevelopment of clivus is correlated to the presence of syringomyelia and the severity of cerebellar tonsillar denscent in CMⅠ patients.