Chiari畸形Ⅰ型患者后颅窝线性容积的MRI测量

Morphometric analysis of the posterior fossa volume in patients with Chiari malformations，MRI measurements

中文关键词:  Chiari畸形  后颅窝容积  线性距离  脊髓空洞

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

中文摘要:

  【摘要】 目的：探讨Chiari畸形Ⅰ型（Chiari Malformation Type Ⅰ，CMI）患者后颅窝容积与小脑扁桃体下疝程度及脊髓空洞间的相关性。方法：患者选自2003年～2010年收治的CMI患者，入选标准为：（1）年龄16～20岁，Risser征5级；（2）经头颈部MRI确诊为CMI伴或不伴脊髓空洞。入选患者均排除可致继发性CMI及颅骨破坏的相关疾病，选取年龄匹配的正常青少年作为对照组，测量两组研究对象头颈正中矢状位MRI中枕骨大孔径（AB），斜坡长度（AD），枕上长度（BC）以及后颅窝矢状径（CD）等指标，并将两组按性别分组后比较后颅窝容积差异。根据MRI影像学表现，将CMI患者按照小脑扁桃体下疝严重程度及是否伴发脊髓空洞进行分组，分析后颅窝容积与小脑扁桃体下疝程度及脊髓空洞间关系。结果：CMI患者共37例，平均年龄17.2岁，男23例（62.2%），女14例（37.8%）。对照组青少年共49例，平均年龄17.5岁，男24例（49.0%），女25例（51.0%）。CMI患者后颅窝各骨性标志间线性距离均明显小于同性别、年龄匹配对照组青少年。Ⅰ度扁桃体下疝CMI患者斜坡长度（AD）明显大于Ⅱ、Ⅲ度扁桃体下疝CMI患者，余指标未见明显差异。CMI伴脊髓空洞患者与单纯CMI患者后颅窝各骨性标志间线性距离亦未见显著性差异。结论：CMI患者存在明显的后颅窝容积减少，斜坡短小可能是促使CMI患者小脑扁桃体下疝加重的重要因素之一，而后颅窝容积减少并非脊髓空洞的主要致病因素。

英文摘要:

  【Abstract】 Objective：To determine the association between the posterior fossa volumes in patients with Chiari malformation type Ⅰ（CMI） and the extent of cerebellar tonsillar displacement as well as syringomyelia.Method：A retrospective radiographic study was performed on patients with CMI，and the inclusion criteria were as followings：（1）age ranging from 16 to 20 years，Risser sign was 5；（2）the diagnosis of CMI in each patient confirmed by a combined head，cervical spine MRI.And age-matched healthy adolescents were recruited as control.On mid-sagittal MRI images，the anteroposterior diameter of the foramen magnum（AB），the length of supraocciput（BC），the anteroposterior diameter of the posterior fossa（CD） and the length of the clivus（AD） were measured to compare the posterior fossa volume between CMI patients and controls.The severity of cerebellar tonsillar descent was classified and the presence of syringomyelia was identified on the sagittal MRI image.Then a further analysis was performed to determine the association between the posterior fossa volume in CMI patients and the severity of cerebellar tonsillar displacement as well as the syringomyelia.Result：37 CMI patients with the mean age of 17.2 year were recruited in this study.Of them，there were 23 males and 14 females.49 normal adolescents with the mean age of 17.5 years were recruited. Of them，there were 24 males and 25 females.Significant differences in all four indexes were found in CMI patients compared with the control group.CMI patients with tonsillar descent of I degree were found to have longer clivus than those with tonsillar descent of Ⅱ or Ⅲ degree.No significant difference of all four indexes was found between CMI patients with or without syringomyelia.Conclusion：The bony components of posterior fossa are malformed in CMI patients，and clivus malformation is critical for cerebellar tonsillar aggravation，while skull malformation may not lead to syringomyelia.