特发性脊柱侧凸患者小脑扁桃体位置与后颅窝容积关系的影像学观察

A morphometric analysis on the correlation between position of cerebellar tonsil and posterior fossa volume in the patients with idiopathic scoliosis

中文关键词:  特发性脊柱侧凸  小脑扁桃体  生理性下疝  后颅窝容积

英文关键词:Idiopathic scoliosis  Cerebellar tonsil  Physiological herniation  Posterior fossa volume

中文摘要:

  【摘要】 目的：比较特发性脊柱侧凸（idiopathic scoliosis，IS）患者与年龄匹配的非脊柱畸形患者后颅窝容积的差异，探讨IS患者后颅窝发育异常与小脑扁桃体生理性下疝的关系。方法：从2009年1月至2011年6月我科收治的500例IS患者中选取70例年龄16~20岁、Risser征5级、术前行站立位全脊柱正侧位X线片及颈枕部MRI检查的患者为研究对象（A组），男48例，女22例，侧凸平均Cobb角51.2°±14.1°。选取年龄匹配的58例非脊柱畸形患者作为对照组（B组），男27例，女31例。测量两组研究对象头颈正中矢状位MRI中小脑扁桃体下缘超出枕骨大孔连线（AB线）的距离（d值）、枕骨大孔前后径（AB）、斜坡长度（AD）、枕上长度（BC）以及后颅窝矢状径（CD），比较两组小脑扁桃体位置及后颅窝容积差异。根据MRI表现，将IS组患者分为伴生理性小脑扁桃体下疝组（A1组）和不伴生理性小脑扁桃体下疝组（A2组），分析后颅窝容积与小脑扁桃体生理性下疝间关系及主弯Cobb角与小脑扁桃体生理性下疝程度的相关性。结果：A组d值和枕骨大孔前后径明显大于B组（P<0.05），而AD、BC以及CD均明显小于B组（P<0.05）。A组患者d值与主弯Cobb角无显著相关性（P>0.05），其生理性小脑扁桃体下疝发生率为22.9%，A1组患者BC显著小于A2组患者（P<0.05），AB、AD、CD两组间均无显著性差异（P>0.05）。结论：IS患者小脑扁桃体位置低可能与其后颅窝枕骨大孔增大而斜坡、枕骨发育受限有关，IS患者成骨异常可能也影响到了其后颅窝发育。

英文摘要:

  【Abstract】 Objectives: To compare the posterior fossa volume of idiopathic scoliosis(IS) patients with that of age-matched healthy adolescents and to determine the correlation between position of cerebellar tonsil and posterior fossa volume in IS patients. Methods: A retrospective radiographic study was performed on 500 patients with IS who received surgical treatment at our center between January 2009 and June 2011. 70 IS patients(group A) were selected with the following inclusion criteria: (1)age ranged from 16 to 20 years, and the Risser sign was 5; (2)each patient had a posteroanterior standing X-ray and a combined head and cervical spine MRI scan. Of them, there were 48 males and 22 females. The Cobb angle of scoliosis was 51.2°±14.1°. 58 age-matched healthy adolescents were recruited as controls. Of them, there were 27 males and 31 females. On sagittal MRI images, the position of the cerebellar tonsil was evaluated by the distance(d) between the inferior pole of cerebellar tonsil and the line connecting the basion and opisthion(AB line). And 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 on mid-sagittal MRI images to make a comparison of the posterior fossa volume between the IS patients and controls. Then a further analysis was performed to determine whether there was significant difference of the posterior fossa volume between IS patients with(group A1) and without physiological tonsillar ectopia(group A2). Then the correlation between curve magnitude and posterior fossa volume was also investigated in this study. Results: It was shown that the positions of cerebellar tonsil in group A were significantly lower than the positions in group B(P<0.05). The incidence of physiological tonsillar ectopia in IS was found to be 22.9%. Significant increment in anteroposterior diameter of the foramen magnum(AB) was found in group A compared to group B(P<0.05), while significant decrements were found in the three remaining indexes(P<0.05). However, Cobb angles of the main curve in group A were found to be not correlated with positions of cerebellar tonsil. Significant difference in no index but the length of supraocciput(BC) was found in IS patients with physiological tonsillar ectopia(group A1) compared to IS patients without physiological tonsillar ectopia(group A2). Conclusions: The high incidence of physiological tonsillar ectopia in IS patients might be caused by the heteroplasia of posterior fossa, indicating that abnormal growth kinetics of endochondral and membranous ossification could be found in the development of posterior fossa.