MR imaging characteristics of posterior cranial fossa in Chiari malformation type I patients
10.3760/cma.j.cn115354-20200206-00060
- VernacularTitle:Chiari畸形Ⅰ型患者后颅窝MRI特点研究
- Author:
Feng LU
1
;
Guangming ZENG
Author Information
1. 福建省立医院南院神经外科，福州 350001
- Keywords:
Chiari malformation type I;
Magnetic resonance imaging;
Cerebellar tonsillar herniation;
Cranial spinal angle
- From:
Chinese Journal of Neuromedicine
2020;19(12):1253-1259
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To investigate the MR imaging characteristic changes of posterior cranial fossa in patients with Chiari malformation type I (CMI) and the pathogenesis of CMI.Methods:A total of 110 patients with CMI accepted posterior fossa decompression in our hospital from January 2013 to June 2017 were chosen as CMI group; 30 healthy subjects with matched gender and age were chosen as control group. On the median sagittal plane of MR imaging, Picture Archiving and Communication System (PACS) software was used to measure the length of clivus, anteroposterior diameter of the foramen magnum, supraocciput length, anteroposterior diameter of the posterior cranial fossa, height of the posterior cranial fossa, inclination angle of the clivus, and cranial spinal angle; and statistical analysis of rank sum test was performed on the above measured results. According to the degrees of cerebellum tonsillar herniation, 110 patients with CMI were classified into groups of degree I, II and III; the clinical data and measurement data of these patients were compared. The independent influencing factors for CMI were analyzed by binary Logistic regression. Correlations of cerebellar subtonsil hernia degree and whether combining with spinal cavity or not with other clinical data and measurement data in CMI patients were analyzed.Results:The length of clivus, supraocciput length, height diameter of the posterior fossa, and inclination angle of clivus were significantly decreased, and cranial spinal angle was significantly increased in CMI group as compared with those in the control group ( P<0.05); the results of binary Logistic regression analysis showed that supraocciput length and inclination angle of clivus were independent risk factors for CMI ( OR=0.057, 95%CI: 0.005-0.650, P=0.021; OR=0.730, 95%CI: 0.592-0.902, P=0.004). (2) The anteroposterior diameter of the foramen magnum in patients from groups of degree II and III was significantly longer than that in patients from group of degree I ( P<0.05); the inclination angle of clivus in patients from group of degree III was significantly larger than that in patients from groups of degree I and II (P<0.05). In CMI patients, the degree of cerebellum tonsillar herniation was negatively correlated with body mass index and inclination angle of clivus ( r=-0.214, P=0.045; r=-0.271, P=0.006), and positively correlated with anteroposterior diameter of the foramen magnum and cranial spinal angle ( r=0.336, P=0.001; r=0.282, P=0.004). Whether combining with spinal cavity or not was positively correlated with length of the clivus in patients with CMI ( r=0.235, P=0.018). Conclusions:The abnormal bony development of the posterior fossa in malformed patients leads to small posterior fossa volume, which is not suitable for the normal development of posterior brain nerve tissue volume. The smaller length of clivus, supraocciput length and inclination angle of clivus are the congenital factors for occurrence of cerebellar tonsillar herniation. Increase of cranial spinal angle may be the acquired reason for worsening of cerebellar tonsillar herniation. The degeneration of atlantoaxial and occipital joints may be involved in the changes of cranial spinal angle.
