Association Between G-protein Coupled Receptor 126 Gene Polymorphism And Adolescent Idiopathic Scoliosis And Morphometric Analysis Of The Posterior Possa In Adolescents With Chiari Malformation Or Idiopathic Syringomyelia

Part one:Association between G-protein coupled receptor 126 gene polymorphism and adolescent idiopathic scoliosisObjective To investigate whether the G-protein coupled receptor 126 (GPR126) gene polymorphisms were associated with the occurrence or curve severity of adolescent idiopathic scoliosis (AIS).Materials and Methods 742 AIS patients from May 2005 to August 2011 and 764 normal controls from March 2005 to January 2011 were recruited. The Cobb angles were≥ 10°in all AIS patients. According to the previous studies, rs6570507 from GPR126 gene were selected. RT-PCR was used to detect and analyze GPR126 gene distribution in AIS group and control group.Results The genotype and allele frequency distribution in rs6570507 were significantly different between AIS patients and normal controls(x2=8.093 and 7.859, P=0.017 and 0.005). The mean maximum Cobb angle was 32°±12°,31°±12° and 30°±12° in patients with genotype of GG, AG and AA respectively. No significant difference was found among these three groups (P>0.05).Conclusion GPR126 gene is strongly associated with the occurrence but not with the curve severity of AIS.Part two:Correlation between posterior fossa volume and the severity of cerebellar tonsillar descent in patients with Chiari malformation.Objective To compare the posterior fossa volume among patients with various degrees of cerebellar tonsillar descent, and to explore the potential morphometric 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 were 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. Morphoetric 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 terms 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 significant 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). Patients with distending syrinx had a larger clivus gradient in comparison to those with other types of syrinx(p <0.05).Conclusion A shorter and flatter clivus might increase the risk of aggravation of tonsillar descent and have an effect on the progression of syrinx.Part three:Morphometric analysis of the posterior possa in adolescents with idiopathic syringomyeliaObjective To investigate the morphometric characteristics of the posterior fossa in adolescents with idiopathic syringomyelia (IS) and to elucidate their clinical significances.Methods A retrospective radiographic review was performed on 25 adolescents who were diagnosed with IS and treated at our clinic between Januarary 2008 and October 2011. Another cohort of normal adolescents and CMI-S patients, matched with the IS patients by age and gender, were recruited to serve as the control group. six parameters were assessed on mid-sagittal MR images, including the linear parameters (the length of the clivus, the anteroposterior diameter of the foramen magnum, the length of supraocciput, the anteroposterior diameter of the posterior fossa, the posterior fossa height) and the angular parameter (the clivus gradient).Results In the IS group, the length of the clivus ranged from 25.4mm to 48.7mm (mean 38.3mm), the anteroposterior diameter of the foramen magnum ranged from 27.2mm to 44.2mm (mean 33.6mm), the length of supraocciput ranged from 23.6 mm to 48.2mm (mean:36.7mm), the anteroposterior diameter of the posterior fossa ranged from 62.9 mm to 88.4mm (mean 74.3mm), the posterior fossa height ranged from 18.51mm to 43.9mm (mean 31.3mm) and the clivus gradient ranged from 30.0°to 77.0°(mean 56.7°). Significant differences were observed in all six morphometric parameters when comparing the IS group and CMI-S group with the normal group respectively. Additionally, all parameters were similar between the IS and CMI-S groups expect for the clivus gradient, which was significantly larger in the IS group (56.69±10.6°)(P<0.05).Conclusion The posterior fossa in patients with IS, sharing the similar characteristcs with that in patients with CMI-S, is indeed smaller than normal. A steeper clivus is observed in patients with IS when comparing with that in patients with CMI-S.