The natural history of radiological presentations in Chiari malformation type I with scoliosis: a cross-sectional study

Objective To investigate the radiological presentations in relation to different ages in scoliosis associated with Chiari malformation typeⅠ(CMI). Methods A retrospective analysis was performed on 80 patients diagnosed with scoliosis associated with CMI from June 2010 to June 2018, who were classified into three groups according to their age: Children(age≤10 years), Adolescents (age 11-18 years) and Adults (age≥19 years). Curves were classified into typical and atypical patterns in the coronal plane. The coronal and sagittal radiographical parameters were measured in the three groups. Moreover, cerebellar tonsillar descent and syringomyelia patterns were measured on MRI, and the parameters among the three groups were compared statistically. Results The incidence of atypical curve patterns in Children (10 patients), Adolescents (44 patients) and Adults (26 patients) was 30.0%, 15.9%, and 50.0%, respectively (χ2=2.654, P=0.265). There was no statistical difference in the distribution of curve patterns among CMI patients with different age. In the coronal profile, Cobb angle (F=16.751, P<0.001) and flexibility (F=3.285, P=0.044) of main curve, Cobb angle of secondary curve (F=9.805, P<0.001) and coronal balance(CB) (F=5.249, P=0.007) showed statistical difference. The elderly patients tended to have larger Cobb angle of main and secondary curve with worse flexibility of main curve, and CB in Adolescents was better than the other two groups. In the sagittal profile, TK (F=4.324, P=0.017), LL (F=4.590, P=0.013), PI (F=5.501, P=0.006), and PT (F=3.220, P=0.045) showed statistical difference in the three groups, which were increasing significantly with aging. MRI parameters showed that younger patients were more likely to have a higher degree of cerebellar tonsillar descent (χ2=18.479, P<0.001) and distended syringomyelia (χ2=23.074, P=0.003). Conclusion With aging, Cobb angle of main curve is progressive, and the flexibility is worse, suggesting that early surgical intervention should be performed to reduce the risk of surgery. In addition, cerebellar tonsillar descent and syringomyelia in elderly patients are milder than young patients, indicating that there might be spontaneous remission. Key words: Arnold-Chiari malformation; Scoliosis; Syringomyelia; Age factors; Cross-sectional studies