Comparison of the pulmonary function between adolescent patients with Chiari malformation associated scoliosis and idiopathic scoliosis

Objective To compare the pulmonary function between adolescent patients with Chiari malformation associated scoliosis (CMS) and adolescent idiopathic scoliosis (AIS). Methods A retrospective analysis was performed on 52 patients with CMS, and 52 patients with AIS were selected as the control group to match the CMS patients by age, sex, and Cobb angle. Preoperative pulmonary function tests were completed by all the patients, including vital capacity (VC), forced vital capacity (FVC), forced expiratory volume in one second (FEV1), maximal mid-expiratory flow (MMEF), and ratio of FEV1 to FVC. The difference of pulmonary function parameters was analyzed between the two groups; Correlation between pulmonary function and radiographic parameters was analyzed in patients with CMS. Results There were no significant differences in terms of sex, age, and the main coronal Cobb angle between the two groups. There were 42(80.7%) and 44(84.6%) of patients with restrictive ventilatory dysfunction (the percentage of predicted FVC 0.05). No significant difference was noted between the two groups in the percentage of predicted VC, FVC, FEV1 and FEV1/FVC (P>0.05). The percentage of predicted MMEF in patients with CMS was lower compared to those with AIS[(57.9±13.3)% vs (67.2±23.3)%, P=0.053]. In patients with CMS, the percentage of predicted VC, FVC, FEV1 and MMEF had significantly negative correlation with the number of vertebrae involved (P<0.01). Main coronal Cobb angle had negative correlation with the percentage of predicted VC, FVC and FEV1 (P<0.05). The percentage of predicted VC, FVC and FEV1 had positive correlation with thoracic kyphosis (P<0.05). Conclusions There are no significant differences in characteristics of the pulmonary dysfunction between patients with AIS and CMS without obviously neural deficit. Both groups mainly present with restrictive ventilation dysfunction. Key words: Scoliosis; Chiari malformation; Idiopathic scoliosis; Pulmonary function