[Analysis of cervical sagittal parameters on MRI in patients with cervical spondylotic myelopathy].

OBJECTIVE

To analyse the correlation between cervical sagittal parameters of cervical spondylotic myelopathy in different sagittal curvature so as to find out representative cervical sagittal alignment parameters by measuring on MRI.

METHODS

A retrospective analysis was made on the clinical data of 88 patients with cervical spondylotic myelopathy between July 2015 and January 2016. The C 2-C 7 Cobb angle, T 1 slope (T 1S), and C 2-C 7 sagittal vertical axis (C 2-C 7 SVA) were measured on T2-weight MRI. According to C 2-C 7 Cobb angle, the patients were divided into lordosis group (≥10° Cobb angle, 48 cases) and straightened group (0-10° Cobb angle, 40 cases). Intraclass correlation coefficient (ICC) was used for the reliability of measured data, Pearson correlation analysis for correlation between cervical sagittal parameters.

RESULTS

ICC was 0.858-0.946, indicating good consistency of measurement parameters. The C 2-C 7 Cobb angle, T 1S, and C 2-C 7 SVA were (5.6±2.4)°, (22.2±6.7)°, and (10.2±5.4) mm in straightened group, and were (20.1±8.2)°, (23.4±8.9)°, and (8.2±4.6) mm in lordosis group respectively. There was no correlation between the 3 parameters in straighten group ( r=0.100, P=0.510 for T 1S and C 2-C 7 Cobb angle; r=-0.100, P=0.500 for T 1S and C 2-C 7 SVA; r=0.080, P=0.610 for C 2-C 7 Cobb angle and C 2-C 7 SVA). There was positive correlation between T 1S and C 2-C 7 Cobb angle ( r=0.540, P=0.000), negative correlation between T 1S and C 2-C 7 SVA ( r=-0.450, P=0.001), and no correlation between C 2-C 7 Cobb angle and C 2-C 7 SVA ( r=-0.003, P=0.980).

CONCLUSION

For cervical spondylotic myelopathy in patients with cervical lordosis, only T 1S measurement on MRI can be used as the main parameter to judge the sagittal curvature, but in patients with straightened cervical Cobb angle, measurements of T 1S, C 2-C 7 Cobb angle, and C 2-C 7 SVA should be taken for the comprehensive evaluation of cervical sagittal curvature.