A novel scoring system for the ossification of the posterior longitudinal ligament of the cervical spine based on MRI - CSFM scoring system.

Abstract Objective To establish a new scoring system to asses spinal cord compression of ossification of posterior longitudinal ligament (OPLL) of cervical spine -CSFM score (The acronym CSFM come from four variables, C: Curvature of the spinal cord, S: increased Signal intensity of spinal cord, F: Cerebrospinal Fluid imaging, M: Cross section Morphology of spinal cord). Methods Through literature review and expert advice to determine variables of CSFM score. CSFM score including four variables (C: Curvature of the spinal cord, S: increased Signal intensity of spinal cord, F: Cerebrospinal Fluid imaging, M: Cross section Morphology of spinal cord). From June 2015 to June 2018, the clinical and imaging data of 387 patients with cervical OPLL in our hospital were retrospectively analyzed. The variables (C, S, F, M) were measured and recorded. Different scores were assigned according to the analysis of the relationship between the variables and JOA score. Then two spine surgeons scored the patients according to the CSFM score, and analyzed the internal consistency and reliability of the CSFM score. Results The CSFM scoring system consists of four variables, each of which is divided into four grades. C (Curvature of the spinal cord): The curvatures are parallel between spinal cord and cervical spine and the curvatures are normal; The curvatures are parallel between spinal cord and cervical spine and the curvatures are straight; The curvatures are parallel between spinal cord and cervical spine and the curvatures are kyphosis; The curvatures are not parallel between spinal cord and cervical spine. S (increased Signal intensity of spinal cord): normal signal; Discrete focus; Fuzzy focus; Intramedullary diffuse. F (CSF imaging): There are cerebrospinal fluid imaging on both anterior and posterior of spinal cord; There was no cerebrospinal fluid imaging on one side of the spinal cord, and no compression; There were no cerebrospinal fluid imaging on both sides of the spinal cord, and no compression; There were no cerebrospinal fluid imaging on both sides of the spinal cord, obvious compression of spinal cord. M(Cross section Morphology of spinal cord): cylinder shape; triangle or crescent shape; boomerang shape; Arc shape. Each variable was assigned a score of 0-3 according to different grades. The total score of the CSFM score was 12, and the minimum score was 0. A higher score indicates more severe spinal cord compression. Conclusions The CSFM scoring system can effectively reflect the degree of spinal cord compression for cervical OPLL.