Relationship of preoperative intramedullary MRI signal intensity and dynamic factors with surgical outcomes of laminoplasty for cervical ossification of the posterior longitudinal ligament

Abstract

Objective: We aimed to analyze the relationship of preoperative signal intensity on magnetic resonance imaging (MRI) and dynamic factor with surgical outcomes of laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL).

Patients and methods: We retrospectively reviewed the records of 29 patients (20 males and 9 females) who underwent double-door laminoplasty for cervical OPLL. T2-weighted MRI was performed preoperatively. To assess the high-signal changes of the spinal cord, signal intensity was classified as grade 0 (low signal, no changes), grade 1 (medium signal, mild changes), and grade 2 (bright signal, pronounced changes). The following factors were analyzed for their relationship with surgical outcome, expressed as the Japanese Orthopedic Association (JOA) score recovery rate: pre- and postoperative C2-C7 range of motion (ROM), segmental ROM, C2-C7 lordotic angle, and spinal cord occupying ratio, as well as disease duration.

Results: Disease duration was significantly longer in patients with pronounced high-signal changes on preoperative MRI (P < 0.05 for grade 2 vs. grade 1 or 0). The mean preoperative JOA score and JOA score recovery rate were significantly lower in patients with pronounced high-signal changes on preoperative MRI (P < 0.05 for grade 2 vs. grade 1 or 0). Preoperatively, segmental ROM was significantly smaller in patients with no MRI signal intensity changes (P < 0.05 for grade 0 vs. grade 1 or 2). Additionally, preoperative segmental ROM was negatively correlated with JOA score recovery rate (R=-0.470, P = 0.01) and positively correlated with high-signal changes on preoperative MRI (R = 0.460, P = 0.012). On multivariate analysis, preoperative segmental ROM was negatively associated with JOA score recovery rate (odds ratio, - 0.407; P = 0.046).

Conclusion: Given its negative correlation with JOA score recovery rate and positive correlation with high-signal changes on preoperative MRI, higher preoperative segmental ROM may be associated with spinal cord damage due to repeated minor trauma, predicting poor surgical outcome of laminoplasty in cervical OPLL.

Keywords: Cervical laminoplasty; Cervical ossification of the posterior longitudinal ligament; Dynamic factor; Intramedullary high-signal change; MRI.