Impact of Signal Intensity Change in MRI on the Clinical Outcomes of Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study

Study Design. A multicenter prospective cohort study. Objective. To evaluate the clinical significance of intramedullary signal intensity (SI) changes on T2-weighted magnetic resonance imaging (MRI) in patients with cervical ossification of the posterior longitudinal ligament (OPLL) and assess their impact on surgical outcomes. Summary of Background Data. In OPLL, SI changes on MRI are frequently observed, but their prognostic significance remains unclear. While some studies associate SI changes with poor neurological function and recovery, others report a weak correlation. Methods. A total of 402 patients with cervical OPLL were analyzed. Patients were classified into SI (+) and SI (-) groups based on preoperative T2-weighted MRI. Clinical outcomes, including the Japanese Orthopaedic Association (JOA) score, the visual analog scale, and the JOA Cervical Myelopathy Evaluation Questionnaire, were evaluated preoperatively and at two years postoperatively. Multiple regression and logistic regression were performed to adjust for confounders. Results. A total of 348 cases (86.6%) were in the SI (+) group. Patients in the SI (+) group were older and had greater cervical range of motion (ROM). They exhibited lower preoperative JOA scores and more severe extremity pain. However, at two-year follow-up, neurological improvement, pain reduction, and patient-reported outcomes did not differ significantly between groups. Conclusion. SI changes on MRI are associated with worse preoperative neurological function and greater pain but do not predict inferior surgical outcomes. Surgical decompression remains effective regardless of SI changes, which can be valuable information for explaining the prognosis to patients in clinical practice.