Does intramedullary signal intensity on MRI affect the surgical outcomes of patients with ossification of posterior longitudinal ligament?

Patients with cervical ossification of posterior longitudinal ligament (OPLL) are susceptible to cord injury, which often develops into myelopathic symptoms. However, little is known regarding the prognostic factors that are involved in minor trauma. We evaluated the relationship between minor trauma and neurological outcome of OPLL and investigated the prognostic factors with a focus on compressive factors and intramedullary signal intensity (SI). A total of 74 patients with cervical myelopathy caused by OPLL at more than three-levels were treated with posterior decompression surgeries. We surveyed the space available for spinal cord (SAC), the severity of SI change on T2-weighted image, and diabetes mellitus (DM). The neurological outcome using Japanese Orthopedic Association (JOA) scale was assessed at admission and at 12-month follow-up. Among the variables tested, preoperative JOA score, severity of intramedullary SI, SAC, and DM were significantly related to neurological outcome. The mean preoperative JOA were 11.3±1.9 for the 41 patients who did not have histories of trauma and 8.0±3.1 for the 33 patients who had suffered minor traumas (p