Risk Prediction for Development of Traumatic Cervical Spinal Cord Injury without Spinal Instability

Study Design Retrospective comparative study. Objective A narrow spinal canal is an important risk factor for predicting a spinal cord injury (SCI); however, the radiologic parameters have not been fully established. The authors conducted a comparative study to forecast SCI risk by determining a predictive spinal canal diameter (SCD) cutoff value from magnetic resonance image (MRI) in the Korean population. Methods On T2-weighted MRI of the cervical spine, the SCD at the pedicle (SCD(pedicle)) and the intervertebral disk level (SCD(disk)) were measured in patients with SCI without spinal instability and in healthy subjects. Additionally, the vertebral body diameter (D(vertebral body)) and intervertebral disk diameter (D(intervertebral disk)) were measured, and the two ratios (SCD(pedicle) to D(vertebral body) and SCD(disk) to D(intervertebral disk)) were calculated. In the SCI group, the extent of high signal intensity on the T2-weighted midsagittal MRI was determined. Results The data obtained from 20 patients in the SCI group (18 men, mean age 61.35 years) and 65 individuals in the control group (47 men, mean age 57.05 years) was compared. All the parameters including the SCD and the calculated ratios were significantly smaller in the SCI group than in the control group. Among them, the area under the receiver operating curve (AUC) value for the SCD(disk)-to-D(intervertebral disk) ratio at C2–C3, with a cutoff ratio value of 0.59, provided the greatest positive predictive value. A low SCD(disk)-to-D(intervertebral disk) ratio at C4–C5 and the presence of >40 mm of high signal intensity on the MRI were related with the presence of complete SCI. Conclusion Because the C2–C3 level is relatively wide compared with the subaxial cervical spine, a small ratio at C2–C3 provided the greatest positive predictive value in SCI. Complete SCI is associated with a small SCD(disk)-to-D(intervertebral disk) ratio at C4–C5 and with extensive high signal intensity on MRI.