Impact of various MRI signal intensity changes on radiological parameters, the neurological status, and surgical outcomes in degenerative cervical myelopathy

Study design: A retrospective study of prospectively collected date. Purpose: The present study aimed to identify patient characteristics, radiological factors, the neurological status, and postoperative outcomes associated with MRI signal intensity changes in degenerative cervical myelopathy (DCM). Material and method: One hundred and fourteen DCM patients who underwent posterior decompression surgeries were enrolled. Pre-and postoperative (12 months) Japanese Orthopedic Association (JOA) scores, cervical alignment and balance on X rays, the cross-sectional area of the spinal cord (CSA) in kinematic CT myelography (CTM). The recovery rate (RR) of the total JOA score and those specific for the upper and lower limb items were evaluated. MRI included T1-weighted imaging (WI) and T2WI. Patients were classified into two groups for a univariate analysis according to the presence or absence of a high signal intensity (HIS) in the sagittal view on T2WI, a low signal intensity (LSI) in the sagittal view on T1WI, the distribution of HSI at a single or multiple levels, and the presence or absence of the snake eye appearance. A multiple logistic regression analysis (MLRA) was performed to identify factors associated with signal intensity changes on MRI. Results: Ninety-six patients (84.3%) were classified into HIS changes in the sagittal view on T2WI. The group with multilevel HSI showed significantly lower RR specific for the lower extremity JOA score (30.8% vs 47.7%; P = 0.016). The snake eye-positive group showed a significantly inferior RR specific for the upper extremity JOA score (40.1% vs 53.2%; P = 0.04). In MLRA, LSI changes on T1WI revealed small CSAF (P = 0.02, Odds ratio; 0.77, 95%CI:0.61-0.97), while HSI changes on T2WI revealed a small CSAF (P = 0.008, Odds ratio;1.36, 95%CI:1.08-1.72) and large C2-7 angle during extension (P = 0.009, Odds ratio;0.73, 95%CI:0.58-0.92). CSAF correlated with multilevel HSI changes (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93). The snake eye appearance correlated with CSAF (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93) and the duration of disease (P = 0.05, Odds ratio;1.01, 95%CI:1.0-1.03). Conclusion: Severe and poorly compensated spinal cord compression during neck flexion may cause signal in-tensity changes. The snake eye appearance may be useful as a sign of the inferior postoperative recovery of upper limb function, and multilevel HSI as a sign of the inferior postoperative recovery of lower limb function.