Indexed on: 28 Sep '17Published on: 28 Sep '17Published in: Spine
Sub-analysis of the prospective AOSpine CSM North America and International studies.To describe the post-operative changes in MRI spinal cord signal intensity in degenerative cervical myelopathy (DCM) patients and to investigate the impact of its post-operative resolution on clinical outcomes.When examining the spinal cord, hyperintensity found in MRI T2-weighted images and hypointensity in T1-weighted images are known to correlate with pre-operative severity of DCM and to predict post-operative neurological recovery. However, the clinical importance of these signal intensity changes in post-operative images has not been established.Among 757 surgical DCM patients enrolled in two prospective multicenter studies, post-operative MRI images obtained between 6 to 24 months after the operation were examined with a focus on T2 hyper- and T1 hypointensity in the spinal cord. The 2-year post-operative Nurick grade, modified Japanese Orthopaedic Association (mJOA) score and mJOA recovery rate (RR) were analyzed between patients with or without resolution of signal intensity changes.A total of 167 patients with pre-operative T2 hyperintensity were included with complete post-operative MRI images. Of these patients, 11% showed resolution of signal intensity changes, 70% retained T2 hyperintensity only, and 19% showed both T2 hyper- and T1 hypointensity post-operatively. There was a stepwise trend toward worse post-operative outcomes, with the no signal intensity change group showing the best outcome and the T1 hypointensity group showing the worst (mean RR: 72% vs. 51% vs. 36%, p = 0.02). Patients who exhibited resolution of T2 hyperintensity showed better outcomes than those who retained it (RR: 72% vs. 47%, p = 0.04), but the resolution of T1 hypointensity was not associated with improved outcomes (RR: 38% vs. 26%, p = 0.36).Post-operative resolution of T2 hyperintensity in DCM patients was associated with the best clinical outcomes, while those with T1 hypointensity showed the worst.3.