Association of Preoperative Cervical Spine Alignment With Spinal Cord Magnetic Resonance Imaging Hyperintensity and Myelopathy Severity

Study Design. This is an ambispective analysis of a prospectively followed cohort of patients with cervical spondylotic myelopathy (CSM). Objective. The goal of this study was to evaluate the impact of sagittal alignment on magnetic resonance imaging (MRI) abnormalities in the cervical spinal cord as well as myelopathy severity in a prospective series of surgical patients. Summary of Background Data. There is emerging evidence that sagittal alignment of the cervical spine in patients with CSM may be associated with disease severity. The impact on actual spinal cord pathology is unclear, with suspected mechanisms including focal static ventral compression, repeated dynamic injury, and increased cord intramedullary tension. The relationship between sagittal imbalance and disease severity remains undefined. Methods. An ambispective analysis of prospectively collected data was performed of surgical patients with CSM at a single tertiary-care neurosurgical center. Demographic data and measures of neurological disability were collected and analyzed for dependency on cervical spine alignment parameters including qualitative (kyphotic vs. lordotic) and quantitative (sagittal Cobb angle (C2-C7) and sagittal vertical axis (SVA, C2-C7)). MRI cord signal hyperintensity at the most pathological level was also evaluated for dependency on the same alignment metrics. Multiple logistic regression analysis was used at the 0.05 level of significance with correction for multiple comparisons. Results. Among 124 patients with CSM, kyphotic alignment was seen in 34% of patients and hyperintense T2 MRI signal was observed in 55% of patients. No difference in MRI signal or myelopathy severity was observed in univariate analysis on global alignment. Among patients with kyphosis, quantitative MRI parameters and myelopathy severity were both correlated with increasing SVA, an observation not seen among patients with lordosis. Conclusion. Global sagittal alignment and SVA interactively associate with quantitative MRI spinal cord signal abnormalities and worse CSM-related disability. The reciprocal relationships of SVA effect in patients with kyphosis and those with lordosis may reflect an optimal spinal alignment to achieve during surgical management.