The Relationship between Preoperative Clinical Presentation and Quantitative MRI Features in Patients with Degenerative Cervical Myelopathy

Abstract

Introduction Degenerative Cervical Myelopathy (DCM) encompasses a group of degenerative conditions of the cervical spine, including cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL), that result in spinal cord pathology through static and dynamic injury mechanisms. While there are a constellation of degenerative findings that present in patients with DCM on MRI, large studies have shown that cervical cord compression and signal changes on MRI can present in asymptomatic or population based cohorts as well. It is therefore the objective of the present research to investigate the correlations between clinical and MRI findings and address this area of controversy. Material and Methods One hundred and fourteen patients enrolled in the prospective and multicenter AOSpine CSM North American study with complete MRI and clinical data were evaluated. Patients were enrolled if they had ≥1 clinical signs of myelopathy. Mid-sagittal MRIs were assessed for maximum spinal cord compression (MSCC) and maximum cord compromise (MCC). Additionally, the presence of T1 and T2 signal changes assessed, and the degree of T2 signal hyperintensity deviation was evaluated by computing a signal change ratio (SCR). MRI features were then statistically related with the presence of upper and lower limb neurological symptoms as well as generalized neurological dysfunction using t-tests. The relationship between duration of symptoms and quantitative MRI features was assessed using Spearman's rank correlation coefficient. Results The average T2 signal change ratio at the region of interest was 1.31, and the mean MCC and MSCC were ~49% and 34%, respectively. Numb hands ( p = 0.01) and Hoffmann's sign ( p = 0.003) were associated with greater MSCC; broad-based, unstable gait ( p = 0.042), impairment of gait ( p = 0.008) and Hoffmann's sign ( p = 0.013) were associated with greater MCC; Numb hands ( p = 0.037), Hoffmann's sign ( p = 0.017), Babinski sign ( p = 0.002), lower limb spasticity ( p = 0.011), L'Hermitte's phenomena ( p = 0.045), hyperreflexia ( p = 0.004), and presence of T1 hypointensity were associated with a greater deviation of signal intensity on T2 MRI. Patients with the presence of T2 signal hyperintensity also had greater MSCC ( p < 0.001) and MCC ( p < 0.001). Patients with L'Hermitte's phenomenon had a statistically significant lower SCR ( p = 0.045), indicating that they more commonly presented with diffuse and faint, or absence of T2 signal hyperintensities. Conclusion MSCC and MCC were predominately associated with upper limb and lower limb manifestations, respectively. SCR was associated with upper limb, lower limb and general neurological deficits. Hoffmann's sign was the only clinical parameter which occurred more commonly in patients with a greater MSCC, MCC and SCR, supporting its role as a sensitive diagnostic tool. L'Hermitte's phenomenon presented more commonly in patients with a lower SCR and thus may serve to indicate mild pathology and potential for reversibility. Going forward, it would be interesting to investigate these correlations over multiple preoperative time periods to evaluate the validity and evolution of these relationships. Ultimately, the culmination of such research may serve as a prelude to the construction of an evidence based prediction model that may help to differentiate between patients that remain stable and identify those who are likely to deteriorate without surgical intervention.