Outcome and predictive factors in rapid progressive cervical spondylotic myelopathy: A retrospective case-control study

Background: Cervical spondylotic myelopathy (CSM) is a major cause of cervical spinal cord dysfunction in people over 55 years of age. Most patients with CSM usually present with chronic and phased compression, however, some patients with CSM develop rapid severe neurological dysfunction without any trauma. To our knowledge, markers that can be used for early identification of patients with potential to develop rapid neurological deterioration have not been totally identified. Here, we evaluate epidemiological, clinical and radiographic features associated with the development and prognosis of rapid progressive cervical spondylotic myelopathy (rp-CSM). Methods: A retrospective study was carried out for 175 patients diagnosed with CSM between March 2011 and January 2017 at West China Hospital. Patients were divided into rp-CSM group and chronic CSM (c-CSM) group based on the time taken for neurological deterioration to occur and the severity of preoperative neurological dysfunction. The clinical outcomes were assessed using the Modified Japanese Orthopaedic Association (mJOA) score, and imaging parameters such as Torg-Pavlov Ratio (TPR), intervertebral disc level compression ratio and increased signal intensity (ISI) on T2W1. Multivariate analysis was used to compare the outcomes between the two groups and identify potential predictors for rapid neurological dysfunction in CSM patients. Results: Out of the 175 patients enrolled in the study, 25 developed rp-CSM (18 males; median age 59.04 +/- 12.81 years) and the remaining 75 (54 males; median age 56.88 +/- 12.31 years) were used as controls for the study (cCSM group). The average time taken to develop severe neurological deterioration was 0.8 month in rp-CSM group and 24 month in c-CSM group (p = 0.001), while the preoperative mJOA scores were 6 in rp-CSM patients and 12 in c-CSM patients (p = 0.014). In addition, rp-CSM patients demonstrated worse outcomes than the controls in one year after surgery (mJOA improvement rate 54.5 % and 80 %, respectively, p = 0.021). There were no differences in the clinical parameters evaluated between the two groups except for the history of diabetes and smoking. Analysis of radiographic parameters indicated that TPR MRI, intervertebral disc level compression ratio and increased signal intensity (ISI) on T2W1 were poor in rp-CSM patients compared to c-CSM patients. Regression analysis also showed that the history of diabetes, TPR MRI < 0.4, compression ratio >= 50 %, and the sagittal diameter of ISI >= 50 % of spinal canal diameter on T2W1 were strongly associated with the rapid progressive neurological dysfunction in patients with CSM. Conclusion: The prognosis of rapid progressive CSM is worse than that of common chronic CSM. The rapid neurological deterioration can be identified by TPR MRI (<0.4), compression ratio (>50 %), sagittal diameter of ISI (>50 % of spinal canal diameter). Besides, a history of diabetes is a risk factor for the development of rp-CSM.