Symptom-specific Analysis of Surgical Outcomes and Predictors of Residual Symptoms in Patients with Mild Degenerative Cervical Myelopathy: An Analysis of Cases with Severe Cord Compression or Progressive Symptoms

Study Design. A retrospective multicenter study. Objectives. To analyze symptom-specific surgical outcomes in patients with mild degenerative cervical myelopathy (DCM) and identify predictors of postoperative residual symptoms. Summary of Background Data. DCM is the most common cause of spinal cord impairment in adults. While surgical intervention is recommended for moderate to severe DCM, optimal treatment strategies for mild DCM remain unclear. Previous studies have focused on total Japanese Orthopaedic Association (JOA)/modified JOA (mJOA) score without detailed symptom-specific analyses. Methods. We reviewed 679 consecutive patients who underwent surgical decompression with or without fusion for DCM across three institutions in Japan. Among them, 104 patients with mild DCM (JOA score 14.5-16.5) were included. We assessed demographic data, radiographic factors, magnetic resonance imaging parameters, and clinical scores. Symptom-specific analyses were conducted using preoperative and 2-year postoperative JOA scores, and the predictors of persistent symptoms were analyzed using multivariable logistic regression. Results. The mean maximum canal compromise was 49.7%, and maximum spinal cord compression was 37.2%. The most common factors leading to surgery was symptom deterioration (94.2%). In symptom-specific analysis, 60.9% of patients exhibited persistent upper extremity sensory impairment, significantly higher than other domains. Multivariable analysis identified angular-edged deformity of the spinal cord on axial MRI as an independent predictor of persistent upper extremity sensory impairment (Odds Ratio: 4.264, 95% confidence interval: 1.312-13.854, P=0.016). Conclusion. The majority of mild DCM patients who underwent surgery had severe spinal cord compression, with symptom progression serving as the trigger for surgical intervention. While surgical intervention improves overall function, upper extremity sensory impairments frequently persisted postoperatively, even in mild cases. Angular-edged deformity was a significant predictor for postoperative upper extremity sensory deficits, emphasizing the need for careful preoperative evaluation of spinal cord morphology to better inform prognosis and guide treatment decisions in patients with mild DCM.