The Impact of Preoperative Neurological Symptom Severity on Postoperative Outcomes in Cervical Spondylotic Myelopathy

Study Design: The study design is a retrospective cohort study. Objective: To compare patient-reported outcomes between patients with mild versus moderate-to-severe myelopathy following surgery for cervical spondylotic myelopathy (CSM). Summary of Background Data: Recent studies have demonstrated that decompression for CSM leads to improved quality of life when measured by patient-reported outcomes. However, it is unknown if preoperative myelopathy classification is predictive of superior postoperative improvements. Materials and Methods: A retrospective review of patients treated surgically for CSM at a single institution from 2014 to 2015 was performed. Preoperative myelopathy severity was classified according to the modified Japanese Orthopaedic Association (mJOA) scale as either mild (>= 15) or moderate-to-severe (<15). Other outcomes included neck disability index (NDI), 12-item short-form survey (SF-12), and visual analog scale (VAS) for arm and neck pain. Differences in outcomes were tested by linear mixed-effects models followed by pairwise comparisons using least square means. Multiple linear regression determined whether any baseline outcomes or demographics predicted postoperative mJOA. Results: There were 67 patients with mild and 50 patients with moderate-to-severe myelopathy. Preoperatively, patients with moderate-to-severe myelopathy reported significantly worse outcomes compared to the mild group for NDI, Physical Component Score (PCS-12), and VAS arm (P = 0.031). While both groups experienced improvements in NDI, PCS-12, VAS Arm and Neck after surgery, only the moderate-to-severe patients achieved improved mJOA (+3.1 points, P < 0.001). However, mJOA was significantly worse in the moderate-to-severe when compared to the mild group postoperatively (-1.2 points, P = 0.017). Both younger age (P = 0.017, beta-coefficient = -0.05) and higher preoperative mJOA (P < 0.001, beta-coefficient = 0.37) predicted higher postoperative mJOA. Conclusions: Although patients with moderate-to-severe myelopathy improved for all outcomes, they did not achieve normal absolute neurological function, indicating potential irreversible spinal cord changes. Early surgical intervention should be considered in patients with mild myelopathy if they seek to prevent progressive neurological decline over time.