Impact of Symptom Duration on Surgical Outcomes and Functional Recovery in Degenerative Cervical Myelopathy

Study Design. Prospective multicenter cohort study. Objectives. To investigate the impact of symptom duration on surgical outcomes and functional recovery in patients with degenerative cervical myelopathy (DCM). Methods. A total of 874 patients with DCM who underwent surgery across 10 institutions were analyzed. Patients were stratified into four groups according to symptom duration: <0.5 years, 0.5–2 years, 2–5 years, and ≥5 years. Clinical outcomes, including JOA score, SF-36, VAS, NPSI, and JOACMEQ, were assessed preoperatively and at 2-year follow-up. The minimum clinically important difference (MCID) was defined as 2.5 points for JOA and 4.0 points for PCS. Multivariate analyses were performed to identify associations between symptom duration and outcomes, adjusting for relevant covariates. Results. All groups exceeded the MCID for ΔJOA. However, only patients with<2 years of symptoms achieved a ΔPCS exceeding the MCID. Shorter symptom duration was associated with better recovery in extremity and bladder function, as well as quality of life, as assessed by the JOACMEQ. Conclusion. Although neurological recovery exceeded the MCID even after five years of symptoms, patient-reported physical function fell below the MCID beyond two years. This discrepancy underscores the importance of performing surgical intervention within two years of symptom onset to optimize both clinical and patient-centered outcomes.