Is Preoperative Duration of Symptoms a Significant Predictor of Functional Status and Quality of Life Outcomes in Patients Undergoing Surgery for the Treatment of Degenerative Cervical Myelopathy?

Abstract

Introduction Longstanding compression of the spinal cord in patients with degenerative cervical myelopathy (DCM) may result in irreversible neural tissue damage. This study aims to analyze whether a longer duration of symptoms is associated with poor surgical outcomes and to determine the optimal timing for decompressive surgery. Material and Methods Three hundred and fifty patients with symptomatic DCM were prospectively enrolled in either the CSM-North America or International study at 12 sites in North America. For each patient, extensive demographic information was collected, including age, co-morbidities, and a self-reported estimate of preoperative duration of symptoms. Postoperative functional status and quality of life were evaluated at 6-, 12- and 24-months using the modified Japanese Orthopaedic Association (mJOA), Nurick grade, Neck Disability Index (NDI) and Short-Form-36 (SF-36) Physical (PCS) and Mental (MCS) Component Scores. Change scores between baseline and 12-month follow-up were computed for each outcome measure. Duration of symptoms was dichotomized into a “short” and “long” group at several cut-offs. An iterative mixed model analytic approach procedure was used to evaluate differences in change scores on the mJOA, Nurick, SF-36 MCS and PCS and NDI between duration groups in 1-month increments. Two models were constructed: 1) an unadjusted model between duration of symptoms and surgical outcome and 2) a model adjusting for significant independent covariates identified through stepwise regression analysis. Results Our cohort consisted of 201 (57.43%) men and 149 (42.57%) women, with a mean age of 57.49 ± 11.77 years (range: 29–87 years). The mean duration of symptoms was 25.71 ± 36.68 months (range: 1–240 months). In unadjusted analysis, patients with a duration of symptoms shorter than 4 months had significantly better functional outcomes based on the mJOA ( p = 0.04) than patients with a longer duration of symptoms (>4 months). On average, patients with a shorter duration of symptom improved by 3.71 on the mJOA, whereas those with a duration 4 months or longer only exhibited a 2.96 mean gain. Twelve months was identified as the next important cut-off beyond which patients had a significantly worse outcomes on the mJOA; however, this difference was smaller. Following adjusted analysis, cut-offs of 4 and 12 months remained significant. Duration of symptoms was not associated with Nurick or SF-36 PCS or MCS in either the unadjusted or adjusted models. Conclusion Patients who are operated on within 4 months of symptom presentation have better mJOA outcomes. It is recommended that patients with DCM are diagnosed in a timely fashion and referred early for surgical consultation. Our study does not support the traditional conservative “watchful waiting” approach to symptomatic patients with DCM.