One- to two-year outcomes after surgery for cervical myelopathy: a systematic review of symptom duration and baseline severity.

backgroundDegenerative cervical myelopathy is a progressive cause of spinal cord dysfunction. While surgery is recommended for moderate, severe, or progressive disease, > 12 months recovery beyond the first postoperative year and the influence of symptom duration remain less clearly defined.

methodsA PRISMA-based systematic review was performed of surgical studies in degenerative cervical myelopathy reporting outcomes at 12 months or longer, with data on symptom duration, baseline severity, or recovery modifiers. Risk of bias was assessed using ROBINS-I. Comparable JOA/mJOA change scores were pooled as standardised mean changes using a random-effects model with Hartung-Knapp adjustment. Leave-one-out sensitivity analysis was performed.

resultsEight studies including 3,991 surgically treated patients met the inclusion criteria; 3,933 contributed > 12 months outcome data. The weighted mean age was 61.4 years, and 62.3% of patients were male. All studies were judged to be at overall moderate risk of bias. Three studies, comprising 1,218 patients, provided extractable JOA/mJOA change-score data. Random-effects meta-analysis showed a pooled neurological improvement of + 1.41 JOA/mJOA points (95% CI + 0.62 to + 2.19), with substantial heterogeneity (I² = 90.4%). Across the remaining studies, neurological improvement was consistently reported at 12 months or longer. Six studies found that longer symptom duration was associated with poorer recovery in at least one outcome domain, although reported thresholds varied from 4 months to more than 2 years. The effect of delayed surgery appeared more consistent for disability, physical function, quality of life, bladder function, and extremity-function outcomes than for JOA/mJOA alone. Evidence on baseline severity was limited to one study and suggested greater absolute neurological improvement in patients with more severe baseline myelopathy; this finding should be considered exploratory.

conclusionAt ≥ 12 months, neurological scores were generally higher than baseline, although the magnitude of change varied. Longer symptom duration was associated with poorer recovery in several patient-reported and functional domains, while improvement was also reported after prolonged symptoms.