Chronic pain after decompression for degenerative cervical myelopathy: a pooled trajectory analysis of individual participant data

Pain is a significant contributor to quality of life for those living with degenerative cervical myelopathy (DCM). The trajectories and factors associated with chronic pain are poorly understood. Patients with DCM were identified from a harmonized data set of the AO Spine Cervical Spondylotic Myelopathy (CSM)-North America, CSM-International, and CSM-Protect studies. Pain scores were prospectively collected using the Neck Disability Index pain intensity (NDI-PI) score preoperatively and at 6-month, 12-month, and 24-month follow-up. Patients were categorized into 3 groups of preoperative pain: severe pain (NDI-PI ≥3), moderate pain (NDI-PI = 2), and minimal pain (NDI-PI ≤1). Latent class trajectory modeling classified patients into distinct trajectories based on their NDI-PI score over 24 months postoperatively. From a total of 952 patients, 32% of patients (n = 305) presented preoperatively with severe pain, 29.1% (n = 277) with moderate pain, and 38.9% (n = 370) with minimal pain. Postoperatively, patients presenting with severe pain followed (1) complete resolution (n = 128, 42.0%), (2) moderate recovery (n = 105, 34.4%), or (3) marginal recovery (n = 72, 23.6%) trajectory. Patients presenting with moderate pain followed the trajectories of (1) pain evolution (n = 22, 7.9%), (2) marginal recovery (n = 104, 37.6%), and (3) complete resolution (n = 151, 54.5%). Patients presenting with minimal pain followed 2 trajectories: (1) no pain evolution (n = 329, 88.9%) and (2) moderate evolution (n = 41, 11.1%). At 24 months, 36.1% (n = 344) of all trajectories ended in chronic pain. Preoperative pain in DCM can be classified into distinct subpopulations with fundamentally differing clinical courses. Surgery is associated with long-term trajectories of pain reduction in painful DCM. However, some patients experience persisting chronic pain.