Spine Fellow University of British Columbia Vancouver, British Columbia, Canada
Introduction: In patients with metastatic spine disease, pain can be axial or radicular, further defined as mechanical (increases with movement/weight bearing) or biological. We sought to delineate how radicular pain specifically responds to treatment.
Methods: Patients treated with surgery and/or radiotherapy for spine metastases reporting radicular pain or axial pain only were identified from the Epidemiology, Process, and Outcomes of Spine Oncology (EPOSO) international multicentre prospective observational study. The primary outcome was numeric pain rating scale (NRS) 3 months post-treatment. Patients with myotomic weakness and Bilsky score < 2 were included for motor assessment.
Results: Of 284 patients, 129 (45%) had radicular pain ± axial pain and 155 (55%) had axial pain alone. Groups did not differ in age, comorbidities, primary cancer type, epidural compression, spinal tumor location, SINS score, or treatment regimen (p>0.05). 202 (71%) patients had surgery ± radiotherapy and 82 (29%) had radiotherapy alone. Radicular pain patients’ mean NRS score was 6.7 (95% CI: 6.2;7.1) at baseline and improved by 3.2 points (95% CI: 2.5;4.0) at 3 months follow-up (p < 0.001). Patients with isolated axial pain had a comparatively lower (p=0.028) preoperative mean score of 5.8 (95% CI: 5.5;6.2) which improved a mean of 2.2 points (95% CI: 1.5;2.9) over the same interval (p < 0.001). Improvement magnitude was higher in radicular pain than those with only axial pain (p=0.041) however, the NRS at 3 months was similar (p=0.97). Surgical patients with radicular pain experienced a larger improvement (mean improvement 3.8, 95% CI: 2.9;4.7) than those treated with radiotherapy alone (1.8, 95% CI: 0.3;3.2, p=0.015), but had a higher pretreatment pain level (7.0 vs 5.6, p=0.027). Biological radicular pain showed similar improvement as mechanical radicular pain (p=0.993). 23 patients were identified with radicular/myotomic weakness (mean 96.3±3.2 AIS score) which improved 1.0±1.1 points at 3 months.
Conclusion : Pain improvement magnitude for patients with radicular pain following surgery and radiotherapy for metastatic spine disease is higher than for axial pain alone. Surgery is associated with a larger improvement in pain scores than radiotherapy alone. No differences were identified based on mechanical or biological pain. Motor improvement following treatment was quite modest.
