Clinical Importance of Redundant Nerve Roots in Patients with Symptomatic Lumbar Spinal Stenosis

Study Design. Post-hoc analysis of data from a randomized clinical trial. Objective. To compare preoperative symptoms of patients with lumbar spinal stenosis (LSS) with and without redundant nerve roots (RNR), and to compare the change in clinical outcomes between those two groups 2 years after decompression surgery. Summary of Background Data. RNR are often seen on MRI in patients with spinal stenosis. Previous studies have reported that patients with RNR are older and have worse symptoms at baseline. A meta-analysis from 2018 concluded that this radiological sign could be seen as a negative predictor of outcome. High quality prospective studies are lacking. Methods. Patient characteristics and reported pain and function scores were compared between LSS groups with (RNR+) and without RNR (RNR-) at baseline and after 2 years follow-up. Primary outcome was the mean change in the Oswestry Disability Score (ODI). Secondary outcomes included mean change in scores of the Zurich Claudication Questionnaire (ZCQ) and the numeric rating scale (NRS) for leg and back pain. Results. Out of 416 patients included in the present analysis, 163 (39%) had RNR at baseline. Both groups were similar in regard to patient age, smoking habits, BMI and duration of symptoms. Both groups also showed similar pain and function scores at baseline. The RNR+ group contained a significantly higher proportion of men, patients with severe stenosis and multiple stenotic levels on MRI. At 2-year follow-up the mean change of ODI was −22.1 in the RNR+ group and −17.4 in RNR- group (mean difference 4.7 (95%CI 1.3-8.2) P =0.007). Statistically significant differences were also found for secondary outcomes ZCQ, and NRS leg and back pain favouring the RNR+ group. Conclusion. Patients with RNR had similar baseline characteristics and similar symptoms as patients without. RNR before surgery were associated with better clinical improvement 2 years after decompression.