Clinical Significance of Postoperative Changes in Redundant Nerve Roots After Decompressive Laminectomy for Lumbar Spinal Canal Stenosis

Abstract

The postoperative time course of redundant nerve roots (RNRs) in patients with lumbar spinal canal stenosis (LSCS) is currently unknown. The purpose of this study is to investigate the relationship between postoperative morphologic changes in detected RNRs and the clinical outcome of patients with LSCS. A total of 33 symptomatic patients with LSCS who demonstrated RNRs on magnetic resonance imaging (MRI) were treated with decompressive laminectomy alone. On the basis of the MRI scans obtained 7 days after surgery, patients were stratified into two groups: group 1 included patients with resolution of RNRs and group 2 included patients with persistent RNRs. Comparative parameters were examined between the two groups of patients. We found that 24 of the 33 patients showed resolution of RNRs and 9 showed persistent RNRs. Although there was no difference in the Japanese Orthopedic Association score between the two groups before treatment, group 1 showed a greater recovery of Japanese Orthopedic Association score 1 month postoperatively. MRI demonstrated that the cross-sectional area of the preoperative dural sac at the stenotic lesion was smaller in group 2 than in group 1; however, there was no difference in cross-sectional area of the postoperative dural sac between the two groups. Within 12 months, there was no evidence of RNRs in six of the nine cases in group 2. Although most patients with LSCS show postoperative resolution of RNRs detected on MRI, some show persistent RNRs postoperatively. The functional outcome of these patients remains poor even if sufficient expansion of the dural sac is achieved postoperatively.