Effects of the hierarchical endoscopic contralateral decompression strategy on short- and medium-term outcomes for patients with unilateral symptomatic lumbar spinal stenosis

Endoscopic unilateral laminectomy for bilateral decompression (Endo-ULBD) is widely utilized for degenerative lumbar spinal stenosis (DLSS). However, the optimal extent of contralateral decompression in patients presenting with unilateral symptoms of DLSS (us-DLSS) remains inadequately defined. To evaluate the short- and mid-term efficacy and safety of varying degrees of contralateral decompression in us-DLSS patients. This retrospective cohort study analyzed us-DLSS patients who underwent Endo-ULBD between November 2023 and June 2025. Patients were stratified into three groups based on the degree of contralateral decompression: insufficient (Gi), moderate (Gm), and sufficient (Gs). Preoperative, postoperative, and final follow-up measurements included dural sac cross-sectional area (DSCA), dural sac expansion ratio (DSER), and Schizas grading. Clinical outcomes were assessed using Visual Analogue Scale (VAS) for back and bilateral lower limbs, Oswestry Disability Index (ODI), and modified Macnab criteria. Correlation analysis identified risk factors for outcomes at final follow-up. A total of 102 patients (117 surgical segments) were enrolled. All patients demonstrated significant improvements in back pain, symptomatic limb pain, and ODI postoperatively and at final follow-up. At final follow-up, modified Macnab outcomes were excellent in 29.41%, good in 42.16%, fair in 20.59%, and poor in 7.84%. Group comparisons revealed that patients in Gm and Gs groups were significantly older and had smaller preoperative DSCA than the Gi group. However, no significant intergroup differences were observed in postoperative or final follow-up DSCA or Schizas grading. VAS scores, ODI, and modified Macnab grades showed no significant differences among groups at any time point. Complication distribution was comparable across all groups. In patients with us-DLSS, inadequate contralateral decompression is associated with a smaller DSER, but the short- and medium-term follow-up results do not indicate worse clinical outcomes or a higher risk of complications. The long-term risks of limited decompression warrant further investigation.