Application of unilateral biportal endoscopy in lumbar double crush syndrome: a retrospective study and literature-based classification

OBJECTIVE: Double Crush Syndrome (DCS) represents a relatively uncommon peripheral neuropathy caused by compression of the same nerve at two distinct sites. A single lumbar nerve root traverses a long pathway within the spinal structure, making it susceptible to compression at multiple sites. This dual-site entrapment results in dysfunction of a single nerve root and may be easily overlooked in clinical practice, often leading to suboptimal therapeutic outcomes. Considering the limited number of reported cases involving double-site compression of lumbar nerve roots, the present study aimed to report our institutional experience in managing such cases. All patients were treated using a unilateral biportal endoscopic (UBE) technique to achieve decompression at both compression sites. Furthermore, a comprehensive literature review on DCS was conducted, and a preliminary classification framework was proposed based on the patterns of pathology described in previous reports. METHODS: A total of 16 patients diagnosed with DCS were retrospectively analyzed. Demographic data, clinical symptom characteristics, pre- and postoperative imaging, intraoperative details, functional outcome scores, patient satisfaction, and postoperative complications were collected and reviewed. These data were used to evaluate the efficacy and safety of UBE in the treatment of lumbar DCS. In addition, all English-language publications on DCS published after the year 2000 were narratively reviewed. The included studies were categorized according to the anatomical locations and pathological types of compression to establish a new classification system for DCS. RESULTS: Among the 16 patients, 12 had a double crush of the L5 nerve root, and 4 had a double crush of the L4 nerve root. All patients underwent single-stage dual-site decompression using the UBE technique. Postoperative clinical symptom scores improved significantly, and no recurrence of symptoms was observed at 1-year follow-up. The mean endoscopic operative time was 118.4 ± 13.5 min, the mean postoperative bed rest duration was 1.8 ± 0.9 days, and the mean postoperative hospital stay was 4.7 ± 1.5 days. The patients' mean postoperative visual analog scale (VAS) for low back pain and leg pain, as well as their Oswestry Disability Index (ODI), showed a significant decrease compared with preoperative values, with no significant changes observed after the 1-month follow-up. Postoperative imaging confirmed complete decompression in all cases, and no severe complications occurred. Based on the literature review, the newly proposed classification system divided DCS into two major categories comprising five subtypes. CONCLUSION: Single‑stage dual‑site UBE decompression is safe and effective for Type IIc lumbar DCS, providing significant and sustained symptom improvement. The proposed classification is a preliminary working framework to improve recognition and management of DCS. Given the retrospective design, small sample, and lack of specific diagnostic criteria, future prospective controlled studies with larger cohorts are needed to validate these findings.