Microscopically-Assisted Uninstrumented Surgical Tumor Decompression (MUST-D) Improves Functional Outcomes and Prolongs Time to Death in Metastatic Epidural Spinal Cord Compression

Introduction: Metastatic epidural spinal cord compression (MESCC) develops in 10% of cancer patients with spinal involvement. Current MESCC management is largely palliative, with primary open decompression with instrumentation and adjuvant radiotherapy as the gold-standard treatment. This study assessed the surgical advantages of an MIS partial vertebrectomy using cement augmentation without instrumentation.

Methods: This is a single-center, decade-long retrospective cohort study from November 2006 to June 2016 of patients undergoing MESCC decompression with our proposed MUST-D technique or standard open instrumented fusion. The MUST-D technique entailed a single-level, uninstrumented MIS partial vertebrectomy and cement augmentation with single-screw anchoring. Recorded outcomes included baseline demographics, preoperative SINS score, tumor distribution, perioperative variables, ambulatory function as Hauser Ambulation Index (HAI), initiation of adjuvant therapy, and time to death.

Results: Of 59 patients undergoing MESCC decompression, 21 had MUST-D surgery and 38 had control open instrumented procedures (60.8 vs 59.2 years, p=0.62). No differences were noted in tumor location across the spinal column (p=0.44) or preoperative SINS score (9.86 vs 10.52, p=0.40). Compared to the open control group, the MUST-D cohort had significantly shorter skin-to-closure time (3.17 vs 5.07 hours, p< 0.001), anesthesia duration (5.43 vs 7.20 hours, p< 0.004), and length of hospital stay (4.67 vs 9.76 days, p=0.012). Trends in EBL were noted (821 vs 1376 mL, p=0.063). Regarding functional outcomes, MUST-D patients had faster postoperative time to ambulation (0.41 vs 3.68 days, p=0.022) and 30-day ambulatory improvements, whereas the control deteriorated (HAI score -1.6 vs 0.33, p=0.008). Kaplan-Meier 1-year survival was similar between groups (p=0.1763), yet MUST-D patients had faster initiation of radiotherapy (25.9 vs 39.3 days, p=0.030) and demonstrated significantly longer time to death (1.29 vs 3.47 years, p=0.040).

Conclusion : MUST-D, when compared to open vertebrectomy and fusion with instrumentation, improves functional ambulatory outcomes, expedites time to radiotherapy, and prolongs survival. Larger prospective studies are encouraged to confirm these findings.