Separation surgery for metastatic epidural spinal cord compression: comparison of a minimally invasive versus open approach.

Objective: The aim of this study was to compare outcomes of separation surgery for metastatic epidural spinal cord compression (MESCC) in patients undergoing minimally invasive surgery (MIS) versus open surgery.
Methods: A retrospective study of patients undergoing MIS or standard open separation surgery for MESCC between 2009 and 2019 was performed. Both groups received circumferential decompression via laminectomy and a transpedicular approach for partial corpectomy to debulk ventral epidural disease, as well as instrumented stabilization. Outcomes were compared between the two groups.
Results: There were 17 patients in the MIS group and 24 in the open surgery group. The average age of the MIS group was significantly older than the open surgery group (65.5 vs 56.6 years, p < 0.05). The preoperative Karnofsky Performance Scale score of the open group was significantly lower than that of the MIS group, with averages of 63.0% versus 75.9%, respectively (p = 0.02). This was also evidenced by the higher proportion of emergency procedures performed in the open group (9 of 24 patients vs 0 of 17 patients, p = 0.004). The average Spine Instability Neoplastic Score, number of levels fused, and operative parameters, including length of stay, were similar. The average estimated blood loss difference for the open surgery versus the MIS group (783 mL vs 430 mL, p < 0.05) was significant, although the average amount of packed red blood cells transfused was not significantly different (325 mL vs 216 mL, p = 0.39). Time until start of radiation therapy was slightly less in the MIS than the open surgery group (32.8 ± 15.6 days vs 43.1 ± 20.3 days, p = 0.069). Among patients who underwent open surgery with long-term follow-up, 20% were found to have local recurrence compared with 12.5% of patients treated with the MIS technique. No patients in either group developed hardware failure requiring revision surgery.
Conclusions: MIS for MESCC is a safe and effective approach for decompression and stabilization compared with standard open separation surgery, and it significantly reduced blood loss during surgery. Although there was a trend toward a faster time to starting radiation treatment in the MIS group, both groups received similar postoperative radiotherapy doses, with similar rates of local recurrence and hardware failure. An increased ability to perform MIS in emergency settings as well as larger, prospective studies are needed to determine the potential benefits of MIS over standard open separation surgery.