Preoperative embolization of spinal tumors: Variables affecting intraoperative blood loss after embolization

Background: Preoperative embolization of spinal tumors is often used to reduce blood loss from surgery. Intraoperative blood loss, even in patients who undergo embolization, is potentially multifactorial; embolization techniques, surgical procedures or tumor characteristics may affect intraoperative blood loss. Purpose: To retrospectively analyze factors affecting intraoperative blood loss in patients who had undergone spinal tumor embolization; and to assess the safety of the procedure. Material and Methods: Sixty-two patients (median age, 60 years) with a tumor involving the thoracic (n=42) or lumbar (n=20) spine underwent preoperative tumor embolization with particles. Multiple variables, including patient characteristics, tumor characteristics, embolization techniques, and surgical procedures, were evaluated with respect to intraoperative blood loss and transfusion requirement. Complications related to the embolization procedures were also recorded. Univariate and multivariate analysis were performed to analyze the variables affecting the intraoperative blood loss and transfusion requirement. Results: Complete or near-complete tumor embolization was achieved in 47 patients. The average estimated blood loss (EBL) and packed red blood cells units transfused during surgery were 2554 mL (range, 250-11,000 mL) and 7 units (range, 0-28 units), respectively. Univariate analysis indicated tumor volume, surgical approach, and invasiveness of the spinal surgery to be significant variables affecting EBL. Tumor histology and extent, tumor vascularity, degree of embolization, and size of embolic particle did not affect operative blood loss. On multivariate analysis, invasiveness of the surgery was the only variable that influenced EBL. Two patients developed irreversible neurologic deficits following embolization. Conclusion: Embolization technique or completeness has a limited effect on operative blood loss after preoperative spinal tumor embolization. Operative blood loss from spinal surgery is dependent primarily on the invasiveness of the surgery. Although preoperative embolization is a relatively safe procedure, there remains a risk of cord ischemia.