Effectiveness of Preoperative Embolization in Patients with Spinal Metastases: A Systematic Review and Meta-Analysis

Refinement of nBCA embolization technique in treatment of metastatic spinal tumors: Case series and technical report

BACKGROUND AND OBJECTIVES

Preoperative embolization of metastatic spinal tumors (MSTs) has proven advantageous in limiting intraoperative blood loss (IBL) during resection. N-butyl cyanoacrylate (nBCA) is a liquid embolic agent known for its rapid hemostatic effects. However, nBCA is associated with a higher risk of distal nontarget embolization. This study highlights the refinement of the embolization technique and assesses its efficacy in performing an initial distal segmental artery plug with concentrated nBCA followed by proximal diluted nBCA for MSTs.

METHODS

A retrospective review of patients with MST (2018-2023) was performed. Patients who underwent preoperative nBCA endovascular embolization prior to tumor resection and spinal instrumentation were included. Baseline standard spinal angiography was performed.

RESULTS

Sixteen patients (13 men, 3 women; 56.0 ± 12.4 years) met inclusion criteria. And 43.75% (7 of 16) had thoracic levels, 37.5% (6 of 16) lumbar, and 18.75% (3 of 16) sacral. The most common primary tumor was renal cell carcinoma (43.75%, 7 of 16). A total of 43 pedicles were embolized (median 3), resulting in complete/near complete obliteration of the tumor blush. Most pedicles (83.7%, 36 of 43) received a single dilute concentration of nBCA; however, 16.3% (7 of 43) received two separate concentrations of nBCA, a denser concentration distally into the segmental artery and a diluted concentration proximally into the tumor bed. Mean IBL was 1150 ± 1201 mL in 3 distal plug patients distal plug patients versus 1625 ± 681 mL in 12 other patients. There were no complications related to embolization.

CONCLUSION

Performing a distal, concentrated nBCA plug during preoperative nBCA embolization of MSTs may increase tumor penetration and reduce IBL.

Does Patient Blood Management Affect Outcomes in Metastatic Spine Tumour Surgery? A Review of Current Concepts

STUDY DESIGN

Narrative review.

OBJECTIVE

The spine is the most common site of metastases, associated with decreased quality of life. Increase in metastatic spine tumour surgery (MSTS) has caused us to focus on the management of blood, as blood loss is a significant morbidity in these patients. However, blood transfusion is also not without its own risks, and hence this led to blood conservation strategies and implementation of a concept of patient blood management (PBM) in clinical practise focusing on these patients.

METHODS

A narrative review was conducted and all studies that were related to blood management in metastatic spine disease as well as PBM surrounding this condition were included.

RESULTS

A total of 64 studies were included in this review. We discussed a new concept of patient blood management in patients undergoing MSTS, with stratification to pre-operative and intra-operative factors, as well as anaesthesia and surgical considerations. The studies show that PBM and reduction in blood transfusion allows for reduced readmission rates, lower risks associated with blood transfusion, and lower morbidity for patients undergoing MSTS.

CONCLUSION

Through this review, we highlight various pre-operative and intra-operative methods in the surgical and anaesthesia domains that can help with PBM. It is an important concept with the significant amount of blood loss expected from MSTS.

LEVEL OF EVIDENCE

Not applicable.

A study on short-term efficacy and safety of Iodine-125 brachytherapy coupled with preoperative arterial chemoembolization for hypervascular spinal metastasis

PURPOSE

Hypervascular spinal metastatic malignancies can cause severe pain and intraoperative bleeding and selection of appropriate treatment can be challenging. This study aimed to observe the short-term efficacy and safety of Iodine-125 brachytherapy (125I BT) combined with preoperative transcatheter arterial chemoembolization (TACE) for hypervascular spinal metastasis.

METHODS

This study included a total of 33 patients (39 lesions) with hypervascular spinal metastasis. All of them carried out a regimen of TACE followed by 125I BT under CT guidance. A brachytherapy planning system has been utilized for the purpose of designing treatment plans and optimizing dose distribution. Pain relief was evaluated using a numeric rating scale (NRS) and intraoperative bleeding was recorded. Follow-up was conducted for 6 months to observe the local control rate and clinical complications.

RESULTS

All patients tolerated combined treatment well and intraoperative blood loss of every patient was not more than 10 ml. The 2- and 6- month local disease control rates were 92.3% and 83.8%. The NRS scores for thirty-three tumor patients before surgery and after one week, two, and six months of surgery were recorded as 7.33 ± 1.80, 7.39 ± 1.89, 3.15 ± 2.35, and 4.16 ± 2.15, respectively. The NRS score 2 months after treatment was found considerably lower in comparison to the NRS score before operation (p < 0.05).

CONCLUSIONS

According to our findings, 125I BT as well as preoperative TACE leads to perioperative hemostasis, pain alleviation, and reduced tumor burden, indicating that this combined treatment could be effective and promising for hypervascular spinal metastases.

Development and validation of a web-based artificial intelligence prediction model to assess massive intraoperative blood loss for metastatic spinal disease using machine learning techniques

BACKGROUND CONTEXT

Intraoperative blood loss is a significant concern in patients with metastatic spinal disease. Early identification of patients at high risk of experiencing massive intraoperative blood loss is crucial as it allows for the development of appropriate surgical plans and facilitates timely interventions. However, accurate prediction of intraoperative blood loss remains limited based on prior studies.

PURPOSE

The purpose of this study was to develop and validate a web-based artificial intelligence (AI) model to predict massive intraoperative blood loss during surgery for metastatic spinal disease.

STUDY DESIGN/SETTING

An observational cohort study.

PATIENT SAMPLE

Two hundred seventy-six patients with metastatic spinal tumors undergoing decompressive surgery from two hospitals were included for analysis. Of these, 200 patients were assigned to the derivation cohort for model development and internal validation, while the remaining 76 were allocated to the external validation cohort.

OUTCOME MEASURES

The primary outcome was massive intraoperative blood loss defined as an estimated blood loss of 2,500 cc or more.

METHODS

Data on patients' demographics, tumor conditions, oncological therapies, surgical strategies, and laboratory examinations were collected in the derivation cohort. SMOTETomek resampling (which is a combination of Synthetic Minority Oversampling Technique and Tomek Links Undersampling) was performed to balance the classes of the dataset and obtain an expanded dataset. The patients were randomly divided into two groups in a proportion of 7:3, with the most used for model development and the remaining for internal validation. External validation was performed in another cohort of 76 patients with metastatic spinal tumors undergoing decompressive surgery from a teaching hospital. The logistic regression (LR) model, and five machine learning models, including K-Nearest Neighbor (KNN), Decision Tree (DT), XGBoosting Machine (XGBM), Random Forest (RF), and Support Vector Machine (SVM), were used to develop prediction models. Model prediction performance was evaluated using area under the curve (AUC), recall, specificity, F1 score, Brier score, and log loss. A scoring system incorporating 10 evaluation metrics was developed to comprehensively evaluate the prediction performance.

RESULTS

The incidence of massive intraoperative blood loss was 23.50% (47/200). The model features were comprised of five clinical variables, including tumor type, smoking status, Eastern Cooperative Oncology Group (ECOG) score, surgical process, and preoperative platelet level. The XGBM model performed the best in AUC (0.857 [95% CI: 0.827, 0.877]), accuracy (0.771), recall (0.854), F1 score (0.787), Brier score (0.150), and log loss (0.461), and the RF model ranked second in AUC (0.826 [95% CI: 0.793, 0.861]) and precise (0.705), whereas the AUC of the LR model was only 0.710 (95% CI: 0.665, 0.771), the accuracy was 0.627, the recall was 0.610, and the F1 score was 0.617. According to the scoring system, the XGBM model obtained the highest total score of 55, which signifies the best predictive performance among the evaluated models. External validation showed that the AUC of the XGBM model was also up to 0.809 (95% CI: 0.778, 0.860) and the accuracy was 0.733. The XGBM model, was further deployed online, and can be freely accessed at https://starxueshu-massivebloodloss-main-iudy71.streamlit.app/.

CONCLUSIONS

The XGBM model may be a useful AI tool to assess the risk of intraoperative blood loss in patients with metastatic spinal disease undergoing decompressive surgery.

Comparison of intraoperative blood loss and perioperative complications between preoperative embolization and nonembolization combined with spinal tumor surgeries: a systematic review and meta-analysis

PURPOSE

The present study aimed to comparatively evaluate intraoperative blood loss (IBL) and perioperative complications between preoperative embolization (PE) and nonembolization (NE) combined with spinal tumor surgeries as well as to determine the subgroup of spinal tumor surgeries suitable for PE.

METHODS

A systematic search in PubMed and EMBASE and an additional search by reference lists of the retrieved studies were undertaken by two reviewers. The mean IBL and perioperative complication rate were employed as the effect size in the general quantitative synthesis through direct calculation. Meta-analysis was performed using standardized mean difference (SMD) and weighted mean difference (WMD) of IBL and the odds ratio (OR) of complications. Heterogeneity was assessed using the I2 statistic.

RESULTS

The reviewers selected 17 published studies for the general quantitative synthesis and meta-analyses. The mean IBL of spinal tumor surgeries was 1786.3 mL in the NE group and 1716.4 mL in the PE group. The mean IBL between the two groups was similar. The pooled WMD and SMD of IBL in spinal tumor surgeries was 324.15 mL (95% CI 89.50-1640.9, p = 0.007) and 0.398 (95% CI 0.114-0.682, p = 0.006), respectively. The reduction of the PE group compared with the NE group for the rates of major complications and major hemorrhagic complications were 7.80% and 5.71%, respectively. The risk of PE-related complications in the PE group was only 1.53% more than in the PE group. The pooled OR of major complications in spinal tumor surgeries was 1.426 (95% CI 0.760-2.674; p = 0.269).

CONCLUSIONS

PE may be suitable for spinal tumor surgeries and some subgroups. From the perspective of complications, PE may also be a feasible option for spinal tumor surgeries.

Current state of preoperative embolization for spinal metastasis - A survey by the EANS spine section

Introduction

Preoperative embolization (PE) for spinal metastasis can be used to reduce tumor blood supply in selected patients. The decision whether and when to perform PE varies largely among spine surgeons and centers.

Research question

The aim was to understand the current decision-making process in European spine centers.

Material and methods

The European Association of Neurosurgical Societies (EANS) spine section designed a 13-item online survey. It was distributed to neurosurgical residents and board-certified neurosurgeons between 7th of February and May 5, 2023.

Results

We analyzed 120 survey responses. Most participants were board-certified neurosurgeons (71%) or residents (26%) in university hospitals (76%). Routinely performed PE was stated not a common practice in 62%. Of those using PE, 25% indicated to perform it in selected cases requiring vertebral body replacement. Reasons for not performing PE included lack of time (44%), unclear benefits (25%), no significant bleeding without PE (19%), and significant bleeding despite PE (8%). Most participants opted for PE < 24h before surgery, but in a separate anesthesia (54%). More experienced participants were more likely to observe reduced blood loss (BL) after PE (p = 0.014). The most common reported complications were neurological deterioration due to spinal cord infarction (n = 15) and swelling due to tumor necrosis (n = 13).

Discussion and conclusions

PE is still not a routine among European spine surgeons and is considered mostly for elective cases with hypervascularized tumors scheduled in a separate anesthesia <24h before tumor resection. Most participants noted reduced intraoperative BL, but also a risk of procedure-related complications.

Preoperative Embolization of Vertebral Metastasis: Comprehensive Review of the Literature

The aim of this review is to determine the safety and efficacy of pre-operative spinal metastases embolization procedures. Two reviewers independently conducted the literature search (on MEDLINE databases), including in the review of all the studies that used pre-operative TAE to treat spinal metastases. Twelve articles on pre-operative spinal metastases embolization were selected. Most of the studies demonstrated the low complication rate of pre-operative embolization. The most important study strength is that there are very few reviews in the literature with the setting on pre-operative vertebral metastases embolization. A limitation of the review is that the studies included were predominately retrospective case-control studies, increasing the risk of bias in the primary data. Plus, divergent surgical and embolization procedures were performed in the studies, causing a potential risk of bias in the pooled results. We can conclude that preoperative arterial embolization of vertebral metastases is a safe, well-tolerated technique that reduces surgical blood loss and facilitates surgical tumor resection.

Efficacy of preoperative embolization for metastatic spinal tumor surgery using angiographic vascularity assessment

OBJECTIVES

Preoperative embolization (PE) for metastatic spinal tumors is a method of minimizing intraoperative blood loss during aggressive surgery. This study specified angiographic standards and investigated the influence of these and other factors on blood loss in patients with spinal metastases and various pathologies.

METHODS

The cohort comprised 126 consecutive patients receiving PE from 2015 to 2021. Their clinical, surgical, and angiographic characteristics were reviewed. Standard angiographic grading was used for vascularity assessment. Degree of embolization was divided into complete (≥ 90%), near complete (67 to < 90%), and partial (< 67%). Logistic regression analysis was used to investigate factors predictive of massive blood loss (> 2500 mL). A proportional odds model was used to assess factors predictive of the degree of embolization.

RESULTS

Mean intraoperative blood loss was 1676 mL. Among the patients, 62 had hypervascular tumors and 64 had nonhypervascular tumors, according to the angiographic classification. Intraoperative blood loss differed significantly with embolization degree, both overall (p < 0.001) and in the hypervascular and nonhypervascular groups (p = 0.01 and 0.03). Angiographic hypervascularity, spinal metastasis invasiveness index, and embolization degree were significant predictors of massive blood loss in univariate analysis, but only embolization degree was significant in multivariate analysis. Only the presence of the radiculomedullary artery at the target level was significant in both the univariate and multivariate analyses for embolization degree.

CONCLUSIONS

In addition to pathological classification, angiographic vascularity assessment is valuable. Although complete embolization is a reasonable goal, it is challenging to achieve in cases of visible radiculomedullary artery.

KEY POINTS

• Angiography has a supplementary role in vascularity assessment for spinal metastatic surgery. • Better embolization degree is associated with less intraoperative blood loss in both angiographic hypervascular and nonhypervascular groups. • Presence of radiculomedullary artery in the target level causes worse embolization outcome.

Preoperative embolization of renal cell carcinoma metastases to the bone prior to stabilization procedures does not result in reduction in intraoperative blood loss

PURPOSE

The effect of preoperative embolization of bone metastases prior to stabilization procedures in reducing intraoperative blood loss remains controversial. This study aimed to analyze the effect of preoperative embolization on orthopedic stabilization procedures of the extremities and spine in cases with bone metastases from renal cell carcinomas. In particular, do these patients suffer less blood loss during the operation and do they need lesser fluid replacements or packed red cell bags intra- and perioperatively? Does preoperative embolization reduce the duration of surgery?

METHODS

We retrospectively reviewed stabilization procedures of the spine and extremities at our institution between 2011 and 2021 for group differences (embolization vs. no embolization) in terms of blood loss, fluid substitution, need for packed red cell transfusions, tumor size, and duration of surgery.

RESULTS

We reviewed 79 stabilization procedures of the spine (n = 36) and extremities (n = 43), of which 30 included preoperative embolization procedures. Surprisingly, the embolization group showed a statistically significant increase in blood loss, the need for fluid substitution, and red cell transfusions. Subgroup analysis revealed a significant negative effect of preoperative embolization on stabilization procedures of the extremities.

CONCLUSION

Based on our data, preoperative embolization of renal cell carcinoma metastases of the extremities had a negative effect on intraoperative blood loss and the need for fluid substitution and should therefore be avoided. Our data did not show an effect on stabilization procedures of the spine.

Preoperative embolization in the treatment of patients with metastatic epidural spinal cord compression: A retrospective analysis

Purpose

The purpose of the study was to assess the effectiveness and safety of preoperative embolization in the treatment of patients with metastatic epidural spinal cord compression (MESCC).

Methods

A retrospective analysis of 138 MESCC patients who underwent decompressive surgery and spine stabilization was performed in a large teaching hospital. Among all enrolled patients, 46 patients were treated with preoperative embolization (the embolization group), whereas 92 patients did not (the control group). Patient's baseline clinical characteristics, surgery-related characteristics, and postoperative neurological status, complications, and survival prognoses were collected and analyzed. Subgroup analysis was performed according to the degree of tumor vascularity between patients with and without preoperative embolization.

Results

Patients with severe hypervascularity experienced more mean blood loss in the control group than in the embolization group, and this difference was statistically significant (P=0.02). The number of transfused packed red cells (PRC) showed a similar trend (P=0.01). However, for patients with mild and moderate hypervascularity, both blood loss and the number of PRC transfusion were comparable across the two groups. Regarding decompressive techniques, the embolization group (64.29%, 9/14) had a higher proportion of circumferential decompression in comparison to the control group (30.00%, 9/30) among patients with severe hypervascularity (P=0.03), whereas the rates were similar among patients with mild (P=0.45) and moderate (P=0.54) hypervascularity. In addition, no subgroup analysis revealed any statistically significant differences in operation time, postoperative functional recovery, postoperative complications, or survival outcome. Multivariate analysis showed that higher tumor vascularity (OR[odds ratio]=3.69, 95% CI [confident interval]: 1.30-10.43, P=0.01) and smaller extent of embolization (OR=4.16, 95% CI: 1.10-15.74, P=0.04) were significantly associated with more blood loss.

Conclusions

Preoperative embolization is an effective and safe method in treating MESCC patients with severe hypervascular tumors in terms of intra-operative blood loss and surgical removal of metastatic tumors. Preoperative tumor vascularity and extent of embolization are independent risk factors for blood loss during surgery. This study implies that MESCC patients with severe hypervascular tumors should be advised to undergo preoperative embolization.

Spinal metastasis: narrative reviews of the current evidence and treatment modalities

The treatment for spinal metastasis has evolved significantly during the past decade. An advancement in systemic therapy has led to a prolonged overall survival in cancer patients, thus increasing the incidence of spinal metastasis. In addition, with the improved treatment armamentarium, the prediction of patient survival using traditional prognostic models may have limitations and these require the incorporation of some novel parameters to improve their prognostic accuracy. The development of minimally-invasive spinal procedures and minimal access surgical techniques have facilitated a quicker patient recovery and return to systemic treatment. These modern interventions help to alleviate pain and improve quality of life, even in candidates with a relatively short life expectancy. Radiotherapy may be considered in non-surgical candidates or as adjuvant therapy for improving local tumour control. Stereotactic radiosurgery has facilitated this even in radioresistant tumours and may even replace surgery in radiosensitive malignancies. This narrative review summarizes the current evidence leading to the paradigm shifts in the modern treatment of spinal metastasis.