The "Spinal Metastasis Invasiveness Index": A Novel Scoring System to Assess Surgical Invasiveness

Complication avoidance, rehabilitation, pain therapy and palliative care for patients with metastatic spine tumors: WFNS spine committee recommendations

OBJECTIVE

This review aims to formulate the most current, evidence-based recommendations regarding complication avoidance, rehabilitation, pain therapy and palliative care for patients with metastatic spine tumors.

METHODS

A systematic literature search in PubMed and MEDLINE, and was performed from 2013 to 2023 using the search terms "complications" + "spine metastases", "spine metastases" + + "rehabilitation", "spine metastases" + "pain therapy" + "palliative care". Screening criteria resulted in 35, 15 and 56 studies respectively that were analyzed. Using the Delphi method and two rounds of voting at two separate international meetings, nine members of the WFNS (World Federation of Neurosurgical Societies) Spine Committee generated nine final consensus statements.

RESULTS

Preoperative assessment for complications following surgery in patients with metastatic spine tumors should include estimation of Karnofsky score, site of primary tumor, number of spinal and visceral metastasis, ASA score and preoperative Hb (Hemoglobin) value. Complication risk factors are age > 65 years, preoperative ASA score of 3 and 4 and greater operative blood loss. Pain management using WHO analgesic concept and early mobilization are needed, starting with non-opioids, weak opioids followed by strong opioids. Morphine is the first choice for moderate to severe pain whereas IV-PCA may be used for severe breakthrough pain with monitoring. Use of bisphosphonates is considered in cases of non-localized pain and not accessible radiation therapy.

CONCLUSIONS

These nine final consensus statements provide current, evidence-based guidelines on complication avoidance, rehabilitation, pain therapy and palliative care for patients with spinal metastases.

Association of CT-DSA vascular assessment and perioperative outcomes in metastatic spinal surgery

INTRODUCTION

Computed tomography-digital subtraction angiography (CT-DSA) is a radiological method for assessing spinal metastatic tumor vascularity. The study aimed to investigate the association between CT-DSA results and perioperative outcomes in spinal metastatic surgery.

MATERIAL AND METHODS

Patients who underwent spinal metastatic operations with preoperative CT-DSA examinations at any time between January 2018 to December 2022. CT-DSA was classified into five grades ranging from grade 0 to grade 4. Grades 3 and 4 were indicative of hypervascularity. We analyzed the perioperative outcomes of intraoperative blood loss amount, massive hemorrhage (≥2500 ml) occurrence, blood transfusion status, operation time, hospital stay duration, and 30-day and 60-day mortality rates. Logistic regression analyses were conducted to identify factors affecting the likelihood of massive hemorrhage in conjunction with CT-DSA.

RESULTS

Data from 212 operations involving 209 patients were analyzed. In total, 30, 36, 66, 56, and 24 operations had CT-DSA grades from grade 0 to grade 4, respectively. Eighty (38 %) studies were indicative of hypervascularity. CT-DSA grade was positively correlated with the amount of operative blood loss, the occurrence of massive hemorrhage, and the amount of blood in blood transfusion (p < 0.05). However, CT-DSA grades was not significantly associated with operation duration or mortality rate. A multivariable analysis indicated that factors such as hemoglobulin, hypervascular pathology, and spinal instability neoplastic scores were positively correlated with CT-DSA grade. CT-DSA grade (odds ratio: 2.37, p = 0.02), spinal metastatic invasiveness index, and tumor size (≥50 mL) were found to be independent predictors in a multivariable logistic regression analysis where factors associated with massive hemorrhage were included. Hypervascular pathology type was not significantly associated with the likelihood of hemorrhage in the univariable and multivariable analyses.

CONCLUSIONS

CT-DSA serves as an effective tool for assessing vascularity, and is associated with intra-operative blood loss and likelihood of experiencing massive hemorrhage. The predictive capability of CT-DSA surpasses that of traditional histopathology classifications, making it a useful method for preoperative planning in spinal metastatic surgeries.

The Evolution of Risk Assessment in Spine Surgery: A Narrative Review

BACKGROUND

Risk assessment is critically important in elective and high-risk interventions, particularly spine surgery. This narrative review describes the evolution of risk assessment from the earliest instruments focused on general surgical risk stratification, to more accurate and spine-specific risk calculators that quantified risk, to the current era of big data.

METHODS

The PubMed and SCOPUS databases were queried on October 11, 2023 using search terms to identify risk assessment tools (RATs) in spine surgery. A total of 108 manuscripts were included after screening with full-text review using the following inclusion criteria: 1) study population of adult spine surgical patients, 2) studies describing validation and subsequent performance of preoperative RATs, and 3) studies published in English.

RESULTS

Early RATs provided stratified patients into broad categories and allowed for improved communication between physicians. Subsequent risk calculators attempted to quantify risk by estimating general outcomes such as mortality, but then evolved to estimate spine-specific surgical complications. The integration of novel concepts such as invasiveness, frailty, genetic biomarkers, and sarcopenia led to the development of more sophisticated predictive models that estimate the risk of spine-specific complications and long-term outcomes.

CONCLUSIONS

RATs have undergone a transformative shift from generalized risk stratification to quantitative predictive models. The next generation of tools will likely involve integration of radiographic and genetic biomarkers, machine learning, and artificial intelligence to improve the accuracy of these models and better inform patients, surgeons, and payers.

Injectable Nanorobot-Hydrogel Superstructure for Hemostasis and Anticancer Therapy of Spinal Metastasis

Surgery remains the standard treatment for spinal metastasis. However, uncontrolled intraoperative bleeding poses a significant challenge for adequate surgical resection and compromises surgical outcomes. In this study, we develop a thrombin (Thr)-loaded nanorobot-hydrogel hybrid superstructure by incorporating nanorobots into regenerated silk fibroin nanofibril hydrogels. This superstructure with superior thixotropic properties is injected percutaneously and dispersed into the spinal metastasis of hepatocellular carcinoma (HCC) with easy bleeding characteristics, before spinal surgery in a mouse model. Under near-infrared irradiation, the self-motile nanorobots penetrate into the deep spinal tumor, releasing Thr in a controlled manner. Thr-induced thrombosis effectively blocks the tumor vasculature and reduces bleeding, inhibiting tumor growth and postoperative recurrence with Au nanorod-mediated photothermal therapy. Our minimally invasive treatment platform provides a novel preoperative therapeutic strategy for HCC spinal metastasis effectively controlling intraoperative bleeding and tumor growth, with potentially reduced surgical complications and enhanced operative outcomes.

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.

The new clinical classification of metastatic spinal malignancies serves as a vital reference for surgical management: a retrospective case-control study

BACKGROUND

It is commonly accepted that surgical treatment is an essential component of the comprehensive management of metastatic spinal malignancies. However, up until now, the clinical classification of metastatic spinal malignancies has not been well-structured.

METHODS

After IRB approval, 86 patients with metastatic spinal malignancies were adopted. According to the vascular distribution, stability of vertebrae, and degree of nerve compression, metastatic spinal malignancies can be classified into five types. Tumors classified as type I typically appear in the vertebral body. Type II tumors are those that develop in the transverse processes, superior and inferior articular processes, and spinal pedicles. Type III denotes malignancies that are present in the spinous process and vertebral plate. Types IVa and IVb are included in type IV. Type IVa combines type I and type II, whereas type IVb combines type II and type III. Type V tumors are those of types I, II, and III that co-occur and spread in different directions into the spinal canal. 20 of included 86 patients who did not receive segmental arterial embolization were set as the non-embolization group. The embolization group included 24 patients who received segmental arterial embolization on both sides of the diseased vertebrae. 42 patients were included in the offending embolization group after receiving responsible arterial embolization. A surgical intervention was performed within 24 h following an embolization. Surgical intervention with the purpose of removing as much of the tumor as possible and providing an effective reconstruction of the spinal column.

RESULTS

In comparison with the non-embolization group and embolization group, the offending embolization group presented unique advantages in terms of bleeding volume (p<0.001), operation time (p<0.001), and local recurrence rate within 12 months (p=0.006).

CONCLUSION

By significantly reducing surgical trauma and local recurrence rate (12 months), responsible arterial vascular embolization procedures together with associated surgical protocols developed on the basis of the clinical classification of metastatic spinal malignancies, are worthy of clinical dissemination.

Development and validation of a novel thoracic spinal stenosis surgical invasiveness index: a single-center study based on 989 patients

BACKGROUND CONTEXT

Surgical invasiveness indices have been established for general spine surgery (surgical invasiveness index [SII]), spine deformity, and metastatic spine tumors; however, a specific index for thoracic spinal stenosis (TSS) has not been developed.

PURPOSE

To develop and validate a novel invasiveness index, incorporating TSS-specific factors for open posterior TSS surgery, which may facilitate the prediction of operative duration and intraoperative blood loss, and the stratification of surgical risk.

STUDY DESIGN

A retrospective observational study.

PATIENT SAMPLE

Overall, 989 patients who underwent open posterior TSS surgeries at our institution during the past 5 years were included.

OUTCOME MEASURES

The operation duration, estimated blood loss, transfusion status, major surgical complications, length of hospital stay, and medical expenses.

METHODS

We retrospectively analyzed the data of 989 consecutive patients who underwent posterior surgery for TSS between March 2017 and February 2022. Among them, 70% (n=692) were randomly placed in a training cohort, and the remaining 30% (n=297) automatically constituted the validation cohort. Multivariate linear regression models of operative time and log-transformed estimated blood loss were created using TSS-specific factors. Beta coefficients derived from these models were used to construct a TSS invasiveness index (TII). The ability of the TII to predict surgical invasiveness was compared with that of the SII and assessed in a validation cohort.

RESULTS

The TII was more strongly correlated with operative time and estimated blood loss (p<.05) and explained more variability in operative time and estimated blood loss than the SII (p<.05). The TII explained 64.2% of operative time and 34.6% of estimated blood loss variation, whereas the SII explained 38.7% and 22.5%, respectively. In further verification, the TII was more strongly associated with transfusion rate, drainage time, and length of hospital stay than SII (p<.05).

CONCLUSIONS

By incorporating TSS-specific components, the newly developed TII more accurately predicts the invasiveness of open posterior TSS surgery than the previous index.

Quantile regression-based prediction of intraoperative blood loss in patients with spinal metastases: model development and validation

PURPOSE

To develop and evaluate a quantile regression-based blood loss prediction model for open surgery of spinal metastases.

METHODS

This was a multicenter retrospective cohort study. Over a 11-year period, patients underwent open surgery for spinal metastases at 6 different institutions were reviewed. The outcome measure is intraoperative blood loss (in mL). The effects of baseline, histology of primary tumor and surgical procedure on blood loss were evaluated by univariate and multivariate analysis to determine the predictors. Multivariate ordinary least squares (OLS) regression and 0.75 quantile regression were used to establish two prediction models. The performance of the two models was evaluated in the training set and the test set, respectively.

RESULTS

528 patients were included in this study. Mean age was 57.6 ± 11.2 years, with a range of 20-86 years. Mean blood loss was 1280.1 ± 1181.6 mL, with a range of 10 ~ 10,000 mL. Body mass index (BMI), tumor vascularization, surgical site, surgical extent, total en bloc spondylectomy and microwave ablation use were significant predictors of intraoperative blood loss. Hypervascular tumor, higher BMI, and broader surgical extent were related with massive blood loss. Microwave ablation is more beneficial in surgery with substantial blood loss. Compared to the OLS regression model, the 0.75 quantile regression model may decrease blood loss underestimate.

CONCLUSION

In this study, we developed and evaluated a prediction model for blood loss in open surgery for spinal metastases based on 0.75 quantile regression, which may minimize blood loss underestimate.

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.

Conditional survival after surgery for metastatic tumors of the spine: does prognosis change over time?

PURPOSE

Conditional survival (CS) provides a dynamic prediction of patient survival by incorporating the time an individual has already survived given their disease specific characteristics. The objective of the current study was to estimate CS among patients after surgery for spinal cord compression or spinal instability, as well as stratify CS according to relevant patient- and disease-related characteristics.

METHODS

The clinical outcomes of 361 patients undergoing surgical management of metastatic spinal tumors were retrospectively analyzed. Stratification of this cohort according to disease and surgery-specific characteristics allowed for univariate and multivariate statistical analyses of our study population. Observed overall and conditional survival estimates were calculated by the Kaplan-Meier method.

RESULTS

12-month conditional survival in patients undergoing surgical management of metastatic spine tumors increased from 57% at baseline to 70% at 24 months following spine surgery. Overall survival (OS) was influenced by CCI grade, Katagiri tumor type, presence of lung metastasis, type of spine surgery, presence of postoperative systemic therapy and ambulatory status at follow-up. Analyses of OS and CS by prognostic strata were similar with exception of stratification by surgery type. Differences in survival between strata tend to converge over time. Unfavorable factors for OS appear to be less relevant after a period of 24 months following spine surgery.

CONCLUSION

Patients after surgery for metastatic tumors of the spine can expect a positive trend in conditional survival as survivorship increases. Even patients with a more severe disease can be encouraged with gains in conditional survival over time.

LEVEL OF EVIDENCE

Level IV (retrospective cohort study).

What's new in the management of metastatic bone disease

Metastatic bone disease is a common complication of malignant tumours. As cancer treatment improves the overall survival of patients, the number of patients with bone metastases is expected to increase. The treatments for bone metastases include surgery, radiotherapy, and bone-modifying agents, with patients with a short expected prognosis requiring less invasive treatment. Patients with metastatic bone disease show greatly varying primary tumour histology, metastases sites and numbers, and comorbidities. Therefore, randomised clinical trials are indispensable to compare treatments for these patients. This editorial reviews recent findings on the diagnosis and prognosis prediction and discusses the current treatment of patients with metastatic bone disease.