Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Dural arteriovenous fistula (dAVF) surgery is a microsurgical procedure that requires confirmation of obliteration using formal cerebral angiography, but the lack of intraoperative angiogram or need for postoperative angiogram in some settings necessitates a search for alternative, less invasive methods to verify surgical success. This study evaluates the use of indocyanine green videoangiography FLOW 800 hemodynamic intraoperatively during cranial and spinal dAVF obliteration to confirm obliteration and predict surgical success. METHODS:A retrospective analysis was conducted using indocyanine green videoangiography FLOW 800 to intraoperatively measure 4 hemodynamic parameters-Delay Time, Speed, Time to Peak, and Rise Time-across venous drainage regions of interest pre/post-dAVF obliteration. Univariate and multivariate statistical analyses to evaluate and visualize presurgical vs postsurgical state hemodynamic changes included nonparametric statistical tests, logistic regression, and Bayesian analysis. RESULTS:A total of 14 venous drainage regions of interest from 8 patients who had successful spinal or cranial dAVF obliteration confirmed with intraoperative digital subtraction angiography were extracted. Significant hemodynamic changes were observed after dAVF obliteration, with median Speed decreasing from 13.5 to 5.5 s-1 (P = .029) and Delay Time increasing from 2.07 to 7.86 s (P = .020). Bayesian logistic regression identified Delay Time as the strongest predictor of postsurgical state, with a 50% increase associated with 2.16 times higher odds of achieving obliteration (odds ratio = 4.59, 95% highest density interval: 1.07-19.95). Speed exhibited a trend toward a negative association with postsurgical state (odds ratio = 0.62, 95% highest density interval: 0.26-1.42). Receiver operating characteristic-area under the curve analysis using logistic regression demonstrated a score of 0.760, highlighting Delay Time and Speed as key features distinguishing preobliteration and postobliteration states. CONCLUSION/CONCLUSIONS:Our findings demonstrate that intraoperative FLOW 800 analysis reliably quantifies and visualizes immediate hemodynamic changes consistent with dAVF obliteration. Speed and Delay Time emerged as key indicators of surgical success, highlighting the potential of FLOW 800 as a noninvasive adjunct to traditional imaging techniques for confirming dAVF obliteration intraoperatively.

Study DesignNarrative Review.ObjectivesTo summarize the scientific contributions generated from the AO Spine Knowledge Forum Tumor (AOSKFT) databases, focusing on primary spine tumors, and highlight key findings, research trends, and future directions.MethodsData from the Primary Tumor Retrospective (PT-Retro) and Primary Tumor Research Outcome Network (PTRON) registries were analyzed. The nineteen studies included were peer-reviewed manuscripts focused on primary spine tumors, excluding abstracts, book chapters, systematic reviews, and metastatic studies.ResultsThe PT-Retro registry compiled data from 1495 patients across 18 primary tumor histologies, offering insights into recurrence, survival, and treatment paradigms. Key findings emphasize the importance of Enneking-appropriate (EA) resection in improving survival and reducing recurrence in tumors such as chordoma, chondrosarcoma, and osteosarcoma. Genetic markers, including hTERT promoter mutations and rs2305089 SNP, were linked to prognosis in specific histologies. Benign tumors, such as giant cell tumors and aneurysmal bone cysts, demonstrated variable outcomes with different surgical approaches and selective arterial embolization.ConclusionsThe AOSKFT registries have significantly advanced knowledge in primary spine tumor management, emphasizing preoperative staging, surgical margins, and multidisciplinary approaches. International, multicentric registries are essential for studying rare diseases like primary spine tumors, enabling robust data collection, improved statistical power, and broader applicability of findings across diverse clinical settings. Ongoing prospective data collection through PTRON will further refine evidence-based care for these rare and challenging conditions.

STUDY DESIGN/METHODS:Delphi Consensus. OBJECTIVE:To define an optimal surgical composite outcome measure in patients with metastatic spine disease (OSCO-M) through international consensus among key opinion leaders. METHODS:Members of the AO Spine Knowledge Forum Tumor, an international group of dedicated spine oncology surgeons and oncologists, participated in a modified Delphi process between March 2023 and November 2024. The study was conducted in two parts. The first part aimed on identifying which outcome variables were deemed important to be included in the composite outcome. The second part focused on the definition of a successful outcome with regards to the agreed variables from Part 1. Each part consisted of a questionnaire and a consensus meeting. Consensus was achieved when a threshold of 70% agreement was reached. RESULTS:A total of 42 dedicated spine oncology surgeons and oncologists from North America, Latin America, Europe, and Asia participated. Over 87% of respondents agreed that composite measures reflect the multidimensional aspect of the surgical process more than an individual outcome variable. Most respondents (93%) agreed/strongly agreed that composite measures should be used to assess the quality of surgical care in spine oncology. Through consensus, the following three outcome variables were selected to define the OSCO-M: the absence of SAVES-V2 (Spinal Adverse Events Severity System, Version 2) Grade 3 adverse events or higher within 30 days of surgery, maintaining or improving ECOG (Eastern Cooperative Oncology Group) performance status at 90 days, and being ambulatory (with or without aid) at 90 days. CONCLUSION/CONCLUSIONS:This is the first study defining a composite outcome measure in oncologic surgery for spinal metastases derived from an international group of key opinion leaders in spine oncology. The OSCO-M may be useful for future research in spine tumor patients and serve as a benchmark to optimize outcomes.

BACKGROUND AND OBJECTIVES/OBJECTIVE:The Patient-Generated Subjective Global Assessment (PG-SGA) is a standardized tool for assessing malnutrition in patients with cancer. The primary aim of this study was to assess the impact of preoperative nutritional status as measured by PG-SGA on survival in patients requiring surgical intervention and/or radiotherapy for spinal metastases. METHODS:Patients with spinal metastases who underwent surgery and/or radiation therapy for symptomatic spinal metastases were enrolled in the AO Spine Metastatic Tumor Research and Outcomes Network, a prospective international multicenter research registry, between September 2017 and August 2022. Using the PG-SGA, nutritional status was classified into 3 categories: A, well nourished; B, moderately malnourished; and C, severely malnourished. RESULTS:A total of 589 patients met the inclusion criteria; 362 were classified as well nourished (61%), 159 were moderately malnourished (27%), and 68 were severely malnourished (12%). The median survival was 491 days, 328 days, and 117 days for well-nourished, moderately malnourished, and severely malnourished patients, respectively. In the multivariate analyses, severe malnourishment (HR 2.5 95% CI 1.4-4.3, P < .01) and an ECOG performance status of 3 or 4 (HR 2.7 95% CI 1.2-6.0) remained associated with significantly worse survival. CONCLUSION/CONCLUSIONS:Malnutrition as measured by the PG-SGA demonstrated to be significantly and independently associated with postoperative survival. The PG-SGA is a simple and useful tool to identify spinal metastases patients at risk of early postoperative mortality, and inclusion in the preoperative evaluation of these patients should be considered.

Spinal dural arteriovenous fistulas (dAVFs) at the craniocervical junction are rare vascular lesions that can cause progressive myelopathy and paralysis. This video presents a 40-year-old male with a left C1 spinal dAVF, who experienced unsteadiness, dizziness, leg weakness, and intermittent facial numbness. Given the lesion's symptomatology, the patient underwent a C1 laminectomy and midline suboccipital craniectomy for definitive obliteration. The authors describe key surgical techniques for fistula exposure and obliteration, with intraoperative angiographic confirmation. Long-term follow-up confirmed complete persistent occlusion on angiography and resolution of his symptoms. This case highlights surgical strategies for managing dAVFs at the craniocervical level. The video can be found here: https://stream.cadmore.media/r10.3171/2025.7.FOCVID2573.

Metastatic spine disease represents a growing therapeutic challenge that demands a balance between incorporating emerging technologies while respecting the fundamental principles during clinical decision-making. Advances in adjuvant therapies, including stereotactic body radiotherapy (SBRT) and chemotherapy, have significantly improved long-term patient survival. Surgical decision-making should be guided by well-established frameworks such as the NOMS (neurologic, oncologic, mechanical, systemic) criteria, the ESCC (epidural spinal cord compression) scale, and the SINS (spinal instability neoplastic score), ensuring a structured and evidence-based approach to treatment. The integration of minimally invasive techniques, including percutaneous instrumentation, ablation techniques, and biportal endoscopic approaches, has reduced surgical morbidity and facilitated faster recovery. Additionally, carbon fiber implants are revolutionizing spinal stabilization by allowing better postoperative visualization of any local recurrence and easier radiation planning. SBRT has emerged as a critical modality, offering precise, high-dose radiation with minimal toxicity to the spinal cord, improving local tumor control and patient outcomes. A multidisciplinary approach remains paramount, requiring collaboration between spine surgeons, radiation oncologists, and medical oncologists. In this narrative review, we aim to provide a comprehensive overview of the current state of metastatic spine tumor management, focusing on: (1) fundamentals of metastatic spine care, (2) minimally invasive surgical techniques, (3) the use of carbon fiber screws, (4) SBRT, and (5) ways to maximize patient safety.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Bone metastases, affecting more than 4.8% of patients with cancer annually, and particularly spinal metastases require urgent intervention to prevent neurological complications. However, the current process of manually reviewing radiological reports leads to potential delays in specialist referrals. We hypothesized that natural language processing (NLP) review of routine radiology reports could automate the referral process for timely multidisciplinary care of spinal metastases. METHODS:We assessed 3 NLP models-a rule-based regular expression (RegEx) model, GPT-4, and a specialized Bidirectional Encoder Representations from Transformers (BERT) model (NYUTron)-for automated detection and referral of bone metastases. Study inclusion criteria targeted patients with active cancer diagnoses who underwent advanced imaging (computed tomography, MRI, or positron emission tomography) without previous specialist referral. We defined 2 separate tasks: task of identifying clinically significant bone metastatic terms (lexical detection), and identifying cases needing a specialist follow-up (clinical referral). Models were developed using 3754 hand-labeled advanced imaging studies in 2 phases: phase 1 focused on spine metastases, and phase 2 generalized to bone metastases. Standard McRae's line performance metrics were evaluated and compared across all stages and tasks. RESULTS:In the lexical detection, a simple RegEx achieved the highest performance (sensitivity 98.4%, specificity 97.6%, F1 = 0.965), followed by NYUTron (sensitivity 96.8%, specificity 89.9%, and F1 = 0.787). For the clinical referral task, RegEx also demonstrated superior performance (sensitivity 92.3%, specificity 87.5%, and F1 = 0.936), followed by a fine-tuned NYUTron model (sensitivity 90.0%, specificity 66.7%, and F1 = 0.750). CONCLUSION/CONCLUSIONS:An NLP-based automated referral system can accurately identify patients with bone metastases requiring specialist evaluation. A simple RegEx model excels in syntax-based identification and expert-informed rule generation for efficient referral patient recommendation in comparison with advanced NLP models. This system could significantly reduce missed follow-ups and enhance timely intervention for patients with bone metastases.

Study DesignLiterature review with clinical recommendations.ObjectiveSpinal metastases represent a late complication of cancer and a major factor in decreased quality of life. The role of surgery for specific indications for spinal metastases is well established. Given the significant morbidity associated with spine surgery in this frail population, efforts are ongoing to decrease the surgical footprint. The objective of this study is to provide the readers with a concise curation of the latest spine literature on reducing the surgical footprint for spine metastases and clinical recommendations for how the practicing clinician should interpret and make use of this evidence.MethodsThe latest spine literature in the topic of reducing the surgical footprint for spine metastases was reviewed and clinical recommendations were formulated. The recommendations are dichotomously graded into strong and conditional based on the integration of scientific methodology and content expert opinion. This opinion considers experience and practical issues such as risks, burdens, costs, patient values, and circumstances.ResultsFour high impact studies were selected for review. The findings suggest that surgery plays a key role in improving patients' quality of life, but incidence of adverse events remains high and hence methods to decrease surgical morbidity are necessary. The integration of radiation into the treatment algorithm allows for less extensive surgical procedures and SBRT should be strongly considered after surgery for spine metastases in appropriate patient populations. Implementation of enhanced recovery after surgery (ERAS) protocols reduce perioperative morbidity for both open and minimally invasive surgeries and should be considered on an institutional level. Utilization of minimally invasive surgical stabilization should be considered as it results in fewer post operative complications, lower infection rates, less blood loss during surgery, and a shorter hospital stay compared to open stabilization of unstable pathology thoracolumbar fractures.ConclusionsThe role and benefits of surgery for metastatic spine disease are well established, yet surgery carries significant risk for adverse events which may negatively affect overall cancer care. Methods for reducing the surgical footprint include incorporation of stereotactic radiation allowing less extensive surgery, implementation of ERAS protocols and utilization of minimally invasive surgical strategies.

BACKGROUND/OBJECTIVES/OBJECTIVE:Malignant peripheral nerve sheath tumors (MPNSTs) are aggressive malignancies with a challenging prognosis, especially for patients with Neurofibromatosis type 1 (NF1). Their low incidence necessitates comprehensive studies to investigate the survival outcome. METHODS:We conducted a systematic review and meta-analysis, including data from 16 studies and 4265 patients, to explore surgical outcomes and survival rates, focusing on time-related outcomes, including overall survival (OS), progression-free survival (PFS), and recurrence rate. RESULTS:The analysis revealed that the OS rate was 86% [95% CI: 75-97%] at 1 year, decreasing to 60% [95% CI: 45-75%] at 3 years, and further declining to 47% [95% CI: 35-58%] by 5 years. For PFS, the 1-year rate was 61% [95% CI: 25-98%], which remained similar at 62% [95% CI: 35-89%] for 3 and 5 years. In NF1-associated MPNSTs, the 1-year OS was relatively high at 93% [95% CI: 83-100%], but it dropped to 68% [95% CI: 53-84%] at 3 years and further to 50% [95% CI: 31-68%] at 5 years. Additionally, the hazard ratio indicated a 38% lower survival rate in NF1 patients than those with sporadic MPNSTs when data were presented in the same study. Recurrence rates were high, with 56% of patients experiencing a relapse, primarily as local recurrences (70.6%). Mortality was significant, with over 50% of patients dying within an average follow-up period of 33.45 months. CONCLUSIONS:MPNSTs, particularly in NF1 patients, are associated with poor prognosis and high recurrence rates. These results underline the necessity of targeted therapeutic strategies and improved programs for screening, mainly through a multidisciplinary approach to optimize management.

Study DesignBibliometric analysis.ObjectivesThis study used bibliometric analyses to characterize the effect of AO Spine Knowledge Forum (KF) participation on publication trends among members. We examined associations of membership in KF organizations with academic productivity, collaboration, and scientific impact.MethodsWe queried the Web of Science database for publications by members of KF Tumor (N = 58), KF Trauma and Infection (N = 45), KF Spinal Cord Injury (N = 38), KF Degenerative (N = 54), and KF Deformity (N = 55). Resulting metadata were exported; statistical and bibliometric analyses were performed using Python packages.ResultsOur query returned 24,267 articles by KF members, of which 18,804 were identified as relevant to respective organizational themes through an algorithmic analysis of titles and abstracts. These works, published between 1980 and 2025, included contributions from 67,895 authors. Research productivity, co-authorship among members (P < 0.001), unique institutional affiliations per article (P < 0.001), and international collaboration increased contemporaneously with the first KF formation (2010). A positive association was found between the number of KF authors per publication and source journal impact factor (P < 0.001). Term analysis highlighted research foci within each KF and influential publications were identified.ConclusionsThese findings suggest that formalization of researcher relationships and the research infrastructure and support provided by the KF model was associated with increased and more impactful research output and collaboration. The KF model could be applied in other organizations whose mission includes collaborative research. Methods used in this study are easily replicable and may be applied to investigate the impact of other professional organizations across various fields.