Faculty Bibliography

BACKGROUND AND OBJECTIVES/OBJECTIVE:Repeat stereotactic radiosurgery (SRS) is a noninvasive option for recurrent vestibular schwannoma (VS). This study evaluates outcomes in patients with long-term follow-up. METHODS:This retrospective multicenter study analyzed 81 patients with recurrent unilateral sporadic VS after initial SRS, with ≥12 months of follow-up. Outcomes included tumor control, hearing preservation, cranial nerve function, and adverse radiation effects (ARE). Kaplan-Meier and Cox regression identified factors affecting outcomes. RESULTS:The median age at the second SRS was 60 years, with a median interval of 58 months between procedures. The median margin doses were 12.0 Gy (single-fraction), 17.25 Gy (3-fraction), and 25 Gy (5-fraction). Tumor control was achieved in 69 patients (85.2%), with 5- and 10-year local control rates of 82% and 76.5%, respectively. Significant predictors of local failure included tumor volume >2.2 cm3 (area under the curve = 0.757, P = .018), prescription biological effective dose (BED) ≤70.3 Gy (hazard ratio [HR]: 0.89, P = .003), and interval between treatments >27.5 months (HR: 1.02, P = .015). In single-fraction SRS, higher prescription dose reduced failure risk (HR: 0.31, P = .002) with a margin dose ≥12 Gy being critical for improved tumor control (P < .001). Serviceable hearing was retained in 12 of 18 cases (66.7%), and facial nerve function was preserved in 72 of 80 cases (90%). ARE occurred in 11 patients (13.6%), most commonly perilesional edema (63.7%). ARE correlated with higher brainstem maximum BED in the entire cohort (HR: 1.02, P = .016) and in single-fraction SRS (HR: 1.02, P = .006). Pseudoprogression (9.8%) was linked to younger age (HR: 0.88, P = .023) and shorter time between SRS (HR: 0.87, P = .012). CONCLUSION/CONCLUSIONS:Repeat SRS is an effective option for recurrent sporadic VS, offering high tumor control and functional preservation. Outcomes depend on age, interval between treatments, tumor volume, and BED. With careful planning, adverse effects are rare and typically transient.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Adult biomechanical studies suggest a significant reduction in flexion-extension motion after occipitocervical and atlantoaxial fusion. Anecdotal experience in children suggests a lower magnitude of reduction in motion after these procedures, but high-quality quantitative assessments of this motion have not yet been performed. As such, the aim of this study was to determine the magnitude of reduction in cervical spine flexion-extension after O-C2 and C1-2 fusion in pediatric patients. METHODS:The Pediatric Spine Study Group international registry was queried for patients aged 21 years or younger who underwent O-C2 or C1-2 instrumentation and fusion. Patients with cervical spine flexion-extension radiographs preoperatively and ≥6 months postoperatively were included. Flexion, extension, and overall range of motion (ROM) of the cervical spine were measured on radiographs using McGregor line and the inferior endplate of C7. RESULTS:In total, 34 patients were included, with 19 undergoing index O-C2 and 15 undergoing index C1-2 stabilization. The mean age was 9.3 ± 4.5 years with average follow-up of 3.5 ± 2.6 years. The most common etiologies were syndromic (n = 20) and congenital (n = 9). Patients undergoing O-C2 fusion had reduced neck extension (80° vs 69.6°, P = .003) and overall ROM (92.9° vs 80°, P = .002) after stabilization, but no significant reduction in flexion (-12.9° vs -10.4°, P = .324). After C1-2 fusion, there was no significant reduction in overall ROM (85.0° vs 77.5°, P = .079), extension (70.5° vs 63.4°, P = .120), or flexion (-14.6° vs -14.0°, P = .831). CONCLUSION/CONCLUSIONS:In this cohort, children undergoing O-C2 stabilization had a 13.9% reduction in flexion-extension motion of the cervical spine, primarily due to a reduction in extension. There may be a smaller reduction in flexion-extension motion after stabilization in children when compared with adult studies. Further studies with video analysis including axial rotation and lateral bending will be necessary to comprehensively quantify cervical spine motion after fusion across the occipitocervical and atlantoaxial junctions.

STUDY DESIGN/METHODS:Retrospective analysis of retrospectively collected data. OBJECTIVE:To determine the effects of preoperative nonsteroidal anti-inflammatory drug (NSAID) use on estimated blood loss (EBL) and postoperative drain output in TLIF procedures. SUMMARY OF BACKGROUND DATA/BACKGROUND:Current standards of care recommend patients prescribed NSAIDs for chronic lower back pain discontinue NSAIDs at least 1 week before spine fusion surgery. The literature surrounding the effects of preoperative NSAID use is unclear, however, with dissonant findings regarding postoperative blood loss and complications. METHODS:A retrospective case review was performed on 429 cases of 1-level or 2-level TLIF, with patient NSAID use recorded within 3 days of surgery, at a single institution. Linear and logistic regressions were used to assess associations between NSAID use, patient and surgical characteristics, EBL, and drain output. RESULTS:NSAID use was significantly positively associated with drain output (P=0.03), with an approximate increase of 21±9.7 mL/day but no significant association with any postoperative complications (P=0.77). Drain output also had significant, independent positive associations with patient age (P=0.007), male sex (P<0.001), and a number of levels fused (P<0.001), and significant negative associations with robot-assisted (P<0.001) and minimally invasive (P=0.04) procedures. No significant association was detected between NSAID use and EBL (P=0.21), though EBL had significant positive associations with operative time (P<0.001) and levels fused (P<0.001), and multiple NSAIDs had a significant positive association with EBL (P<0.001). CONCLUSIONS:NSAID use had a statistically significant, but small, effect on drain output and no detectable effect on postoperative complications within 3 days of TLIF procedures, suggesting most patients can safely continue NSAID use up until their date of surgery. Future studies should further delineate the effects of preoperative NSAID use, such that a more refined risk profile could be developed from patient and surgical characteristics and NSAID use information.

BACKGROUND AND OBJECTIVES/OBJECTIVE:Neurosurgical clinical research depends on medical data collection and evaluation that is often laborious, time consuming, and inefficient. The goal of this work was to implement and evaluate a novel departmental data infrastructure (Neuro Data Hub) designed to provide specialized data services for neurosurgical research. Data acquisition would become available purely by request. METHODS:through collaboration between Department Leadership and Medical Center Information Technology, integrating it with Institutional Review Board workflows and an existing Epic electronic health record Datalake infrastructure. The system implementation included monthly departmental meetings and an asynchronous Research Electronic Data Capture-based request system. Data requests submitted between August 2023 and November 2024 were analyzed and categorized as basic, complex, or Natural Language Processing (NLP)-augmented, with optional visualization and database creation services. Request volumes, types, and execution times were assessed. RESULTS:The Hub processed 39 research data requests (2.6/month), comprising 3 basic, 22 complex, and 14 NLP-augmented requests. Two complex requests included visualization services, and one NLP request included database creation. Average request execution time was 36.5 days, with NLP-augmented requests showing increasing adoption over time. CONCLUSION/CONCLUSIONS:The Neuro Data Hub represents a paradigm shift from centralized to department-level data services, providing specialized support for neurosurgical research and democratizing access to institutional data. While effective, implementation may be limited by institutional information technology infrastructure requirements. This model could serve as a template for any form of medical-clinical research program seeking to improve data accessibility and research capabilities.

PURPOSE/OBJECTIVE:To use validated bibliometric methods to map the evolution of CP treatment, with a particular focus on how definitions of treatment success, surgical techniques, and pathological subtypes have shifted over time. METHODS:A Web of Science (WoS) query was designed to capture all available articles related to pediatric CPs. Articles not published in English were excluded from the cohort. The Bibliometrix R-tool, VOSviewer, and various Python packages were employed to perform bibliometric analyses. RESULTS:The WoS query identified 2608 articles, with 2348 articles meeting inclusion criteria. Of these, 90% were published in the last 27 years. Reflecting the multidisciplinary collaborative management of CPs, neurosurgery, oncology, and endocrinology-focused journals produced the most publications in the corpus. Authorship analysis revealed substantial international and interinstitutional collaboration. Keyword analysis and landmark article identification illuminated eras in the field's development. Notably, a transition to measuring treatment success by quality of life, instead of gross total resection, occurred during the 1990s. The 2000s were highlighted by applying the newfound transsphenoidal approach to pediatric CPs. Finally, the 2010s made use of high-fidelity sequencing to begin uncovering the genetic profiles that drive these tumors. CONCLUSION/CONCLUSIONS:Interinstitutional and interdisciplinary collaboration has allowed physicians to provide pediatric patients with CPs care for their patients using the best knowledge and technology available. Genetics offers a new frontier for the treatment of pediatric CPs increases, and continued collaboration will be necessary to ensure that the standard of care evolves appropriately.

Carotid webs are increasingly recognized as an underdiagnosed etiology of ischemic stroke, especially in young, otherwise healthy patients. These fibrous intimal protrusions create regions of flow stasis within the internal carotid artery, predisposing to thromboembolism. Diagnosis remains challenging due to their subtle radiographic appearance and underappreciation in clinical practice. While antiplatelet therapy or anticoagulation used to be the cornerstone of management, medical therapy alone has been found to be insufficient for stroke prevention in symptomatic patients. Definitive intervention includes carotid artery stenting or carotid endarterectomy; both have demonstrated excellent safety and efficacy. Risk stratification for symptomatic and asymptomatic carotid webs remains an area of active research, with emerging evidence suggesting that specific anatomic features, termed the carotid web angioarchitecture, may help predict stroke risk. Further studies are needed to determine the role of preventative intervention. A deeper understanding of carotid web pathogenesis, natural history, and hemodynamic impact is critical for guiding clinical decision-making.

Large Language Models (LLMs) offer a framework for understanding language processing in the human brain. Unlike traditional models, LLMs represent words and context through layered numerical embeddings. Here, we demonstrate that LLMs' layer hierarchy aligns with the temporal dynamics of language comprehension in the brain. Using electrocorticography (ECoG) data from participants listening to a 30-minute narrative, we show that deeper LLM layers correspond to later brain activity, particularly in Broca's area and other language-related regions. We extract contextual embeddings from GPT-2 XL and Llama-2 and use linear models to predict neural responses across time. Our results reveal a strong correlation between model depth and the brain's temporal receptive window during comprehension. We also compare LLM-based predictions with symbolic approaches, highlighting the advantages of deep learning models in capturing brain dynamics. We release our aligned neural and linguistic dataset as a public benchmark to test competing theories of language processing.

The performance of Large Language Models (LLMs) on multiple-choice question (MCQ) benchmarks is frequently cited as proof of their medical capabilities. We hypothesized that LLM performance on medical MCQs may in part be illusory and driven by factors beyond medical content knowledge and reasoning capabilities. To assess this, we created a novel benchmark of free-response questions with paired MCQs (FreeMedQA). Using this benchmark, we evaluated three state-of-the-art LLMs (GPT-4o, GPT-3.5, and LLama-3-70B-instruct) and found an average absolute deterioration of 39.43% in performance on free-response questions relative to multiple-choice (p = 1.3 * 10^-5) which was greater than the human performance decline of 22.29%. To isolate the role of the MCQ format on performance, we performed a masking study, iteratively masking out parts of the question stem. At 100% masking, the average LLM multiple-choice performance was 6.70% greater than random chance (p = 0.002) with one LLM (GPT-4o) obtaining an accuracy of 37.34%. Notably, for all LLMs the free-response performance was near zero. Our results highlight the shortcomings in medical MCQ benchmarks for overestimating the capabilities of LLMs in medicine, and, broadly, the potential for improving both human and machine assessments using LLM-evaluated free-response questions.

This position statement provides updated member guidance from the American Academy of Neurology (AAN) regarding (1) communication with surrogate decision makers about brain death/death by neurologic criteria (BD/DNC), (2) management of surrogate decision-maker objections to BD/DNC, (3) the ethical considerations associated with BD/DNC determination in a pregnant person, and (4) enhancing public trust in BD/DNC. This position statement is intended to complement recommendations in the 2023 "Pediatric and Adult Brain Death/Death by Neurologic Criteria Consensus Guideline" published by the AAN, American Academy of Pediatrics, Child Neurology Society, and Society of Critical Care Medicine, as well as the 2021 AAN Code of Professional Conduct. It replaces the 2019 AAN position statement, "Brain death, the determination of brain death, and member guidance for brain death accommodation requests."

BACKGROUND:Arteriovenous malformations (AVMs) are uncommon cerebral lesions that can cause significant neurological complications. Surgical resection is the gold standard for treatment, but endovascular embolization and stereotactic radiosurgery (SRS) are viable alternatives. OBJECTIVE:To compare the outcomes of endovascular embolization versus SRS in the treatment of AVMs with Spetzler-Martin grades I-III. METHODS:This study combined retrospective data from 10 academic institutions in North America and Europe. Patients aged 1 to 90 years who underwent endovascular embolization or SRS for AVMs with Spetzler-Martin grades I-III between January 2010 and December 2023 were included. RESULTS:The study included 244 patients, including 84 who had endovascular embolization and 160 who had SRS. Before propensity score matching (PSM), complete obliteration at the last follow-up was achieved in 74.5% of the SRS group compared with 57.8% of the embolization group (OR=0.47; 95% CI 0.26 to 0.48; P=0.01). After propensity score matching, SRS still achieved significantly higher occlusion rates at last follow-up (78.9% vs 55.3%; OR=0.32; 95% CI 0.12 to 0.90; P=0.03).Hemorrhagic complications were higher in the embolization group than in the SRS group, although this difference did not reach statistical significance after PSM (13.2% vs 2.6%; OR=5.6; 95% CI 0.62 to 50.47; P=0.12). Similarly, re-treatment rate was higher in the embolization group (10.5% vs 5.3%; OR=2.11; 95% CI 0.36 to 12.31; P=0.40) compared with the SRS group. CONCLUSION/CONCLUSIONS:Our findings indicate that SRS has a significantly higher obliteration rate at last follow-up compared with endovascular embolization. Also, SRS has a higher tendency for fewer hemorrhagic complications and lower re-treatment rate. Further prospective studies are needed.