Anatomical determinants of occipitocervical fusion in skull base chordoma resection: a systematic review of the literature with illustrative cases.

OBJECTIVE: Skull base chordomas are rare, locally osseo-destructive lesions that present unique surgical challenges due to their involvement of critical neurovascular and bony structures at the craniovertebral junction (CVJ). Radical cytoreductive surgery improves survival but also carries significant morbidity, including the potential for occipitocervical (OC) destabilization requiring instrumented fusion. The published experience on OC fusion after CVJ chordoma resection is limited, and the anatomical predictors of OC instability in this context remain unclear. METHODS: PubMed and Embase were systematically searched according to the PRISMA guidelines for studies describing skull base chordoma resection and OC fusion. The search strategy was predefined in the authors' PROSPERO protocol (CRD42024496158). RESULTS: The systematic review identified 11 surgical case series describing 209 skull base chordoma patients and 116 (55.5%) who underwent OC instrumented fusion. Most patients underwent lateral approaches (n = 82) for chordoma resection, followed by midline (n = 48) and combined (n = 6) approaches. OC fusion was most often performed as a second-stage procedure (n = 53), followed by single-stage resection and fusion (n = 38). The degree of occipital condyle resection associated with OC fusion was described in 9 studies: total unilateral condylectomy reliably predicted OC fusion regardless of surgical approach. After lateral transcranial approaches, 4 studies cited at least 50%-70% unilateral condylectomy as necessitating OC fusion. After midline approaches-most frequently the endoscopic endonasal approach (EEA)-at least 75% unilateral condylectomy (or 50% bilateral condylectomy) led to OC fusion. Additionally, resection of the medial atlantoaxial joint elements (the C1 anterior arch and tip of the dens), usually via EEA, reliably necessitated OC fusion. Two illustrative cases are subsequently presented, further exemplifying how the extent of CVJ bony elements removed via EEA to achieve complete chordoma resection predicts the need for OC fusion. CONCLUSIONS: Unilateral total condylectomy, 50% bilateral condylectomy, and resection of the medial atlantoaxial joint elements were the most frequently described independent predictors of OC fusion in skull base chordoma resection. Additionally, consistent with the occipital condyle harboring a significantly thicker joint capsule at its posterolateral aspect, an anterior midline approach seems to tolerate a greater degree of condylar resection (75%) than a lateral transcranial approach (50%-70%) prior to generating OC instability.

Intraoperative MRI: A Review of Applications Across Neurosurgical Specialties.

Intraoperative MRI (iMRI) made its debut to great fanfare in the mid-1990s. However, the enthusiasm for this technology with seemingly obvious benefits for neurosurgeons has waned. We review the benefits and utility of iMRI across the field of neurosurgery and present an overview of the evidence for iMRI for multiple neurosurgical disciplines: tumor, skull base, vascular, pediatric, functional, and spine. Publications on iMRI have steadily increased since 1996, plateauing with approximately 52 publications per year since 2011. Tumor surgery, especially glioma surgery, has the most evidence for the use of iMRI contributing more than 50% of all iMRI publications, with increased rates of gross total resection in both adults and children, providing a potential survival benefit. Across multiple neurosurgical disciplines, the ability to use a multitude of unique sequences (diffusion tract imaging, diffusion-weighted imaging, magnetic resonance angiography, blood oxygenation level-dependent) allows for specialization of imaging for various types of surgery. Generally, iMRI allows for consideration of anatomic changes and real-time feedback on surgical outcomes such as extent of resection and instrument (screw, lead, electrode) placement. However, implementation of iMRI is limited by cost and feasibility, including the need for installation, shielding, and compatible tools. Evidence for iMRI use varies greatly by specialty, with the most evidence for tumor, vascular, and pediatric neurosurgery. The benefits of real-time anatomic imaging, a lack of radiation, and evaluation of surgical outcomes are limited by the cost and difficulty of iMRI integration. Nonetheless, the ability to ensure patients are provided by a maximal yet safe treatment that specifically accounts for their own anatomy and highlights why iMRI is a valuable and underutilized tool across multiple neurosurgical subspecialties.

An Institutional Experience of Directional Deep Brain Stimulation and a Review of the Literature.

INTRODUCTION: Directional deep brain stimulation (dDBS) has been suggested to have a similar therapeutic effect when compared with the traditional omnidirectional DBS, but with an improved therapeutic window that yields optimized clinical effect owing to the ability to better direct, or "steer," electric current. We present our single-center, retrospective analysis of our experience in the use of dDBS in patients with movement disorders and provide a review of the literature. MATERIALS AND METHODS: We identified all patients with Parkinson disease (PD) and essential tremor (ET) who received a dDBS system between 2018 and 2022 and retrospectively examined characteristics of their longitudinal treatment. A total of 70 leads were identified across 42 patients (28 PD, 14 ET). RESULTS: Three types of systems were implemented (single-segment activation, 45.2% of patients; multiple independent current control, 50.0%; and local field potential sensing-enabled, 4.7%). The subthalamic nucleus or globus pallidus internus was targeted in PD, and the ventral intermediate nucleus of the thalamus in ET. Across the entire cohort (n = 70 leads), at initial programming, 54.2% of leads (n = 38) were programmed using directional stimulation. At the most recent reprogramming, 58.6% of leads (n = 41) implemented directionality. In patients with PD, the average decrease in levodopa-equivalent daily dose at six months after implantation was 35.4% ± 39.2%. Despite the ability to steer current to relieve stimulation-induced side effects, ten leads in six patients required surgical revision owing to electrode malposition. CONCLUSIONS: We show wide adaptability and implementation of directional stimulation, adding to the growing compendium of real-world uses of dDBS therapy. We used directionality to improve clinical response in both patients with PD and patients with ET and found that its programming flexibility was used at high rates long after implantation and initial programming. In patients with PD, dDBS led to a significant reduction in dopaminergic medication, suggesting sustained clinical improvement. Nonetheless, accurate surgical placement remains necessary to ensure optimal clinical outcomes.

Postoperative stereotactic radiosurgery for intracranial solitary fibrous tumors: systematic review and pooled quantitative analysis.

BACKGROUND: Intracranial solitary fibrous tumors (SFTs), formerly hemangiopericytomas (HPCs), are rare, aggressive dural-based mesenchymal tumors. While adjuvant radiation therapy has been suggested to improve local tumor control (LTC), especially after subtotal resection, the role of postoperative stereotactic radiosurgery (SRS) and the optimal SRS dosing strategy remain poorly defined. METHODS: PubMed, EMBASE, and Web of Science were systematically searched according to PRISMA guidelines for studies describing postoperative SRS for intracranial SFTs. The search strategy was defined in the authors' PROSPERO protocol (CRD42023454258). RESULTS: 15 studies were included describing 293 patients harboring 476 intracranial residual or recurrent SFTs treated with postoperative SRS. At a mean follow-up of 21-77 months, LTC rate after SRS was 46.4-93% with a mean margin SRS dose of 13.5-21.7 Gy, mean maximum dose of 27-39.6 Gy, and mean isodose at the 42.5-77% line. In pooled analysis of individual tumor outcomes, 18.7% of SFTs demonstrated a complete SRS response, 31.7% had a partial response, 18.9% remained stable (overall LTC rate of 69.3%), and 30.7% progressed. When studies were stratified by margin dose, a mean margin dose > 15 Gy showed an improvement in LTC rate (74.7% versus 65.7%). CONCLUSIONS: SRS is a safe and effective treatment for intracranial SFTs. In the setting of measurable disease, our pooled data suggests a potential dose response of improving LTC with increasing SRS margin dose. Our improved understanding of the aggressive biology of SFTs and the tolerated adjuvant SRS parameters supports potentially earlier use of SRS in the postoperative treatment paradigm for intracranial SFTs.

Characterizing complications associated with skull clamps: A review of the manufacturer and user facility device experience database.

OBJECTIVE: Head immobilization with skull clamps is a prerequisite of many neurosurgical procedures. Adverse events relating to the use of skull clamps have been reported, however, given the paucity of published reports, we sought to conduct a more comprehensive analysis using the Manufacturer and User Facility Device Experience (MAUDE) database. METHODS: The MAUDE database was queried for neurosurgical skull clamp events over a 10-year period between January 2013 and December 2022. Reports were qualitatively analyzed and categorically assigned by the study authors as 'mechanical failure,' 'slippage,' 'contamination,' 'insufficient information,' and 'other.' Patient injury reports were also classified as 'abrasion,' 'laceration,' 'hematoma,' 'fracture,' 'intracranial hemorrhage (ICH),' 'other,' 'insufficient information,' and 'death.' RESULTS: Of 3672 reports retrieved, 2689 (73.2%) were device malfunctions, with mechanical failure (50.7%) and slippage (47.7%) being the most common causes. There were 983 reports (26.8%) involving patient injury which included lacerations (n = 776, 78.9%), fractures (n = 24, 2.4%), abrasions (n = 23, 2.3%), hematomas (n = 7, 0.71%), ICH (n = 3, 0.31%), and other causes (n = 6, 0.61%). Five (0.1%) deaths due to skull clamp related complications were also reported. CONCLUSIONS: This study provides a more comprehensive picture of adverse events in neurosurgical procedures relating to the use of skull clamps. Mechanical failures of device parts were the most common device-related complication, and lacerations the most common adverse patient-related event. While more severe patient-related events were reported, they are relatively rare. The MAUDE database is useful for characterizing underreported device-related and patient-related adverse events.

First use of radiation for the treatment of arteriovenous malformation.

In 1921, Norwegian neurosurgeon Vilhelm Magnus (1871-1929) described the first use of radiation for the treatment of an arteriovenous malformation (AVM) in his monograph, Bidrag til hjernechirurgiens klinik og resultater. Seeing as this monograph has never been widely translated nor digitized, the authors discuss the impact of Magnus' original work and the ethics surrounding its citation. The senior author of this paper gained access to and directly translated key sections of Magnus' publication. Without Norwegian language skills, reading and understanding Magnus' text would have been impossible. Magnus described the use of radiation therapy in a single patient found to have an AVM (or "angioma"). He states that she was "well" 8 years later. No other information on that treatment is given, but for good reason Magnus has been given credit in the literature for the first use of radiation of any kind to treat a person with AVM. Most papers that have referenced Magnus' monograph cite it even though it is probable that the authors did not see it, let alone read its contents. While it is appropriate that his innovation has been properly credited, the authors discuss the limits of citing publications sight unseen.

Local Field Potentials in Deep Brain Stimulation: Investigation of the Most Cited Articles.

Objective: Deep brain stimulation (DBS) allows for direct electrical stimulation of neural circuitry and recording of local field potentials (LFPs). A bibliometric analysis can be implemented to identify studies that have shaped a research field and influenced future study; however, no such analysis investigating the implementation of LFPs in DBS has been performed. The objective of the present study was to identify the most highly cited articles pertaining to DBS LFPs to identify and evaluate the research that has contributed the most to this growing field. Methods: The Science Citation Index of the Web of Science was implemented to identify the top 84 most cited articles pertaining to DBS LFPs. Information regarding the publication, including author information and study aims, was extracted. Results: The most highly cited articles had had a mean of 109 citations and had been published between 2002 and 2019, with a mode in 2016. The articles had predominantly investigated the subthalamic nucleus (68% of clinical studies) in humans (83.8% of clinical studies). The studies of humans had recruited a mean of 12.5 subjects. Most of the identified articles (56.0%) had reported class III clinical evidence. Conclusions: The implementation of DBS LFPs is a novel field that is rapidly growing. However, a need exists for more studies with larger patient cohorts and more randomized controlled trials to further elucidate the benefits of this technology. These results will allow for the identification and recognition of the most influential studies pertaining to DBS LFPs, appreciation of the current and future research trends, and inform us regarding areas warranting further investigation.

#Neurosurgery: A Cross-Sectional Analysis of Neurosurgical Content on TikTok.

Objectives: TikTok is a social media platform that has gained popularity and become a powerful engine to disseminate public health and medical information. To date, no study has characterized the qualities of popular TikTok videos related to neurosurgery, or assessed biases in the content of these videos. Methods: The TikTok web browser application was queried using "#neurosurgery" to identify neurosurgery-related videos. The top 100 videos meeting inclusion criteria were analyzed and video characteristics determined. Bias was assessed by the DISCERN scoring system using 3 independent reviewers. A Kruskal-Wallis H test was used to correlate video popularity with video characteristics and to correlate bias with creator and video type. Results: The 100 videos evaluated totaled 8.8 million likes, 104,718 comments, and 100,856 shares. The oldest video was posted February 2020 and the most recent March 2022. Videos were most commonly entertaining (n = 64, 64%), and educational (n = 46, 46%). Video popularity was associated with videos that aimed to entertain, and least associated with videos depicting neurosurgery lifestyle. Low DISCERN scores, indicating more biased content, were seen across the neurosurgical content with the entertaining video category demonstrating the highest bias. Conclusions: Neurosurgical content on TikTok contains a high degree of bias across all creator and video types. Entertaining videos are associated with the highest numbers of likes but also the greatest bias. These data may be used to guide institutions and neurosurgeons to grow interest in the field of neurosurgery and disseminate unbiased information while expanding their social media presence.