Microsurgical versus endovascular treatment of ethmoidal dural arteriovenous fistulas: systematic review and meta-analysis with a single-center case series.

OBJECTIVE: Ethmoidal dural arteriovenous fistulas (DAVFs) are often associated with cortical venous drainage (CVD) and a higher incidence of hemorrhage compared with DAVFs in other locations. They may be treated with open surgical disconnection or with endovascular treatment (EVT). In this systematic review and meta-analysis, the authors compare the outcomes of ethmoidal DAVFs treated with open microsurgery versus EVT and report four additional cases of ethmoidal DAVFs treated with open microsurgery in their institution. METHODS: A literature search of the PubMed and Scopus databases was conducted between December 2021 and May 2022 to identify relevant articles published between 1990 and 2021 using the PRISMA guidelines. References were reviewed and screened by two authors independently, and disagreements were resolved through consensus. Exclusion criteria included non-English-language studies, those with an incorrect study design, those reporting DAVFs in a nonethmoidal location, and studies whose outcomes were not stratified based on DAVF location. Inclusion criteria were any studies reporting on ethmoidal DAVFs treated by either microsurgery or EVT. A risk of bias assessment was performed using the Newcastle-Ottawa Scale. The authors performed a pooled proportional meta-analysis to compare patient outcomes. RESULTS: Twenty studies were included for analysis. Of 224 patients, 142 were treated with surgery, while 103 were treated with EVT. Seventy percent (148/210) of the patients were symptomatic at presentation, with hemorrhage being the most common presentation (48%). CVD was present in 98% of patients and venous ectasia in 61%. The rates of complete DAVF obliteration with surgery and EVT were 89% and 70%, respectively (95% CI -30% to -10%, p < 0.03). Twenty percent (21/103) of endovascularly treated fistulas required subsequent surgery. Procedure-related complications occurred in 10% of the surgical cases, compared with 13% of the EVT cases. The authors' case series included 4 patients with ethmoidal DAVFs treated surgically with complete obliteration, without any postoperative complications. CONCLUSIONS: The complete obliteration rates of ethmoidal DAVF appear to be higher and more definitive with microsurgical intervention than with EVT. While complication rates between the two procedures seem similar, patients treated with EVT may require further interventions for definitive treatment. The limitations of this study include its retrospective nature, the quality of studies included, and the continued evolving technologies of EVT. Future studies should focus on the association between venous drainage pattern and the proclivity toward venous ectasia or rate of hemorrhage at presentation.

Predicting Ventriculoperitoneal Shunt Dependence in High Grade Aneurysmal Subarachnoid Hemorrhage.

INTRODUCTION: Aneurysmal subarachnoid hemorrhage (aSAH) commonly presents with hydrocephalus due to obstruction of cerebrospinal fluid (CSF) passage across the ventricular system in the brain. Placement of an external ventricular device (EVD) and in some cases ventriculoperitoneal shunt (VPS) are often necessary for patients requiring prolonged CSF diversion. The study aimed at evaluating critical factors that play a role in determining the need for extended extraventricular drainage. METHODS: We performed a retrospective observational cohort study of two groups of patients with radiological imaging confirmed high grade aSAH (Hunt & Hess grades 3-5) who required VPS placement, shunt-dependent group, and who did not require long term CSF diversion, non-shunt-dependent group. We collected and analyzed data regarding the daily CSF output for 10 days following EVD placement, daily EVD height, intracranial pressure (ICP) and cerebral perfusion pressure (CPP), indicators of hydrocephalus, and CSF characteristics. RESULTS: The cohort, comprising of 8 patients in the shunt-dependent group and 32 patients in the non-shunt-dependent group, displayed median daily CSF output of 275.1 mL/day and 193.4 mL/day, respectively (P = .0005). ROC curve for CSF drainage for the two groups showed an area under the curve (AUC) of 0.71 with a 95% confidence interval (CI) 0.65 to 0.77. Qualitative analysis of CSF characteristics revealed that the shunt-dependent group had more proteinaceous, darker red color, and greater proportion of red blood cells (RBCs) although not statistically significant. CONCLUSIONS: Determinants of prolonged CSF drainage requirements in patients with high grade aSAH are not fully elucidated to this date and there is no standardized protocol for CSF diversion. Our study revealed potential markers that can be used in the assessment for the need for long term CSF diversion. Our limited sample size necessitates further research to establish clear correlations and cutoffs of these parameters in predicting long term CSF diversion requirements.

Effects of variable power on tissue ablation dynamics during magnetic resonance-guided laser-induced thermal therapy with the Visualase system.

PURPOSE: Magnetic resonance-guided laser-induced thermal therapy (MRgLITT) is a minimally invasive procedure used to treat various intracranial pathologies. This study investigated the effects of variable power on maximal estimated thermal damage during ablation and duration required to reach maximal ablation. MATERIALS/METHODS: All ablations were performed using the Visualase Thermal Therapy System (Medtronic Inc., Minneapolis, Minnesota), which uses a 980 nm diffusing tip diode laser. Cases were stratified into low, medium and high power. Maximal thermal damage estimate (TDEmax) achieved in a single plane and time to reach maximal damage (ttdemax) were measured and compared between groups using a 2×3 Fixed Factor Analysis of Covariance. Ablation area change for cases in which an initial thermal dose was followed by a subsequent dose, with increased power, was also assessed. RESULTS: We used real-time ablation data from 93 patients across various intracranial pathologies. ttdemax (mean ± SEM) decreased linearly as power increased (low: 139.2 ± 10.4 s, medium: 127.5 ± 4.3 s, high: 103.7 ± 5.8 s). In cases where a second thermal dose was delivered at higher power, the TDE expanded an average of 51.4 mm2 beyond the initial TDE generated by the first ablation, with the second ablation approaching TDEmax at a higher rate than the initial ablation. CONCLUSION: Increased power results in a larger TDEmax and an increased ablation rate. In cases where an initial thermal dose does not fully ablate the target lesion, a second ablation at higher power can increase the area of ablation with an increased ablation rate.

Analysis of Concussions Reported in American Professional Football Injury Reports in the 2019 Through 2023 Regular Seasons.

OBJECTIVE: The National Football League (NFL) has seen increasing scrutiny regarding its management of concussions, especially following an on-field incident involving the Miami Dolphins' quarterback Tua Tagovailoa in the 2022 season. We hope to elucidate the recent trends in the diagnosis and management of concussions during the course of 5 NFL seasons from 2019 to 2023. METHODS: We queried the NFL injury reports from the 2019 through 2023 database recording players listed with concussions. The weeks missed were calculated using the NFL game logs. Players' concussions that did not occur in the games, those complicated by other injuries, and those affected by roster status were excluded. RESULTS: Searches of the NFL injury reports resulted in the identification of 664 of 692 concussions (96%) that occurred in regular season games across the 2019-2023 seasons. During the course of these 5 seasons, 31% of the players returned without missing a game, 39% of the players missed 1 game, and 30% of the players missed ≥2 games. No significant difference in the number of concussions per game or weeks missed was observed across the seasons observed. Players with concussions on teams that made the playoffs saw fewer weeks missed than those on non-playoff teams (0.86 vs. 1.37; P = 0.002). CONCLUSIONS: Since the start of the 2021 NFL season, an increasing incidence of concussions has been noted; however, there was no change observed in the number of weeks missed after the concussions. Trends in the rates of concussions across the seasons remain largely stable, despite increased scrutiny over concussions in the sport.

Can Publicly Available Artificial Intelligence Successfully Identify Current Procedural Terminology Codes for Common Procedures in Neurosurgery?

OBJECTIVE: Coding for neurosurgical procedures is a complex process that is dynamically changing year to year, through the annual introduction and removal of codes and modifiers. The authors hoped to elucidate if publicly available artificial intelligence (AI) could offer solutions for neurosurgeons with regard to coding. METHODS: Multiple publicly available AI platforms were asked to provide Current Procedural Terminology (CPT) codes and Revenue Value Units (RVU) values for common neurosurgical procedures of the brain and spine with a given indication for the procedure. The responses of platforms were recorded and compared to the currently valid CPT codes used for the procedure and the amount of RVUs that would be gained. RESULTS: Six platforms and Google were asked for the appropriate CPT codes for 10 endovascular, spinal, and cranial procedures each. The highest performing platforms were as follows: Perplexity.AI identified 70% of endovascular, BingAI identified 55% of spinal, and ChatGPT 4.0 with Bing identified 75% of cranial CPT codes. With regard to RVUs, the top performer gained 78% of endovascular, 42% of spinal, and 70% of cranial possible RVUs. With regard to accuracy, AI platforms on average outperformed Google (45% vs. 25%, P = 0.04236). CONCLUSIONS: The ability of publicly available AIs to successfully code for neurosurgical procedures holds great promise in the future. Future development of AI should focus on improving accuracy with regard to CPT codes and providing supporting documentation for its decisions. Improvement on the existing capabilities of AI platforms can allow for increased operational efficiency and cost savings for practices.

Controlling Signal Artifact With Software Threshold Imaging for Magnetic Resonance-Guided Laser Interstitial Thermal Therapy.

BACKGROUND: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) uses intraoperative temperature mapping and thermal damage estimates to guide ablations of intracranial targets. In select cases, signal artifact presents at the target site and impairs intraprocedural decision-making by obscuring the visualization of both temperature imaging and the thermal damage estimate calculation. To date, the etiology and impact of signal artifact are unknown. However, user-selected MRgLITT software settings may play a role in generating artifact. OBJECTIVE: To assess the effect of the thresholding feature in MRgLITT software on signal artifact generation during intracranial ablations. METHODS: Ablations were performed with the Visualase MRI-guided Laser Ablation System (Medtronic). For each LITT procedure, raw thermal data were extracted at a reference threshold of 40 and reprocessed at 5 additional threshold values ranging from 35 to 60. Artifact growth rates relative to threshold values were derived using simple linear regressions and then assessed within the context of laser power and duration using Pearson correlations. RESULTS: A total of 33 patients were included, with 28 artifact-containing and 5 artifact-free cases. For artifact-containing cases, a 13% increase in artifact area occurred for every 1-point increase in threshold (R2 > 0.99). Artifact growth rates were not correlated with laser power (r = 0.15, P = .44) or duration (r = 0.0049, P = .98). One of the 5 artifact-free cases developed artifact at a threshold of 60. CONCLUSION: Artifact generation is likely multifactorial involving tissue properties and software settings. Operators can minimize software-introduced artifact by reducing threshold values.

Mathematical Modeling of Thermal Damage Estimate Volumes in MR-guided Laser Interstitial Thermal Therapy.

BACKGROUND AND PURPOSE: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that produces real-time thermal damage estimates (TDEs) of ablation. Currently, MRgLITT software provides limited quantitative parameters for intraoperative monitoring, but orthogonal TDE-MRI slices can be utilized to mathematically estimate ablation volume. The objective of this study was to model TDE volumes and validate using post-24 hours MRI ablative volumes. METHODS: Ablations were performed with the Visualase Laser Ablation System (Medtronic). Using ellipsoidal parameters determined for dual-TDEs from orthogonal MRI planes, TDE volumes were calculated by two definite integral methods (A and B) implemented in Matlab (MathWorks). Post-24 hours MRI ablative volumes were measured in OsiriX (Pixmeo) by two-blinded raters and compared to TDE volumes via paired t-test and Pearson's correlations. RESULTS: Twenty-two ablations for 20 patients with various intracranial pathologies were included. Average TDE volume calculated with method A was 3.44 ± 1.96 cm3 and with method B was 4.83 ± 1.53 cm3 . Method A TDE volumes were significantly different than post-24 hours volumes (P < .001). Method B TDE volumes were not significantly different than post-24 hours volumes (P = .39) and strongly correlated with each other (r = .85, R2 = .72, P < .0001). A total of eight of 22 (36%) method A versus 17 of 22 (77%) method B TDE volumes were within 25% of the post-24 hours ablative volume. CONCLUSION: We present a viable mathematical method integrating dual-plane TDEs to calculate volumes. Future algorithmic iterations will incorporate additional calculated variables that improve ablative volume estimations.

Effects of Intraoperative Magnetic Resonance Thermal Imaging Signal Artifact During Laser Interstitial Thermal Therapy on Thermal Damage Estimate and Postoperative Magnetic Resonance Imaging Ablative Area Concordance.

BACKGROUND: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has considered the impact of this artifact on TDE accuracy. OBJECTIVE: To determine the effect of intraoperative MRTI signal artifact on postoperative magnetic resonance imaging (MRI)-predicted ablative area. METHODS: All ablations were performed using the Visualase MRI-Guided Laser Ablation System (Medtronic). Patients were grouped based on whether the intraoperative MRTI contained signal artifact that distorted the ablative region. Cross-sectional area of the ablative lesion from the MRI image was measured, and the difference between intraoperative TDE and postoperative MRI cross-sectional area was calculated and compared between groups with and without intraoperative MRTI artifact. RESULTS: A total of 91 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 43.9% of cases overall. The mean absolute difference between TDE and the postoperative MRI cross-sectional area was 94.8 mm2 (SEM = 11.6) in the group with intraoperative MRTI artifact and 54.4 mm2 (SEM = 5.5) in the nonartifact group. CONCLUSION: MRTI signal artifact is common during LITT. The presence of signal artifact during intraoperative MRTI results in higher variation between intraoperative TDE and postoperative MRI cross-sectional ablative area. In cases in which intraoperative MRTI artifact is observed, there may be a larger degree of variation between observed intraoperative TDE and measured postoperative MRTI ablative area.

Understanding the Relationship Between Real-Time Thermal Imaging and Thermal Damage Estimate During Magnetic Resonance-Guided Laser Interstitial Thermal Therapy.

OBJECTIVE: Magnetic resonance-guided laser interstitial thermal therapy is a minimally invasive procedure that uses intraoperative magnetic resonance thermometry (MRT) to generate a thermal damage estimate (TDE) of the ablative area. This study aimed to compare areas produced by the MRT heat map with the system-generated TDE produced by Visualase software. METHODS: All ablations were performed using the Visualase laser ablation system. MRT heat map and TDE were quantified using MATLAB version R2014a. TDE was compared with the summed area of green, yellow, and red areas (heat map 63.9 [HM63.9]) and the summed area of light blue, green, yellow, and red areas (heat map 50.4 [HM50.4]) produced by the MRT heat map. RESULTS: Fifty-six patients undergoing magnetic resonance-guided laser interstitial thermal therapy were examined. Mean TDE produced was 236 mm2 (SEM = 9.5). Mean HM63.9 was 231 mm2 (SEM = 8.7), and mean HM50.4 was 370 mm2 (SEM = 12.8). There was no significant difference between TDE and HM63.9 (P = 0.51). There was a significant difference between TDE and HM50.4 (P < 0.001) and between HM63.9 and HM50.4 (P < 0.001). CONCLUSIONS: The system-generated TDE consistently remains contained within the boundaries of the MRT heat map. At standard factory settings, TDE and the area produced within the periphery of HM63.9 are similar in magnitude. The light blue portion of the MRT heat map may serve as an additional means of predicting when critical structures may be at risk during laser ablation if exposed to further thermal stress.

Radiation Necrosis in Intracranial Lesions.

Radiation necrosis (RN) is a challenging potential complication of cranial radiation therapy. Believed to result from a complex interplay of vascular, glial, and immunologic factors, the exact mechanism of RN remains unclear. Patients who develop RN typically have a history of treatment with stereotactic radiation surgery or some other form of radiation-based therapy. The time frame for its development is variable, but it most often occurs one to three years following radiation therapy. Reported treatment doses capable of inducing radiation necrosis are variable, with higher doses per fraction more likely to induce RN. Furthermore, RN remains a challenging diagnosis for clinicians to make, as its presentation is often nonspecific and imaging studies might not clearly differentiate RN from tumor recurrence or pseudoprogression. RN is initially managed with corticosteroids, followed by bevacizumab, surgical resection, or laser interstitial thermal therapy if symptoms persist. In this review, we examine the literature regarding pathophysiology, incidence, imaging characteristics, and management strategies for radiation necrosis.

Characterization of Magnetic Resonance Thermal Imaging Signal Artifact During Magnetic Resonance Guided Laser-Induced Thermal Therapy.

BACKGROUND: Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has attempted to characterize this artifact. OBJECTIVE: To characterize MRTI signal the artifact in select cases to better understand its potential relevance and impact on the ablation procedure. METHODS: All ablations were performed using the Visualase magnetic resonance imaging-guided laser ablation system (Medtronic). Patients were included if the MRTI contained signal artifact that distorted the ablative region during the first thermal dose delivered. Ablation artifact was quantified using MATLAB version R2018a (Mathworks Inc, Natick, Massachusetts). RESULTS: A total of 116 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 37.0% of cases overall. Incidence of artifact was greater at higher powers (P < .001) and with longer ablation times (P = .024), though artifact size did not correlate with laser power or ablation duration. CONCLUSION: MRTI signal artifact is common during LITT. Higher powers and longer ablation times result in greater incidence of ablation artifact, though artifact size is not correlated with power or duration. Future studies should aim to evaluate effects of artifact on postoperative imaging and, most notably, patient outcomes.

Ablation dynamics of subsequent thermal doses delivered to previously heat-damaged tissue during magnetic resonance-guided laser-induced thermal therapy.

OBJECTIVE: Intraoperative dynamics of magnetic resonance-guided laser-induced thermal therapy (MRgLITT) have been previously characterized for ablations of naive tissue. However, most treatment sessions require the delivery of multiple doses, and little is known about the ablation dynamics when additional doses are applied to heat-damaged tissue. This study investigated the differences in ablation dynamics between naive versus damaged tissue. METHODS: The authors examined 168 ablations from 60 patients across various surgical indications. All ablations were performed using the Visualase MRI-guided laser ablation system (Medtronic), which employs a 980-nm diffusing tip diode laser. Cases with multiple topographically overlapping doses with constant power were selected for this study. Single-dose intraoperative thermal damage was used to calculate ablation rate based on the thermal damage estimate (TDE) of the maximum area of ablation achieved (TDEmax) and the total duration of ablation (tmax). We compared ablation rates of naive undamaged tissue and damaged tissue exposed to subsequent thermal doses following an initial ablation. RESULTS: TDEmax was significantly decreased in subsequent ablations compared to the preceding ablation (initial ablation 227.8 ± 17.7 mm2, second ablation 164.1 ± 21.5 mm2, third ablation 124.3 ± 11.2 mm2; p = < 0.001). The ablation rate of subsequent thermal doses delivered to previously damaged tissue was significantly decreased compared to the ablation rate of naive tissue (initial ablation 2.703 mm2/sec; second ablation 1.559 mm2/sec; third ablation 1.237 mm2/sec; fourth ablation 1.076 mm/sec; p = < 0.001). A negative correlation was found between TDEmax and percentage of overlap in a subsequent ablation with previously damaged tissue (r = -0.164; p < 0.02). CONCLUSIONS: Ablation of previously ablated tissue results in a reduced ablation rate and reduced TDEmax. Additionally, each successive thermal dose in a series of sequential ablations results in a decreased ablation rate relative to that of the preceding ablation. In the absence of a change in power, operators should anticipate a possible reduction in TDE when ablating partially damaged tissue for a similar amount of time compared to the preceding ablation.

A Unique Case of Recurrent Intracranial Extravascular Papillary Endothelial Hyperplasia After Gross Total Resection and Brachytherapy.

BACKGROUND: Extravascular papillary endothelial hyperplasia (EPEH) is an extremely uncommon form of papillary endothelial hyperplasia characterized by an exuberant reactive endothelial proliferation in areas of extravascular hemorrhage rather than within the vascular lumen. Intracranial EPEH is known to develop after radiosurgery in patients with intracranial neoplasms, suggesting a causative relationship between radiotherapy and the development of EPEH. Intracranial EPEH is typically treated with surgical resection; to date, there have been no reported cases of EPEH recurrence after gross total resection. CASE DESCRIPTION: A 75-year-old man with a history of atypical meningioma presented to our hospital with progressive right upper and lower extremity weakness. Eight and a half years before admission, he had undergone surgical resection and stereotactic radiosurgery for a World Health Organization grade II meningioma. Several years later, he experienced a mass in the prior resection cavity and was subsequently treated with gross total resection and cesium-131 brachytherapy seeds. Postoperative pathologic examination of the resected tissue at that time showed EPEH with no evidence of recurrent atypical meningioma. On this admission, magnetic resonance imaging showed a recurrent mass in the area of prior resection, at which time the patient underwent a third craniotomy and gross total resection. Postoperative histopathologic examination showed findings consistent with the diagnosis of recurrent EPEH. CONCLUSIONS: This case report is the first known recurrence of intracranial EPEH occurring after gross total resection and brachytherapy.