Lateral compartment of the cavernous sinus from the endoscopic endonasal approach: anatomical considerations and surgical relevance to adenoma surgery.

OBJECTIVE: The cavernous sinus (CS) has 4 compartments: superior, inferior, posterior, and lateral. Among these, the lateral compartment is the most common location for residual tumor, given the risk of neurovascular injury. The authors' study aimed to delineate the anatomical landmarks in this area and illustrate the technical nuances of the lateral transcavernous approach. METHODS: Twenty-two colored silicone-injected specimens were dissected via an endoscopic endonasal approach to the lateral compartment of the CS. The anatomical landmarks and the internal carotid artery (ICA) mobilization technique were investigated. Two illustrative cases are provided. RESULTS: The lateral compartment of the CS is bounded by the carotid-oculomotor membrane (COM) and optic strut as the roof and the petrolingual ligament and lingual process as the floor. It is divided into 2 asymmetrical subcompartments: the upper, larger subcompartment, located superior to the abducens nerve, accommodates the lateral parasellar ligament (LPL), inferolateral trunk (ILT), and branches of the tentorial artery; and the lower, smaller subcompartment, inferior to the abducens nerve, accommodates only the sympathetic nerve branches as they join the abducens nerve. The LPL is a well-defined ligamentous band and was identified in 38 (86%) hemispheres with 2 distinct configurations: 1) robust LPL (59%), with highly compacted ligamentous bands tightly adherent to the ICA; and 2) dispersed LPL (27%), with less compaction and adherence to ICA. The main attachment of the LPL to the cavernous ICA was most commonly observed at the horizontal ICA segment (55%), followed by the anterior (18%) and posterior (14%) genua. The ILT, as the main vessel in the lateral compartment, was identified in 41 (93%) hemispheres and originated from the horizontal ICA segment (80%) or the anterior genu (14%), from either the lateral (52%) or inferior (41%) aspect of the cross-section of the ICA. In 64% of hemispheres, the LPL wrapped the ILT, abducens nerve, and sympathetic nerve to form a broad and firm neurovascular-ligamental complex. Transection of the LPL, ILT, and COM enables medial ICA mobilization and enhances access to the lateral compartment of the CS, potentially increasing the exposure width by 6 ± 1 mm. CONCLUSIONS: This study provides valuable insights into the anatomical intricacies of the lateral compartment of the CS and underscores the potential benefits of the endoscopic endonasal lateral transcavernous approach. Further clinical applications are essential for validating these findings and optimizing surgical outcomes.

Endoscopic Endonasal Approach to the Ventral Petroclival Fissure: Anatomical Findings and Surgical Techniques.

Objective The endoscopic endonasal approach has emerged as an excellent option for the treatment of lesions involving the petroclival fissure (PCF). Here, we investigate the surgical anatomy of the ventral PCF and its application in endoscopic endonasal surgery. Methods Sixteen head specimens were used to investigate the anatomical features of PCF and relevant technical nuances in translacerum, extreme medial, and contralateral transmaxillary (CTM) approaches. Two representative endoscopic endonasal surgeries involving the PCF were selected to illustrate the clinical application. Results From the endoscopic endonasal view, the ventral PCF is presented as a lazy L sign, which is divided into two distinct segments: (1) upper (or petrosphenoidal) segment, which extends vertically from the foramen lacerum inferiorly to the junction of the petrosal process of sphenoid bone and petrous apex superiorly, and (2) lower (or petroclival) segment, which extends inferolaterally from the foramen lacerum to the ventral jugular foramen. Approaching both segments of the ventral PCF first requires full exposure of the foramen lacerum, followed either by exposure of the anterior wall of cavernous sinus and paraclival internal carotid artery for upper segment access, or transection of pterygosphenoidal fissure and Eustachian tube mobilization for lower segment access. Combined with a CTM approach, the lateral extension of the surgical access can be improved for both upper and lower segment PCF approaches. Conclusion This study provides a detailed investigation of the microsurgical anatomy of the ventral part of PCF, relevant surgical approaches, and technical nuances that may facilitate its safe exposure intraoperatively.

Metabolic Insight into Glioma Heterogeneity: Mapping Whole Exome Sequencing to In Vivo Imaging with Stereotactic Localization and Deep Learning.

Intratumoral heterogeneity (ITH) complicates the diagnosis and treatment of glioma, partly due to the diverse metabolic profiles driven by underlying genomic alterations. While multiparametric imaging enhances the characterization of ITH by capturing both spatial and functional variations, it falls short in directly assessing the metabolic activities that underpin these phenotypic differences. This gap stems from the challenge of integrating easily accessible, colocated pathology and detailed genomic data with metabolic insights. This study presents a multifaceted approach combining stereotactic biopsy with standard clinical open-craniotomy for sample collection, voxel-wise analysis of MR images, regression-based GAM, and whole-exome sequencing. This work aims to demonstrate the potential of machine learning algorithms to predict variations in cellular and molecular tumor characteristics. This retrospective study enrolled ten treatment-naïve patients with radiologically confirmed glioma. Each patient underwent a multiparametric MR scan (T1W, T1W-CE, T2W, T2W-FLAIR, DWI) prior to surgery. During standard craniotomy, at least 1 stereotactic biopsy was collected from each patient, with screenshots of the sample locations saved for spatial registration to pre-surgical MR data. Whole-exome sequencing was performed on flash-frozen tumor samples, prioritizing the signatures of five glioma-related genes: IDH1, TP53, EGFR, PIK3CA, and NF1. Regression was implemented with a GAM using a univariate shape function for each predictor. Standard receiver operating characteristic (ROC) analyses were used to evaluate detection, with AUC (area under curve) calculated for each gene target and MR contrast combination. Mean AUC for five gene targets and 31 MR contrast combinations was 0.75 ± 0.11; individual AUCs were as high as 0.96 for both IDH1 and TP53 with T2W-FLAIR and ADC, and 0.99 for EGFR with T2W and ADC. These results suggest the possibility of predicting exome-wide mutation events from noninvasive, in vivo imaging by combining stereotactic localization of glioma samples and a semi-parametric deep learning method. The genomic alterations identified, particularly in IDH1, TP53, EGFR, PIK3CA, and NF1, are known to play pivotal roles in metabolic pathways driving glioma heterogeneity. Our methodology, therefore, indirectly sheds light on the metabolic landscape of glioma through the lens of these critical genomic markers, suggesting a complex interplay between tumor genomics and metabolism. This approach holds potential for refining targeted therapy by better addressing the genomic heterogeneity of glioma tumors.

Image-based assessment of natural killer cell activity against glioblastoma stem cells.

Glioblastoma (GBM) poses a significant challenge in oncology and stands as the most aggressive form of brain cancer. A primary contributor to its relentless nature is the stem-like cancer cells, called glioblastoma stem cells (GSCs). GSCs have the capacity for self-renewal and tumorigenesis, leading to frequent GBM recurrences and complicating treatment modalities. While natural killer (NK) cells exhibit potential in targeting and eliminating stem-like cancer cells, their efficacy within the GBM microenvironment is limited due to constrained infiltration and function. To address this limitation, novel investigations focusing on boosting NK cell activity against GSCs are imperative. This study presents two streamlined image-based assays assessing NK cell migration and cytotoxicity towards GSCs. It details protocols and explores the strengths and limitations of these methods. These assays could aid in identifying novel targets to enhance NK cell activity towards GSCs, facilitating the development of NK cell-based immunotherapy for improved GBM treatment.

Creating a neuroanatomy education model with augmented reality and virtual reality simulations of white matter tracts.

OBJECTIVE: The utilization of digital technologies has experienced a notable surge, particularly in cases where access to cadavers is constrained, within the context of practical neuroanatomy training. This study evaluates augmented reality (AR)- and virtual reality (VR)-based educational models for neuroanatomy education. METHODS: Three-dimensional models were created using advanced photogrammetry. VR- and AR-based educational models were developed by arranging these 3D models to align with the learning objectives of neurosurgery residents and second-year medical students whose cadaveric training was disrupted due to an earthquake in Turkey. Participants engaged with and evaluated the VR- and AR-based educational models, followed by the completion of a 20-item graded user experience survey. A 10-question mini-test was given to assess the baseline knowledge level prior to training and to measure the achievement of learning objectives after training. RESULTS: Forty neurosurgery residents were trained with a VR-based educational model using VR headsets. An AR-based educational model was provided online to 200 second-year medical students for their practical neuroanatomy lesson. The average correct answer rates before the training were 7.5/10 for residents and 4.8/10 for students. These rates were significantly improved after the training to 9.7/10 for residents and to 8.7/10 for students (p < 0.001). Feedback from the users concurred that VR- and AR-based training could significantly enhance the learning experience in the field of neuroanatomy. CONCLUSIONS: VR/AR-based educational models have the potential to improve education. VR/AR-based training systems can serve as an auxiliary tool in neuroanatomy training, offering a realistic alternative to traditional learning tools.

Occipital Sinus-Sparing Linear Paramedian Dural Incision: A Technical Note and Case Series for Median Suboccipital Approach.

BACKGROUND: Durotomies, traditionally used during the midline suboccipital approach, involve sacrificing the occipital sinus (OS) with consequent shrinking of the dura, risk of venous complications, difficulty performing watertight closure, and a higher rate of postoperative cerebrospinal fluid (CSF) leaks. The present technical note describes the OS-sparing linear paramedian dural incision, which leads to a decrease in the risk of complications during the median suboccipital approach in our case series. METHODS: The OS-sparing linear incision technique involves a dural incision placed 1 cm lateral to the OS. The angle of view of the microscope is frequently changed to overcome the narrowed exposure of the linear durotomy. Copious irrigation with saline prevents drying of the dura. A running watertight closure of the dura is performed. The overall results of 5 cases are reviewed. RESULTS: The cases were 3 tumors and 2 cavernomas. The OS was preserved in all 5, and no duraplasty was needed. The average dura closure time was 16.8 minutes. No CSF leak occurred, and no wound complications were observed. A gross total resection of the lesion was achieved in all the patients. The mean follow-up was 10.2 months, and there were no late complications related to the dura closure. CONCLUSIONS: In comparison to the types of durotomies conventionally used for the midline suboccipital approach, the OS-sparing linear paramedian dural incision entails lower risks of bleeding, venous complications, CSF leaks, and infections by avoiding duraplasty. Validation of this technical note on a larger patient cohort is needed.

The Temporoparietal Fascia Flap Transposition Technique for Ventral Skull Base Reconstruction: Anatomic Analysis and Surgical Application.

BACKGROUND AND OBJECTIVES: The temporoparietal fascia (TPF) flap is an alternative for revision endoscopic skull base reconstruction in the absence of the nasoseptal flap, and we aimed to investigate the anatomy and surgical application of TPF flap transposition in endoscopic endonasal surgery. METHODS: Six lightly embalmed postmortem human heads and 30 computed tomography angiography imaging scans were used to analyze the anatomic features of the TPF flap transposition technique. Three cases selected from a 512 endoscopic endonasal cases database were presented for the clinical application of the TPF flap. RESULTS: The TPF flap, composed by the deepest 3 scalp layers (galea aponeurotica, loose areolar connective tissue, and pericranium), can be harvested and then transposed through the infratemporal-maxillary-pterygoid tunnel to the ventral skull base. The superficial temporal artery as its feeding artery, gives frontal and parietal branches with similar diameter (1.5 ± 0.3 mm) at its bifurcation. The typical bifurcation was present in 50 sides (83.3%), with single (frontal) branch in 5 sides (8.3%), single (parietal) branch in 2 sides (3.3%), and multiple branches (>2) in 3 sides (5%). The transposed TPF flap was divided into 3 parts according to its anatomic location: (1) infratemporal part with an area of 19.5 ± 2.5 cm2, (2) maxillary part with an area of 23.7 ± 2.8 cm2, and (3) skull base part with an area of 44.2 ± 4 cm2. Compared with the nasoseptal flap, nasal floor flap, inferior turbinate flap, and extended septal flap, the coverage area of the skull base part of the TPF flap was significantly larger than any of them (P < .0001). CONCLUSION: The TPF flap technique is an effective alternative for endoscopic endonasal skull base reconstruction. The TPF flap could successfully cover large skull base defects through the infratemporal-maxillary-pterygoid tunnel.

Current status of artificial intelligence technologies in pituitary adenoma surgery: a scoping review.

PURPOSE: Pituitary adenoma surgery is a complex procedure due to critical adjacent neurovascular structures, variations in size and extensions of the lesions, and potential hormonal imbalances. The integration of artificial intelligence (AI) and machine learning (ML) has demonstrated considerable potential in assisting neurosurgeons in decision-making, optimizing surgical outcomes, and providing real-time feedback. This scoping review comprehensively summarizes the current status of AI/ML technologies in pituitary adenoma surgery, highlighting their strengths and limitations. METHODS: PubMed, Embase, Web of Science, and Scopus were searched following the PRISMA-ScR guidelines. Studies discussing the use of AI/ML in pituitary adenoma surgery were included. Eligible studies were grouped to analyze the different outcomes of interest of current AI/ML technologies. RESULTS: Among the 2438 identified articles, 44 studies met the inclusion criteria, with a total of seventeen different algorithms utilized across all studies. Studies were divided into two groups based on their input type: clinicopathological and imaging input. The four main outcome variables evaluated in the studies included: outcome (remission, recurrence or progression, gross-total resection, vision improvement, and hormonal recovery), complications (CSF leak, readmission, hyponatremia, and hypopituitarism), cost, and adenoma-related factors (aggressiveness, consistency, and Ki-67 labeling) prediction. Three studies focusing on workflow analysis and real-time navigation were discussed separately. CONCLUSION: AI/ML modeling holds promise for improving pituitary adenoma surgery by enhancing preoperative planning and optimizing surgical strategies. However, addressing challenges such as algorithm selection, performance evaluation, data heterogeneity, and ethics is essential to establish robust and reliable ML models that can revolutionize neurosurgical practice and benefit patients.

Image-Based Assessment of Natural Killer Cell Activity against Glioblastoma Stem Cells.

Glioblastoma (GBM) poses a significant challenge in oncology and stands as the most aggressive form of brain cancer. A primary contributor to its relentless nature is the stem-like cancer cells, called glioblastoma stem cells (GSCs). GSCs have the capacity for self-renewal and tumorigenesis, leading to frequent GBM recurrences and complicating treatment modalities. While natural killer (NK) cells exhibit potential in targeting and eliminating stem-like cancer cells, their efficacy within the GBM microenvironment is limited due to constrained infiltration and function. To address this limitation, novel investigations focusing on boosting NK cell activity against GSCs are imperative. This study presents two streamlined image-based assays assessing NK cell migration and cytotoxicity towards GSCs. It details protocols and explores the strengths and limitations of these methods. These assays could aid in identifying novel targets to enhance NK cell activity towards GSCs, facilitating the development of NK cell-based immunotherapy for improved GBM treatment.