ARISE-The Accuracy Evaluation of a Patient-Specific 3D-Printed Biopsy System Based on MRI Data: A Cadaveric Study.

BACKGROUND: Brain biopsy is required for the accurate specification and further diagnosis of intracranial findings. The conventional stereotactic frames are used clinically for biopsies and offer the highest possible precision. Unfortunately, they come with some insurmountable technical and logistical limitations. The aim of the present work is to determine the clinical precision in the needle biopsy of the human brain using a new patient-specific stereotactic navigation device based on 3D printing. METHODS: MRI data sets of human cadaver heads were used to plan 32 intracranial virtual biopsy targets located in different brain regions. Based on these data, 16 individualized stereotactic frames were 3D-printed. After the intraoperative application of the stereotactic device to the cadaver's head, the actual needle position was verified by postoperative CT. RESULTS: Thirty-two brain areas were successfully biopsied. The target point accuracy was 1.05 ± 0.63 mm, which represents the difference between the planned and real target points. The largest target point deviation was in the coronal plane at 0.60 mm; the smallest was in the transverse plane (0.45 mm). CONCLUSIONS: Three-dimensional-printed, personalized stereotactic frames or platforms are an alternative to the commonly used frame-based and frameless stereotactic systems. They are particularly advantageous in terms of accuracy, reduced medical imaging, and significantly simplified intraoperative handling.

The Ratio of Baseline Ventricle Volume to Total Brain Volume Predicts Postoperative Ventriculo-Peritoneal Shunt Dependency after Sporadic Vestibular Schwannoma Surgery.

Background/Objectives: Obstructive hydrocephalus associated with vestibular schwannoma (VS) is the most common in giant VS. Despite tumor removal, some patients may require ongoing ventriculo-peritoneal (VP) surgery. This investigation explores the factors contributing to the requirement for VP surgery following VS surgery in instances of persistent hydrocephalus (HCP). Methods: Volumetric MRI analyses of pre- and postoperative tumor volumes, cerebellum, cerebrum, ventricle system, fourth ventricle, brainstem, and peritumoral edema were conducted using Brainlab Smartbrush and 3D Slicer. The total brain volume was defined as the sum of the cerebrum, cerebellum, and brainstem. ROC analyses were performed to identify the optimum cut-off values of the volumetric data. Results: Permanent cerebrospinal fluid (CSF) diversion after surgery was indicated in 12 patients (12/71; 16.9%). The ratio of baseline volume fraction of brain ventricles to total brain ventricle volume (VTB ratio) was found to predict postoperative VP shunt dependency. The AUC was 0.71 (95% CI: 0.51-0.91), and the optimum threshold value (

Predictors for the Occurrence of Seizures in Meningioma.

Seizure is a common symptom of meningioma that has a major impact on patients' quality of life. The purpose of this study was to identify predictive factors for the occurrence of preoperative and postoperative seizures. The data of patients with resection of histologically confirmed meningioma at University Hospital Leipzig from 2009 to 2018 were retrospectively examined. Univariate and multivariate logistic regression analyses of different factors influencing seizure outcome were performed. The male gender was identified as an independent positive predictor for preoperative seizures (odds ratio [OR] 1.917 [95% confidence interval {CI} 1.044-3.521], p = 0.036), whereas headache (OR 0.230 [95% CI 0.091-0.582], p = 0.002) and neurological deficits (OR 0.223; [95% CI 0.121-0.410], p < 0.001) were demonstrated to be negative predictive factors. Sensorimotor deficit after surgery (OR 4.490 [95% CI 2.231-9.037], p < 0.001) was found to be a positive predictor for the occurrence of postoperative seizures. The identified predictors for the occurrence of seizures in meningioma can contribute to improving seizure treatment and patients' quality of life.

The Impact of Tumor Elongation on Facial Nerve Outcome after Surgery for Koos Grade 3 and 4 Vestibular Schwannomas in the Semi-Sitting Position via the Retrosigmoid Approach.

Background: Facial nerve paralysis is a severe dysfunction after vestibular schwannoma (VS) surgery. Methods: This monocentric study analyzed 61 patients who underwent sporadic VS surgery in a standardized manner. The primary endpoint was the facial nerve outcome (FNO) at 3 months after VS surgery. FNO was dichotomized into "good" (House-Brackmann (HB) score ≤ 2) and "poor" (HB > 2). Results: Poor FNO was observed in 11 patients (18.0%) at 3 months after VS surgery. Radiomic tumor shape features were analyzed, and the AUC of elongation in the prediction of a poor HB at 3 months was 0.70 (95% CI: 0.56-0.85, p = 0.03) and the optimum threshold value (≤/>0.35) yielded a sensitivity and specificity of 64.0% and 75.4%, respectively. Multivariable logistic regression analyses considering the extent of resection (0.35) revealed that more elongated VSs (≤0.35; OR: 5.8; 95%CI: 1.2-28.2; p = 0.03) and those with an increased EoR (≥93.4%; OR: 6.5; 95%CI: 1.0-42.5; p = 0.05) are independently associated with poorer FNO at 3 months after surgery. Conclusions: Highly elongated VS shape seems to be a risk factor for worsened facial nerve outcome at 3 months after surgery for Koos grade 3 and 4 tumors.

Sexual dysfunction after surgery for primary sporadic cranial meningiomas: prevalence and risk factors.

BACKGROUND: Although postoperative quality of life (QoL) has been studied in relation to a variety of aspects following meningioma resection, the impact of meningiomas on sexual life has not been investigated. The aim of this study is to determine the impact of cranial meningioma surgery on patients' postoperative sexual life. METHODS: A standardized questionnaire, anonymous and based on the Arizona Sexual Experiences Scale (ASEX), was sent to 87 patients who had been selected for participation in the study based on the following criteria: a postoperative Karnofsky performance of ≥ 80 and below 60 years of age at diagnosis. RESULTS: 53 patients (53/87; 61%) responded to the survey. The study identified eleven patients (20.8%) who reported sexual dysfunction (SD) according to ASEX criteria. Six of these patients were women (55%) and five were men (45%). Univariable analysis revealed that SD was observed with greater frequency in patients with non-skull base tumors (p = 0.006) and in those with a left-hemispheric meningioma (p = 0.046). Multivariable analysis revealed that non-skull base tumor location is the only independent factor being associated with SD (OR = 5.71, 95% CI = 1.02-31.81, p = 0.047). CONCLUSION: This first investigation of sexual functioning post-surgery for cranial meningiomas indicates that SD is a prevalent issue among non-skull base meningioma patients. Consequently, we recommend that pre- and postoperative sexual health should be further addressed in future QoL investigations of cranial meningioma patients.

Intraoperative tranexamic acid administration in cranial meningioma surgery: a meta-analysis of prospective randomized, double-blinded, and placebo-controlled trials.

Objective: Cranial meningioma surgeries often involve significant blood loss and transfusions. Tranexamic acid (TXA) has been used to reduce blood loss in various surgeries. This meta-analysis of randomized placebo-controlled trials (RCTs) evaluates the impact of TXA in cranial meningioma surgery. Methods: Pubmed, Web of Science, and Cochrane Library were searched for RCTs. Studies were compared for: Blood loss, operative time, hospital stay, reoperation rates, allogeneic and autologous transfusion, and incidence of complications. Results: Seven RCTs with 490 patients receiving TXA and 491 receiving placebos were included. TXA significantly shortened operative time (Mean Difference (MD): -20.95; 95%CI: -39.94 to -1.95; p=0.03). Blood loss was lower with TXA (MD: -262.7 ml; 95%CI: -397.6 to -127.8; p=0.0001). Odds of reoperation were not significantly different (OR: 0.44; 95%CI: 0.13-1.45; p=0.18). TXA significantly reduced the need for RBC transfusions (OR: 0.47; 95%CI: 0.22-0.99; p<0.05). No significant differences were observed regarding postoperative seizures (OR: 1.06; 95%CI: 0.56-2.03; p=0.85), hydrocephalus (OR: 0.25; 95%CI: 0.03-2.29; p=0.22), or hematoma (OR: 0.52; 95%CI: 0.22-1.28; p=0.16). Hospital stay was shortened in the TXA group (MD: -1.23; 95%CI: -2.41 to -0.05; p=0.04). Conclusion: This meta-analysis suggests that a single intraoperative dose of TXA reduces blood loss, allogeneic blood transfusions and shortens surgery time.

Melanoma Brain Metastases Patient-Derived Organoids: An In Vitro Platform for Drug Screening.

BACKGROUND AND AIMS: Brain metastases are prevalent in the late stages of malignant melanoma. Multimodal therapy remains challenging. Patient-derived organoids (PDOs) represent a valuable pre-clinical model, faithfully recapitulating key aspects of the original tumor, including the heterogeneity and the mutational status. This study aimed to establish PDOs from melanoma brain metastases (MBM-PDOs) and to test the feasibility of using them as a model for in vitro targeted-therapy drug testing. METHODS: Surgical resection samples from eight patients with melanoma brain metastases were used to establish MBM-PDOs. The samples were enzymatically dissociated followed by seeding into low-attachment plates to generate floating organoids. The MBM-PDOs were characterized genetically, histologically, and immunohistologically and compared with the parental tissue. The MBM-PDO cultures were exposed to dabrafenib (BRAF inhibitor) and trametinib (MEK inhibitor) followed by a cell viability assessment. RESULTS: Seven out of eight cases were successfully cultivated, maintaining the histological, immunohistological phenotype, and the mutational status of the parental tumors. Five out of seven cases harbored BRAF V600E mutations and were responsive to BRAF and MEK inhibitors in vitro. Two out of seven cases were BRAF wild type: one case harboring an NRAS mutation and the other harboring a KIT mutation, and both were resistant to BRAF and MEK inhibitor therapy. CONCLUSIONS: We successfully established PDOs from melanoma brain metastases surgical specimens, which exhibited a consistent histological and mutational profile with the parental tissue. Using FDA-approved BRAF and MEK inhibitors, our data demonstrate the feasibility of employing MBM-PDOs for targeted-therapy in vitro testing.

NextLens-The Next Generation of Surgical Navigation: Proof of Concept of an Augmented Reality System for Surgical Navigation.

Objective The aim of this work was the development of an augmented reality system including the functionality of conventional surgical navigation systems. Methods An application software for the Augmented Reality System HoloLens 2 from Microsoft was developed. It detects the position of the patient as well as position of surgical instruments in real time and displays it within the two-dimensional (2D) magnetic resonance imaging or computed tomography (CT) images. The surgical pointer instrument, including a pattern that is recognized by the HoloLens 2 sensors, was created with three-dimensional (3D) printing. The technical concept was demonstrated at a cadaver skull to identify anatomical landmarks. Results With the help of the HoloLens 2 and its sensors, the real-time position of the surgical pointer instrument could be shown. The position of the 3D-printed pointer with colored pattern could be recognized within 2D-CT images when stationary and in motion at a cadaver skull. Feasibility could be demonstrated for the clinical application of transsphenoidal pituitary surgery. Conclusion The HoloLens 2 has a high potential for use as a surgical navigation system. With subsequent studies, a further accuracy evaluation will be performed receiving valid data for comparison with conventional surgical navigation systems. In addition to transsphenoidal pituitary surgery, it could be also applied for other surgical disciplines.

Single-centre real-life observational study on mortality and outcomes: decompressive craniectomy and brain death in traumatic brain injury, haemorrhage, and other cerebral diseases.

BACKGROUND: Decompressive hemicraniectomy (DHC) is used after severe brain damages with elevated, refractory intracranial pressure (ICP). In a non age-restricted population, mortality rates and long-term outcomes following DHC are still unclear. This study's objectives were to examine both, as well as to identify predictors of unfavourable outcomes. METHODS: We undertook a retrospective observational analysis of patients aged 18 years and older who underwent DHC at the University Hospital of Bonn between 2018 and 2020, due to traumatic brain injury (TBI), haemorrhage, tumours or infections. Patient outcomes were assessed by conducting telephone interviews, utilising questionnaires for modified Rankin Scale (mRS) and extended Glasgow Outcome scale (GOSE). We evaluated the health-related quality of life using the EuroQol (EQ-5D-5L) scale. RESULTS: A total of 144 patients with a median age of 58.5 years (range: 18 to 85 years) were evaluated. The mortality rate was 67%, with patients passing away at a median of 6.0 days (IQR [1.9-37.6]) after DHC. Favourable outcomes, as assessed by the mRS and GOSE were observed in 10.4% and 6.3% of patients, respectively. Cox regression analysis revealed a 2.0% increase in the mortality risk for every year of age (HR = 1.017; 95% CI [1.01-1.03]; p = 0.004). Uni- and bilateral fixed pupils were associated with a 1.72 (95% CI [1.03-2.87]; p = 0.037) and 3.97 (95% CI [2.44-6.46]; p < 0.001) times higher mortality risk, respectively. ROC-analysis demonstrated that age and pupillary reactivity predicted 6-month mortality with an AUC of 0.77 (95% CI [0.69-0.84]). The only parameter significantly associated with a better quality of life was younger age. CONCLUSIONS: Following DHC, mortality remains substantial, and favourable outcomes occur rarely. Particularly in elderly patients and in the presence of clinical signs of herniation, mortality rates are notably elevated. Hence, the indication for DHC should be set critically.

Radiomic white matter parameters of functional integrity of the corticospinal tract in high-grade glioma.

Tractography has become a widely available tool for the planning of neurosurgical operations as well as for neuroscientific research. The absence of patient interaction makes it easily applicable. However, it leaves uncertainty about the functional relevance of the identified bundles. We retrospectively analyzed the correlation of white matter markers with their clinical function in 24 right-handed patients who underwent first surgery for high-grade glioma. Morphological affection of the corticospinal tract (CST) and grade of paresis were assessed before surgery. Tractography was performed manually with MRTrix3 and automatically with TractSeg. Median and mean fractional anisotropy (FA) from manual tractography showed a significant correlation with CST affection (p = 0.008) and paresis (p = 0.015, p = 0.026). CST affection correlated further most with energy, and surface-volume ratio (p = 0.014) from radiomic analysis. Paresis correlated most with maximum 2D column diameter (p = 0.005), minor axis length (p = 0.006), and kurtosis (p = 0.008) from radiomic analysis. Streamline count yielded no significant correlations. In conclusion, mean or median FA can be used for the assessment of CST integrity in high-grade glioma. Also, several radiomic parameters are suited to describe tract integrity and may be used to quantitatively analyze white matter in the future.

The safety and use of perioperative dexamethasone in the perioperative management of primary sporadic supratentorial meningiomas.

Objective: Despite the lack of prospective evidence for the perioperative use of dexamethasone in meningioma surgery, its use is well established in the daily routine of several centers. The present study evaluates the effect of dexamethasone on postoperative complications, peritumoral T2/FLAIR hyperintensity, and progression-free survival in patients with supratentorial meningiomas undergoing resection. Methods: A total of 148 patients who underwent resection of a primary sporadic supratentorial meningioma at the authors' institution between 2018 and 2020 were included in this retrospective cohort. Safety criteria were side effects of dexamethasone (e.g. hyperglycemia), surgical morbidities, length of stay, and mortality. The individual Karnofsky Performance Scales (KPS) were evaluated regarding the individual development and the delta of KPS at 3- and 12-months compared to baseline KPS was calculated. Longitudinal assessment of the peritumoral T2-/FLAIR hyperintensity changes was performed. Results: The use of both pre- and postoperative dexamethasone did not influence the incidence rates of wound infections, infarctions, postoperative seizures, pulmonary embolism, postoperative hemorrhage, mortality, length of stay, new-onset hyperglycemia and new neurological deficits. Perioperative Dexamethasone use was associated with an improved Karnofsky performance development at 3- (delta of KPS 3.3 vs. -1.9, p=0.001) and 12-months (delta of KPS 3.8 vs. -1.1, p=0.008) compared to the preoperative Karnofsky performance status. Multivariable analysis revealed that perioperative dexamethasone use enhances the KPS improvement (OR: 3.65, 95% CI: 1.01-13.18, p=0.048). Persistent peritumoral T2/FLAIR hyperintensity changes were observed in 35 cases of 70 patients with available follow-up images and a baseline edema (50.0%). Perioperative dexamethasone use enhanced the reduction of the preoperative peritumoral T2-/FLAIR hyperintensity changes (mean reduction of maximum diameter: 1.8 cm vs. 1.1 cm, p=0.023). Perioperative dexamethasone use was independently associated with a lower risk for persistent peritumoral T2-/FLAIR hyperintensity changes (OR: 3.77, 95% CI: 1.05-13.54, p=0.042) The perioperative use of dexamethasone did not influence the progression-free survival time in Simpson grade I or II resected WHO grade 1 meningiomas (log-rank test: p=0.27). Conclusion: Perioperative dexamethasone use seems to be safe in surgery for primary supratentorial meningiomas. Dexamethasone use might enhance the functionality by reducing postoperative peritumoral T2-/FLAIR hyperintensities. These findings highlight the need for prospective data.

Perioperative psychological distress in patients with intracranial tumors; a single center study.

PURPOSE: Distress Thermometer (DT) was adopted to evaluate distress in neuro-oncology on a scale from 1 to 10. DT values above 4 indicate major distress and should initiate psycho(onco)logical co-therapy. However, data about peri-operative distress is scarce. Hence, we evaluated peri-operative distress levels in a neurosurgical patient cohort with various intracranial tumors using the DT. METHODS: We conducted a retrospective study including inpatients with brain tumors who underwent surgery in our department between October 2015 and December 2019. Patients were routinely assessed for distress using the DT before or after initial surgery. A comparative analysis was performed via Wilcoxon rank-sum test. RESULTS: 254 patients were eligible. Mean DT value of the entire cohort was 5.4 ± 2.4. 44.5% (n = 114) of all patients exceeded DT values of ≥ 6. In our cohort, poor post-operative neurological performance and occurrence of motor deficits were significantly associated with major distress. When analysed for peri-operative changes, DT values significantly declined within the male sub-cohort (6.0 to 4.6, p = 0.0033) after surgery but remained high for the entire cohort (5.7 and 5.3, p = 0.1407). Sub-cohort analysis for other clinical factors revealed no further significant changes in peri-operative distress. CONCLUSION: Distress levels were high across the entire cohort which indicated a high need for psychological support. Motor deficits and poor post-operative neurological performance were significantly associated with DT values above 6. Distress levels showed little peri-operative variation.

A Long-Term Comparative Analysis of Endovascular Coiling and Clipping for Ruptured Cerebral Aneurysms: An Individual Patient-Level Meta-Analysis Assessing Rerupture Rates.

Background: Although the initial functional outcome findings of the International Subarachnoid Aneurysm Trial (ISAT) study favored coiling at one year after aneurysmal subarachnoid hemorrhage (aSAH), concerns arose regarding limited long-term rerupture data. This meta-analysis is the first to analyze longitudinal individual patient data (IPD) of target aneurysm rerupture in terms of treatment modality. Methods: The present meta-analysis included studies that compared clipping with coiling of ruptured aneurysms regarding long-term rerupture. Rerupture rates' individual patient data (IPD) were extracted from published Kaplan-Meier curves utilizing the R package IPDfromKM in R Version 4.3.1. Results: A total of 3153 patients from two studies were included. The clipping arm included 1755 patients, whereas the coiling arm included 1398 patients. Median reconstructed follow-up was 6.1 years (IQR = 0.5-11.7). The rerupture rates in the clipping arm and the coiling arm were 0.5% and 1.5%, respectively (p = 0.002). Kaplan-Meier chart analysis of the 3153 patients revealed a shortened time to rerupture in the coiling arm (log-rank test: p = 0.01). The hazard ratio (HR) for coiling compared with clipping regarding rerupture was 3.62 (95% CI:1.21-10.86, p = 0.02). Conclusion: Target aneurysm rerupture was rare beyond the initial year. Pooled long-term IPD from the 3153 patients revealed that reruptures of target aneurysms are more common after coiling and might be considered in the pretherapeutic decision-making process for aSAH.

The importance of considering competing risks in recurrence analysis of intracranial meningioma.

BACKGROUND: The risk of recurrence is overestimated by the Kaplan-Meier method when competing events, such as death without recurrence, are present. Such overestimation can be avoided by using the Aalen-Johansen method, which is a direct extension of Kaplan-Meier that accounts for competing events. Meningiomas commonly occur in older individuals and have slow-growing properties, thereby warranting competing risk analysis. The extent to which competing events are considered in meningioma literature is unknown, and the consequences of using incorrect methodologies in meningioma recurrence risk analysis have not been investigated. METHODS: We surveyed articles indexed on PubMed since 2020 to assess the usage of competing risk analysis in recent meningioma literature. To compare recurrence risk estimates obtained through Kaplan-Meier and Aalen-Johansen methods, we applied our international database comprising ~ 8,000 patients with a primary meningioma collected from 42 institutions. RESULTS: Of 513 articles, 169 were eligible for full-text screening. There were 6,537 eligible cases from our PERNS database. The discrepancy between the results obtained by Kaplan-Meier and Aalen-Johansen was negligible among low-grade lesions and younger individuals. The discrepancy increased substantially in the patient groups associated with higher rates of competing events (older patients with high-grade lesions). CONCLUSION: The importance of considering competing events in recurrence risk analysis is poorly recognized as only 6% of the studies we surveyed employed Aalen-Johansen analyses. Consequently, most of the previous literature has overestimated the risk of recurrence. The overestimation was negligible for studies involving low-grade lesions in younger individuals; however, overestimation might have been substantial for studies on high-grade lesions.

A Novel Scoring System Predicting Red Blood Cell Transfusion Requirements in Patients Undergoing Invasive Spine Surgery.

Background: Access to blood products is crucial for patient safety during the perioperative course. However, reduced donations and seasonally occurring blood shortages pose a significant challenge to the healthcare system, with surgeries being postponed. The German Blood Transfusion act requires that RBC packages become assigned to an individual patient, resulting in a significant reduction in the available blood products, further aggravating shortages. We aimed to develop a scoring system predicting transfusion probability in patients undergoing spine surgery to reduce assignment and, thus, increase the availability of blood products. Methods: The medical records of 252 patients who underwent spine surgery were evaluated and 18 potential predictors for RBC transfusion were tested to construct a logistic-regression-based predictive scoring system for blood transfusion in patients undergoing spine surgery. Results: The variables found to be the most important included the type of surgery, vertebral body replacement, number of stages, and pre-operative Hb concentration, indicating that surgical specification and the extent of the surgical procedure were more influential than the pre-existing patient condition and medication. Conclusions: Our model showed a good discrimination ability with an average AUC [min, max] of 0.87 [0.6, 0.97] and internal validation with a similar AUC of 0.84 [0.66, 0.97]. In summary, we developed a scoring system to forecast patients' perioperative transfusion needs when undergoing spine surgery using pre-operative predictors, potentially reducing the need for RBC allocation and, thus, resulting in an increased availability of this valuable resource.

Analysis of the Technical Accuracy of a Patient-Specific Stereotaxy Platform for Brain Biopsy.

The use of stereotactic frames is a common practice in neurosurgical interventions such as brain biopsy and deep brain stimulation. However, conventional stereotactic frames have been shown to require modification and adaptation regarding patient and surgeon comfort as well as the increasing demand for individualized medical treatment. To meet these requirements for carrying out state-of-the-art neurosurgery, a 3D print-based, patient-specific stereotactic system was developed and examined for technical accuracy. Sixteen patient-specific frames, each with two target points, were additively manufactured from PA12 using the Multi Jet Fusion process. The 32 target points aim to maximize the variability of biopsy targets and depths for tissue sample retrieval in the brain. Following manufacturing, the frames were measured three-dimensionally using an optical scanner. The frames underwent an autoclave sterilization process prior to rescanning. The scan-generated models were compared with the planned CAD models and the deviation of the planned target points in the XY-plane, Z-direction and in the resulting direction were determined. Significantly lower (p < 0.01) deviations were observed when comparing CAD vs. print and print vs. sterile in the Z-direction (0.17 mm and 0.06 mm, respectively) than in the XY-plane (0.46 mm and 0.16 mm, respectively). The resulting target point deviation (0.51 mm) and the XY-plane (0.46 mm) are significantly higher (p < 0.01) in the CAD vs. print comparison than in the print vs. sterile comparison (0.18 mm and 0.16 mm, respectively). On average, the results from the 32 target positions examined exceeded the clinically required accuracy for a brain biopsy (2 mm) by more than four times. The patient-specific stereotaxic frames meet the requirements of modern neurosurgical navigation and make no compromises when it comes to accuracy. In addition, the material is suitable for autoclave sterilization due to resistance to distortion.

IMAGINER: improving accuracy with a mixed reality navigation system during placement of external ventricular drains. A feasibility study.

OBJECTIVE: The placement of a ventricular catheter, that is, an external ventricular drain (EVD), is a common and essential neurosurgical procedure. In addition, it is one of the first procedures performed by inexperienced neurosurgeons. With or without surgical experience, the placement of an EVD according to anatomical landmarks only can be difficult, with the potential risk for inaccurate catheter placement. Repeated corrections can lead to avoidable complications. The use of mixed reality could be a helpful guide and improve the accuracy of drain placement, especially in patients with acute pathology leading to the displacement of anatomical structures. Using a human cadaveric model in this feasibility study, the authors aimed to evaluate the accuracy of EVD placement by comparing two techniques: mixed reality and freehand placement. METHODS: Twenty medical students performed the EVD placement procedure with a Cushing's ventricular cannula on the right and left sides of the ventricular system. The cannula was placed according to landmarks on one side and with the assistance of mixed reality (Microsoft HoloLens 2) on the other side. With mixed reality, a planned trajectory was displayed in the field of view that guides the placement of the cannula. Subsequently, the actual position of the cannula was assessed with the help of a CT scan with a 1-mm slice thickness. The bony structure as well as the left and right cannula positions were registered to the CT scan with the planned target point before the placement procedure. CloudCompare software was applied for registration and evaluation of accuracy. RESULTS: EVD placement using mixed reality was easily performed by all medical students. The predefined target point (inside the lateral ventricle) was reached with both techniques. However, the scattering radius of the target point reached through the use of mixed reality (12 mm) was reduced by more than 54% compared with the puncture without mixed reality (26 mm), which represents a doubling of the puncture accuracy. CONCLUSIONS: This feasibility study specifically showed that the integration and use of mixed reality helps to achieve more than double the accuracy in the placement of ventricular catheters. Because of the easy availability of these new tools and their intuitive handling, we see great potential for mixed reality to improve accuracy.

Mixed reality for spine surgery: a step into the future with a human cadaveric accuracy study.

OBJECTIVE: Current application of mixed reality as a navigation aid in the field of spinal navigation points to the potential of this technology in spine surgery. Crucial factors for acceptance include intuitive workflow, system stability, reliability, and accuracy of the method. The authors therefore aimed to investigate the accuracy of the system in visualization of anatomical structures using mixed reality in the example of pedicles of the thoracic spine in a human cadaveric study. Potential difficulties and limitations are discussed. METHODS: CT scans of a human cadaveric spinal column specimen were performed. After segmentation and import into the advanced HoloLens 2 software, the vertebrae were exposed. The vertebral arches were preserved on one side for a landmark-based surface registration, whereas pedicles were exposed on the other side in order to measure and evaluate deviation of the overlay holographs with regard to the exact anatomical structure. Accuracy was measured and statistically evaluated. RESULTS: In this work it was demonstrated that the overlay of the virtual 3D model pedicles with the real anatomical structures with anatomical landmark registration was within an acceptable surgical accuracy with the mean value of 2.1 mm (maximum 3.8 mm, minimum 1.2 mm). The highest accuracy was registered at the medial and lateral pedicle wall, and the measurement results were best in the region of the middle thoracic spine. CONCLUSIONS: The accuracy analysis for mixed reality (i.e., between the virtual and real anatomical situation of the thoracic spine) showed a very good agreement when focus was on the pedicles. This work is thus a rare proof of the precision of segmentation to the potential surgical area. The results encourage researchers to open up mixed reality technology in its development and application for spinal navigation.

Students' perspectives regarding needs for and opportunities with mixed-reality education in neurosurgery at German medical schools.

OBJECTIVE: Despite mixed reality being an emerging tool for tailored neurosurgical treatment and safety enhancement, the use of mixed reality in the education of German medical students is not established in the field of neurosurgery. The present study aimed to investigate medical students' perspectives on the use of mixed reality in neurosurgical medical education. METHODS: Between July 3, 2023, and August 31, 2023, an online survey was completed by German medical students through their affiliated student associations and educational institutions. The survey included 16 items related to mixed reality in neurosurgery, with participants providing ratings on a 4-point Likert scale to indicate their level of agreement with these statements. RESULTS: A total of 150 students from 27 medical schools in Germany took part in the survey. A significant majority comprising 131 (87.3%) students expressed strong to intense interest in mixed-reality courses in neurosurgery, and 108 (72%) reported an interest in incorporating mixed reality into their curriculum. Furthermore, 94.7% agreed that mixed reality may enhance their understanding of operative neuroanatomy and 72.7% agreed with the idea that teaching via mixed-reality methods may increase the probability of the use of mixed reality in their future career. The majority (116/150 [77.3%]) reported that the preferred optimum timepoint for teaching with mixed reality might be within the first 3 years of medical school. In particular, more students in the first 2 years preferred to start mixed-reality courses in the first 2 years of medical school compared to students in their 3rd to 6th years of medical school (71.9% vs 41.5%, p = 0.003). Residents and attending specialists were believed to be appropriate teachers by 118 students (78.7%). CONCLUSIONS: German medical students exhibited significant interest and willingness to engage in mixed reality in neurosurgery. Evidently, there is a high demand for medical schools to provide mixed-reality courses. Students seem to prefer the courses as early as possible in their medical school education in order to transfer preclinical neuroanatomical knowledge into operative neurosurgical anatomy by using this promising technique.

Outcomes After Decompressive Surgery for Severe Cerebral Venous Sinus Thrombosis Associated or Not Associated with Vaccine-Induced Immune Thrombosis with Thrombocytopenia: A Multicenter Cohort Study.

BACKGROUND: Clinical observations indicated that vaccine-induced immune thrombosis with thrombocytopenia (VITT)-associated cerebral venous sinus thrombosis (CVST) often has a space-occupying effect and thus necessitates decompressive surgery (DS). While comparing with non-VITT CVST, this study explored whether VITT-associated CVST exhibits a more fulminant clinical course, different perioperative and intensive care unit management, and worse long-term outcome. METHODS: This multicenter, retrospective cohort study collected patient data from 12 tertiary centers to address priorly formulated hypotheses concerning the clinical course, the perioperative management with related complications, extracerebral complications, and the functional outcome (modified Rankin Scale) in patients with VITT-associated and non-VITT CVST, both with DS. RESULTS: Both groups, each with 16 patients, were balanced regarding demographics, kind of clinical symptoms, and radiological findings at hospital admission. Severity of neurological symptoms, assessed with the National Institute of Health Stroke Scale, was similar between groups at admission and before surgery, whereas more patients with VITT-associated CVST showed a relevant midline shift (≥ 4 mm) before surgery (100% vs. 68.8%, p = 0.043). Patients with VITT-associated CVST tended to undergo DS early, i.e., ≤ 24 h after hospital admission (p = 0.077). Patients with VITT-associated CVST more frequently received platelet transfusion, tranexamic acid, and fibrinogen perioperatively. The postoperative management was comparable, and complications were evenly distributed. More patients with VITT-associated CVST achieved a favorable outcome (modified Rankin Scale ≤ 3) at 3 months (p = 0.043). CONCLUSIONS: Although the prediction of individual courses remains challenging, DS should be considered early in VITT-associated CVST because an overall favorable outcome appears achievable in these patients.