Search

Intraoperative imaging has become widely accepted in neurosurgery in recent years. The possibility to objectively determine the extent of tumor removal is highly advantageous. If the resection is incomplete, clinicians can attempt to remove the residual tumor that was missed during the same operation. Furthermore, the positioning of implants in spinal surgery, as well as in cranial surgery, can be controlled and modified during the procedure. Intraoperative imaging acts as immediate quality control and offers improved patient safety. This article gives a brief overview of the different intraoperative imaging modalities and their potential applications in modern neurosurgery., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Intraoperative high-field MRI in combination and close integration with microscope-based navigation serving as a common interface for the presentation of multimodal data in the surgical field seems to be one of the most promising surgical setups allowing avoiding unwanted tumor remnants while preserving neurological function. Multimodal navigation integrates standard anatomical, structural, functional, and metabolic data. Navigation achieves visualizing the initial extent of a lesion with the concomitant identification of neighboring eloquent brain structures, as well as, providing a tool for a direct correlation of histology and multimodal data. With the help of intraoperative imaging navigation data can be updated, so that brain shift can be compensated for and initially missed tumor remnants can be localized reliably.

Objective: To introduce a new robotic system to the field of neurosurgery and report on a preliminary assessment of accuracy as well as on envisioned application concepts. Based on experience with another system (Evolution 1, URS Inc., Schwerin, Germany), technical advancements are discussed., Material/methods: The basic module is an industrial 6 degrees of freedom robotic arm with a modified control element. The system combines frameless stereotaxy, robotics, and endoscopy. The robotic reproducibility error and the overall error were evaluated. For accuracy testing CT markers were placed on a cadaveric head and pinpointed with the robot's tool tip, both fully automated and telemanipulatory. Applicability in a clinical setting, user friendliness, safety and flexibility were assessed., Results: The new system is suitable for use in the neurosurgical operating theatre. Hard- and software are user-friendly and flexible. The mean reproducibility error was 0.052-0.062 mm, the mean overall error was 0.816 mm. The system is less cumbersome and much easier to use than the Evolution 1., Conclusions: With its user-friendly interface and reliable safety features, its high application accuracy and flexibility, the new system is a versatile robotic platform for various neurosurgical applications. Adaptations for different applications are currently being realized., (Copyright (c) 2007 S. Karger AG, Basel.)

Mixed reality navigation (MRN) technology is emerging as an increasingly significant and interesting topic in neurosurgery. MRN enables neurosurgeons to "see through" the head with an interactive, hybrid visualization environment that merges virtual- and physical-world elements. Offering immersive, intuitive, and reliable guidance for preoperative and intraoperative intervention of intracranial lesions, MRN showcases its potential as an economically efficient and user-friendly alternative to standard neuronavigation systems. However, the clinical research and development of MRN systems present challenges: recruiting a sufficient number of patients within a limited timeframe is difficult, and acquiring low-cost, commercially available, medically significant head phantoms is equally challenging. To accelerate the development of novel MRN systems and surmount these obstacles, the study presents a dataset designed for MRN system development and testing in neurosurgery. It includes CT and MRI data from 19 patients with intracranial lesions and derived 3D models of anatomical structures and validation references. The models are available in Wavefront object (OBJ) and Stereolithography (STL) formats, supporting the creation and assessment of neurosurgical MRN applications. Subject terms: Mixed reality, Navigation, Neurosurgery, Intracranial lesion, Computed tomography, Magnetic resonance imaging [ABSTRACT FROM AUTHOR]

Mixed Reality Navigation (MRN) is pivotal in augmented reality-assisted intelligent neurosurgical interventions. However, existing MRN registration methods face challenges in concurrently achieving low user dependency, high accuracy, and clinical applicability. This study proposes and evaluates a novel registration method based on a laser crosshair simulator, evaluating its feasibility and accuracy. A novel registration method employing a laser crosshair simulator was introduced, designed to replicate the scanner frame's position on the patient. The system autonomously calculates the transformation, mapping coordinates from the tracking space to the reference image space. A mathematical model and workflow for registration were designed, and a Universal Windows Platform (UWP) application was developed on HoloLens-2. Finally, a head phantom was used to measure the system's target registration error (TRE). The proposed method was successfully implemented, obviating the need for user interactions with virtual objects during the registration process. Regarding accuracy, the average deviation was 3.7 ± 1.7 mm. This method shows encouraging results in efficiency and intuitiveness and marks a valuable advancement in low-cost, easy-to-use MRN systems. The potential for enhancing accuracy and adaptability in intervention procedures positions this approach as promising for improving surgical outcomes. [ABSTRACT FROM AUTHOR]

Objective: At the beginning of 2020, the COVID-19 pandemic enforced a rapid reallocation of healthcare resources. Our neurosurgical department is located in the German county of Marburg–Biedenkopf, about 80 km from the nearest major city. We were able to maintain our previously established open-door policy after the emergence of COVID-19. Here, we report on dynamics in the catchment area for neurotrauma patients at our department during the pandemic. Methods: 763 consecutive neurotrauma cases admitted to our department between 1 January 2018 and 31 December 2021 were analyzed retrospectively. Patients' age, gender, origin, diagnoses, and outcomes were recorded. The number of patients hospitalized with a COVID-19 infection in Germany (PHCG) were retrieved from the Robert Koch Institute (RKI). We defined calendar weeks with >1000 PHCG as high COVID-19 caseload weeks (HCLW). Chi-square and Fisher's exact served as statistical tests. Results: In 2020 and 2021, we observed a significantly increased number of neurotrauma patients who, with primary residence outside of our district, were admitted to our hospital compared to 2018 and 2019 (p < 0.001), while there were no significant differences in in-house mortality. During HCLW, a significantly increased number of neurotrauma patients with primary residence in the densely populated southwestern margin (SWM) of the contiguous part of our catchment area were referred to us compared to the time prior to the pandemic and between HCLW (p = 0.003). In neurotrauma patients admitted from the SWM during HCLW, there was no tendency towards higher in-house mortality. Conclusion: An open-door policy may moderate the risk of involuntarily triaging neurotrauma patients during a pandemic. [ABSTRACT FROM AUTHOR]

Background: Registration accuracy is a main factor influencing overall navigation accuracy. Standard fiducial- or landmark-based patient registration is user dependent and error-prone. Intraoperative imaging offers the possibility for user-independent patient registration. The aim of this paper is to evaluate our initial experience applying intraoperative computed tomography (CT) for navigation registration in cranial neurosurgery, with a special focus on registration accuracy and effective radiation dose.Methods: A total of 200 patients (141 craniotomy, 19 transsphenoidal, and 40 stereotactic burr hole procedures) were investigated by intraoperative CT applying a 32-slice movable CT scanner, which was used for automatic navigation registration. Registration accuracy was measured by at least three skin fiducials that were not part of the registration process.Results: Automatic registration resulted in high registration accuracy (mean registration error: 0.93 ± 0.41 mm). Implementation of low-dose scanning protocols did not impede registration accuracy (registration error applying the full dose head protocol: 0.87 ± 0.36 mm vs. the low dose sinus protocol 0.72 ± 0.43 mm) while a reduction of the effective radiation dose by a factor of 8 could be achieved (mean effective radiation dose head protocol: 2.73 mSv vs. sinus protocol: 0.34 mSv).Conclusion: Intraoperative CT allows highly reliable navigation registration with low radiation exposure. [ABSTRACT FROM AUTHOR]

Background The reversible posterior leukoencephalopathy (RPL) syndrome with typical vasogenic edema in the occipital lobe and associated cortical blindness is a rare finding; however, the brainstem variant is even more infrequent. Etiologies discussed include blood pressure dysregulations, renal failure, or immunosuppression. Patient A 63-year-old man with the characteristic radiographic findings of RPL syndrome presented with reversible cortical blindness and internuclear ophthalmoplegia (INO) after resection of an infratentorial hemangiopericytoma. The patient postoperatively presented with diplopia and mental status alterations followed by visual loss; these symptoms completely recovered within a few days. Fluid-attenuated inversion recovery-, and T2-weighted magnetic resonance imaging (MRI) revealed bilateral hyperintense lesions not only in the white matter of the parieto-occipital region but also in the rostral paramedian mesencephalon and pons. Conclusions We hypothesize that the patient had an RPL, coincidentally in classic-, and brainstem localization, caused by perioperative fluctuations of blood pressure. [ABSTRACT FROM AUTHOR]

Objective: Up to now, fiber tractography in the clinical routine is mostly based on diffusion tensor imaging (DTI). However, there are known drawbacks in the resolution of crossing or kissing fibers and in the vicinity of a tumor or edema. These restrictions can be overcome by tractography based on High Angular Resolution Diffusion Imaging (HARDI) which in turn requires larger numbers of gradients resulting in longer acquisition times. Using compressed sensing (CS) techniques, HARDI signals can be obtained by using less non-collinear diffusion gradients, thus enabling the use of HARDI-based fiber tractography in the clinical routine. Methods: Eight patients with gliomas in the temporal lobe, in proximity to the optic radiation (OR), underwent 3T MRI including a diffusion-weighted dataset with 30 gradient directions. Fiber tractography of the OR using a deterministic streamline algorithm based on DTI was compared to tractography based on reconstructed diffusion signals using HARDI+CS. Results: HARDI+CS based tractography displayed the OR more conclusively compared to the DTI-based results in all eight cases. In particular, the potential of HARDI+CS-based tractography was observed for cases of high grade gliomas with significant peritumoral edema, larger tumor size or closer proximity of tumor and reconstructed fiber tract. Conclusions: Overcoming the problem of long acquisition times, HARDI+CS seems to be a promising basis for fiber tractography of the OR in regions of disturbed diffusion, areas of high interest in glioma surgery. [ABSTRACT FROM AUTHOR]

Diffusion Tensor Imaging (DTI) and fiber tractography are established methods to reconstruct major white matter tracts in the human brain in-vivo. Particularly in the context of neurosurgical procedures, reliable information about the course of fiber bundles is important to minimize postoperative deficits while maximizing the tumor resection volume. Since routinely used deterministic streamline tractography approaches often underestimate the spatial extent of white matter tracts, a novel approach to improve fiber segmentation is presented here, considering clinical time constraints. Therefore, fiber tracking visualization is enhanced with statistical information from multiple tracking applications to determine uncertainty in reconstruction based on clinical DTI data. After initial deterministic fiber tracking and centerline calculation, new seed regions are generated along the result’s midline. Tracking is applied to all new seed regions afterwards, varying in number and applied offset. The number of fibers passing each voxel is computed to model different levels of fiber bundle membership. Experimental results using an artificial data set of an anatomical software phantom are presented, using the Dice Similarity Coefficient (DSC) as a measure of segmentation quality. Different parameter combinations were classified to be superior to others providing significantly improved results with DSCs of 81.02%±4.12%, 81.32%±4.22% and 80.99%±3.81% for different levels of added noise in comparison to the deterministic fiber tracking procedure using the two-ROI approach with average DSCs of 65.08%±5.31%, 64.73%±6.02% and 65.91%±6.42%. Whole brain tractography based on the seed volume generated by the calculated seeds delivers average DSCs of 67.12%±0.86%, 75.10%±0.28% and 72.91%±0.15%, original whole brain tractography delivers DSCs of 67.16%, 75.03% and 75.54%, using initial ROIs as combined include regions, which is clearly improved by the repeated fiber tractography method. [ABSTRACT FROM AUTHOR]

Pre-operative planning and intra-operative guidance in neurosurgery require detailed information about the location of functional areas and their anatomo-functional connectivity. In particular, regarding the language system, post-operative deficits such as aphasia can be avoided. By combining functional magnetic resonance imaging and diffusion tensor imaging, the connectivity between functional areas can be reconstructed by tractography techniques that need to cope with limitations such as limited resolution and low anisotropic diffusion close to functional areas. Tumors pose particular challenges because of edema, displacement effects on brain tissue and infiltration of white matter. Under these conditions, standard fiber tracking methods reconstruct pathways of insufficient quality. Therefore, robust global or probabilistic approaches are required. In this study, two commonly used standard fiber tracking algorithms, streamline propagation and tensor deflection, were compared with a previously published global search, Gibbs tracking and a connection-oriented probabilistic tractography approach. All methods were applied to reconstruct neuronal pathways of the language system of patients undergoing brain tumor surgery, and control subjects. Connections between Broca and Wernicke areas via the arcuate fasciculus (AF) and the inferior fronto-occipital fasciculus (IFOF) were validated by a clinical expert to ensure anatomical feasibility, and compared using distance- and diffusion-based similarity metrics to evaluate their agreement on pathway locations. For both patients and controls, a strong agreement between all methods was observed regarding the location of the AF. In case of the IFOF however, standard fiber tracking and Gibbs tracking predominantly identified the inferior longitudinal fasciculus that plays a secondary role in semantic language processing. In contrast, global search resolved connections in almost every case via the IFOF which could be confirmed by probabilistic fiber tracking. The results show that regarding the language system, our global search is superior to clinically applied conventional fiber tracking strategies with results similar to time-consuming global or probabilistic approaches. [ABSTRACT FROM AUTHOR]

We investigated whether the inclusion of the PFA-100 in the preoperative screening of neurosurgical patients might reduce perioperative bleeding complications. Patients with intracranial space-occupying lesions who were scheduled for neurosurgery underwent routine preoperative PFA-100 testing. In case of an abnormal PFA test, patients received prophylactic treatment with desmopressin. 93 consecutive patients were compared to 102 consecutive patients with comparable characteristics operated before introduction of the PFA-100 testing. 2 patients (2.2%) in the PFA group and 2 patients (2.0%) in the non-PFA group experienced clinically relevant intracranial bleeding confirmed by computed tomography (OR 1.05, 95% CI 0.39-2.82; P = 1.0). Transfusions were not significantly different between the two groups. 13 (14.0%) patients in the PFA group and 5 (4.9%) patients in the non- PFA group received desmopressin (OR 3.2, 95% CI 1.1-9.2; P = 0.045). Preoperative screening with the PFA-100 did result in a significant increase in the administration of desmopressin, which could not reduce perioperative bleeding complications or transfusions. [ABSTRACT FROM AUTHOR]

Between June 1995 and June 2000 teleradiology was performed in 1024 neurosurgical cases (945 patients). An analogue image transfer system was used for presentation of computed tomography (CT) and magnetic resonance imaging (MRI) scans from seven referring hospitals in southern Germany. The system used a 19,200 baud modem connection via the ordinary telephone network. The diagnoses on presentation were intracerebral haematoma (50%), trauma (27%), subarachnoid haemorrhage (4%), stroke (5%) and others (14%). Retrospective analysis showed that in 67% of cases admission and therefore ground-based transportation of the patients to our neurosurgical centre was not necessary for different reasons (moribund status, no surgical intervention required or no neurosurgical problem at all). If each patient had been transferred, then the potential savings for ground transportation were €339.93 per case (with accompanying physician of the affiliated hospital) or €373.96 per case (with accompanying experienced ICU physician), respectively (€1 is US$1.4). The total cost of the image transfer system for all eight hospitals was €96,000; this was amortised after 282 teleconsultations, which occurred after 15 months of usage. A simple teleradiology system in neurosurgery enables rapid and reliable telephone consultations, mainly on patients with trauma, stroke and intracerebral haematoma at low cost. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the feasibility and point out the indications of intraoperative MR imaging in neurosurgical procedures. The MR imaging was performed using a 0.2-T scanner which was located in a radiofrequency-shielded operating theater. Three major setups for intraoperative imaging were possible: inside the scanner; at the 5-Gauss line; or in an adjacent operating theater. Additionally, in lesions adjacent to eloquent brain areas microscope- and pointer-based neuronavigation with integrated functional data was applied. Three hundred ten patients were investigated in the previous 5 years, among them gliomas ( n=95), pituitary tumors ( n=81), and 39 non-lesional cases in whom resective or disconnective epilepsy surgery was carried out. We did not observe any adverse effects due to intraoperative MR imaging. Image quality was sufficient to evaluate the extent of the tumor resection in the majority of cases. The main indications for intraoperative MR imaging were the evaluation of the extent of a resection in glioma, ventricular tumor, pituitary tumor, and in epilepsy surgery. Intraoperative MR imaging offers the possibility of further tumor removal during the same surgical procedure in case of tumor remnants, increasing the rate of complete tumor removal. Furthermore, the effects of brain shift, which would lead to inaccurate neuronavigation, can be compensated for by an update of the neuronavigation system with intraoperative MR image data. [ABSTRACT FROM AUTHOR]

Background: The coronavirus 2019 (COVID-19) pandemic forced students and teachers to rapidly adopt digital education methods. Proper guidance for and refinement of such methods is continuously required. Here, we report on the educational experience students and academic staff at the neurosurgical department of a German university hospital made with digital teaching modules (DTMs) that were newly developed due to the transition to digital teaching during the first year of the COVID-19 pandemic and on the insights gained therefrom. Methods: Nine newly created DTMs provided students the option to anonymously evaluate each module by assigning a score from 0 (worst value) to 5 (best value) to it. Access count, evaluation count, average evaluation, number of included (interactive) figures, number of presented cases, number of linked publications, and number of included multiple-choice questions for each DTM were recorded retrospectively. For each DTM, we aimed to correlate access count, evaluation count, and average evaluation with the number of included (interactive) figures, number of presented cases, number of linked publications, and number of included multiple-choice questions. E-mail responses from individual students as to the DTMs were collected. Among students, an anonymous, voluntary online survey regarding the DTMs was conducted. Results: Number of figures and average evaluation per DTM were significantly positively correlated (Spearman's rho = 0.85; p = 0.0037). Number of figures and number of evaluations per DTM were also significantly positively correlated (Spearman's rho = 0.78; p = 0.0137). Responses from individual students indicated that illustrative cases and interactive figures might further increase DTM popularity. Conclusion: As a valuable adjunct in medical student education, DTMs should contain (interactive) figures, illustrative cases, a scoring option, and the option to give individual feedback towards the academic staff. [ABSTRACT FROM AUTHOR]

Background: Patients' fear of the coronavirus disease 2019 (COVID-19) may delay inevitable treatment, putting potential benefits at risk. This single-center retrospective study aims to analyze temporal relationships of the first wave of the COVID-19 pandemic in Germany with the number of patients who sought and received elective neurosurgical treatment at a German university hospital. Methods: Daily outpatient numbers (ON) and elective procedures (EP) were recorded at our department between 1 January 2020 and 30 June 2020 (baseline: between 1 January 2019 and 30 June 2019). In patients who received EP, we recorded indication, outcome, and length of stay (LOS). Moving averages of ON (MAON) and of EP were calculated. Data on governmental action taken in response to the pandemic and on coronavirus-positive cases in Germany (CPCG) were superimposed. Exponential and arc tangent curves (ATC) were fitted to the absolute numbers of CPCG. Phase shifts were estimated, and Spearman's rank correlation coefficient, rho, was calculated between the 2020 MAON and the derivative function of the fitted ATC (DFATC). Wilcoxon rank sum served as statistical test. Significance was assumed with p values of less than 0.05. Results: ON were significantly decreased in April 2020 as compared to April 2019 (p = 0.010). A phase shift between the German lockdown, the DFATC, and the decrease in MAON was not detected, while a phase shift of 10 days between the DFATC and the subsequent increase in MAON was detected. The DFATC was significantly negatively correlated (rho = −0.92, p < 0.0001) to the MAON until 31 March 2020, and, when shifted by 10 days, the DFATC was significantly negatively correlated (rho = −0.87, p < 0.0001) to the MAON from 01 April 2020. EP (p = 0.023), including the subset of non-oncological EP (p = 0.032), were significantly less performed in the first half of 2020 as compared to the first half of 2019. In March and April 2020, we conducted significantly more EP due to motor deficits (p = 0.0267, and less), visual disturbances (p = 0.0488), and spinal instability (p = 0.0012), and significantly less EP due to radicular pain (p = 0.0489), as compared to March and April 2019. LOS ranked significantly higher in patients who received cranial or spinal EP in March and April 2020 as compared to March and April 2019 (p = 0.0497). Significant differences in outcome were not observed. Conclusion: The beginning of the COVID-19 pandemic was correlated to an immediate and significant decrease in ON, and to a significant decrease in the number of EP performed. The subsequent increase in ON was delayed. Adequate measures to promote timely discharge of patients may become increasingly relevant as the pandemic proceeds. Although we observed a shift in the range of indications towards significantly more EP in patients with neurological deficiencies, care should be taken to avoid potentially deleterious delays of necessary elective treatment in future pandemic situations. [ABSTRACT FROM AUTHOR]

Abstract: Background: Surgical treatment of brainstem cavernous angioma involving eloquent fiber tracts is one of the most challenging areas of contemporary neurosurgery. Diffusion tensor imaging–based fiber tracking adds essential information for preoperative planning in neurosurgical practice. Integration of the tractography into neuronavigation system makes it possible for the intraoperative visualization of the major fiber tracts. It may help increase the likelihood of the total resection of tumors adjacent to the eloquent fiber tracts and avoid new neurologic deficits after surgery. Case Description: We report our valuable experience of such integration for the resection of a deeply located brainstem cavernous angioma. Conclusion: Inclusion of tractography in standard imaging protocols for neuronavigation systems can provide important information regarding neural tracts for the planning of brainstem surgery. It can also increase the safety of neurosurgical intervention near white matter tracts in the brainstem. [Copyright &y& Elsevier]

Abstract: For a non-invasive identification of eloquent brain areas in neurosurgical procedures up to now only preoperative functional brain mapping techniques are available. These are based, e.g., on preoperative functional magnetic resonance imaging (fMRI) investigations in awake patients. The aim of this study was to investigate the feasibility to perform fMRI during neurosurgical procedures in anesthetized patients. For that purpose, a passive stimulation paradigm with peripheral nerve stimulation was applied. A 1.5-T MR scanner placed in a radiofrequency-shielded operating room with an adapted operating table was used for intraoperative fMRI. The fMRI data were analyzed during acquisition by an online statistical evaluation package installed on the MR scanner console. In addition, phase reversal of somatosensory evoked potentials was used for verification of intraoperative fMRI. In four anesthetized patients with lesions in the vicinity of the central region a total of 11 fMRI measurements were successfully acquired and analyzed online. Activation was found in the somatosensory cortex, which could be confirmed by intraoperative phase reversal for each measurement. Furthermore, statistical parametric mapping (SPM) was employed for an extensive offline data analysis. We did not observe any neurological deterioration or complications due to the stimulation technique. Intraoperative fMRI is technically feasible allowing a real-time identification of eloquent brain areas despite brain shift. [Copyright &y& Elsevier]