Neuronavigation: geneology, reality, and prospects

Potential of sonobiopsy as a novel diagnosis tool for brain cancer

Brain tumors have a poor prognosis. Early, accurate diagnosis and treatment are crucial. Although brain surgical biopsy can provide an accurate diagnosis, it is highly invasive and risky and is not suitable for follow-up examination. Blood-based liquid biopsies have a low detection rate of tumor biomarkers and limited evaluation ability due to the existence of the blood-brain barrier (BBB). The BBB is composed of brain capillary endothelial cells through tight junctions, which prevents the release of brain tumor markers to the human peripheral circulation, making it more difficult to diagnose, predict prognosis, and evaluate therapeutic response through brain tumor markers than other tumors. Focused ultrasound (FUS)-enabled liquid biopsy (sonobiopsy) is an emerging technique using FUS to promote the release of tumor markers into the circulatory system and cerebrospinal fluid, thus facilitating tumor detection. The feasibility and safety data from both animal models and clinical trials support sonobiopsy as a great potential in the diagnosis of brain diseases.

Challenges with segmenting intraoperative ultrasound for brain tumours

Objective - Addressing the challenges that come with identifying and delineating brain tumours in intraoperative ultrasound. Our goal is to both qualitatively and quantitatively assess the interobserver variation, amongst experienced neuro-oncological intraoperative ultrasound users (neurosurgeons and neuroradiologists), in detecting and segmenting brain tumours on ultrasound. We then propose that, due to the inherent challenges of this task, annotation by localisation of the entire tumour mass with a bounding box could serve as an ancillary solution to segmentation for clinical training, encompassing margin uncertainty and the curation of large datasets. Methods - 30 ultrasound images of brain lesions in 30 patients were annotated by 4 annotators - 1 neuroradiologist and 3 neurosurgeons. The annotation variation of the 3 neurosurgeons was first measured, and then the annotations of each neurosurgeon were individually compared to the neuroradiologist's, which served as a reference standard as their segmentations were further refined by cross-reference to the preoperative magnetic resonance imaging (MRI). The following statistical metrics were used: Intersection Over Union (IoU), Sørensen-Dice Similarity Coefficient (DSC) and Hausdorff Distance (HD). These annotations were then converted into bounding boxes for the same evaluation. Results - There was a moderate level of interobserver variance between the neurosurgeons [ I o U : 0.789 , D S C : 0.876 , H D : 103.227 ] and a larger level of variance when compared against the MRI-informed reference standard annotations by the neuroradiologist, mean across annotators [ I o U : 0.723 , D S C : 0.813 , H D : 115.675 ] . After converting the segments to bounding boxes, all metrics improve, most significantly, the interquartile range drops by [ I o U : 37 % , D S C : 41 % , H D : 54 % ] . Conclusion - This study highlights the current challenges with detecting and defining tumour boundaries in neuro-oncological intraoperative brain ultrasound. We then show that bounding box annotation could serve as a useful complementary approach for both clinical and technical reasons.

Extended reality in cranial and spinal neurosurgery - a bibliometric analysis

PURPOSE

This bibliometric analysis of the top 100 cited articles on extended reality (XR) in neurosurgery aimed to reveal trends in this research field. Gender differences in authorship and global distribution of the most-cited articles were also addressed.

METHODS

A Web of Science electronic database search was conducted. The top 100 most-cited articles related to the scope of this review were retrieved and analyzed for trends in publications, journal characteristics, authorship, global distribution, study design, and focus areas. After a brief description of the top 100 publications, a comparative analysis between spinal and cranial publications was performed.

RESULTS

From 2005, there was a significant increase in spinal neurosurgery publications with a focus on pedicle screw placement. Most articles were original research studies, with an emphasis on augmented reality (AR). In cranial neurosurgery, there was no notable increase in publications. There was an increase in studies assessing both AR and virtual reality (VR) research, with a notable emphasis on VR compared to AR. Education, surgical skills assessment, and surgical planning were more common themes in cranial studies compared to spinal studies. Female authorship was notably low in both groups, with no significant increase over time. The USA and Canada contributed most of the publications in the research field.

CONCLUSIONS

Research regarding the use of XR in neurosurgery increased significantly from 2005. Cranial research focused on VR and resident education while spinal research focused on AR and neuronavigation. Female authorship was underrepresented. North America provides most of the high-impact research in this area.

Innovations in Spine Surgery: A Narrative Review of Current Integrative Technologies

Neurosurgical technologies have become increasingly more adaptive, featuring real-time and patient-specific guidance in preoperative, intraoperative, and postoperative settings. This review offers insight into how these integrative innovations compare with conventional approaches in spine surgery, focusing on machine learning (ML), artificial intelligence, augmented reality and virtual reality, and spinal navigation systems. Data on technology applications, diagnostic and procedural accuracy, intraoperative times, radiation exposures, postoperative outcomes, and costs were extracted and compared with conventional methods to assess their advantages and limitations. Preoperatively, augmented reality and virtual reality have applications in surgical training and planning that are more immersive, case specific, and risk-free and have been shown to enhance accuracy and reduce complications. ML algorithms have demonstrated high accuracy in predicting surgical candidacy (up to 92.1%) and tailoring personalized treatments based on patient-specific variables. Intraoperatively, advantages include more accurate pedicle screw insertion (96%-99% with ML), enhanced visualization, reduced radiation exposure (49 μSv with O-arm navigation vs. 556 μSv with fluoroscopy), increased efficiency, and potential for fewer intraoperative complications compared with conventional approaches. Postoperatively, certain ML and artificial intelligence models have outperformed conventional methods in predicting all postoperative complications of >6000 patients as well as predicting variables contributing to in-hospital and 90-day mortality. However, applying these technologies comes with limitations, such as longer operative times (up to 35.6% longer) with navigation, dependency on datasets, costs, accessibility, steep learning curve, and inherent software malfunctions. As these technologies advance, continuing to assess their efficacy and limitations will be crucial to their successful integration within spine surgery.

A deep learning classification task for brain navigation in rodents using micro-Doppler ultrasound imaging

Positioning and navigation are essential components of neuroimaging as they improve the quality and reliability of data acquisition, leading to advances in diagnosis, treatment outcomes, and fundamental understanding of the brain. Functional ultrasound imaging is an emerging technology providing high-resolution images of the brain vasculature, allowing for the monitoring of brain activity. However, as the technology is relatively new, there is no standardized tool for inferring the position in the brain from the vascular images. In this study, we present a deep learning-based framework designed to address this challenge. Our approach uses an image classification task coupled with a regression on the resulting probabilities to determine the position of a single image. To evaluate its performance, we conducted experiments using a dataset of 51 rat brain scans. The training positions were extracted at intervals of 375 μm, resulting in a positioning error of 176 μm. Further GradCAM analysis revealed that the predictions were primarily driven by subcortical vascular structures. Finally, we assessed the robustness of our method in a cortical stroke where the brain vasculature is severely impaired. Remarkably, no specific increase in the number of misclassifications was observed, confirming the method's reliability in challenging conditions. Overall, our framework provides accurate and flexible positioning, not relying on a pre-registered reference but rather on conserved vascular patterns.

Design and Simulate Intracranial Support to Guide Maxillo Surgery: A Study Based on Bioengineering

BACKGROUND

Intraoperative navigation allows for the creation of a real-time relationship between the anatomy imagined during diagnosis/planning and the site of surgical interest. This procedure takes place by identifying and registering trustworthy anatomical markers on planning images and using a point locator during the operation. The locator is calibrated in the workspace by placing a Dynamic Reference Frame (DRF) sensor.

OBJECTIVE

This study aims to calculate the localization accuracy of an electromagnetic locator of neuro-maxillofacial surgery, moving the standard sensor position to a different position more suitable for maxillofacial surgery.

MATERIALS AND METHODS

The upper dental arch was chosen as an alternative fixed point for the positioning of the sensor. The prototype of a bite support device was designed and generated via 3D printing. CT images of a skull phantom with 10 anatomical landmarks were acquired. The testing procedure consisted of 10 measurements for each position of the sensor: precisely 10 measurements with the sensor placed on the forehead and 10 measurements with the sensor placed on the bite support device. It also evaluated the localization error by comparing the two procedures.

RESULTS

The localization error, when the sensor was placed on the bite support device, was lower in the sphere located on the temporal bone. It was the same in the spheres located on the maxillary bone. The test analysis of the data of the new device showed that it is reliable; the tests are reproducible and can be considered as accurate as the traditional ones. In addition, the sensor mounted on this device has proven to be slightly superior in terms of accuracy and accuracy in areas such as the middle third of the face and jaw.

DISCUSSION AND CONCLUSION

The realization of the bite support device allowed the sensor to change position concerning its natural site. This procedure allows us to explore structures, such as the frontal site, which were initially difficult to approach with neuronavigation and improves the approach to midface structures, already studied with neuronavigation. The new calibration, with the position of the sensor on the support device in the same reference points sphere, highlighted the reduction in the location error. We can say that the support proposed in this study lays the foundations for a new navigation approach for patients in maxillofacial surgery, by changing the position of the sensor. It has strong points in improving the localization error for some reference points without determining disadvantages both in the calibration and in the surgical impediment.

Virtual Surgical Planning and Patient-Specific Instruments for Correcting Lower Limb Deformities in Pediatric Patients: Preliminary Results from the In-Office 3D Printing Point of Care

(1) Background: Virtual reality and 3D printing are transforming orthopedic surgery by enabling personalized three-dimensional (3D) models for surgical planning and Patient-Specific Instruments (PSIs). Hospitals are establishing in-house 3D printing centers to reduce costs and improve patient care. Pediatric orthopedic surgery also benefits from these technologies, enhancing the precision and personalization of treatments. This study presents preliminary results of an In-Office 3D Printing Point of Care (PoC), outlining considerations and challenges in using this program for treating lower limb deformities in pediatric patients through Virtual Surgical Planning (VSP) and 3D-printed Patient-Specific Instruments (PSIs). (2) Materials and Methods: Pediatric patients with congenital or acquired lower limb deformities undergoing surgical correction based on VSP, incorporating 3D-printed PSIs when required, were included in this study. The entire process of VSP and 3D printing at the In-Office PoC was illustrated. Data about deformity characteristics, surgical procedures, and outcomes, including the accuracy of angular correction, surgical times, and complications, were reported. (3) Results: In total, 39 bone correction procedures in 29 patients with a mean age of 11.6 ± 4.7 years (range 3.1-18.5 years) were performed according to VSP. Among them, 23 procedures were accomplished with PSIs. Surgeries with PSIs were 45 min shorter, with fewer fluoroscopy shots. Optimal correction was achieved in 37% of procedures, while the remaining cases showed under-corrections (41%) or over-corrections (22%). Major complications were observed in four patients (13.8%). (4) Conclusions: The In-Office 3D Printing Point of Care is becoming an essential tool for planning and executing complex corrections of lower limb deformities, but additional research is needed for optimizing the prediction and accuracy of the achieved corrections.

Image-to-Patient Registration in Computer-Assisted Surgery of Head and Neck: State-of-the-Art, Perspectives, and Challenges

Today, image-guided systems play a significant role in improving the outcome of diagnostic and therapeutic interventions. They provide crucial anatomical information during the procedure to decrease the size and the extent of the approach, to reduce intraoperative complications, and to increase accuracy, repeatability, and safety. Image-to-patient registration is the first step in image-guided procedures. It establishes a correspondence between the patient's preoperative imaging and the intraoperative data. When it comes to the head-and-neck region, the presence of many sensitive structures such as the central nervous system or the neurosensory organs requires a millimetric precision. This review allows evaluating the characteristics and the performances of different registration methods in the head-and-neck region used in the operation room from the perspectives of accuracy, invasiveness, and processing times. Our work led to the conclusion that invasive marker-based methods are still considered as the gold standard of image-to-patient registration. The surface-based methods are recommended for faster procedures and applied on the surface tissues especially around the eyes. In the near future, computer vision technology is expected to enhance these systems by reducing human errors and cognitive load in the operating room.

Virtual and Augmented Reality in Spine Surgery: A Systematic Review

BACKGROUND

Augmented reality (AR) and virtual reality (VR) implementation in spinal surgery has expanded rapidly over the past decade. This systematic review summarizes the use of AR/VR technology in surgical education, preoperative planning, and intraoperative guidance.

METHODS

A search query for AR/VR technology in spine surgery was conducted through PubMed, Embase, and Scopus. After exclusions, 48 studies were included. Included studies were then grouped into relevant subsections. Categorization into subsections yielded 12 surgical training studies, 5 preoperative planning, 24 intraoperative usage, and 10 radiation exposure.

RESULTS

VR-assisted training significantly reduced penetration rates or increased accuracy rates compared to lecture-based groups in 5 studies. Preoperative VR planning significantly influenced surgical recommendations and reduced radiation exposure, operating time, and estimated blood loss. For 3 patient studies, AR-assisted pedicle screw placement accuracy ranged from 95.77% to 100% using the Gertzbein grading scale. Head-mounted display was the most common interface used intraoperatively followed by AR microscope and projector. AR/VR also had applications in tumor resection, vertebroplasty, bone biopsy, and rod bending. Four studies reported significantly reduced radiation exposure in AR group compared to fluoroscopy group.

CONCLUSIONS

AR/VR technologies have the potential to usher in a paradigm shift in spine surgery. However, the current evidence indicates there is still a need for 1) defined quality and technical requirements for AR/VR devices, 2) more intraoperative studies that explore usage outside of pedicle screw placement, and 3) technological advancements to overcome registration errors via the development of an automatic registration method.

Themes in neuronavigation research: A machine learning topic analysis

Objective

To understand trends in neuronavigation we employed machine learning methods to perform a broad literature review which would be impractical by manual inspection.

Methods

PubMed was queried for articles with "Neuronavigation" in any field from inception-2020. Articles were designated neuronavigation-focused (NF) if "Neuronavigation" was a major MeSH. The latent dirichlet allocation topic modeling technique was used to identify themes of NF research.

Results

There were 3896 articles of which 1727 (44%) were designated as NF. Between 1999-2009 and 2010-2020, the number of NF publications experienced 80% growth. Between 2009-2014 and 2015-2020, there was a 0.3% decline. Eleven themes covered 1367 (86%) NF articles. "Resection of Eloquent Lesions" comprised the highest number of articles (243), followed by "Accuracy and Registration" (242), "Patient Outcomes" (156), "Stimulation and Mapping" (126), "Planning and Visualization" (123), "Intraoperative Tools" (104), "Placement of Ventricular Catheters" (86), "Spine Surgery" (85), "New Systems" (80), "Guided Biopsies" (61), and "Surgical Approach" (61). All topics except for "Planning and Visualization", "Intraoperative Tools", and "New Systems" exhibited a monotonic positive trend. When analyzing subcategories, there were a greater number of clinical assessments or usage of existing neuronavigation systems (77%) rather than modification or development of new apparatuses (18%).

Conclusion

NF research appears to focus on the clinical assessment of neuronavigation and to a lesser extent on the development of new systems. Although neuronavigation has made significant strides, NF research output appears to have plateaued in the last decade.

Augmented Reality to Compensate for Navigation Inaccuracies

This study aims to report on the capability of microscope-based augmented reality (AR) to evaluate registration and navigation accuracy with extracranial and intracranial landmarks and to elaborate on its opportunities and obstacles in compensation for navigation inaccuracies. In a consecutive single surgeon series of 293 patients, automatic intraoperative computed tomography-based registration was performed delivering a high initial registration accuracy with a mean target registration error of 0.84 ± 0.36 mm. Navigation accuracy is evaluated by overlaying a maximum intensity projection or pre-segmented object outlines within the recent focal plane onto the in situ patient anatomy and compensated for by translational and/or rotational in-plane transformations. Using bony landmarks (85 cases), there was two cases where a mismatch was seen. Cortical vascular structures (242 cases) showed a mismatch in 43 cases and cortex representations (40 cases) revealed two inaccurate cases. In all cases, with detected misalignment, a successful spatial compensation was performed (mean correction: bone (6.27 ± 7.31 mm), vascular (3.00 ± 1.93 mm, 0.38° ± 1.06°), and cortex (5.31 ± 1.57 mm, 1.75° ± 2.47°)) increasing navigation accuracy. AR support allows for intermediate and straightforward monitoring of accuracy, enables compensation of spatial misalignments, and thereby provides additional safety by increasing overall accuracy.

Influence of Industry in Hydrocephalus and Vertebral Augmentation Literature

OBJECTIVE

To investigate whether financial bias exists in hydrocephalus and vertebral augmentation literature.

METHODS

A systematic literature search was performed in PubMed of studies concerning vertebral augmentation and cerebrospinal fluid valves. The relationship between reported conflicts of interest and the nature of the conclusion (positive vs. neutral and negative) was analyzed.

RESULTS

Having a conflict of interest was significantly associated with reporting a positive conclusion in studies investigating valves for hydrocephalus (92.3% positive conclusion vs. 36.4%; P = 0.001), but not for cement augmentation studies (80.5% positive conclusion vs. 65.7%; P = 0.087). As studies concerning vertebral augmentation implants had only positive conclusions, no analysis could be performed.

CONCLUSIONS

Our findings suggest a positive relationship between reported conflict of interest and positive outcome in neurosurgical literature concerning cerebrospinal fluid valves.

Clinical research-When it matters

Clinical research runs through the entire progress of the science and technology which has been currently and previously applied to the medical field. It has gradually developed into a standardized procedure and played an important role in understanding the etiology and characteristics of diseases. Clinical researchs assess the effectiveness and safety of new/improved diagnostic or therapeutic technologies, implants, instruments, or drug applications, to discover new data and improve potential deficiencies in previous medical knowledge.

Artificial Intelligence in Brain Tumour Surgery-An Emerging Paradigm

Artificial intelligence (AI) platforms have the potential to cause a paradigm shift in brain tumour surgery. Brain tumour surgery augmented with AI can result in safer and more effective treatment. In this review article, we explore the current and future role of AI in patients undergoing brain tumour surgery, including aiding diagnosis, optimising the surgical plan, providing support during the operation, and better predicting the prognosis. Finally, we discuss barriers to the successful clinical implementation, the ethical concerns, and we provide our perspective on how the field could be advanced.

Diffusion MRI tractography for neurosurgery: the basics, current state, technical reliability and challenges

Diffusion magnetic resonance imaging (dMRI) tractography is currently the only imaging technique that allows for non-invasive delineation and visualisation of white matter (WM) tractsin vivo,prompting rapid advances in related fields of brain MRI research in recent years. One of its major clinical applications is for pre-surgical planning and intraoperative image guidance in neurosurgery, where knowledge about the location of WM tracts nearby the surgical target can be helpful to guide surgical resection and optimise post-surgical outcomes. Surgical injuries to these WM tracts can lead to permanent neurological and functional deficits, making the accuracy of tractography reconstructions paramount. The quality of dMRI tractography is influenced by many modifiable factors, ranging from MRI data acquisition through to the post-processing of tractography output, with the potential of error propagation based on decisions made at each and subsequent processing steps. Research over the last 25 years has significantly improved the anatomical accuracy of tractography. An updated review about tractography methodology in the context of neurosurgery is now timely given the thriving research activities in dMRI, to ensure more appropriate applications in the clinical neurosurgical realm. This article aims to review the dMRI physics, and tractography methodologies, highlighting recent advances to provide the key concepts of tractography-informed neurosurgery, with a focus on the general considerations, the current state of practice, technical challenges, potential advances, and future demands to this field.

Computer-assisted surgery in medical and dental applications

INTRODUCTION

Computer-assisted surgery (CAS) is a broad surgical methodology that utilizes computer technology to both plan and execute surgical intervention. CAS is widespread in both medicine and dentistry as it allows for minimally invasive and precise surgical procedures. Key innovations in volumetric imaging, virtual surgical planning software, instrument tracking, and robotics have assisted in facilitating the transfer of surgical plans to precise execution of surgical procedures. CAS has long been used in certain medical specialties including neurosurgery, cardiology, orthopedic surgery, otolaryngology, and interventional radiology, and has since expanded to oral and maxillofacial application, particularly for computer-assisted implant surgery.

AREAS COVERED

This review provides an updated overview of the most current research for CAS in medicine and dentistry, with a focus on neurosurgery and dental implant surgery. The MEDLINE electronic database was searched and relevant original and review articles from 2005 to 2020 were included.

EXPERT OPINION

Recent literature suggests that CAS performs favorably in both neurosurgical and dental implant applications. Computer-guided surgical navigation is well entrenched as standard of care in neurosurgery. Whereas static computer-assisted implant surgery has become established in dentistry, dynamic computer-assisted navigation is newly poised to trend upward in dental implant surgery.

The Path to Surgical Robotics in Neurosurgery

Robotic systems may help efficiently execute complicated tasks that require a high degree of accuracy, and this, in large part, explains why robotics have garnered widespread use in a variety of neurosurgical applications, including intracranial biopsies, spinal instrumentation, and placement of intracranial leads. The use of robotics in neurosurgery confers many benefits, and inherent limitations, to both surgeons and their patients. In this narrative review, we provide a historical overview of robotics and its implementation across various surgical specialties, and discuss the various robotic systems that have been developed specifically for neurosurgical applications. We also discuss the relative advantages of robotic systems compared to traditional surgical techniques, particularly as it pertains to integration of image guidance with the ability of the robotic arm to reliably execute pre-planned tasks. As more neurosurgeons adopt the use of robotics in their practice, we postulate that further technological advancements will become available that will help achieve improved technical capabilities, user experience, and overall patient clinical outcomes.

THE SAFETY AND EFFICACY OF ROBOT-ASSISTED STEREOTACTIC BIOPSY FOR BRAIN GLIOMA: EARLIEST INSTITUTIONAL EXPERIENCES AND EVALUATION OF LITERATURE

Robot-assisted brain tumor biopsy is becoming one of the most important innovative technologies in neurosurgical practice. The idea behind its engagement is to advance the safety and efficacy of the biopsy procedure, which is much in demand when planning the management of endocranial tumor pathology. Herein, we provide our earliest institutional experiences in utilizing this mesmerizing technology. Cranial robotic device was employed for stereotactic robot-assisted brain glioma biopsy in three consecutive patients from our series: an anaplastic isocitrate dehydrogenase (IDH) negative astrocytoma (WHO grade III) located in the right trigone region of the periventricular white matter; a low grade diffuse astrocytoma (WHO grade II) of bilateral thalamic region spreading into the right mesencephalic area; and an IDH-wildtype glioblastoma (WHO grade IV) of the right frontal lobe producing a contralateral midline shifting. Robot-assisted tumor biopsy was successfully performed to get tissue samples for histopathologic and immunohistochemical analysis. The adjacent tissue iatrogenic damage of the eloquent cortical areas was minimal, while the immediate postoperative recovery was satisfactory in all patients. In conclusion, considering the preliminary results of our early experiences, robot-assisted tumor biopsy was proven to be a feasible and accurate procedure when surgery for brain glioma was not an option. It may increase safety and precision, without expanding surgical time, being similarly effective when compared to standard stereotactic and manual biopsy. Using this method to provide accurate sampling for histopathologic and immunohistochemical analysis is a safe and easy way to determine management strategies and outcome of different types of brain glioma.

A Projector-Based Augmented Reality Navigation System for Computer-Assisted Surgery

In the medical field, guidance to follow the surgical plan is crucial. Image overlay projection is a solution to link the surgical plan with the patient. It realizes augmented reality (AR) by projecting computer-generated image on the surface of the target through a projector, which can visualize additional information to the scene. By overlaying anatomical information or surgical plans on the surgery area, projection helps to enhance the surgeon's understanding of the anatomical structure, and intuitively visualizes the surgical target and key structures of the operation, and avoid the surgeon's sight diversion between monitor and patient. However, it still remains a challenge to project the surgical navigation information on the target precisely and efficiently. In this study, we propose a projector-based surgical navigation system. Through the gray code-based calibration method, the projector can be calibrated with a camera and then be integrated with an optical spatial locator, so that the navigation information of the operation can be accurately projected onto the target area. We validated the projection accuracy of the system through back projection, with average projection error of 3.37 pixels in x direction and 1.51 pixels in y direction, and model projection with an average position error of 1.03 ± 0.43 mm, and carried out puncture experiments using the system with correct rate of 99%, and qualitatively analyzed the system's performance through the questionnaire. The results demonstrate the efficacy of our proposed AR system.

Hidden Error in Optical Stereotactic Navigation Systems and Strategy to Maximize Accuracy

BACKGROUND

Optical neuronavigation has been established as a reliable and effective adjunct to many neurosurgical procedures. Operations such as asleep deep brain stimulation (aDBS) benefit from the potential increase in accuracy that these systems offer. Built into these technologies is a degree of tolerated error that may exceed the presumed accuracy resulting in suboptimal outcomes.

OBJECTIVE

The objective of this study was to identify an underlying source of error in neuronavigation and determine strategies to maximize accuracy.

METHODS

A Medtronic Stealth system (Stealth Station 7 hardware, S8 software, version 3.1.1) was used to simulate an aDBS procedure with the Medtronic Nexframe system. Multiple configurations and orientations of the Nexframe-Nexprobe system components were examined to determine potential sources of, and to quantify navigational error, in the optical navigation system. Virtual entry point and target variations were recorded and analyzed. Finally, off-plan error was recorded with the AxiEM system and visual observation on a phantom head.

RESULTS

The most significant source of error was found to be the orientation of the reference marker plate configurations to the camera system, with the presentation of the markers perpendicular to the camera line of site being the most accurate position. Entry point errors ranged between 0.134 ± 0.048 and 1.271 ± 0.0986 mm in a complex, reproducible pattern dependent on the orientation of the Nexprobe reference plate. Target errors ranged between 0.311 ± 0.094 and 2.159 ± 0.190 mm with a similarly complex, repeatable pattern. Representative configurations were tested for physical error at target with errors ranging from 1.2 mm to 1.4 mm. Throughout data acquisition, no orientation was indicated as outside the acceptable tolerance by the Stealth software.

CONCLUSIONS

Use of optical neuronavigation is expected to increase in frequency and variety of indications. Successful implementation of this technology depends on understanding the tolerances built into the system. In situations that depend on extremely high precision, surgeons should familiarize themselves with potential sources of error so that systems may be optimized beyond the manufacturer's built-in tolerances. We recommend that surgeons align the navigation reference plate and any optical instrument's reference plate spheres in the plane perpendicular to the line of site of the camera to maximize accuracy.

Using non-invasive neuroimaging to enhance the care, well-being and experimental outcomes of laboratory non-human primates (monkeys)

Over the past 10-20 years, neuroscience witnessed an explosion in the use of non-invasive imaging methods, particularly magnetic resonance imaging (MRI), to study brain structure and function. Simultaneously, with access to MRI in many research institutions, MRI has become an indispensable tool for researchers and veterinarians to guide improvements in surgical procedures and implants and thus, experimental as well as clinical outcomes, given that access to MRI also allows for improved diagnosis and monitoring for brain disease. As part of the PRIMEatE Data Exchange, we gathered expert scientists, veterinarians, and clinicians who treat humans, to provide an overview of the use of non-invasive imaging tools, primarily MRI, to enhance experimental and welfare outcomes for laboratory non-human primates engaged in neuroscientific experiments. We aimed to provide guidance for other researchers, scientists and veterinarians in the use of this powerful imaging technology as well as to foster a larger conversation and community of scientists and veterinarians with a shared goal of improving the well-being and experimental outcomes for laboratory animals.

Promises and Perils of Artificial Intelligence in Neurosurgery

Artificial intelligence (AI)-facilitated clinical automation is expected to become increasingly prevalent in the near future. AI techniques may permit rapid and detailed analysis of the large quantities of clinical data generated in modern healthcare settings, at a level that is otherwise impossible by humans. Subsequently, AI may enhance clinical practice by pushing the limits of diagnostics, clinical decision making, and prognostication. Moreover, if combined with surgical robotics and other surgical adjuncts such as image guidance, AI may find its way into the operating room and permit more accurate interventions, with fewer errors. Despite the considerable hype surrounding the impending medical AI revolution, little has been written about potential downsides to increasing clinical automation. These may include both direct and indirect consequences. Directly, faulty, inadequately trained, or poorly understood algorithms may produce erroneous results, which may have wide-scale impact. Indirectly, increasing use of automation may exacerbate de-skilling of human physicians due to over-reliance, poor understanding, overconfidence, and lack of necessary vigilance of an automated clinical workflow. Many of these negative phenomena have already been witnessed in other industries that have already undergone, or are undergoing "automation revolutions," namely commercial aviation and the automotive industry. This narrative review explores the potential benefits and consequences of the anticipated medical AI revolution from a neurosurgical perspective.

Navigated Deep Brain Stimulation Surgery: Evaluating the Combined Use of a Frame-Based Stereotactic System and a Navigation System

Deep brain stimulation (DBS) is a complex surgical procedure that requires detailed anatomical knowledge. In many fields of neurosurgery navigation systems are used to display anatomical structures during an operation to aid performing these surgeries. In frame-based DBS, the advantage of visualization has not yet been evaluated during the procedure itself. In this study, we added live visualization to a frame-based DBS system, using a standard navigation system and investigated its accuracy and potential use in DBS surgery. As a first step, a phantom study was conducted to investigate the accuracy of the navigation system in conjunction with a frame-based approach. As a second step, 5 DBS surgeries were performed with this combined approach. Afterwards, 3 neurosurgeons and 2 neurologists with different levels of experience evaluated the potential use of the system with a questionnaire. Moreover, the additional personnel, costs and required set up time were noted and compared to 5 consecutive standard procedures. In the phantom study, the navigation system showed an inaccuracy of 2.1 mm (mean SD 0.69 mm). In the questionnaire, a mean of 9.4/10 points was awarded for the use of the combined approach as a teaching tool, a mean of 8.4/10 for its advantage in creating a 3-dimensional (3-D) map and a mean of 8/10 points for facilitating group discussions. Especially neurosurgeons and neurologists in training found it useful to better interpret clinical results and side effects (mean 9/10 points) and neurosurgeons appreciated its use to better interpret microelectrode recordings (mean 9/10 points). A mean of 6/10 points was awarded when asked if the benefits were worth the additional efforts. Initially 2 persons, then one additional person was required to set up the system with no relevant added time or costs. Using a navigation system for live visualization during frame-based DBS surgery can improve the understanding of the complex 3-D anatomy and many aspects of the procedure itself. For now, we would regard it as an excellent teaching tool rather than a necessity to perform DBS surgeries.

Technologic Evolution of Navigation and Robotics in Spine Surgery: A Historical Perspective

Spine surgery is continuously evolving. The synergy between medical imaging and advances in computation has allowed for stereotactic neuronavigation and its integration with robotic technology to assist in spine surgery. The discovery of x-rays in 1895, the development of image intensifiers in 1940, and then advancements in computational science and integration have allowed for the development of computed tomography. In combination with the advancements of stereotaxy in the late 1980s, and manipulation of volumetric and special data for 3-dimensional reconstruction in 1998, computed tomography has revolutionized neuronavigational systems. Integrating all these technologies, robotics in spine surgery was introduced in 2004. Since then, it has become a safe modality that can reproducibly place accurate pedicle screws. Robotics may have the added benefits of improving the surgical workflow and optimizing surgeon ergonomics. Growing at a rapid rate, the second-generation spinal robotics have overcome preliminary limitations and errors. However, comparatively, robotics in spine surgery remains in its infancy. By leveraging technologic advancements in medical imaging, computation, and stereotactic navigation, robotics in spine surgery will continue to mature and expand in utility.

Surgical treatment and prognosis of focal brainstem gliomas in children: A 7 year single center experience

This study aims to describe the role of open surgical treatment for focal brainstem gliomas (FBSGs) with the assistance of multimodal neuronavigation and intraoperative neurophysiological monitoring (IOM) in children to investigate the efficacy of microsurgical treatment in pediatric FBSGs. Also the prognostic factors related to the overall survival (OS) of FBSGs to describe the patient and tumor characteristics relevant to prognosis/outcome were focused on. Clinical data of 63 pediatric patients below 16 years of age with FBSGs admitted to the Neurosurgical Unit of Beijing Tiantan Hospital from January 2012 to December 2018 were retrospectively analyzed. All patients underwent initial surgical treatment, followed by magnetic resonance diffusion tensor imaging (DTI), neuronavigation and IOM. Gross or near total resection (GTR or NTR) was achieved in 57/63 (90.5%) cases, and subtotal resection (STR) was achieved in 6/63 (9.5%) cases. Postoperative adjuvant therapy was received by 27/63 (42.9%) cases. Postoperative pathological examination revealed that 36/63 (57.1%) cases had grade I gliomas, 22/63 (34.9%) had grade II, and 5/63 (8.0%) had grade III-IV gliomas according to the WHO classification. The mean Karnofsky score preoperatively was 60, and at the time of follow-up was 90. Consecutively, 6 cases demonstrated disease progression, and 5 of these were deceased. The OS in all patients was 81.2% at 5 years. Histological grade (P < .001) and age at diagnosis (P = .023) showed significant association with prolonged OS. Multimodal neuronavigation and IOM allow very precise intracranial surgery, contributing to a maximally safe resection that might decrease the postoperative disability and mortality rate. This study also showed that pediatric FBSGs were mostly low-grade tumors with excellent surgical outcomes. Consequently, it is suggested that microsurgery can be used to treat FBSGs in children in order to provide better prognosis and survival outcomes.

Optimizing MR imaging for intraoperative image guidance in sellar pathologies

PURPOSE

With the advancement of extended endonasal approaches, the ability to surgically reach parasellar tumor extensions increase. The aim of the study was to propose an optimized imaging protocol for surgical guidance in the cavernous sinus (CS) for proper visualization structures at risk.

METHODS

Prospective case control analysis of 20 consecutive pituitary adenoma patients scheduled for endoscopic transnasal surgery. Assessment of the capability of three different MRI sequences (MPRAGE, VIBE, CISS) by 4 investigators to correctly visualize sellar and parasellar structures. Invasiveness and position of the normal pituitary gland were compared with the intraoperative findings.

RESULTS

The consensus between the 4 examiners to achieve the same results for all modalities was 40% for MPRAGE, 70% for VIBE and 60% for CISS sequences (p = 0.155). A consensus of Knosp Grade per patient was 80% for MPRAGE, 100% for VIBE and 90% for CISS (overall kappa 0.60). A higher Knosp Grade was found in MPRAGE sequences compared to the other sequences. Intraoperative status of invasiveness was correctly identified in 12/20 (60%) with MPRAGE, 19/20 (95%) with VIBE and 11/20 (55%) with CISS sequences. The position of the normal pituitary gland was most frequent evaluable in 15/20 (75%) and correctly identified in 12/15 (80%) cases.

CONCLUSION

Our data showed that VIBE sequences obtain the highest degree of consensus with intraoperative findings of invasiveness and position of the normal pituitary gland. VIBE sequences, due to their high spatial resolution and at the same time fast image acquisition could provide improved imaging for neuronavigation.

Automated neurosurgical stereotactic planning for intraoperative use: a comprehensive review of the literature and perspectives

The creation of intracranial stereotactic trajectories, from entry point to target point, is still mostly done manually by the neurosurgeon. The development of automated stereotactic planning tools has been described in the literature. This systematic review aims to assess the effectiveness of stereotactic planning procedure automation and develop tools for patients undergoing neurosurgical stereotactic procedures. PubMed/MEDLINE, EMBASE, Google Scholar, CINAHL, PsycINFO, and Cochrane Register of Controlled Trials databases were searched from inception to September 1, 2019, at the exception of Google Scholar (from 1 January 2010 to September 1, 2019) in French and English. Eligible studies included all studies proposing automated stereotactic planning. A total of 1543 studies were screened. Forty-two studies were included in the systematic review, including 18 (42.9%) conference papers. The surgical procedures planned automatically were mainly deep brain stimulation (n = 14, 33.3%), stereoelectroencephalography (n = 12, 28.6%), and not specified (n = 10, 23.8%). The most frequently used surgical constraints to plan the trajectory were blood vessels (n = 32, 76.2%), cerebral sulci (n = 27, 64.3%), and cerebral ventricles (n = 23, 54.8%). The distance from blood vessels ranged from 1.96 to 4.78 mm for manual trajectories and from 2.47 to 7.0 mm for automated trajectories. At least one neurosurgeon was involved in 36 studies (85.7%). The automated stereotactic trajectory was preferred in 75.4% of the studied cases (range 30-92.9). Only 3 (7.1%) studies were multicentric. No study reported prospective use of the planning software. Stereotactic planning automation is a promising tool to provide valuable stereotactic trajectories for clinical applications.

Surface-Registration Frameless Stereotactic Navigation Is Less Accurate During Prone Surgeries: Intraoperative Near-Infrared Visualization Using Second Window Indocyanine Green Offers an Adjunct

BACKGROUND

Frameless neuronavigation allows neurosurgeons to visualize and relate the position of surgical instruments to intracranial pathologies based on preoperative tomographic imaging. However, neuronavigation can often be inaccurate. Multiple factors have been proposed as potential causes, and new technologies are needed to overcome these challenges.

OBJECTIVE

To evaluate the accuracy of neuronavigation systems compared to near-infrared (NIR) fluorescence imaging using Second Window Indocyanine Green, a novel technique, and to determine factors that lead to neuronavigation errors.

METHODS

A retrospective analysis was conducted on 56 patients who underwent primary resections of intracranial tumors. Patients received 5 mg/kg ICG approximately 24 h preoperatively. Intraoperatively, neuronavigation was used to plan craniotomies to place the tumors in the center. After craniotomy, NIR imaging visualized tumor-specific NIR signals. The accuracy of neuronavigation and NIR fluorescence imaging for delineating the tumor boundary prior to durotomy was compared.

RESULTS

The neuronavigation centers and NIR centers were 23.0 ± 7.7 % and 2.6 ± 1.1 % deviated from the tumor centers, respectively, relative to the craniotomy sizes. In 12 cases, significant changes were made to the planned durotomy based on NIR imaging. Patient position was a significant predictor of neuronavigation inaccuracy on both univariate and multivariate analysis, with the prone position having significantly higher inaccuracy (29.2 ± 8.1 %) compared to the supine (16.2 ± 8.1 %, p value < 0.001) or the lateral (17.9 ± 5.1 %, p value = 0.003) positions.

CONCLUSION

Patient position significantly affects neuronavigation accuracy. Intraoperative NIR fluorescence imaging before durotomy offers an opportunity to readjust the neuronavigation image space to better align with the patient space.

Intraoperative Magnetic Resonance Imaging-Guided Glioma Resections in Awake or Asleep Settings and Feasibility in the Context of a Public Health System

Background

Despite the most recent surgical aids and tools, surgical removal of infiltrating brain tumors remains a challenge. Unclear margins, edematous areas, and infiltrative behavior are the main causes for failing gross total removals. Also, excessive resection of peri-tumoral tissue often carries risks of damaging the nearby functioning cortical and subcortical structures with an unacceptable decrease in patient's quality of life and postoperative functional status, and the risk of making patients not eligible to adjuvant treatments. Awake surgery and intraoperative magnetic resonance imaging (ioMRI) are among the most effective aids in preventing damage to functional brain while maximizing the extent of resection.

Methods

We present our series of 46 patients operated on at Southmead Hospital (North Bristol NHS Trust) in between July 2014 and February 2017 using ioMRI plus or minus awake surgery. Setting, patient features, indications, type and size of tumors, surgical times, extent of resection, morbidity, and survival are analyzed and discussed.

Results

Overall, ioMRI check led to a +43% resections in Group 1 and +58% in Group 2. In grade 2 tumors, GTR was 46% in Group 1 and 55% in Group 2 (41% in control group). In grade 3 tumors, GTR was 57% in Group 1 and 66% in Group 2 (30% in control group). In Grade 4 tumors, GTR was 63% in Group 1, 66% in Group 2 (36% in control group). In terms of theatre occupation, the use of ioMRI added 1/2 operative session; the addition of awake surgery implied the use of another 1/2 operative session. Morbidity did not differ among the groups, with low incidence of permanent post-operative deficits (<5%). Group 2 OS was statistically longer when compared to the control group.

Conclusions

Using ioMRI together with awake surgery is demanding for the anesthetic team, staff nurses, and for the patient. Nevertheless, low morbidity, greater total resections rates, and longer survival suggest its use is effective in making more approachable gliomas of all grades that we would consider “complex” due to their intrinsic features or locations.

A Multimodality Navigation System for Endoscopic Fetal Surgery: A Phantom Case Study for Congenital Diaphragmatic Hernia

This article presents a multi-modality tracking and navigation system achieved by merging optical tracking and ultrasound imaging into a novel navigation software to help in surgical pre-planning and real-time target setting and guidance. Fetal surgeries require extensive experience in coordination of hand-eye-ultrasound-surgical equipment, knowledge, and precise assessment of relative anatomy. While there are navigation systems available for similar constrained working spaces in arthroscopic and cardiovascular procedures, fetal minimally invasive surgery does not yet have a dedicated navigation platform capable of supporting robotic instruments that can be adapted to the set of unique procedures. This article discusses the testing of the novel multi-modality navigation system in a phantom environment developed for this purpose. The outcomes suggest that the subjects demonstrated an increase in average reaching accuracy by about 60% and an overall reduction in time taken by 33.6%. They also showed higher levels of confidence in reaching the targets, which was visualised from the pattern of trajectory of movements during the procedure. To evaluate the navigation system, a phantom surgical environment was found necessary. Therefore, the article also discusses the details of the development of a fetal phantom environment for congenital diaphragmatic hernia for surgical testing, evaluation, and training. A surgical procedure was conducted on the phantom using the proposed tracking navigation system and using only ultrasound.

Clinical Application of Multimodal Neuronavigation System in Neuroendoscope-Assisted Skull Base Chordoma Resection

Skull base chordoma is a rare tumor arising from embryonic remnants of the notochord with invasive potential. Due to the destruction of osseous landmarks and invasion of surrounding structures, surgical resection is challenging. The authors explored the clinical value of a multimodal neuronavigation system in skull base chordoma resection using a neuroendoscope. Between January 2012 and January 2016, the authors utilized neuroendoscopy to excise skull base chordoma in 93 patients. The authors performed 45 operations assisted by multimodal neuronavigation (neuronavigation group) and 48 without intraoperative imaging guidance (control group). In the control group, 35 patients (73%) underwent gross total resection. In the neuronavigation group, all patients underwent gross total resection without radiographically identified bleeding. Only 1 patient (2%) in the neuronavigation group showed a temporary reduction in vision, which improved after symptomatic treatment. In contrast, there were 4 patients (8%) with postoperative complication, including 2 patients with intracranial hematoma and 2 with neurological deficits. Complication rates were higher than the neuronavigation group. In the follow-up period, 2 patients in the control group with subtotal resection had recurrence within 24 months, but without extracranial metastases. The multimodal neuronavigation system could contribute intraoperative real-time guidance for spatial relationships between lesions and adjacent neurovascular structures, as well as eroded and distorted anatomical landmarks through multiple image fusion and 3-dimensional reconstruction. It significantly improves surgical outcome and provides a new insight into the management of skull base chordomas.

Surgical Navigation in Orthopedics: Workflow and System Review

Orthopedic surgery is a widely performed clinical procedure that deals with problems in relation to the bones, joints, and ligaments of the human body, such as musculoskeletal trauma, spine diseases, sports injuries, degenerative diseases, infections, tumors, and congenital disorders. Surgical navigation is generally recognized as the next generation technology of orthopedic surgery. The development of orthopedic navigation systems aims to analyze pre-, intra- and/or postoperative data in multiple modalities and provide an augmented reality 3-D visualization environment to improve clinical outcomes of surgical orthopedic procedures. This chapter investigates surgical navigation techniques and systems that are currently available in orthopedic procedures. In particular, optical tracking, electromagnetic localizers and stereoscopic vision, as well as commercialized orthopedic navigation systems are thoroughly discussed. Moreover, advances and development trends in orthopedic navigation are also discussed in this chapter. While current orthopedic navigation systems enable surgeons to make precise decisions in the operating room by integrating surgical planning, instrument tracking, and intraoperative imaging, it still remains an active research field which provides orthopedists with various technical disciplines, e.g., medical imaging, computer science, sensor technology, and robotics, to further develop current orthopedic navigation methods and systems.

Computer-aided surgery meets predictive, preventive, and personalized medicine

Computer-aided surgery (CAS) is now nearly 30 years old. It has brought to surgery a variety of tools, techniques, and paradigm changes that have had an impact on how surgeries are planned, executed, and evaluated. In this review, we examine the predictive, preventive, and personalized medicine (PPPM) aspects of CAS. We present a brief history of CAS, summarize its the state of the art, and discuss current trends and future developments related to PPPM. Of the three Ps, we note that the most important impact of CAS is on Personalization, in all the steps of the surgical treatment: preoperative planning, intraoperative execution, and postoperative evaluation. Prediction in CAS is reflected in the preoperative evaluation of the various surgical options and in the evaluation of the possible surgical outcomes. Prevention in CAS is related to intraoperative execution, to help prevent possible surgical complications. We foresee that CAS will play an increasingly important role in PPPM in the coming years.

Correction of orbital wall fracture close to the optic canal using computer-assisted navigation surgery

BACKGROUND

Repairing orbital wall fractures can result in serious complications, including enophthalmos, diplopia, or even blindness. Especially, surgeons worry about damaging the optic nerve while dissecting the optic canal area. We avoid these complications by using a navigation system that was adapted to stereotactic concept based on three-dimensional imaging of the patient's anatomy. Here, we report 5 cases of orbital wall fracture that were repaired using a navigation system.

METHODS

The Navigation System II (Stryker, Freiburg, Germany) and the iNtellect Cranial Navigation (version 1.1) platform were used for each operation. A computer-assisted navigation surgery was performed according to the following procedures: (1) image set, (2) planning, (3) apparatus setup, (4) registration, and (5) intraoperative navigation. Operations were performed under general anesthesia. Dissection was performed up to the periosteum immediately anterior to the optic canal, near the fracture. Vulnerable surrounding structures were identified with the intraoperative pointer. After navigation, we inserted an implant into the defect, successfully, avoiding damage to the optic canal and optic nerve.

RESULTS

None of the patients had any surgical complications. Postoperative computed tomography scans demonstrated that the fractures were corrected, and continuity was maintained without displacement. The three-dimensional image allowed us to easily visualize intraoperative anatomical structure, allowing us to avoid unnecessary procedures and to correct the orbital wall. The mean volume of fractured orbital cavity was 29.2 cm(3) (range, 28.3-30.4 cm(3)) preoperatively and 27.0 cm(3) (range, 25.9-28.5 cm(3)) postoperatively; thus, the defects were corrected by 2.2 cm(3) (range, 1.3-2.8 cm(3)) on average.

CONCLUSIONS

We used a navigation system to perform accurate and safe surgery in patients with extensive orbital wall fracture, including around the optic canal. By using the functions to visualize the locations indicated by the pointer, we were able to perform successful dissections and implantations in areas adjacent to the optic canal. The good outcomes obtained here provide evidence that surgical correction of the orbital wall using a navigation system is useful in cases of deep, extensive orbital wall fracture.

An advanced navigation protocol for endoscopic transsphenoidal surgery

OBJECTIVE

To report our clinical experience with an advanced navigation protocol that provides seamless integration into the operating workflow of endoscopic transsphenoidal surgery.

PATIENTS AND METHODS

From 32 consecutive cases of endoscopic transsphenoidal surgery, an optimal setup of continuous electromagnetic instrument navigation was created. Additionally, our standard multimodality image navigation of T1-weighted magnetic resonance (MR) images for soft tissue, MR angiogram for vascular structures, and computed tomography (CT) for solid bone was advanced by the addition of a CT surface rendering for fine paranasal sinus structures. The anatomic structures visualized and their clinical impacts were compared between standard and advanced visualization protocol. Bone-windowed CT images served as reference. The accuracy of the navigation setup was assessed by intraoperative landmark tests. Potential tissue shift was calculated by comparing pre- and postoperative MR angiograms of 20 macroadenomas.

RESULTS

After a learning curve of 2 cases (1 ferromagnetic interference and 1 dislocation of the patient reference tracker), the advanced navigation protocol was feasible in 30 cases. Advanced multimodality imaging was able to visualize significantly finer paranasal sinus structures than multimodality image navigation without CT surface rendering, equal to bone-windowed CT images (P < 0.001, McNemar test). This was found helpful for orientation in cases of complex sphenoid sinus anatomy. The accuracy of the advanced navigation setup corresponded to standard optic navigation with skull fixation. A tissue shift of median 2 mm (range 0-9 mm) was observed in the posterior genu of the internal carotid arteries after tumor resection.

CONCLUSIONS

The advanced navigation protocol permits continuous suction-tracked navigation guidance during endoscopic transsphenoidal surgery and optimal visualization of solid bone, fine paranasal sinus structures, soft-tissue and vascular structures. This may add to the safety of the procedure especially in cases of anatomical variations and in cases of recurrent adenomas with distorted anatomy.

Neck tumor dissection improved with 3-dimensional ultrasound image guidance: technical case report

BACKGROUND AND IMPORTANCE

Three-dimensional ultrasound navigation has been performed to assist in resection of cranial and spinal tumors, but to the best of our knowledge, no one has described the use of real-time 3-dimensional ultrasound navigation in the resection of neck tumors beyond biopsy.

CLINICAL PRESENTATION

This case report describes the use of 3-dimensional ultrasonic navigation in assisting with resection of a large neck paraganglioma. The 3-dimensional ultrasonic navigation improved real-time visualization of the carotid arteries, the trachea, and other vital structures.

CONCLUSION

The use of 3-dimensional ultrasound navigation should be considered in aiding resection of large neck tumors because it can allow more efficient and safer tumor resection.

The silent loss of neuronavigation accuracy: a systematic retrospective analysis of factors influencing the mismatch of frameless stereotactic systems in cranial neurosurgery

BACKGROUND

Neuronavigation has become an intrinsic part of preoperative surgical planning and surgical procedures. However, many surgeons have the impression that accuracy decreases during surgery.

OBJECTIVE

To quantify the decrease of neuronavigation accuracy and identify possible origins, we performed a retrospective quality-control study.

METHODS

Between April and July 2011, a neuronavigation system was used in conjunction with a specially prepared head holder in 55 consecutive patients. Two different neuronavigation systems were investigated separately. Coregistration was performed with laser-surface matching, paired-point matching using skin fiducials, anatomic landmarks, or bone screws. The initial target registration error (TRE1) was measured using the nasion as the anatomic landmark. Then, after draping and during surgery, the accuracy was checked at predefined procedural landmark steps (Mayfield measurement point and bone measurement point), and deviations were recorded.

RESULTS

After initial coregistration, the mean (SD) TRE1 was 2.9 (3.3) mm. The TRE1 was significantly dependent on patient positioning, lesion localization, type of neuroimaging, and coregistration method. The following procedures decreased neuronavigation accuracy: attachment of surgical drapes (DTRE2 = 2.7 [1.7] mm), skin retractor attachment (DTRE3 = 1.2 [1.0] mm), craniotomy (DTRE3 = 1.0 [1.4] mm), and Halo ring installation (DTRE3 = 0.5 [0.5] mm). Surgery duration was a significant factor also; the overall DTRE was 1.3 [1.5] mm after 30 minutes and increased to 4.4 [1.8] mm after 5.5 hours of surgery.

CONCLUSION

After registration, there is an ongoing loss of neuronavigation accuracy. The major factors were draping, attachment of skin retractors, and duration of surgery. Surgeons should be aware of this silent loss of accuracy when using neuronavigation.

Synchronized 2D/3D optical mapping for interactive exploration and real-time visualization of multi-function neurological images

Efficient software with the ability to display multiple neurological image datasets simultaneously with full real-time interactivity is critical for brain disease diagnosis and image-guided planning. In this paper, we describe the creation and function of a new comprehensive software platform that integrates novel algorithms and functions for multiple medical image visualization, processing, and manipulation. We implement an opacity-adjustment algorithm to build 2D lookup tables for multiple slice image display and fusion, which achieves a better visual result than those of using VTK-based methods. We also develop a new real-time 2D and 3D data synchronization scheme for multi-function MR volume and slice image optical mapping and rendering simultaneously through using the same adjustment operation. All these methodologies are integrated into our software framework to provide users with an efficient tool for flexibly, intuitively, and rapidly exploring and analyzing the functional and anatomical MR neurological data. Finally, we validate our new techniques and software platform with visual analysis and task-specific user studies.

Navigation in surgery

INTRODUCTION

"Navigation in surgery" spans a broad area, which, depending on the clinical challenge, can have different meanings. Over the past decade, navigation in surgery has evolved beyond imaging modalities and bulky systems into the rich networking of the cloud or devices that are pocket-sized.

DISCUSSION

This article will review various aspects of navigation in the operating room and beyond. This includes a short history of navigation, the evolution of surgical navigation, as well as technical aspects and clinical benefits with examples from neurosurgery, spinal surgery, and orthopedics.

CONCLUSION

With improved computer technology and a trend towards advanced information processing within hospitals, navigation is quickly becoming an integral part in the surgical routine of clinicians.

Clinical use of a neuronavigation system in hemangioblastoma resection of posterior cranial fossa

The aim of this study was to retrospectively evaluate the effectiveness of the Stryker Leibinger neuronavigation system in surgical resection of hemangioblastomas of the posterior fossa. The study included 16 cases of solid hemangioblastoma of posterior cranial fossa treated since we began using Stryker Leibinger neuronavigation system-assisted microneurosurgery in 2003. These cases were compared on the basis of time, blood loss, and complications to 19 similar cases of solid hemangioblastoma that underwent conventional microneurosurgical resection prior to 2003. All patients in the experimental (neuronavigation-assisted) group underwent surgical resection without complications while the control groups' resections all involved blood loss related to the longer operation time. Neuronavigation also resulted in a clear field of surgical vision and clear lesion boundaries, making it easier to remove lesions and reduce accidental injury of adjacent normal structures. The application of navigation technology is very valuable for solid hemangioblastoma operations not only by shortening operative time, thereby significantly reducing operative blood loss, but also by making surgical excision easier, reducing damage to adjacent normal structures, and decreasing surgical complications and mortality.

Neuronavigational neuroendoscopy--to be or not to be? An international pilot questionnaire-based study

OBJECTIVE

The almost age-old neuroendoscopy (NE) and neuronavigation (NN) in its twenties independently and indisputably have proved their high value as neurosurgical armamentarium and became even indispensable in some pathologies. However, nowadays the effectiveness of their simultaneous and combined application still is a matter of debate. The purpose of our pilot international, questionnaire-based survey was to assess the position of the opinion leaders in the field of neuroendoscopy worldwide toward the neuronavigational neuroendoscopy (NNNE).

METHODS

Within 3 months, a questionnaire with 17 questions was emailed repeatedly to 55 leading academic neuroendoscopic neurosurgeons from 50 institutions in 24 countries. The questionnaire covered aspects of personal and institutional experience in NE, NN, and NNNE, the most frequently treated pathologies by NNNE as well as inquiring the neurosurgeons' opinion for the importance and future of NNNE.

RESULTS

Forty-one questionnaires were returned (response rate = 74.6%). Six questionnaires were excluded because of incomplete or incorrect answers, leaving in the survey 35 respondents from 35 institutions in 18 countries. The less experienced neurosurgeons rely in higher degree on NNNE. Most frequently, NNNE is performed for hydrocephalus (procedures other than third ventriculostomy), transsphenoidal surgery, tumor biopsy, and cyst fenestration. Regardless their neurosurgical and NE experience, more than 75% of the respondents state that NNNE extends the range of neuroendoscopic procedures in their neurosurgical departments.

CONCLUSION

NNNE represents a valuable operative technique with excellent future prospects. NNNE extends the range of neuroendoscopic procedures, transforming some number of patients from "nonoperable" neuroendoscopically to suitable for neuroendoscopy.

The microsurgical treatment of cranio-orbital tumors assisted by intraoperative electrophysiologic monitoring and neuronavigation

OBJECTIVE

Total resection of cranio-orbital tumors without any major complications is still a challenge for neurosurgeons. Intraoperative electrophysiologic monitoring and neuronavigational system have been widely used in microneurosurgery, but their effects during microsurgical treatment of cranio-orbital tumors warrant further investigation.

METHODS

Thirty-eight patients with cranio-orbital tumors admitted to our hospital underwent microsurgery assisted by intraoperative electrophysiologic monitoring. We also simultaneously performed intraoperative neuronavigation in 20 patients. A retrospective review of clinical notes, operation records and prognoses of all patients was performed.

RESULTS

Gross total resection was achieved in 29 patients (76%), near total resection in 5 (13%), subtotal resection in 3 (8%) and partial resection in 1 (3%). With the helps of electromyogram (EMG) monitoring of levator palpebrae superioris (LPS) muscle and navigation system, no surgical damages to the oculomotor nerve and other important structures occurred. A follow-up study showed that 31 patients (82%) resumed normal lives (Glasgow Outcome Scale (GOS) score 5), 5 patients (13%) had independent lives (GOS score 4), and 2 patients (5%) were unable to live independently (GOS score 3).

CONCLUSION

Microsurgical treatment assisted by intraoperative electrophysiologic monitoring and neuronavigation might be a useful method for resection of cranio-orbital tumors, especially better for protection of the important cranial nerve and structure in the kull base.