Enhancing Reality: A Systematic Review of Augmented Reality in Neuronavigation and Education

Evolution of the meta-neurosurgeon: A systematic review of the current technical capabilities, limitations, and applications of augmented reality in neurosurgery

Background

Augmented reality (AR) applications in neurosurgery have expanded over the past decade with the introduction of headset-based platforms. Many studies have focused on either preoperative planning to tailor the approach to the patient's anatomy and pathology or intraoperative surgical navigation, primarily realized as AR navigation through microscope oculars. Additional efforts have been made to validate AR in trainee and patient education and to investigate novel surgical approaches. Our objective was to provide a systematic overview of AR in neurosurgery, provide current limitations of this technology, as well as highlight several applications of AR in neurosurgery.

Methods

We performed a literature search in PubMed/Medline to identify papers that addressed the use of AR in neurosurgery. The authors screened three hundred and seventy-five papers, and 57 papers were selected, analyzed, and included in this systematic review.

Results

AR has made significant inroads in neurosurgery, particularly in neuronavigation. In spinal neurosurgery, this primarily has been used for pedicle screw placement. AR-based neuronavigation also has significant applications in cranial neurosurgery, including neurovascular, neurosurgical oncology, and skull base neurosurgery. Other potential applications include operating room streamlining, trainee and patient education, and telecommunications.

Conclusion

AR has already made a significant impact in neurosurgery in the above domains and has the potential to be a paradigm-altering technology. Future development in AR should focus on both validating these applications and extending the role of AR.

Single-Center Experience of Resection of 120 Cases of Intradural Spinal Tumors

BACKGROUND

Our study presents a single-center experience of resection of intradural spinal tumors either with or without using intraoperative computed tomography-based registration and microscope-based augmented reality (AR). Microscope-based AR was recently described for improved orientation in the operative field in spine surgery, using superimposed images of segmented structures of interest in a two-dimensional or three-dimensional mode.

METHODS

All patients who underwent surgery for resection of intradural spinal tumors at our department were retrospectively included in the study. Clinical outcomes in terms of postoperative neurologic deficits and complications were evaluated, as well as neuroradiologic outcomes for tumor remnants and recurrence.

RESULTS

112 patients (57 female, 55 male; median age 55.8 ± 17.8 years) who underwent 120 surgeries for resection of intradural spinal tumors with the use of intraoperative neuromonitoring were included in the study, with a median follow-up of 39 ± 34.4 months. Nine patients died during the follow-up for reasons unrelated to surgery. The most common tumors were meningioma (n = 41), schwannoma (n = 37), myopapillary ependymomas (n = 12), ependymomas (n = 10), and others (20). Tumors were in the thoracic spine (n = 46), lumbar spine (n = 39), cervical spine (n = 32), lumbosacral spine (n = 1), thoracic and lumbar spine (n = 1), and 1 tumor in the cervical, thoracic, and lumbar spine. Four biopsies were performed, 10 partial resections, 13 subtotal resections, and 93 gross total resections. Laminectomy was the common approach. In 79 cases, patients experienced neurologic deficits before surgery, with ataxia and paraparesis as the most common ones. After surgery, 67 patients were unchanged, 49 improved and 4 worsened. Operative time, extent of resection, clinical outcome, and complication rate did not differ between the AR and non-AR groups. However, the use of AR improved orientation in the operative field by identification of important neurovascular structures.

CONCLUSIONS

High rates of gross total resection with favorable neurologic outcomes in most patients as well as low recurrence rates with comparable complication rates were noted in our single-center experience. AR improved intraoperative orientation and increased surgeons' comfort by enabling early identification of important anatomic structures; however, clinical and radiologic outcomes did not differ, when AR was not used.

Mixed Reality-Based Navigation for Pedicle Screw Placement: A Preliminary Study Using a 3D-Printed Spine Model

Background and objectives Mixed reality (MR) is one of the image processing technologies that allows the user to manipulate three-dimensional (3D) virtual images (hologram). The aim of this study was to evaluate the accuracy of MR-based pedicle screw (PS) placement using 3D spine models. Materials and methods Using the preoperative CT data of a patient with adolescent idiopathic scoliosis (AIS) who had undergone posterior spinal fusion in our hospital, a 3D-printed spine model was created. On the other hand, a 3D hologram of the same patient was automatically created using the preoperative CT data uploaded to the Holoeyes MD service website (Holoeyes Inc., Tokyo, Japan). Using a Magic Leap One® headset (Magic Leap Inc., Plantation, FL), the 3D hologram with lines of predetermined PS trajectories was superimposed onto the 3D-printed spine model and PS were inserted bilaterally along with the trajectory lines from T5 to L3. As a control, we used a readymade 3D spine model of AIS and inserted PS bilaterally with a freehand technique from T4 to L3. The rate of pedicle violation was compared between the MR-based and freehand techniques. Results A total of 22 and 24 PS were placed into the 3D-printed spine model of our patient and the readymade 3D spine model, respectively. The rate of pedicle violation was 4.5% (1/22 screws) in the MR-based technique and 29.2% (7/24 screws) in the freehand technique (P = 0.049). Conclusions We demonstrated a significantly lower rate of PS misplacement in the MR-based technique than in the freehand technique. Therefore, an MR-assisted system is a promising tool for PS placement in terms of feasibility, safety, and accuracy, warranting further studies including cadaveric and clinical studies.

Augmented Reality and Virtual Reality in Spine Surgery: A Comprehensive Review

Augmented reality (AR) and virtual reality (VR) are powerful technologies with proven utility and tremendous potential. Spine surgery, in particular, may benefit from these developing technologies for resident training, preoperative education for patients, surgical planning and execution, and patient rehabilitation. In this review, the history, current applications, challenges, and future of AR/VR in spine surgery are examined.

Augmented Reality Integration in Skull Base Neurosurgery: A Systematic Review

Background and Objectives: To investigate the role of augmented reality (AR) in skull base (SB) neurosurgery. Materials and Methods: Utilizing PRISMA methodology, PubMed and Scopus databases were explored to extract data related to AR integration in SB surgery. Results: The majority of 19 included studies (42.1%) were conducted in the United States, with a focus on the last five years (77.8%). Categorization included phantom skull models (31.2%, n = 6), human cadavers (15.8%, n = 3), or human patients (52.6%, n = 10). Microscopic surgery was the predominant modality in 10 studies (52.6%). Of the 19 studies, surgical modality was specified in 18, with microscopic surgery being predominant (52.6%). Most studies used only CT as the data source (n = 9; 47.4%), and optical tracking was the prevalent tracking modality (n = 9; 47.3%). The Target Registration Error (TRE) spanned from 0.55 to 10.62 mm. Conclusion: Despite variations in Target Registration Error (TRE) values, the studies highlighted successful outcomes and minimal complications. Challenges, such as device practicality and data security, were acknowledged, but the application of low-cost AR devices suggests broader feasibility.

Virtual, Augmented, and Mixed Reality Applications for Surgical Rehearsal, Operative Execution, and Patient Education in Spine Surgery: A Scoping Review

Background and Objectives: Advances in virtual reality (VR), augmented reality (AR), and mixed reality (MR) technologies have resulted in their increased application across many medical specialties. VR's main application has been for teaching and preparatory roles, while AR has been mostly used as a surgical adjunct. The objective of this study is to discuss the various applications and prospects for VR, AR, and MR specifically as they relate to spine surgery. Materials and Methods: A systematic review was conducted to examine the current applications of VR, AR, and MR with a focus on spine surgery. A literature search of two electronic databases (PubMed and Scopus) was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The study quality was assessed using the MERSQI score for educational research studies, QUACS for cadaveric studies, and the JBI critical appraisal tools for clinical studies. Results: A total of 228 articles were identified in the primary literature review. Following title/abstract screening and full-text review, 46 articles were included in the review. These articles comprised nine studies performed in artificial models, nine cadaveric studies, four clinical case studies, nineteen clinical case series, one clinical case-control study, and four clinical parallel control studies. Teaching applications utilizing holographic overlays are the most intensively studied aspect of AR/VR; the most simulated surgical procedure is pedicle screw placement. Conclusions: VR provides a reproducible and robust medium for surgical training through surgical simulations and for patient education through various platforms. Existing AR/MR platforms enhance the accuracy and precision of spine surgeries and show promise as a surgical adjunct.

Validation of real-time inside-out tracking and depth realization technologies for augmented reality-based neuronavigation

PURPOSE

Concomitant with the significant advances in computing technology, the utilization of augmented reality-based navigation in clinical applications is being actively researched. In this light, we developed novel object tracking and depth realization technologies to apply augmented reality-based neuronavigation to brain surgery.

METHODS

We developed real-time inside-out tracking based on visual inertial odometry and a visual inertial simultaneous localization and mapping algorithm. The cube quick response marker and depth data obtained from light detection and ranging sensors are used for continuous tracking. For depth realization, order-independent transparency, clipping, and annotation and measurement functions were developed. In this study, the augmented reality model of a brain tumor patient was applied to its life-size three-dimensional (3D) printed model.

RESULTS

Using real-time inside-out tracking, we confirmed that the augmented reality model remained consistent with the 3D printed patient model without flutter, regardless of the movement of the visualization device. The coordination accuracy during real-time inside-out tracking was also validated. The average movement error of the X and Y axes was 0.34 ± 0.21 and 0.04 ± 0.08 mm, respectively. Further, the application of order-independent transparency with multilayer alpha blending and filtered alpha compositing improved the perception of overlapping internal brain structures. Clipping, and annotation and measurement functions were also developed to aid depth perception and worked perfectly during real-time coordination. We named this system METAMEDIP navigation.

CONCLUSIONS

The results validate the efficacy of the real-time inside-out tracking and depth realization technology. With these novel technologies developed for continuous tracking and depth perception in augmented reality environments, we are able to overcome the critical obstacles in the development of clinically applicable augmented reality neuronavigation.

The Role of Augmented Reality Neuronavigation in Transsphenoidal Surgery: A Systematic Review

In the field of minimally invasive neurosurgery, microscopic transsphenoidal surgery (MTS) and endoscopic transsphenoidal surgery (ETS) have been widely accepted as a safe approach for pituitary lesions and, more recently, their indications have been extended to lesions at various skull base regions. It is mandatory during transsphenoidal surgery (TS) to identify key anatomical landmarks in the sphenoid sinus and distinguish them from the lesion. Over the years, many intraoperative tools have been introduced to improve the neuronavigation systems aiming to achieve safer and more accurate neurosurgical interventions. However, traditional neuronavigation systems may lose the accuracy of real-time location due to the discrepancy between the actual surgical field and the preoperative 2D images. To deal with this, augmented reality (AR)-a new sophisticated 3D technology that superimposes computer-generated virtual objects onto the user's view of the real world-has been considered a promising tool. Particularly, in the field of TS, AR can minimize the anatomic challenges of traditional endoscopic or microscopic surgery, aiding in surgical training, preoperative planning and intra-operative orientation. The aim of this systematic review is to analyze the potential future role of augmented reality, both in endoscopic and microscopic transsphenoidal surgeries.

Application of Glasses-Free Augmented Reality Localization in Neurosurgery

OBJECTIVE

The accurate localization of intracranial lesions is critical in neurosurgery. Most surgeons locate the vast majority of neurosurgical sites through skull surface markers, combined with neuroimaging examination and marking lines. This project's primary purpose was to develop an augmented reality (AR) technology or tool that can be used for surgical positioning using the naked eye.

METHODS

Brain models were predesigned with intracranial lesions using computerized tomography scan, and Digital Imaging and Communications in Medicine data were segmented and modeled by 3D slicer software. The processed data were imported into a smartphone 3D viewing software application (Persp 3D) and were used by a Remebot surgical robot. The localization of intracranial lesions was performed, and the AR localization error was calculated compared with standard robot localization.

RESULTS

After mastering the AR localization registration method, surgeons achieved an average localization error of 1.39 ± 0.82 mm.

CONCLUSIONS

The error of AR positioning technology in surgical simulation tests based on brain modeling was millimeter level, which has verified the feasibility of clinical application. More efficient registration remains a need that should be addressed.

Structural networking of the developing brain: from maturation to neurosurgical implications

Modern neuroscience agrees that neurological processing emerges from the multimodal interaction among multiple cortical and subcortical neuronal hubs, connected at short and long distance by white matter, to form a largely integrated and dynamic network, called the brain "connectome." The final architecture of these circuits results from a complex, continuous, and highly protracted development process of several axonal pathways that constitute the anatomical substrate of neuronal interactions. Awareness of the network organization of the central nervous system is crucial not only to understand the basis of children's neurological development, but also it may be of special interest to improve the quality of neurosurgical treatments of many pediatric diseases. Although there are a flourishing number of neuroimaging studies of the connectome, a comprehensive vision linking this research to neurosurgical practice is still lacking in the current pediatric literature. The goal of this review is to contribute to bridging this gap. In the first part, we summarize the main current knowledge concerning brain network maturation and its involvement in different aspects of normal neurocognitive development as well as in the pathophysiology of specific diseases. The final section is devoted to identifying possible implications of this knowledge in the neurosurgical field, especially in epilepsy and tumor surgery, and to discuss promising perspectives for future investigations.

Augmented reality for intracranial meningioma resection: a mini-review

Augmented reality (AR) integrates computer-generated content and real-world scenarios. Artificial intelligence's continuous development has allowed AR to be integrated into medicine. Neurosurgery has progressively introduced image-guided technologies. Integration of AR into the operating room has permitted a new perception of neurosurgical diseases, not only for neurosurgical planning, patient positioning, and incision design but also for intraoperative maneuvering and identification of critical neurovascular structures and tumor boundaries. Implementing AR, virtual reality, and mixed reality has introduced neurosurgeons into a new era of artificial interfaces. Meningiomas are the most frequent primary benign tumors commonly related to paramount neurovascular structures and bone landmarks. Integration of preoperative 3D reconstructions used for surgical planning into AR can now be inserted into the microsurgical field, injecting information into head-up displays and microscopes with integrated head-up displays, aiming to guide neurosurgeons intraoperatively to prevent potential injuries. This manuscript aims to provide a mini-review of the usage of AR for intracranial meningioma resection.

Technical evolution of pediatric neurosurgery: the evolution of intraoperative imaging

Imaging has always been fundamental to neurosurgery, and its evolution over the last century has made a dramatic transformation in the ability of neurosurgeons to define pathology and preserve normal tissue during their operations. In the mid-70 s, the development of computerized cross-sectional imaging with CT scan and subsequently MRI have revolutionized the practice of neurosurgery. Later, further advances in computer technology and medical engineering have allowed the combination of many modalities to bring them into the operating theater. This evolution has allowed real-time intraoperative imaging, in the hope of helping neurosurgeons achieve accuracy, maximal safe resection, and the implementation of minimally invasive techniques in brain and spine pathologies. Augmented reality and robotic technologies are also being applied as useful intra-operative techniques that will improve surgical planning and outcomes in the future. In this article, we will review imaging modalities and provide our institutional perspective on how we have integrated them into our practice.

Mixed Reality as a Teaching Tool for Medical Students in Neurosurgery

Background and Objectives: Simulation-based learning within neurosurgery provides valuable and realistic educational experiences in a safe environment, enhancing the current teaching model. Mixed reality (MR) simulation can deliver a highly immersive experience through head-mounted displays and has become one of the most promising teaching tools in medical education. We aimed to identify whether an MR neurosurgical simulation module within the setting of an undergraduate neurosurgical hands-on course could improve the satisfaction of medical students. Materials and Methods: The quasi-experimental study with 223 medical students [120 in the conventional group (CG) and 103 in the MR-group (MRG)] was conducted at the University Hospital Münster, Münster, Germany. An MR simulation module was presented to the intervention group during an undergraduate neurosurgical hands-on course. Images of a skull fracture were reconstructed into 3D formats compatible with the MR-Viewer (Brainlab, Munich, Germany). Participants could interact virtually with the model and plan a surgical strategy using Magic Leap goggles. The experience was assessed by rating the course on a visual analog scale ranging from 1 (very poor) to 100 (very good) and an additional Likert-scale questionnaire. Results: The satisfaction score for CG and MRG were 89.3 ± 13.3 and 94.2 ± 7.5, respectively. The Wilcoxon rank-sum test showed that MR users (Mdn = 97.0, IQR = 4, n = 103) were significantly more satisfied than CG users (Mdn = 93.0, IQR = 10, n = 120; ln(W) = 8.99, p < 0.001) with moderate effect size (r^biserial = 0.30, CI95 [0.15, 0.43]), thus indicating that the utilization of MR-simulation is associated with greater satisfaction. Conclusions: This study reports a positive response from medical students towards MR as an educational tool. Feedback from the medical students encourages the adoption of disruptive technologies into medical school curricula.

Intra-operative applications of augmented reality in glioma surgery: a systematic review

Background

Augmented reality (AR) is increasingly being explored in neurosurgical practice. By visualizing patient-specific, three-dimensional (3D) models in real time, surgeons can improve their spatial understanding of complex anatomy and pathology, thereby optimizing intra-operative navigation, localization, and resection. Here, we aimed to capture applications of AR in glioma surgery, their current status and future potential.

Methods

A systematic review of the literature was conducted. This adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline. PubMed, Embase, and Scopus electronic databases were queried from inception to October 10, 2022. Leveraging the Population, Intervention, Comparison, Outcomes, and Study design (PICOS) framework, study eligibility was evaluated in the qualitative synthesis. Data regarding AR workflow, surgical application, and associated outcomes were then extracted. The quality of evidence was additionally examined, using hierarchical classes of evidence in neurosurgery.

Results

The search returned 77 articles. Forty were subject to title and abstract screening, while 25 proceeded to full text screening. Of these, 22 articles met eligibility criteria and were included in the final review. During abstraction, studies were classified as "development" or "intervention" based on primary aims. Overall, AR was qualitatively advantageous, due to enhanced visualization of gliomas and critical structures, frequently aiding in maximal safe resection. Non-rigid applications were also useful in disclosing and compensating for intra-operative brain shift. Irrespective, there was high variance in registration methods and measurements, which considerably impacted projection accuracy. Most studies were of low-level evidence, yielding heterogeneous results.

Conclusions

AR has increasing potential for glioma surgery, with capacity to positively influence the onco-functional balance. However, technical and design limitations are readily apparent. The field must consider the importance of consistency and replicability, as well as the level of evidence, to effectively converge on standard approaches that maximize patient benefit.

Using virtual lines of navigation for a successful transcortical approach

Background

Neuronavigation systems have become essential tools in image-guided neurosurgery that aid in the accurate resection of brain tumors. Recent advancements to these devices can indicate the precise location of lesions but can also project an augmented reality (AR) image on the microscope eyepiece to facilitate a successful surgical operation. Although the transcortical approach is a very popular method in neurosurgery, it can lead to disorientation and can cause unnecessary brain damage when the distance from the brain surface to the lesion is long. Herein, we report on an actual case in which a virtual line from AR images was used to assist the transcortical approach.

Methods

A virtual line connecting the entry point and the target point, which were set as the navigation route, was created using Stealth station S7^® (Medtronic, Minneapolis, USA). This line was projected as an AR image on the microscope eyepiece. It was possible to reach the target point by proceeding through the white matter along the displayed virtual line.

Results

The lesion was reached within a short duration using virtual line without disorientation.

Conclusion

Setting a virtual line as an AR image using neuronavigation is a simple and accurate method that can effectively support the conventional transcortical approach.

Improved Accuracy and Lowered Learning Curve of Ventricular Targeting Using Augmented Reality-Phantom and Cadaveric Model Testing

BACKGROUND

Augmented reality (AR) has demonstrated significant potential in neurosurgical cranial, spine, and teaching applications. External ventricular drain (EVD) placement remains a common procedure, but with error rates in targeting between 10% and 40%.

OBJECTIVE

To evaluate Novarad VisAR guidance system for the placement of EVDs in phantom and cadaveric models.

METHODS

Two synthetic ventricular phantom models and a third cadaver model underwent computerized tomography imaging and registration with the VisAR system (Novarad). Root mean square (RMS), angular error (γ), and Euclidian distance were measured by multiple methods for various standard EVD placements.

RESULTS

Computerized tomography measurements on a phantom model (0.5-mm targets showed a mean Euclidean distance error of 1.20 ± 0.98 mm and γ of 1.25° ± 1.02°. Eight participants placed EVDs in lateral and occipital burr holes using VisAR in a second phantom anatomic ventricular model (mean RMS: 3.9 ± 1.8 mm, γ: 3.95° ± 1.78°). There were no statistically significant differences in accuracy for postgraduate year level, prior AR experience, prior EVD experience, or experience with video games ( P > .05). In comparing EVDs placed with anatomic landmarks vs VisAR navigation in a cadaver, VisAR demonstrated significantly better RMS and γ, 7.47 ± 0.94 mm and 7.12° ± 0.97°, respectively ( P ≤ .05).

CONCLUSION

The novel VisAR AR system resulted in accurate placement of EVDs with a rapid learning curve, which may improve clinical treatment and patient safety. Future applications of VisAR can be expanded to other cranial procedures.

Magic Leap 1 versus Microsoft HoloLens 2 for the Visualization of 3D Content Obtained from Radiological Images

The adoption of extended reality solutions is growing rapidly in the healthcare world. Augmented reality (AR) and virtual reality (VR) interfaces can bring advantages in various medical-health sectors; it is thus not surprising that the medical MR market is among the fastest-growing ones. The present study reports on a comparison between two of the most popular MR head-mounted displays, Magic Leap 1 and Microsoft HoloLens 2, for the visualization of 3D medical imaging data. We evaluate the functionalities and performance of both devices through a user-study in which surgeons and residents assessed the visualization of 3D computer-generated anatomical models. The digital content is obtained through a dedicated medical imaging suite (Verima imaging suite) developed by the Italian start-up company (Witapp s.r.l.). According to our performance analysis in terms of frame rate, there are no significant differences between the two devices. The surgical staff expressed a clear preference for Magic Leap 1, particularly for the better visualization quality and the ease of interaction with the 3D virtual content. Nonetheless, even though the results of the questionnaire were slightly more positive for Magic Leap 1, the spatial understanding of the 3D anatomical model in terms of depth relations and spatial arrangement was positively evaluated for both devices.

Head-Mounted Augmented Reality in the Planning of Cerebrovascular Neurosurgical Procedures: A Single-Center Initial Experience

BACKGROUND

Augmented reality (AR) technology has played an increasing role in cerebrovascular neurosurgery over the last 2 decades. Hence, we aim to evaluate the technical and educational value of head-mounted AR in cerebrovascular procedures.

METHODS

This is a single-center retrospective study of patients who underwent open surgery for cranial and spinal cerebrovascular lesions between April and August 2022. In all cases, the Medivis Surgical AR platform and HoloLens 2 were used for preoperative and intraoperative (preincision) planning. Surgical plan adjustment due to the use of head-mounted AR and subjective educational value of the tool were recorded.

RESULTS

A total of 33 patients and 35 cerebrovascular neurosurgical procedures were analyzed. Procedures included 12 intracranial aneurysm clippings, 6 brain and 1 spinal arteriovenous malformation resections, 2 cranial dural arteriovenous fistula obliterations, 3 carotid endarterectomies, two extracranial-intracranial direct bypasses, two encephaloduroangiosynostosis for Moyamoya disease, 1 biopsy of the superficial temporal artery, 2 microvascular decompressions, 2 cavernoma resections, 1 combined intracranial aneurysm clipping and encephaloduroangiosynostosis for Moyamoya disease, and 1 percutaneous feeder catheterization for arteriovenous malformation embolization. Minor changes in the surgical plan were recorded in 16 of 35 procedures (45.7%). Subjective educational value was scored as "very helpful" for cranial, spinal arteriovenous malformations, and carotid endarterectomies; "helpful" for intracranial aneurysm, dural arteriovenous fistulas, direct bypass, encephaloduroangiosynostosis, and superficial temporal artery-biopsy; and "not helpful" for cavernoma resection and microvascular decompression.

CONCLUSIONS

Head-mounted AR can be used in cerebrovascular neurosurgery as an adjunctive tool that might influence surgical strategy, enable 3-dimensional understanding of complex anatomy, and provide great educational value in selected cases.

Positioning Transclival Tumor-Treating Fields for the Treatment of Diffuse Intrinsic Pontine Gliomas

Diffuse intrinsic pontine glioma (DIPG) carries an extremely poor prognosis, with 2-year survival rates of <10% despite the maximal radiation therapy. DIPG cells have previously been shown to be sensitive to low-intensity electric fields in vitro. Accordingly, we sought to determine if the endoscopic endonasal (EE) implantation of an electrode array in the clivus would be feasible for the application of tumor-treating fields (TTF) in DIPG. Anatomic constraints are the main limitation in pediatric EE approaches. In our Boston Children’s Hospital’s DIPG cohort, we measured the average intercarotid distance (1.68 ± 0.36 cm), clival width (1.62 ± 0.19 cm), and clival length from the base of the sella (1.43 ± 0.69 cm). Using a linear regression model, we found that only clival length and sphenoid pneumatization were significantly associated with age (R2 = 0.568, p = 0.005 *; R2 = 0.605, p = 0.0002 *). Critically, neither of these parameters represent limitations to the implantation of a device within the dimensions of those currently available. Our findings confirm that the anatomy present within this age group is amenable to the placement of a 2 × 1 cm electrode array in 94% of patients examined. Our work serves to demonstrate the feasibility of implantable transclival devices for the provision of TTFs as a novel adjunctive therapy for DIPG.

Use of Mixed Reality in Neuro-Oncology: A Single Centre Experience

(1) Background: Intra-operative neuronavigation is currently an essential component to most neurosurgical operations. Recent progress in mixed reality (MR) technology has attempted to overcome the disadvantages of the neuronavigation systems. We present our experience using the HoloLens 2 in neuro-oncology for both intra- and extra-axial tumours. (2) Results: We describe our experience with three patients who underwent tumour resection. We evaluated surgeon experience, accuracy of superimposed 3D image in tumour localisation with standard neuronavigation both pre- and intra-operatively. Surgeon training and usage for HoloLens 2 was short and easy. The process of image overlay was relatively straightforward for the three cases. Registration in prone position with a conventional neuronavigation system is often difficult, which was easily overcome during use of HoloLens 2. (3) Conclusion: Although certain limitations were identified, the authors feel that this system is a feasible alternative device for intra-operative visualization of neurosurgical pathology. Further studies are being planned to assess its accuracy and suitability across various surgical disciplines.

Development of a 3D Printed Brain Model with Vasculature for Neurosurgical Procedure Visualisation and Training

BACKGROUND

Simulation-based techniques using three-dimensional models are gaining popularity in neurosurgical training. Most pre-existing models are expensive, so we felt a need to develop a real-life model using 3D printing technology to train in endoscopic third ventriculostomy.

METHODS

The brain model was made using a 3D-printed resin mold from patient-specific MRI data. The mold was filled with silicone Ecoflex™ 00-10 and mixed with Silc Pig^® pigment additives to replicate the color and consistency of brain tissue. The dura mater was made from quick-drying silicone paste admixed with gray dye. The blood vessels were made from a silicone 3D-printed mold based on magnetic resonance imaging. Liquid containing paprika oleoresin dye was used to simulate blood and was pumped through the vessels to simulate pulsatile motion.

RESULTS

Seven residents and eight senior neurosurgeons were recruited to test our model. The participants reported that the size and anatomy of the elements were very similar to real structures. The model was helpful for training neuroendoscopic 3D perception and navigation.

CONCLUSIONS

We developed an endoscopic third ventriculostomy training model using 3D printing technology that provides anatomical precision and a realistic simulation. We hope our model can provide an indispensable tool for young neurosurgeons to gain operative experience without exposing patients to risk.

Augmented Reality in Stereotactic Neurosurgery: Current Status and Issues

Stereotactic neurosurgery is an established technique, but it has several limitations. In frame-based stereotaxy using a stereotactic frame, frame setting errors may decrease the accuracy of the procedure. Frameless stereotaxy using neuronavigation requires surgeons to shift their view from the surgical field to the navigation display and to advance the needle while assuming a physically uncomfortable position. To overcome these limitations, several researchers have applied augmented reality in stereotactic neurosurgery. Augmented reality enables surgeons to visualize the information regarding the target and preplanned trajectory superimposed over the actual surgical field. In frame-based stereotaxy, a researcher applies tablet computer-based augmented reality to check for the setting errors of the stereotactic frame, thereby improving the safety of the procedure. Several researchers have reported performing frameless stereotaxy guided by head-mounted-display-based augmented reality that enables surgeons to advance the needle at a more natural posture. These studies have shown that augmented reality can address the limitations of stereotactic neurosurgery. Conversely, they have also revealed the limited accuracy of current augmented reality systems for small targets, which indicates that further development of augmented reality systems is needed.

A Tool-free Neuronavigation Method based on Single-view Hand Tracking

This work presents a novel tool-free neuronavigation method that can be used with a single RGB commodity camera. Compared with freehand craniotomy placement methods, the proposed system is more intuitive and less error prone. The proposed method also has several advantages over standard neuronavigation platforms. First, it has a much lower cost, since it doesn't require the use of an optical tracking camera or electromagnetic field generator, which are typically the most expensive parts of a neuronavigation system, making it much more accessible. Second, it requires minimal setup, meaning that it can be performed at the bedside and in circumstances where using a standard neuronavigation system is impractical. Our system relies on machine-learning-based hand pose estimation that acts as a proxy for optical tool tracking, enabling a 3D-3D pre-operative to intra-operative registration. Qualitative assessment from clinical users showed that the concept is clinically relevant. Quantitative assessment showed that on average a target registration error (TRE) of 1.3cm can be achieved. Furthermore, the system is framework-agnostic, meaning that future improvements to hand-tracking frameworks would directly translate to a higher accuracy.

Augmented and virtual reality usage in awake craniotomy: a systematic review

Augmented and virtual reality (AR, VR) are becoming promising tools in neurosurgery. AR and VR can reduce challenges associated with conventional approaches via the simulation and mimicry of specific environments of choice for surgeons. Awake craniotomy (AC) enables the resection of lesions from eloquent brain areas while monitoring higher cortical and subcortical functions. Evidence suggests that both surgeons and patients benefit from the various applications of AR and VR in AC. This paper investigates the application of AR and VR in AC and assesses its prospective utility in neurosurgery. A systematic review of the literature was performed using PubMed, Scopus, and Web of Science databases in accordance with the PRISMA guidelines. Our search results yielded 220 articles. A total of six articles consisting of 118 patients have been included in this review. VR was used in four papers, and the other two used AR. Tumour was the most common pathology in 108 patients, followed by vascular lesions in eight patients. VR was used for intraoperative mapping of language, vision, and social cognition, while AR was incorporated in preoperative training of white matter dissection and intraoperative visualisation and navigation. Overall, patients and surgeons were satisfied with the applications of AR and VR in their cases. AR and VR can be safely incorporated during AC to supplement, augment, or even replace conventional approaches in neurosurgery. Future investigations are required to assess the feasibility of AR and VR in various phases of AC.

Attitudes Toward Neurosurgery Education for the Nonneurosurgeon: A Survey Study and Critical Analysis of U.S. Military Training Techniques and Future Prospects

BACKGROUND

The U.S. military requires medical readiness to support forward-deployed combat operations. Because time and distance to neurosurgical capabilities vary within the deployed trauma system, nonneurosurgeons are required to perform emergent cranial procedures in select cases. It is unclear whether these surgeons have sufficient training in these procedures.

METHODS

This quality-improvement study involved a voluntary, anonymized specialty-specific survey of active-duty surgeons about their experience and attitudes toward U.S. military emergency neurosurgical training.

RESULTS

Survey responses were received from 104 general surgeons and 26 neurosurgeons. Among general surgeons, 81% have deployed and 53% received training in emergency neurosurgical procedures before deployment. Only 16% of general surgeons reported participating in craniotomy/craniectomy procedures in the last year. Nine general surgeons reported performing an emergency neurosurgical procedure while on deployment/humanitarian mission, and 87% of respondents expressed interest in further predeployment emergency neurosurgery training. Among neurosurgeons, 81% had participated in training nonneurosurgeons and 73% believe that more comprehensive training for nonneurosurgeons before deployment is needed. General surgeons proposed lower procedure minimums for competency for external ventricular drain placement and craniotomy/craniectomy than did neurosurgeons. Only 37% of general surgeons had used mixed/augmented reality in any capacity previously; for combat procedures, most (90%) would prefer using synchronous supervision via high-fidelity video teleconferencing over mixed reality.

CONCLUSIONS

These survey results show a gap in readiness for neurosurgical procedures for forward-deployed general surgeons. Capitalizing on capabilities such as mixed/augmented reality would be a force multiplier and a potential means of improving neurosurgical capabilities in the forward-deployed environments.

Virtual Pedagogy in Neurosurgery During the COVID-19 Pandemic: Perspectives from University Hospital in Nepal

Objectives

Since the onset of the COVID-19 pandemic many large institutions have turned towards virtual education. Neurosurgery in our institute, recognizing its benefits, readily embraced the virtual learning experience using Zoom Inc (San Jose, California) beginning on May 21, 2020. The result of this form of educational experience may not be apparent readily. Hence, nearing the end of one year of monthly Zoom meetings, an effort was undertaken to assess the feasibility and the barriers of effective virtual teaching learning activity in neurosurgery among the participants.

Methods

The participants consisted of neurosurgeons and trainees from department of neurosurgery Tribhuvan University Teaching Hospital in Nepal, neurosurgeons based in Seattle, United States of America and neurosurgeons based in Sweden, who have been regularly attending the monthly virtual education organized by Dr. Wohns. At the end of one-year experience of monthly Zoom teaching and learning activities between the participants a questionnaire comprising objective questions related to their experience of virtual education in neurosurgery was distributed to the participants and answers were collected and analyzed.

Results

A total of 18 persons out of 25 responded to the questionnaire. Majority of participants responded favorably to virtual education. A few responders faced disturbance in internet connectivity affecting the quality of video and sound during the presentations. None of the participants faced inconvenience due to time difference. Most responders preferred to continue virtual education even after the pandemic.

Conclusions

Overall most participants responded favorably to virtual education which has helped them increase their participation and hence broaden their knowledge in the field. Most participants look forward to continuing this form of education even in future. Thus, this form of education may be incorporated at least in part in the future of neurosurgical training.

Microscope-Based Augmented Reality with Intraoperative Computed Tomography-Based Navigation for Resection of Skull Base Meningiomas in Consecutive Series of 39 Patients

Background: The aim of surgery for skull base meningiomas is maximal resection with minimal damage to the involved cranial nerves and cerebral vessels; thus, implementation of technologies for improved orientation in the surgical field, such as neuronavigation and augmented reality (AR), is of interest. Methods: Included in the study were 39 consecutive patients (13 male, 26 female, mean age 64.08 ± 13.5 years) who underwent surgery for skull base meningiomas using microscope-based AR and automatic patient registration using intraoperative computed tomography (iCT). Results: Most common were olfactory meningiomas (6), cavernous sinus (6) and clinoidal (6) meningiomas, meningiomas of the medial (5) and lateral (5) sphenoid wing and meningiomas of the sphenoidal plane (5), followed by suprasellar (4), falcine (1) and middle fossa (1) meningiomas. There were 26 patients (66.6%) who underwent gross total resection (GTR) of the meningioma. Automatic registration applying iCT resulted in high accuracy (target registration error, 0.82 ± 0.37 mm). The effective radiation dose of the registration iCT scans was 0.58 ± 1.05 mSv. AR facilitated orientation in the resection of skull base meningiomas with encasement of cerebral vessels and compression of the optic chiasm, as well as in reoperations, increasing surgeon comfort. No injuries to critical neurovascular structures occurred. Out of 35 patients who lived to follow-up, 33 could ambulate at their last presentation. Conclusion: A microscope-based AR facilitates surgical orientation for resection of skull base meningiomas. Registration accuracy is very high using automatic registration with intraoperative imaging.

Evaluation of an Augmented Reality Application for Learning Neuroanatomy in Psychology

Neuroanatomy is difficult for psychology students because of spatial visualization and the relationship among brain structures. Some technologies have been implemented to facilitate the learning of anatomy using three-dimensional (3D) visualization of anatomy contents. Augmented reality (AR) is a promising technology in this field. A mobile AR application to provide the visualization of morphological and functional information of the brain was developed. A sample of 67 students of neuropsychology completed tests for visuospatial ability, anatomical knowledge, learning goals, and experience with technologies. Subsequently, they performed a learning activity using one of the visualization methods considered: a 3D method using the AR application and a two-dimensional (2D) method using a textbook to color, followed by questions concerning their satisfaction and knowledge. After using the alternative method, the students expressed their preference. The two methods improved knowledge equally, but the 3D method obtained higher satisfaction scores and was more preferred by students. The 3D method was also more preferred by the students who used this method during the activity. After controlling for the method used in the activity, associations were found between the preference of the 3D method because of its usability and experience with technologies. These results found that the AR application was highly valued by students to learn and was as effective as the textbook for this purpose.

The use of augmented reality in transsphenoidal surgery: A systematic review

BACKGROUND

Augmented reality (AR) has become a promising tool in neurosurgery. It can minimise the anatomical challenges faced by conventional endoscopic or microscopic transsphenoidal reoperations and can assist in intraoperative guidance, preoperative planning, and surgical training.

OBJECTIVES

The aims of this systematic review are to describe, compare, and evaluate the use of AR in endoscopic and microscopic transsphenoidal surgery, incorporating the latest primary research.

METHODS

A systematic review was performed to explore and evaluate existing primary evidence for using AR in transsphenoidal surgery. A comprehensive search of MEDLINE and EMBASE was conducted from database inception to 11th August 2021 for primary data on the use of AR in microscopic and endoscopic endonasal skull base surgery. Additional articles were identified through searches on PubMed, Google Scholar, JSTOR, SCOPUS, Web of Science, Engineering Village, IEEE transactions, and HDAS. A synthesis without meta-analysis (SWiM) analysis was employed quantitatively and qualitatively on the impact of AR on landmark identification, intraoperative navigation, accuracy, time, surgeon experience, and patient outcomes.

RESULTS

In this systematic review, 17 studies were included in the final analysis. The main findings were that AR provides a convincing improvement to landmark identification, intraoperative navigation, and surgeon experience in transsphenoidal surgery, with a further positive effect on accuracy and time. It did not demonstrate a convincing positive effect on patient outcomes. No studies reported comparative mortalities, morbidities, or cost-benefit indications.

CONCLUSION

AR-guided transsphenoidal surgery, both endoscopic and microscopic, is associated with an overall improvement in the areas of intraoperative guidance and surgeon experience as compared with their conventional counterparts. However, literature on this area, particularly comparative data and evidence, is very limited. More studies with similar methodologies and quantitative outcomes are required to perform appropriate meta-analyses and to draw significant conclusions.

Real-time augmented reality application in presurgical planning and lesion scalp localization by a smartphone

OBJECTIVE

A smartphone augmented reality (AR) application (app) was explored for clinical use in presurgical planning and lesion scalp localization.

METHODS

We programmed an AR App on a smartphone. The accuracy of the AR app was tested on a 3D-printed head model, using the Euclidean distance of displacement of virtual objects. For clinical validation, 14 patients with brain tumors were included in the study. Preoperative MRI images were used to generate 3D models for AR contents. The 3D models were then transferred to the smartphone AR app. Tumor scalp localization was marked, and a surgical corridor was planned on the patient's head by viewing AR images on the smartphone screen. Standard neuronavigation was applied to evaluate the accuracy of the smartphone. Max-margin distance (MMD) and area overlap ratio (AOR) were measured to quantitatively validate the clinical accuracy of the smartphone AR technique.

RESULTS

In model validation, the total mean Euclidean distance of virtual object displacement using the smartphone AR app was 4.7 ± 2.3 mm. In clinical validation, the mean duration of AR app usage was 168.5 ± 73.9 s. The total mean MMD was 6.7 ± 3.7 mm, and total mean AOR was 79%.

CONCLUSIONS

The smartphone AR app provides a new way of experience to observe intracranial anatomy in situ, and it makes surgical planning more intuitive and efficient. Localization accuracy is satisfactory with lesions larger than 15 mm.

Augmented reality visualization in brain lesions: a prospective randomized controlled evaluation of its potential and current limitations in navigated microneurosurgery

Background

Augmented reality (AR) has the potential to support complex neurosurgical interventions by including visual information seamlessly. This study examines intraoperative visualization parameters and clinical impact of AR in brain tumor surgery.

Methods

Fifty-five intracranial lesions, operated either with AR-navigated microscope (n = 39) or conventional neuronavigation (n = 16) after randomization, have been included prospectively. Surgical resection time, duration/type/mode of AR, displayed objects (n, type), pointer-based navigation checks (n), usability of control, quality indicators, and overall surgical usefulness of AR have been assessed.

Results

AR display has been used in 44.4% of resection time. Predominant AR type was navigation view (75.7%), followed by target volumes (20.1%). Predominant AR mode was picture-in-picture (PiP) (72.5%), followed by 23.3% overlay display. In 43.6% of cases, vision of important anatomical structures has been partially or entirely blocked by AR information. A total of 7.7% of cases used MRI navigation only, 30.8% used one, 23.1% used two, and 38.5% used three or more object segmentations in AR navigation. A total of 66.7% of surgeons found AR visualization helpful in the individual surgical case. AR depth information and accuracy have been rated acceptable (median 3.0 vs. median 5.0 in conventional neuronavigation). The mean utilization of the navigation pointer was 2.6 × /resection hour (AR) vs. 9.7 × /resection hour (neuronavigation); navigation effort was significantly reduced in AR (P < 0.001).

Conclusions

The main benefit of HUD-based AR visualization in brain tumor surgery is the integrated continuous display allowing for pointer-less navigation. Navigation view (PiP) provides the highest usability while blocking the operative field less frequently. Visualization quality will benefit from improvements in registration accuracy and depth impression.

German clinical trials registration number.

DRKS00016955.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00701-021-05045-1.

Augmented Reality in Spinal Surgery: Highlights From Augmented Reality Lectures at the Emerging Technologies Annual Meetings

Introduction

Augmented reality (AR) is an advanced technology and emerging field that has been adopted into spine surgery to enhance care and outcomes. AR superimposes a three-dimensional computer-generated image over the normal anatomy of interest in order to facilitate visualization of deep structures without the ability to directly see them.

Objective

To summarize the latest literature and highlight AR from the annual “Spinal Navigation, Emerging Technologies and Systems Integration” meeting lectures presented by the Seattle Science Foundation (SSF) on the development and use of augmented reality in spinal surgery. 

Methods

 We performed a comprehensive literature review from 2016 to 2020 on PubMed to correlate with lectures given at the annual “Emerging Technologies” conferences. After the exclusion of papers that concerned non-spine surgery specialties, a total of 54 papers concerning AR in spinal applications were found. The articles were then categorized by content and focus.

Results

The 54 papers were divided into six major focused topics: training, proof of concept, feasibility and usability, clinical evaluation, state of technology, and nonsurgical applications. The greatest number of papers were published during 2020. Each paper discussed varied topics such as patient rehabilitation, proof of concept, workflow, applications in neurological and orthopedic spine surgery, and outcomes data.

Conclusions

The recent literature and SSF lectures on AR provide a solid base and demonstrate the emergence of an advanced technology that offers a platform for an advantageous technique that is superior, in that it allows the operating surgeon to focus directly on the patient rather than a guidance screen.

Evaluation of augmented-reality based navigation for brain tumor surgery

To date, several researchers have introduced augmented reality navigation (ARN) into neurological surgery. While its application in brain tumor surgery seems promising, reports on its utility have been limited, thus warranting further evaluation. To clarify the stages and approaches in which ARN is useful and assess the effect of presurgical discussion with surgeons, we assessed usefulness using a hand-held ARN system we had developed, which displays three-dimensional (3D) virtual structures overlaid on a real-time image of the surgical field via a tablet PC monitor. The system was tested in 20 patients undergoing various procedures, with the first 10 consecutive cases being unselected and the following 10 cases being selected, for whom 3D models were prepared per the surgeons' request. Thereafter, the surgeons ranked its usefulness during each stage of surgery. Consequently, case selection and presurgical discussions with surgeons considerably improved the usefulness, with the "useful" gradings improving from 50% to 88% across all surgical stages. Accordingly, usefulness improved from 50% to 90%, 67% to 100%, and 40% to 80% during the skin incision and craniotomy, dura incision, and intradural procedure stages, respectively. ARN was useful for superficial tumor resection, but less so for deep-seated tumor resection, except when using the transcortical and interhemispheric approaches. In conclusion, a tablet-type ARN can be useful during skin incisions, craniotomy and dura incisions, superficial tumor resections, and transcortical and interhemispheric approaches for deep-seated tumors. Case selection and presurgical discussions with surgeons were essential for the efficacy of ARN.

Examining the benefits of extended reality in neurosurgery: A systematic review

While well-established in other surgical subspecialties, the benefits of extended reality, consisting of virtual reality (VR), augmented reality (AR), and mixed reality (MR) technologies, remains underexplored in neurosurgery despite its increasing utilization. To address this gap, we conducted a systematic review of the effects of extended reality (XR) in neurosurgery with an emphasis on the perioperative period, to provide a guide for future clinical optimization. Seven primary electronic databases were screened following guidelines outlined by PRISMA and the Institute of Medicine. Reported data related to outcomes in the perioperative period and resident training were all examined, and a focused analysis of studies reporting controlled, clinical outcomes was completed. After removal of duplicates, 2548 studies were screened with 116 studies reporting measurable effects of XR in neurosurgery. The majority (82%) included cranial based applications related to tumor surgery with 34% showing improved resection rates and functional outcomes. A rise in high-quality studies was identified from 2017 to 2020 compared to all previous years (p = 0.004). Primary users of the technology were: 56% neurosurgeon (n = 65), 28% residents (n = 33) and 5% patients (n = 6). A final synthesis was conducted on 10 controlled studies reporting patient outcomes. XR technologies have demonstrated benefits in preoperative planning and multimodal neuronavigation especially for tumor surgery. However, few studies have reported patient outcomes in a controlled design demonstrating a need for higher quality data. XR platforms offer several advantages to improve patient outcomes and specifically, the patient experience for neurosurgery.

Augmented Reality-Assisted Craniotomy for Parasagittal and Convexity En Plaque Meningiomas and Custom-Made Cranio-Plasty: A Preliminary Laboratory Report

BACKGROUND

This report discusses the utility of a wearable augmented reality platform in neurosurgery for parasagittal and convexity en plaque meningiomas with bone flap removal and custom-made cranioplasty.

METHODS

A real patient with en plaque cranial vault meningioma with diffuse and extensive dural involvement, extracranial extension into the calvarium, and homogeneous contrast enhancement on gadolinium-enhanced T1-weighted MRI, was selected for this case study. A patient-specific manikin was designed starting with the segmentation of the patient's preoperative MRI images to simulate a craniotomy procedure. Surgical planning was performed according to the segmented anatomy, and customized bone flaps were designed accordingly. During the surgical simulation stage, the VOSTARS head-mounted display was used to accurately display the planned craniotomy trajectory over the manikin skull. The precision of the craniotomy was assessed based on the evaluation of previously prepared custom-made bone flaps.

RESULTS

A bone flap with a radius 0.5 mm smaller than the radius of an ideal craniotomy fitted perfectly over the performed craniotomy, demonstrating an error of less than ±1 mm in the task execution. The results of this laboratory-based experiment suggest that the proposed augmented reality platform helps in simulating convexity en plaque meningioma resection and custom-made cranioplasty, as carefully planned in the preoperative phase.

CONCLUSIONS

Augmented reality head-mounted displays have the potential to be a useful adjunct in tumor surgical resection, cranial vault lesion craniotomy and also skull base surgery, but more study with large series is needed.

Augmented Reality for Retrosigmoid Craniotomy Planning

While medical imaging data have traditionally been viewed on two-dimensional (2D) displays, augmented reality (AR) allows physicians to project the medical imaging data on patient's bodies to locate important anatomy. We present a surgical AR application to plan the retrosigmoid craniotomy, a standard approach to access the posterior fossa and the internal auditory canal. As a simple and accurate alternative to surface landmarks and conventional surgical navigation systems, our AR application augments the surgeon's vision to guide the optimal location of cortical bone removal. In this work, two surgeons performed a retrosigmoid approach 14 times on eight cadaver heads. In each case, the surgeon manually aligned a computed tomography (CT)-derived virtual rendering of the sigmoid sinus on the real cadaveric heads using a see-through AR display, allowing the surgeon to plan and perform the craniotomy accordingly. Postprocedure CT scans were acquired to assess the accuracy of the retrosigmoid craniotomies with respect to their intended location relative to the dural sinuses. The two surgeons had a mean margin of davg = 0.6 ± 4.7 mm and davg = 3.7 ± 2.3 mm between the osteotomy border and the dural sinuses over all their cases, respectively, and only positive margins for 12 of the 14 cases. The intended surgical approach to the internal auditory canal was successfully achieved in all cases using the proposed method, and the relatively small and consistent margins suggest that our system has the potential to be a valuable tool to facilitate planning a variety of similar skull-base procedures.

Efficacy of a virtual reality-based basic and clinical fused curriculum for clinical education on the lumbar intervertebral disc

OBJECTIVE

Today, minimally invasive procedures have become mainstream surgical procedures. Percutaneous endoscopic transforaminal discectomy for lumbar disc herniation (LDH) requires profound knowledge of the laparoscopic lumbar anatomy. Immersive virtual reality (VR) provides three-dimensional patient-specific models to help in the process of preclinical surgical preparation. In this study, the authors investigated the efficacy of VR application in LDH for training orthopedic residents and postgraduates.

METHODS

VR images of the lumbar anatomy were created with immersive VR and mAnatomy software. The study was conducted among 60 residents and postgraduates. A questionnaire was developed to assess the effect of and satisfaction with this VR-based basic and clinical fused curriculum. The teaching effect was also evaluated through a postlecture test, and the results of the prelecture surgical examination were taken as baselines.

RESULTS

All participants in the VR group agreed that VR-based education is practical, attractive, and easy to operate, compared to traditional teaching, and promotes better understanding of the anatomical structures involved in LDH. Learners in the VR group achieved higher scores on an anatomical and clinical fusion test than learners in the traditional group (84.67 ± 14.56 vs 76.00 ± 16.10, p < 0.05).

CONCLUSIONS

An immersive VR-based basic and clinical fused curriculum can increase residents' and postgraduates' interest and support them in mastering the structural changes and complicated symptoms of LDH. However, a simplified operational process and more realistic haptics of the VR system are necessary for further surgical preparation and application.

Supratentorial high-grade gliomas: maximal safe anatomical resection guided by augmented reality high-definition fiber tractography and fluorescein

OBJECTIVE

The theoretical advantages of augmented reality (AR) with diffusion tensor imaging (DTI)-based high-definition fiber tractography (HDFT) and sodium fluorescein (F) in high-grade glioma (HGG) surgery have not been investigated in detail. In this study, the authors aimed to evaluate the safety and efficacy profiles of HDFT-F microscope-based AR cytoreductive surgery for newly diagnosed supratentorial HGGs.

METHODS

Data of patients with newly diagnosed supratentorial HGGs who underwent surgery using the AR HDFT-F technique were reviewed and compared with those of a cohort of patients who underwent conventional white-light surgery assisted by infrared neuronavigation. The safety and efficacy of the techniques were reported based on the postoperative Neurological Assessment in Neuro-Oncology (NANO) scores, extent of resection (EOR), and Kaplan-Meier curves, respectively. The chi-square test was conducted for categorical variables. A p value < 0.05 was considered statistically significant.

RESULTS

A total of 54 patients underwent surgery using the AR HDFT-F technique, and 63 underwent conventional white-light surgery assisted by infrared neuronavigation. The mean postoperative NANO scores were 3.8 ± 2 and 5.2 ± 4 in the AR HDFT-F group and control group, respectively (p < 0.05). The EOR was higher in the AR HDFT-F group (p < 0.05) than in the control group. With a mean follow-up of 12.2 months, the rate of progression-free survival (PFS) was longer in the study group (log-rank test, p = 0.006) than in the control group. Moreover, the complication rates were 9.2% and 9.5% in the study and control groups, respectively.

CONCLUSIONS

Overall, AR HDFT-F-assisted surgery is safe and effective in maximizing the EOR and PFS rate for patients with newly diagnosed supratentorial HGGs, and in optimizing patient functional outcomes.

[Surgical Education in the Digital Age - Virtual Reality, Augmented Reality and Robotics in the Medical School]

Hintergrund Die digitale Transformation der Medizin verändert den Beruf des Arztes. Augmented und Virtual Reality (AR/VR) und die Robotik erfahren einen zunehmenden Einsatz in unterschiedlichen klinischen Kontexten und bedürfen einer begleitenden Aus- und Weiterbildung, die bereits im Medizinstudium beginnen muss. Hier besteht aktuell eine große Diskrepanz zwischen dem hohen Bedarf und der Anzahl an wissenschaftlich überprüften Konzepten. Ziel der vorliegenden Arbeit war die Konzeptionierung und strukturierte Evaluation eines neu entwickelten Lern-/Lehrkonzepts zur digitalen Transformation mit Fokus auf die chirurgische Lehre.

Methoden 35 Studierende haben in 3 Kursen des Blended-Learning-Curriculums „Medizin im digitalen Zeitalter“ teilgenommen. Das 4. Modul dieses Kurses thematisiert Virtual Reality, Augmented Reality und Robotik in der Chirurgie. Es gliedert sich in die folgenden Kursteile: (1) immersive Simulation einer laparoskopischen Cholezystektomie, (2) leberchirurgische Operationsplanung mittels AR/VR, (3) Basisfertigkeiten am VR-Simulator für robotische Chirurgie, (4) kollaborative OP Planung im virtuellen Raum und (5) Expertengespräch. Nach Abschluss des Gesamtcurriculums erfolgte eine qualitative und quantitative Evaluation des Kurskonzepts mittels semistrukturierter Interviews sowie anhand von standardisierten Prä-post-Evaluationsfragebögen.

Ergebnisse Im qualitativen Auswertungsverfahren der Interviews wurden 79 Textaussagen 4 Schwerpunktkategorien zugewiesen. Den größten Anteil (35%) nahmen hierbei Äußerungen zum „Expertengespräch“ ein, das von den Studierenden als elementarer Teil des Kurskonzepts gewertet wurde. Darüber hinaus empfanden die Studierenden den Kurs als horizonterweiterndes „Lernerlebnis“ (29% der Aussagen) mit einem hohen „Praxisbezug“ (27%). Die quantitative Studierendenevaluation zeigt eine positive Entwicklung für die Teilkompetenzen Wissen und Fertigkeiten sowie eine Tendenz zu einer positiven Haltung nach Kursabschluss.

Schlussfolgerung Die chirurgische Lehre ist zur Entwicklung digitaler Kompetenzen prädestiniert. Dabei muss die Geschwindigkeit des Veränderungsprozesses der digitalen Transformation im chirurgischen Fachgebiet beachtet und im curricularen Konzept verankert werden.

Current Perspectives on Augmented Reality in Medical Education: Applications, Affordances and Limitations

This systematic review has been developed against a background of rapid developments in augmented reality (AR) technology and its application in medical education. The objectives are to provide a critical synthesis of current trends in the field and to highlight areas for further research. The data sources used for the study were the PubMed, Web of Science and Discover databases. Sources included in the study comprised peer reviewed journal articles published between 2015 and 2020. Inclusion criteria included empirical research findings related to learning outcomes and the populations for the selected studies were medical students. Studies were appraised in terms of to what extent the use of AR contributed to learning gains in knowledge and/or skill. Twenty-one studies were included in the analysis, and the dates of these suggested an increasing trend of publications in this area. The uses of AR in each selected study were analyzed through a lens of affordance, to identify which specific affordances of AR appear to be most effective in this domain. Results of the study indicated that AR seems to be more effective in supporting skill development rather than knowledge gain when compared to other techniques. Some key affordances of AR in medical education are identified as developing practical skills in a spatial context, device portability across locations and situated learning in context. It is suggested that a focus on relevant affordances when designing AR systems for medical education may lead to better learning outcomes. It is noted that the majority of AR systems reported in the selected studies are concentrated in the areas of anatomy and surgery, but that are also other areas of practice being explored, and these may provide opportunities for new types of AR learning systems to be developed for medical education.

First experience with augmented reality neuronavigation in endoscopic assisted midline skull base pathologies in children

INTRODUCTION

Endoscopic skull base approaches are broadly used in modern neurosurgery. The support of neuronavigation can help to effectively target the lesion avoiding complications. In children, endoscopic-assisted skull base surgery in combination with navigation systems becomes even more important because of the morphological variability and rare diseases affecting the sellar and parasellar regions. This paper aims to analyze our first experience on augmented reality navigation in endoscopic skull base surgery in a pediatric case series.

PATIENTS AND METHODS

A retrospective review identified seventeen endoscopic-assisted endonasal or transoral procedures performed in an interdisciplinary setting in a period between October 2011 and May 2020. In all the cases, the surgical target was a lesion in the sellar or parasellar region. Clinical conditions, MRI appearance, intraoperative conditions, postoperative MRI, possible complications, and outcomes were analyzed.

RESULTS

The mean age of our patients was 14.5 ± 2.4 years. The diagnosis varied, but craniopharyngiomas (31.2%) were mostly represented. AR navigation was experienced to be very helpful for effectively targeting the lesion and defining the intraoperative extension of the pathology. In 65% of the oncologic cases, a radical removal was proven in postoperative MRI. The mean follow-up was 89 ± 79 months. There were no deaths in our series. No long-term complications were registered; two cerebrospinal fluid (CSF) fistulas and a secondary abscess required further surgery.

CONCLUSION

The implementation of augmented reality to endoscopic-assisted neuronavigated procedures within the skull base was feasible and did provide relevant information directly in the endoscopic field of view and was experienced to be useful in the pediatric cases, where anatomical variability and rarity of the pathologies make surgery more challenging.

Virtual education in neurosurgery during the COVID-19 pandemic

OBJECTIVE

Neurosurgical education in the US has changed significantly as a consequence of the novel coronavirus (COVID-19) pandemic. Institutional social distancing requirements have resulted in many neurosurgical programs utilizing video conferencing for educational activities. However, it is unclear how or if these practices should continue after the pandemic. The objective of this study was to characterize virtual education in neurosurgery and understand how it should be utilized after COVID-19.

METHODS

A 24-question, 3-part online survey was administered anonymously to all 117 US neurosurgical residency programs from May 15, 2020, to June 15, 2020. Questions pertained to the current use of virtual conferencing, preferences over traditional conferences, and future inclinations. The Likert scale (1 = strongly disagree, 3 = neutral, 5 = strongly agree) was used. Comparisons were calculated using the Mann-Whitney U-test. Statistical significance was set at 0.05.

RESULTS

One-hundred eight responses were recorded. Overall, 38 respondents (35.2%) were attendings and 70 (64.8%) were trainees. Forty-one respondents (38.0%) indicated attending 5–6 conferences per week and 70 (64.8%) attend national virtual conferences. When considering different conference types, there was no overall preference (scores < 3) for virtual conferences over traditional conferences. In regard to future use, respondents strongly agreed that they would continue the practice at some capacity after the pandemic (median score 5). Overall, respondents agreed that virtual conferences would partially replace traditional conferences (median score 4), whereas they strongly disagreed with the complete replacement of traditional conferences (median score 1). The most common choices for the partial replacement of tradition conferences were case conferences (59/108, 55%) and board preparation (64/108, 59%). Lastly, there was a significant difference in scores for continued use of virtual conferencing in those who attend nationally sponsored conferences (median score 5, n = 70) and those who do not (median score 4, n = 38; U = 1762.50, z = 2.97, r = 0.29, p = 0.003).

CONCLUSIONS

Virtual conferences will likely remain an integral part of neurosurgical education after the COVID-19 pandemic has abated. Across the country, residents and faculty report a preference for continued use of virtual conferencing, especially virtual case conferences and board preparation. Some traditional conferences may even be replaced with virtual conferences, in particular those that are more didactic. Furthermore, nationally sponsored virtual conferences have a positive effect on the preferences for continued use of virtual conferences.

A New Technique that Combines Navigation-Assisted Lateral Interbody Fusion and Percutaneous Placement of Pedicle Screws in the Lateral Decubitus Position with the Surgeon Using Wearable Smart Glasses: A Small Case Series and Technical Note

BACKGROUND

We describe a new technique that combines navigation-assisted extreme lateral interbody fusion (NALIF) and percutaneous placement of pedicle screws in the lateral decubitus position with the surgeon using wearable smart glasses.

METHODS

We explain our method for nonfluoroscopic NALIF and single-position (SP)- percutaneous pedicle screw (PPS) surgery for patients with degenerative lumbar diseases using wearable smart glasses. The wearable smart glasses provide a semitransparent overlay of the navigation information onto the image seen through the lenses. This technique does not require fluoroscopy during lateral interbody fusion or PPS insertion. It is convenient because it does not require a Jamshidi needle or guidewire when inserting PPSs.

RESULTS

Using this method, the surgeon can glance at the 3-dimensional images on the wearable smart glasses while still viewing the operation field. A review of 24 cases yielded an average operation time of 89.5 ± 16.4 minutes and 66.7 ± 67.0 mL of blood loss, without any severe intra- or postoperative complications.

CONCLUSIONS

Nonfluoroscopic NALIF and SP-PPS placement surgery is a safe and effective means for implanting cages and PPSs in this minimally invasive approach without compromising the results. Although further investigations are needed, the wearable smart glasses may be a useful surgical aid when performing NALIF and SP-PPS placement in patients with degenerative lumbar diseases.