Innovations in craniovertebral junction training: harnessing the power of mixed reality and head-mounted displays

OBJECTIVE

The objective of this study was to analyze the potential and convenience of using mixed reality as a teaching tool for craniovertebral junction (CVJ) anomaly pathoanatomy.

METHODS

CT and CT angiography images of 2 patients with CVJ anomalies were used to construct mixed reality models in the HoloMedicine application on the HoloLens 2 headset, resulting in four viewing stations. Twenty-two participants were randomly allocated into two groups, with each participant rotating through all stations for 90 seconds, each in a different order based on their group. At every station, objective questions evaluating the understanding of CVJ pathoanatomy were answered. At the end, subjective opinion on the user experience of mixed reality was provided using a 5-point Likert scale. The objective performance of the two viewing modes was compared, and a correlation between performance and participant experience was sought. Subjective feedback was compiled and correlated with experience.

RESULTS

In both groups, there was a significant improvement in median (interquartile range [IQR]) objective performance with mixed reality compared with DICOM: 1) group A: case 1, median 6 (IQR 6-7) versus 5 (IQR 3-6), p = 0.009; case 2, median 6 (IQR 6-7) versus 5 (IQR 3-6), p = 0.02; 2) group B: case 1, median 6 (IQR 5-7) versus 4 (IQR 2-5), p = 0.04; case 2, median 6 (IQR 6-7) versus 5 (IQR 3-7), p = 0.03. There was significantly higher improvement in less experienced participants in both groups for both cases: 1) group A: case 1, r = -0.8665, p = 0.0005; case 2, r = -0.8002, p = 0.03; 2) group B: case 1, r = -0.6977, p = 0.01; case 2, r = -0.7417, p = 0.009. Subjectively, mixed reality was easy to use, with less disorientation due to the visible background, and it was believed to be a useful teaching tool.

CONCLUSIONS

Mixed reality is an effective teaching tool for CVJ pathoanatomy, particularly for young neurosurgeons and trainees. The versatility of mixed reality and the intuitiveness of the user experience offer many potential applications, including training, intraoperative guidance, patient counseling, and individualized medicine; consequently, mixed reality has the potential to transform neurosurgery.

Assessment of learning curves on a simulated neurosurgical task using metrics selected by artificial intelligence

OBJECTIVE

Understanding the variation of learning curves of experts and trainees for a given surgical procedure is important in implementing formative learning paradigms to accelerate mastery. The study objectives were to use artificial intelligence (AI)-derived metrics to determine the learning curves of participants in 4 groups with different expertise levels who performed a series of identical virtual reality (VR) subpial resection tasks and to identify learning curve differences among the 4 groups.

METHODS

A total of 50 individuals participated, 14 neurosurgeons, 4 neurosurgical fellows and 10 senior residents (seniors), 10 junior residents (juniors), and 12 medical students. All participants performed 5 repetitions of a subpial tumor resection on the NeuroVR (CAE Healthcare) platform, and 6 a priori-derived metrics selected using the K-nearest neighbors machine learning algorithm were used to assess participant learning curves. Group learning curves were plotted over the 5 trials for each metric. A mixed, repeated-measures ANOVA was performed between the first and fifth trial. For significant interactions (p < 0.05), post hoc Tukey's HSD analysis was conducted to determine the location of the significance.

RESULTS

Overall, 5 of the 6 metrics assessed had a significant interaction (p < 0.05). The 4 groups, neurosurgeons, seniors, juniors, and medical students, showed an improvement between the first and fifth trial on at least one of the 6 metrics evaluated.

CONCLUSIONS

Learning curves generated using AI-derived metrics provided novel insights into technical skill acquisition, based on expertise level, during repeated VR-simulated subpial tumor resections, which will allow educators to develop more focused formative educational paradigms for neurosurgical trainees.

Crisis Management Simulation: Review of Current Experience

Crisis management simulation is important in training the next generation of surgeons. In this review, we highlight our experiences with the cavernous carotid injury model. We then delve into other crisis simulation models available for the neurosurgical specialty. The discussion focuses upon how these trainings can continue to evolve. Much work is yet to be done in this exciting arena and we present several avenues for future discovery. Simulation continues to be an important training tool for the surgical learner.

Biomechanical modeling and computer simulation of the brain during neurosurgery

Computational biomechanics of the brain for neurosurgery is an emerging area of research recently gaining in importance and practical applications. This review paper presents the contributions of the Intelligent Systems for Medicine Laboratory and its collaborators to this field, discussing the modeling approaches adopted and the methods developed for obtaining the numerical solutions. We adopt a physics-based modeling approach and describe the brain deformation in mechanical terms (such as displacements, strains, and stresses), which can be computed using a biomechanical model, by solving a continuum mechanics problem. We present our modeling approaches related to geometry creation, boundary conditions, loading, and material properties. From the point of view of solution methods, we advocate the use of fully nonlinear modeling approaches, capable of capturing very large deformations and nonlinear material behavior. We discuss finite element and meshless domain discretization, the use of the total Lagrangian formulation of continuum mechanics, and explicit time integration for solving both time-accurate and steady-state problems. We present the methods developed for handling contacts and for warping 3D medical images using the results of our simulations. We present two examples to showcase these methods: brain shift estimation for image registration and brain deformation computation for neuronavigation in epilepsy treatment.

Development and validation of the Skills Assessment in Microsurgery for Brain Aneurysms (SAMBA) instrument for predicting proficiency in aneurysm surgery

OBJECTIVE

Surgical performance evaluation was first described with the OSATS (Objective Structured Assessment of Technical Skills) and modified for aneurysm microsurgery simulation with the OSAACS (Objective Structured Assessment of Aneurysm Clipping Skills). These methods rely on the subjective opinions of evaluators, however, and there is a lack of objective evaluation for proficiency in the microsurgical treatment of brain aneurysms. The authors present a new instrument, the Skill Assessment in Microsurgery for Brain Aneurysms (SAMBA) scale, which can be used similarly in a simulation model and in the treatment of unruptured middle cerebral artery (MCA) aneurysms to predict surgical performance; the authors also report on its validation.

METHODS

The SAMBA scale was created by consensus among 5 vascular neurosurgeons from 2 different neurosurgical departments. SAMBA results were analyzed using descriptive statistics, Cronbach's alpha indexes, and multivariate ANOVA analyses (p < 0.05).

RESULTS

Expert, intermediate-level, and novice surgeons scored, respectively, an average of 33.9, 27.1, and 16.4 points in the real surgery and 33.3, 27.3, and 19.4 points in the simulation. The SAMBA interrater reliability index was 0.995 for the real surgery and 0.996 for the simulated surgery; the intrarater reliability was 0.983 (Cronbach's alpha). In both the simulation and the real surgery settings, the average scores achieved by members of each group (expert, intermediate level, and novice) were significantly different (p < 0.001). Scores among novice surgeons were more diverse (coefficient of variation = 12.4).

CONCLUSIONS

Predictive validation of the placenta brain aneurysm model has been previously reported, but the SAMBA scale adds an objective scoring system to verify microsurgical ability in this complex operation, stratifying proficiency by points. The SAMBA scale can be used as an interface between learning and practicing, as it can be applied in a safe and controlled environment, such as is provided by a placenta model, with similar results obtained in real surgery, predicting real surgical performance.

The relative efficacy of 3 different freehand frontal ventriculostomy trajectories: a prospective neuronavigation-assisted simulation study

OBJECTIVE Ventriculostomy is a relatively common neurosurgical procedure, often performed in the setting of acute hydrocephalus. Accurate positioning of the catheter is vital to minimize morbidity and mortality, and several anatomical landmarks are currently used. The aim of this study was to prospectively evaluate the relative performance of 3 recognized trajectories for frontal ventriculostomy using imaging-derived metrics: perpendicular to skull (PTS), contralateral medial canthus/external auditory meatus (CMC/EAM), and ipsilateral medial canthus/external auditory meatus (IMC/EAM). METHODS Participants completed 9 simulated ventriculostomy attempts (3 of each trajectory) on a model head with Medtronic StealthStation coregistered imaging. Performance measures were distance of the ventricular catheter tip to the foramen of Monro (FoM) and presence of the catheter tip in a lateral ventricle. RESULTS Thirty-one individuals of varying seniority and prior ventriculostomy experience performed a total of 279 simulated freehand frontal ventriculostomies. The PTS and CMC/EAM trajectories were found to be significantly more likely to result in both the catheter tip being closer to the FoM and in a lateral ventricle compared with the IMC/EAM trajectory. These findings were not influenced by the prior ventriculostomy experience of the participant, corroborating the significance of these results. CONCLUSIONS The PTS and CMC/EAM trajectories were superior to the IMC/EAM trajectories during freehand frontal ventriculostomy in this study, and further data from studies incorporating varying ventricular sizes and bur hole locations are required to facilitate a change in clinical practice. In addition, neuronavigation and other guidance techniques for ventriculostomy are becoming increasingly popular and may be superior to freehand techniques, necessitating further prospective data evaluating their safety, efficacy, and feasibility for routine clinical use.

Simulated ventriculostomy training with conventional neuronavigational equipment used clinically in the operating room: prospective validation study

OBJECTIVES

Simulation is gaining increasing interest as a method of delivering high-quality, time-effective, and safe training to neurosurgical residents. However, most current simulators are purpose-built for simulation, being relatively expensive and inaccessible to many residents. The purpose of this study was to provide the first comprehensive validity assessment of ventriculostomy performance metrics from the Medtronic StealthStation S7 Surgical Navigation System, a neuronavigational tool widely used in the clinical setting, as a training tool for simulated ventriculostomy while concomitantly reporting on stress measures.

DESIGN

A prospective study where participants performed 6 simulated ventriculostomy attempts on a model head with StealthStation-coregistered imaging. The performance measures included distance of the ventricular catheter tip to the foramen of Monro and presence of the catheter tip in the ventricle. Data on objective and self-reported stress and workload measures were also collected.

SETTING

The operating rooms of the National Hospital for Neurology and Neurosurgery, Queen Square, London.

PARTICIPANTS

A total of 31 individuals with varying levels of prior ventriculostomy experience, varying in seniority from medical student to senior resident.

RESULTS

Performance at simulated ventriculostomy improved significantly over subsequent attempts, irrespective of previous ventriculostomy experience. Performance improved whether or not the StealthStation display monitor was used for real-time visual feedback, but performance was optimal when it was. Further, performance was inversely correlated with both objective and self-reported measures of stress (traditionally referred to as concurrent validity). Stress and workload measures were well-correlated with each other, and they also correlated with technical performance.

CONCLUSIONS

These initial data support the use of the StealthStation as a training tool for simulated ventriculostomy, providing a safe environment for repeated practice with immediate feedback. Although the potential implications are profound for neurosurgical education and training, further research following this proof-of-concept study is required on a larger scale for full validation and proof that training translates into improved long-term simulated and patient outcomes.