The challenges and future of neurosurgical training—is extended reality the way moving forward?

Introduction

Neurosurgery is a high-stakes field characterized by rapidly evolving surgical techniques and approaches. The shift toward minimally invasive procedures and the increasing use of endovascular methods for conditions traditionally treated with open surgery presents new challenges for neurosurgical trainees. Surgeons must constantly upskill to keep up with advancements, and trainees are often expected to perform high-risk surgeries with limited exposure to certain procedures. This challenge is compounded by the growing need to protect patients from being used as “practice targets” and the rising litigation risk in the field, where complications are increasingly less tolerated (1,2).

Historically, neurosurgical training has been mentorship-based, with the Halsted model (“see one, do one, teach one”) being central to the education process. Over time, cadaveric training and technological innovations such as intraoperative video recordings and three-dimensional (3D) imaging have enhanced this model, allowing specialists worldwide to share knowledge, highlighting new approaches and techniques for different conditions. In the last few years, the use of extended reality (XR) has steadily become a significant part of the curriculum for some programs. XR is a continuum from absolute reality to utter virtuality, encompassing the more commonly known terms of augmented reality (AR), virtual reality (VR) and mixed reality (MR) (3). This paper seeks to assess how these emerging technologies are benefiting trainees and whether they are viable and scalable complements to the current neurosurgical training methods.

Challenges of neurosurgery training—a global perspective

Neurosurgery training presents several challenges that are prevalent throughout different regions. In various surveys done, one recurring theme was limited opportunities in conducting surgeries. A survey of neurosurgery residents in Germany revealed that 39% of the participants shared that there were limited opportunities for performing surgeries independently (4). In South Korea, 47% of the surveyed neurosurgical residents reported limited time for surgery (5). This is likely due to multiple factors such as increased number of trainees over the years which has resulted in less patients per trainee and increased judicialization of the medical system in which senior doctors are more likely to perform the bulk of the surgery. In addition, with the reinforcement and implementation of stricter and more regulated work hours, this has reduced the time and opportunity for trainees to partake in surgery. Restricted work hours, whilst it allows for better work-life balance, can have an adverse impact on the emergency operative experience (6). The obligation of compensatory time off has made an additional constraint in squaring the circle of improving their surgical skills.

In low- and middle-income countries (LMICs), lack of formal training was reported by 63% of the surveyed neurosurgical residents in Sub-Saharan Africa (7) and only 5.6% of the surveyed neurosurgical residents in Pakistan thought the training program was sufficient (8). In comparison to the higher-income countries (HICs), the added challenges that LMICs face are a lack of learning resources and infrastructure to support their neurosurgical training journey, and minimal exposure to specialty training (9).

Neurosurgery training is also heterogenous, the ways in which programs are run can differ tremendously amongst countries and institutions. At a national and regional level, these differences may be subjected to the resources and facilities that they have. This may be further complicated by the incongruent learning objectives between trainees and mentors. This point was raised in a qualitative survey by neurosurgical residents in France (10). For example, in an operative case—trainees may expect to learn primarily the technical acts during the procedure whereas the mentors may be more interested in teaching them a global concept of decision-making (10).

This calls for a need to structure and standardize the neurosurgery training program, in both LMICs and HICs. Resources should be shared through online platforms or remote teaching so that trainees in LMICs can have a more comprehensive neurosurgical experience. More importantly, the lack of limited opportunity for surgery may hinder trainees from refining their technical skills and building up their confidence in handling emergency or unexpected situations

Traditional methods of neurosurgery training

Traditional methods of neurosurgery training primarily occur in the operating theatre. Through hands-on experience, either taking on the role of an assistant or primary surgeon, trainees can refine their skills. They are exposed to real-life clinical scenarios and forced to think on the spot when unexpected situations occur. This can serve as an important steppingstone in honing their clinical acumen and building their surgical confidence. The benefits of learning in the operating theatre are tremendous and thus having little surgical time and independent operating time is detrimental to a neurosurgeon’s eventual ability. Unfortunately, this is an increasingly commonly cited issue in residency training (4,5).

A prevalent complementary method to circumvent the lack of operating theatre time is training with the use of cadavers. Harvey Cushing was said to have performed about 30 cadaver dissections in the process of developing his method of total extirpation of the Gasserian ganglion for trigeminal neuralgia (11). Through repetition, this enabled him to lower mortality rates and improve surgical outcomes for his patients. Today, modifications are made to cadavers in an attempt to simulate real-life scenarios as much as possible. For example, perfusion of the cadavers’ vessels not only delineates anatomy but can sometimes simulate common surgical situations such as “bleeding” to a certain degree (12). Despite these enhancements and the fact that human cadavers offer near similar anatomy to live patients, there are still challenges in reproducing human physiology. Replicating coagulation, creating variations in blood flow, producing active cerebrospinal flow to mimic intraoperative events are either not possible or rudimentary in their execution. A study by Gnanakumar et al. (13) which evaluated the effectiveness of cadaveric simulation in neurosurgical training found that whilst cadaveric simulation is a popular training tool, it has shown limited evidence of reliably translating to operative proficiency. Other practical disadvantages of cadaveric based learning or simulation is the shortage of human cadavers worldwide, increasing infrastructural expenses and the ethico-legal uncertainties (14). The challenge of using cadaveric training is evident as it was found that that 70.1% of neurosurgical residents in a global survey reported no availability of dissection labs in their home institutions (9).

Modern methods of neurosurgical training

In order to train proficient surgeons, learning and practicing surgical techniques prior to performing it on a real patient is paramount. “Simulation” is essential in honing surgical techniques. In a meta-analysis performed by Davids et al. (15), looking at the importance of simulation for skills training in neurosurgery, it was found that there was a significant 82.7% improvement in procedural knowledge. Looking at the measurement of technical skills, outcomes such as speed and accuracy were analysed which also had a significant 32.5% improvement of accuracy in the learner’s acquisition of procedural skills with simulation. Besides the aforementioned organic simulation models using cadavers, inorganic simulation with synthetic bench models or XR have become an equivalent alternative with todays technology.

Use of XR

XR is a continuum from absolute reality to utter virtuality, encompassing the more commonly known terms of AR, VR and MR (3). XR has not only been employed in the healthcare sector, but also in the aviation, automotive and military sector. In aviation, through the implementation of XR technology, time and cost reductions are made by reducing the need for actual aircraft flying hours, and traditional flight simulators which are expensive (16,17). It also creates a risk-free environment for pilots to train in, enabling them to learn how to react in unpredictable circumstances such as bad weather. With this, they may be able to learn from previous aircraft accidents and better manage such scenarios in real-life if encountered. Surgery is similar to the aviation industry whereby technical demands and the risks are both high. Thus there is also potential for the application of XR to aid our neurosurgical trainees in becoming better prepared and confident surgeons.

VR

VR creates a fully virtual world, creating a completely immersive simulated environment. In neurosurgical training, this may be more widely used in learning neuroanatomy and in the planning of surgical procedures for patients. Neurosurgical procedures are often performed through small openings at a variety at depths. This demands a keen sense of 3-dimensional space and the relative position of structures within it. A meta-analysis of randomized controlled studies of VR-based technology on anatomy teaching was performed by Zhao et al. (18). In the selected studies, majority of the VR studies were compared with traditional methods of 2D images, dissection and textbooks. Overall findings showed moderate enhancement in test scores of the learners when compared to traditional methods. Newer forms of educational tools such as 3D stereoscopic images or 3D printed models can further supplement VR anatomical models.

In addition to the use of VR to teach anatomy, VR has a certain role in introducing neurosurgical techniques. A systematic review by Chan et al. (17) looked at the measurement of technical performance in neurosurgery procedures after subjects went through a training program using a VR surgical system. One of the more commonly used VR systems was NeuroVR (CAE, Inc.) which consists of a VR benchtop simulator with a head and haptic feedback-enabled surgical instruments. It enabled the trainees to practice brain tumour removal and aneurysm repair using close-to-real surgical instruments. In these studies they measured automated performance metrics (APMs) namely distance to target, completion time, kinematics of surgical tool use, blood volume loss. The APMs as raw data points were unable to differentiate surgeon performance, and may require second-order metrics to make sense of the collected data. There may be a role for machine learning and artificial intelligence (AI) models to use the measure APMs to help with classifying the training level (17,19). This can help in highlighting the strength and identifying the deficits that need to be addressed in the trainees.

AR

AR is the overlay of digital information onto the user’s real-world environment. This can be with smartphone devices or specialized AR glasses. A systematic review by Suresh et al. (20) looked at the role of AR in surgical training by analysing 45 papers across various surgical disciplines. The validity of the AR tools was analysed using Messick’s ‘modern concept of validity’ based on five parameters; content, response processes, internal structure, relations to other variables and consequences (21). The level of effectiveness (LoE) of simulation-based mastery learning (SMBL) was also used to analyse the translational level of the AR training models (22). There are four LoE as shown in Figure 1. The use of Messick’s modern concept of validity and LoE allows for comparison of the tools used across different studies.

Figure 1 Level of effectiveness.

Examples of the AR tools in this study are System for Telementoring with Augmented Reality (STAR) which projects the operative instructions directly onto the wearer’s field of view and the ImmersiveTouch System which uses a specialized glasses and a robotic stylus to have an interactive 3D environment with haptic feedback. In the review, it was found that AR SMBL had an overall positive effect on surgical trainee’s performance when compared to traditional methods. Seven of the 45 papers that were studied were related to the neurosurgical specialty. One neurosurgery AR SMBL that stood out was the use of the HoloLens in localization and drilling of the burr hole at a targeted lesion. Whilst there was only 1 out of 4 significant improvements in the measured outcomes when comparing between the 2D and AR methods, it showed potential in reducing the steep learning curve for trainees. Of note, only 1 out of the 7 neurosurgery papers had a LoE of 3 whist the rest had a LoE of 1–2, highlighting the need to finetune and improve the translational effects of SMBL in neurosurgery.

Besides its use training, AR also plays an important role in actual neurosurgery operations The use of AR and VR increased the rates of complete resection rates in glioma surgery from to 69.6% in comparison to a control group with just 36.4% (23). VR can help with lesion segmentation, fiber tracking and functional cortex localization to optimize the surgical planning. Thereafter, with the use of an AR microscope-based neuronavigation system, it can then reconstruct structures of interest with the option to be made visible or invisible easily. When used in combination with intraoperative magnetic resonance imaging (MRI) suites, residual tumour can be further identified and resected, improving complete resection rates. This highlights the importance of incorporating AR early in neurosurgical training to ensure trainees are comfortable with its use during operations on live patients. However, as apparent, such resources are costly and often not accessible to LMICs.

MR

MR is the combination of the virtual environment with the real world, allowing for both interaction with the virtual and real world. The HoloLens, which was the world’s first untethered MR device, has been used in spine surgery training to help guide rod placement and manipulation of phantom patient or human cadavers, improving their accuracy and reducing operative times (24-26).

Discussion

Overview of the benefits and challenges of XR

The use of XR in neurosurgical training enhances visualization and understanding of complex anatomy. Studies have demonstrated that learning anatomy while immersed in a virtual environment can help aid in retention and recollection of the topographic and operative anatomy. Another significant advantage of XR is its ability to create a risk-free environment where trainees can practice complex procedures without inflicting harm on patients.

XR technologies can also enable remote training and information sharing which can expand access to neurosurgical education, helping to mitigate the knowledge difference between developing and developed countries. In a UK-Uganda partnership to educate the trainees on emergency and essential surgery, outcomes of a VR training course were measured. It showed that all delegates reported improvement in their operative procedures (19). Some positive feedback received was the greater freedom and ability to move and view as compared to conventional static views. However, the barriers to accessibility are still affordability of equipment—such as possession of a smart phone and internet access.

As XR technology is still in its early days, full integration of XR into neurosurgical practice (training and surgical use) faces several technological hurdles. One major obstacle is in integrating the technology with existing navigation systems, ensuring there is around the clock support and servicing when required. Ergonomically, some of these systems also require wearing bulky equipment, something which the surgeons may require some time getting used to. Content creation is also labor intensive and costly. This high start-up cost, which includes acquiring the necessary equipment, may not be feasible for all institutions as healthcare budgets are often prioritised to other areas. From a scientific point of view, despite there being an increasing numbers of reports on the use of XR, more quantitative studies are required to analyse the validity, cost, user performance and experience, outcomes and its significance over longer durations (26-29) in order to justify its broader adoption. At present, most of the papers are exploratory and demonstrative in nature with small sample sizes.

Limitations

This review is not quantitative and thus, may lack reliability. Moreover, given the heterogeneity of XR tools, the early-stages of its use in the neurosurgical training, the long-term impact on surgical performance has yet been analysed in depth. This may make it difficult to ascertain the true impacts and challenges that arise from the use of XR tools in neurosurgical training.

Moving forward

Traditional methods of teaching though valuable, are increasingly less relevant in todays’ world for a variety of reasons. Therefore there is a need to shift to the use of XR in neurosurgical education, training and operations. The earlier trainees are exposed to it, the less steep the learning curve they would have to overcome. Over time, technological advances of XR will create better simulation models such as the use of haptic feedback which is increasing being explored.

To enable this shift, and to ensure its accessibility to LMICs, technological costs need to be reduced and resources need to be diverted to developing this field. This can only be achieved by resource rich countries in conjunction with industry players. The involvement of industry also ensures quick integration into existing surgical instruments and microscopes which will then garner interest and usage. This generates a virtuous cycle which will accelerate the growth of this field.

Finally, the effects of XR is not just in improving the technical aspects of trainees. XR can also help garner more interest in neurosurgery amongst medical students as demonstrated by a study by Trucknmueller et al. (24,30). Their study demonstrated how augmented 360 degree VR videos involving neurosurgical procedures inspired medical students. encouraging them to developed greater interest in the neurosurgery specialty.

Conclusions

The future of neurosurgical education will likely involve a combination of traditional methods and cutting-edge technologies. With continued advancements, XR has the potential to become an essential component of the neurosurgical training paradigm, helping to address the challenges of limited surgical opportunities and enhance the skill development of future neurosurgeons worldwide. Thus, XR has the potential to significantly influence neurosurgical training, and just how quickly and equitably this transformation will occur remains to be seen.

Acknowledgments

None.

Footnote

Peer Review File: Available at https://asj.amegroups.com/article/view/10.21037/asj-25-2/prf

Funding: None.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at https://asj.amegroups.com/article/view/10.21037/asj-25-2/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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