Key-words:
Medical education - neurological surgery - neurosurgery - neurosurgical education
- simulation
Introduction
The master-apprentice system has been the cornerstone of medical education for centuries,
especially when it comes to teaching surgical skills. This method, however, has several
flaws that pose as a growing issue as the society's pressure on the health-care facilities
increases and surgical trainees are permitted fewer operating opportunities.[[1]],[[2]],[[3]] In this context, medical simulation emerges as a feasible and promising alternative.[[1]],[[4]],[[5]],[[6]],[[7]]
The concept of simulation as an effective way of learning became popular with the
airline industries, which required commercial pilots to exhaustively train in flight
simulators before allowing them to carry passengers.[[1]],[[6]],[[7]] Defined as “devices, life-like virtual environments, and contrived social situations
that mimic problems, events or conditions that arise in professional (medical) encounters,”[[4]],[[8]] medical simulation rose from the belief that simulation could be applied in the
medical field, accelerating the acquisition, and the development of various skills.
Simulation not only helps trainees to gain confidence but also expertise as they can
apply theory - and makes mistakes - in a safe environment, without putting neither
patients nor themselves at risk. This is particularly important in the early stages
of learning, but it remains valid even when it comes to more experienced students
and doctors. After all, we expect even experts to keep honing their psychomotor skills
and updating their techniques.[[9]]
The deliberate practice in a controlled space also eliminates the need to settle for
the scenarios that casually appear, which neither guarantee quantity, quality nor
variability.[[1]] On the contrary, this practice has the potential of unifying knowledge by presenting
the same wide range of cases to different individuals.
Another exciting benefit is that by simulating, the students' become no longer limited
to the working hours and the learning curve is shortened, as the patient is not necessary.[[10]],[[11]] The above-mentioned features, in addition to the simulation's time-efficiency,
ultimately lead to error reduction and better overall care, which is reflected by
diminished health costs in the long run.[[1]],[[4]],[[5]],[[6]] Therefore, we can imply that simulation, when compared to the master-apprentice
ongoing model of teaching, is probably more cost-effective.
In this context, neurosurgery is a particularly complex field, in which the number
and the difficulty of the procedures continue to increase at the same time that little
– or no – error is tolerated, for mistakes can dangerously threaten the patient's
life or functionality.[[9]] Hence, any effort to improve neurosurgeons' training without possibly jeopardizing
the patients is valid.
In this article, we will discuss the current state of neurosurgery simulation, highlighting
the potential benefits of this approach, as well as its drawbacks. We will also assess
specific training methods, and make considerations towards the future of neurosurgical
simulation.
Historical Background and Current Situation of Simulation Methods
Historical Background and Current Situation of Simulation Methods
The search for novel methods of teaching led to many advances, which must undergo
extensive validation processes that assess efficacy, cost-effectiveness, validity,
versatility, and others, to become the part of residency programs.[[6]],[[9]],[[12]] Coelho et al. divided the adjuvant surgical training options into four major subgroups:
animal models, cadaver training, training with synthetic physical models and VR simulators.[[6]]
Historically, animal and cadaveric dissection has contributed to the medical field
since the Antiquity, with some reports dating the era of the Greek philosopher Alcmaeon
of Croton, during the 6th century BC.[[6]],[[13]],[[14]] The Greek physician Galenus described numerous anatomical structures, which guided
medical practice until Leonardo da Vinci's drawings.[[15]],[[16]] The father of modern anatomy, however, was a title given to the Belgium Andreas
Vesalius due to his most famous work “De humani corporis fabrica.”[[15]]
While this approach continues to be the most prevalent outside operating rooms, it
presents significant limitations such as the availability of fresh cadavers and the
social – and religious – stigma.[[17]] The presence of anatomical variations and comorbidities are other shortcomings
that often hinder the students from experiencing the same scenarios.[[6]],[[13]]
Synthetic physical models are another well-established facet of medical training.
First developed in the 18th century, they were, in the beginning, solely represented
by waxwork replicas. No advance in such category occurred until the advent of “Resusci-Anne,”
a mannequin made by the toy manufacturer Asmund Laerdal, for cardiopulmonary resuscitation
in the 1950s.[[18]],[[19]] These models have quickly become popular since then, especially for rehearsing
anesthesia and trauma-related minor procedures (such as chest tube placement and cricothyroidotomy).
Nonetheless, they do not offer the students the level of reality proximity as the
VR simulators do.[[17]],[[20]]
These machines, allocated in the last subgroup, appear to address all the aforementioned
problems, as the technological arsenal continuously improves and VR accuracy becomes
closer to the real scenarios by the second, allowing students to practice in a riskless
standardized environment that can be objectively evaluated and incremented.[[6]],[[9]] Moreover, the technological advances enable the patient's specific anatomy – obtained
through image examination – to be fully reproduced in three-dimensional models, allowing
physicians to practice different approaches for a complex surgery before actually
facing the patient.[[21]] As surgical simulation is a promising research field, a paradigm shift has been
noticed especially in the past decades, with the increasing use of simulators.
In neurosurgery, nevertheless, the simulation platforms development is somewhat slower
than in the other medical areas. This is partially explained by the institutions and
professionals' skepticism and by their resistance to change. Despite that fact, over
the last 20–25 years, multiple virtual simulators have been created for many procedures,
among which neuroendoscopy, percutaneous rhizotomy, endovascular stenting and coiling,
third ventriculostomy, cranial microsurgery, and pedicle screw and external ventricular
drain placement stand out.[[21]],[[22]],[[23]],[[24]],[[25]],[[26]],[[27]],[[28]],[[29]],[[30]],[[31]],[[32]]
Physical Simulation
The physical simulation includes cadaveric training, animal and synthetic models.
Despite being able to achieve significant anatomical accuracy and being nowadays considered
the first line of practice, physical simulation has noteworthy disadvantages.[[13]],[[22]]
Phantom models, also known as physical synthetic models, are artificial structures
used to mimic body parts, allowing medical training at a reasonable cost and without
the availability, storage, and ethical issues that surround cadavers.[[33]] However, even when maintenance is not required, these models' duration is limited
due to repetitive use, resulting in need of purchasing new devices, which are often
very expensive.[[34]],[[35]] Moreover, these models are generally mass-produced, leading to few or no anatomic
variations' representations.[[34]] VR simulators, on the other hand, are not associated with these issues since they
are digital programs that can mimic anatomic variances – including those of the real
patient – and that do not suffer from repetition.[[7]],[[13]],[[36]],[[37]],[[38]]
Although they give the students a close notion to what they will face in the operation
room regarding surgical anatomy, both cadaveric, the oldest reported form of medical
simulation, and animal training fail to provide pathology.[[39]] Moreover, they involve critical ethical restrictions.[[1]],[[39]],[[40]]
Regarding animal training, the equipment and the specific preparation required to
offset the initial lower cost.[[33]] As for the cadavers, there are not as many available as necessary to adequately
address the needs of residency programs worldwide and the costs related to these bodies'
maintenance are daunting.[[5]],[[40]],[[41]],[[42]] Furthermore, the quality of the cadaveric tissues relies on the adopted embalming
regimen and feedback is not immediate.[[42]],[[43]]
Studies have already demonstrated the efficacy of cadaveric models training for skull
base tumor debulking,[[44]] aneurysm clipping,[[44]],[[45]],[[46]],[[47]],[[48]] cerebrospinal flow evaluation,[[49]] and internal carotid artery injury [[Table 1]].[[50]]
Table 1: Key points, techniques, and messages of physical simulation
Virtual Reality Simulation
Virtual Reality Simulation
VR simulation relies on different levels of immersion.[[22]] Based on the movement illusion that results from the visuospatial input and the
vestibular system stimulation by acceleration and angulation,[[17]] it has three fundamental components – graphic rendering, tissue deformation, and
haptic feedback.[[51]] The goal is to be as realistic as possible, aiming to ensure the best surgical
training. Validity and feasibility are indispensable, and a suitable method for errors'
identification and measurement ought to be employed to guarantee the device's effectiveness.
There are three types of VR.[[51]],[[52]] In the first, called “nonimmersive VR” and exemplified by the “Visual Human Project,”[[53]] the user stays an observer, with restricted interaction via computer, as a visual
representation is constructed by the integration of standardized data, cadaveric dissections,
and intraoperative images.[[54]]
As the name implies, in the second one, the “immersive VR,” the user is fully immersed
in an artificial three-dimensional computer-generated scenario, much like an underwater
diver. There are five immersive VR neurostimulators of significant importance: NeuroTouch,
ImmersiveTouch, Temposurg, Dextroscope, and Robo Sim.[[13]],[[22]],[[51]]
The main problem regarding these simulators is the large capital investment that their
purchase and maintenance required.[[13]],[[22]],[[51]] This still prevents the majority of the residency programs from incorporating them,
especially outside the United States and Europe.
Indirect simulators such as video games and web-based surgical devices also show potential,
particularly when integrated to kinetic technology.[[22]] A retrospective cohort assessed the surgeons that performed laparoscopic procedures
revealed that those who played video games for over 3 h/week in the past were a 25%
more efficient and made fewer mistakes.[[52]] Unfortunately, when it comes to neurosurgery, the small consumer market and the
substantial funding necessary to develop these products discourage the related industries.[[13]],[[22]],[[51]]
Particularly, interesting when it comes to minimally invasive neurosurgery, due to
the limited haptic feedback associated to the procedures, VR obviates the need for
physical models, and the odds are that this type of simulation will soon become the
first-line of practice outside the operating room.[[13]],[[51]] However, despite the investment in VR, synthetic physical simulators are still
considered more reliable, mainly due to their reasonable cost and efficiency, with
several studies demonstrating that the abilities acquired on such simulators are directly
transformed into performance improvement at operations. The differences and similarities
between physical models and VR are further demonstrated in [[Figure 1]] and [[Table 2]].
Figure 1: Venn diagram demonstrating the relation between physical simulation and virtual reality
Table 2: Key points, techniques, and messages of virtual reality
Our contribution
Our group has published a work that presents the development and assessment of an
interactive and stereoscopic resource for teaching neuroanatomy. [[Figure 2]] illustrates this VR simulator.[[53]] The authors concluded that the method had a positive impact on students' knowledge,
encouraging significantly higher learning when compared with traditional teaching
models.[[53]]
Figure 2: One of the many photographs of the brain obtained in a study oriented by professor
Eberval Gadelha Figueiredo, at the University of Sao Paulo, Brazil. This image, along
the others, was processed in the VR Worx 2.6 software (VR Toolbox, Inc.) - a resource
that allowed them to be seen as a continuum, giving the impression that the brain
was moving, and revealing its anatomical particularities1531
Assessment Tools
Every training method must be validated before becoming fully integrated into the
residency curriculum – and simulation devices are not an exception. To achieve the
desired impact, not only an appropriate training program but also an extensive and
thorough evaluation is mandatory. In clinical skills' simulation training, the education
validity of the simulator is often questioned. Therefore, objective assessment tools,
capable of measuring the trainee's performance, are vital.
Knowledge (knows), performance (shows how), competence (knows how), and action (does)
are the four pillars of the clinical competence pyramidal framework developed by Miller
[[Figure 3]].[[54]] The evaluation of the first three stages trains the resident to act in a professional
setting properly.[[4]]
Figure 3: A representation of Miller's four-stage framework for clinical competence: action,
performance, competence itself, and knowledge[54]
When it comes to simulation, the simulator itself can be considered a measurement
tool, once it usually generates a report on performance based on specific measurement
and preestablished goals. In this section, we will briefly discuss some of the most
used evaluation tools in simulation training, considering both its advantages and
disadvantages.[[4]]
Surveys
Participants' overall satisfaction toward the experience, self-efficacy, comfort,
and confidence can be estimated through a subjective tool, which consists either in
open-ended answers or in rating scales analysis. The quality of the given feedback,
as well as the training relevance and educational value, can be measured.[[55]]
Procedural checklists
Based on a binary or a rating scale, this is an objective method of evaluation, despite
its subjective design. Reliable and widely used in the medical field, this tool is
a good option, once it also allows post hoc assessment of videotaped exercises. The
checklists neither comprise the sequence of actions nor the timing evaluation.[[54]],[[55]],[[56]],[[57]],[[58]],[[59]]
Pre- and post-tests
Aiming to evaluate not only knowledge but also decision-making and clinical reasoning,
these – usually – multiple choice tests are administered both before training and
after training. The tests can be either different or not, depending on the situation
and the assessor. Results often demonstrate knowledge improvement after the evaluated
experiences, as disclosed by greater posttests scores on a study by Picard et al.,
which analyzed the impact of simulation courses and refresher lectures.[[54]],[[56]],[[60]]
As a further consideration, one need to keep in mind that cognitive science is essential
whenever developing new training equipment and assessment methods, which despite the
advances are yet scarce. In light of this, the cognitive load (CL) theory must be
taken into consideration.[[61]],[[62]]
CL is a limited mental effort that refers to the amount of information imposed on
working memory. This limitation reflects on how the information is ultimately stored.
For instance, too much information or too complicated, unstructured tasks can determine
a cognitive overload, jeopardizing the learning process. The inherent, immutable difficulty
of a task is known as its intrinsic load. On the other hand, the way in which such
task is designed is the extraneous load, and the germane load is the schemas' automation
and construction.[[61]],[[62]] It is thought that repetitive, well-structured practice can positively affect one's
CL.[[62]]
In turn, the situation awareness (SA) is another relevant concept. SA, defined as
a person's understanding of their dynamic environment, can be divided into three levels.
The first is the perception of the environment; the second, the comprehension of such
information, and the third is the projection of future actions and events. These levels'
assessment can provide significant information regarding the trainees' perceptual
processes and CL [[Table 3]].[[63]]
Table 3: Key points, techniques and messages of assessment tools
Conclusion
Neurosurgery is one of the most demanding medical areas, requiring an extreme level
of expertise, as even the smallest error might have dire consequences. With increasing
time, ethical, and medico-legal constraints currently in place, as well as fewer operation
opportunities, it is of vital importance to find alternative teaching methods. Even
though nothing can perfectly replace the experience of being in an operating room
with an actual patient, simulation – in its many forms – allows students to become
more confident and skilled, in a controlled environment, where there are no restrictions
regarding working hours. Moreover, it allows experts to practice novel approaches
to enhance the patients' safety and improve outcomes.
Up to this moment, physical models, largely represented by cadaveric training, which
is the oldest form of simulation, remain the “golden standard” worldwide despite its
many limitations. Nonetheless, the current situation is on the verge of change: the
rapidly emerging researches and technological advances are allowing VR simulators
to gain space. The cost remains the most prominent obstacle for VR simulators to become
commercially available and for a bigger assessment of these devices' beneficial effects
to be made. The diversity and number of neurosurgical procedures, as well as the different
types of tissues found – which offer specific resistance and have particular densities
– are also significant hurdles, as the industries keep trying to mimic the exact tactile
sensation of operating. Overall, the simulation has a pivotal role in medicine and
neurosurgery is not an exception. Already proved feasible and effective, the different
types of simulation should be implemented in the residency educational programs aiming
to address the trainees' needs, ultimately helping them to become experienced professionals
and to better serve the community.
