Despite significant advances in technology and intraoperative techniques over the last century, operations on the brain and spinal cord still carry a significant risk of serious morbidity or mortality. To an extent, such complications reflect the natural history of the diseases treated by neurosurgeons. However, a number of analyses have identified that potentially avoidable technical errors also contribute to poor surgical outcome.1-4
The acquisition of expertise in operative neurosurgery demands that trainees learn to be both precise and gentle when handling neural tissue. Historically, trainees have developed operative neurosurgical skills through the surgical apprenticeship model, following the old adage “see one, do one, and teach one.” Exposure to a high volume of cases has traditionally represented the cornerstone of neurosurgical training as opposed to a formal surgical curriculum based on educational theory.
In recent years, a number of factors have challenged the traditional surgical apprenticeship model. Events such as the inquiry into children’s heart surgery at the Bristol Royal Infirmary5 have underlined the expectation that surgeons be trained to an acceptable level before treating patients.5-7 Simultaneously, changes in the delivery of health care and the role of other healthcare professionals such as surgical nurse practitioners have reduced learning opportunities in the operating room.8 Limitations on the working week of doctors were pioneered in the United States after the death of an 18-year-old female inpatient in 1984, determined by a grand jury to be partly a result of long hours worked by unsupervised interns and residents.9 Reductions in the working week and improved supervision for junior doctors followed. In the United Kingdom, similar changes occurred after the introduction of the European Working Time Directive, which limits the working week of junior doctors to 48 hours. The introduction of Modernising Medical Careers in the United Kingdom has shortened the length of training and restricted the number of hours worked per week, further reducing the surgical caseload of neurosurgical trainees.
In an era of reduced clinical exposure among surgical trainees, simulation may offer the opportunity to supplement clinical exposure and to improve operative skills in a safe, controlled environment through repeated physical practice. Exciting developments include high-fidelity simulation, which places trainees in immersive yet complex environments reflecting the technical and nontechnical challenges experienced in the real-life operating room.10-12 Another highlight is the development of a prototype called the Modelled Anatomical Replica for Training Young Neurosurgeons by the Royal College of Surgeons of England, which is a replica of a head constructed to provide a useful tool for the practice of procedures such as burr-hole drilling, insertion of external ventricular drains, and craniotomies (Figure 1). Alongside simulation-based learning, there is also burgeoning evidence that mental practice, in which mental imagery is used to rehearse a skill before a performance, may be used to improve performance.13,14
Most of the work on simulation and script-based mental rehearsal to date has been applied to general surgery. However, it could be argued that the margin of error in neurosurgery is narrower and that such errors could lead to catastrophic results; one could therefore put forward an especially strong case for these 2 educational initiatives in reducing technical errors and improving patient outcomes. In this review, we discuss the theoretical arguments for simulation-based learning and script-based mental rehearsal in neurosurgery and the evidence for their efficacy in allied surgical fields.
SIMULATION-BASED DELIBERATE PRACTICE
Ericsson’s Theory of Deliberate Practice Applied to Simulation-Based Learning
A number of educational concepts have been proposed to describe the acquisition of psychomotor skills, including relatively complex tasks such as operative neurosurgical procedures. Ericsson and Smith have advocated an “expert performance” approach to skill acquisition based on identifying and studying individuals who are able to perform exceptionally within a particular domain relative to their peers. When neurosurgical trainees first begin operating, they rely heavily on close supervision from consultant mentors. Gradually over time, they acquire the skills necessary for independent practice. Although all neurosurgeons tend to improve with experience initially, most will reach a stable average level of performance within a relatively short period of time and maintain this status for the rest of their professional lives. A few surgeons, however, develop their skills more rapidly and continue to improve in the subsequent years. These individuals are eventually recognized as expert surgeons, masters within their field. An improved understanding of the factors that determine these differences in professional achievement may permit the development of a more effective neurosurgical curriculum.
What is “Expert Performance”?
An essential prerequisite to any analysis of the acquisition of expertise in operative neurosurgery is a robust description of the attributes that characterize expert performance. Interestingly, early attempts by Elstein et al15 failed to identify superior performance by peer-nominated expert physicians using simulations of commonly encountered medical scenarios. One of the criticisms of these early studies was their use of professional status to define expertise. Ericsson16 has instead defined expert performance as “superior, reproducible performance that can be measured.” Given that the goals of operative neurosurgery are relatively straightforward—maximal therapeutic effect and minimal iatrogenic injury—surgeons whose patients consistently achieve the best outcomes should, almost by definition, be recognized as experts. A number of studies have demonstrated improved outcome in patients operated on by a surgeon who frequently performs that procedure.17 Unfortunately, variations in patient and disease factors often make such crude comparisons unreliable. An alternative approach is using simulators to capture expert performance on standardized tasks. For example, the Imperial College Surgical Assessment Device, which quantitatively evaluates surgical dexterity, has been shown to discriminate between novice and senior surgeons when performing simple surgical procedures on part-task simulators such as simple suturing, suturing at depth, and knot tying.18 High-tech simulators used in general surgery such as laparoscopy trainers have also identified experienced surgeons as performing significantly better than less experienced surgeons in terms of speed, economy of movement, and consistency.19
Nature vs Nurture and Expertise
The relative influence of nature and nurture on the acquisition and maintenance of such expert performance has been the subject of debate for many years. A commonly held view, described by Sir Francis Galton more than a century ago, is that although experience initially improves performance in all trainees, a plateau is eventually reached, which is determined primarily by innate capacity.20 The best evidence for hereditable characteristics comes from sports such as basketball, for which anatomic features such as height differ systematically in experts compared with the general population. However, the search for stable hereditable factors in other domains such as surgery has been largely unsuccessful, suggesting that training may affect maximal performance to a greater extent than previously thought.
A number of studies support the idea that experience rather than inherent ability or talent allows individuals to attain expert performance.16 Longitudinal assessments of the performance of individuals who eventually attain expertise, even child prodigies, invariably show gradual rather than abrupt improvements. Moreover, the age at which expert performance is attained is remarkably consistent among different careers. Peak performance is usually reached in the middle to late 20s for many sports and 1 or 2 decades later in the arts and sciences. Individuals achieving exceptional performance have invariably engaged in a minimum of approximately 10 years of intense involvement in a field, far longer in many cases. The postgraduate training for neurosurgery in the United Kingdom, for example, includes 2 years of foundation (general) training, 8 years of core neurosurgical training, and possibly another year or so in a fellowship pursuing a specialist interest.
The implicit assumption that all practice and experience inevitably lead to maximal performance has been challenged repeatedly in the educational literature. In a series of studies of Morse code operators, Bryan and Harter demonstrated that although a plateau in performance was quickly attained, even very experienced operators could be encouraged to improve their performance dramatically through deliberate efforts when offered promotions or external awards.20 These findings have been validated by similar laboratory studies assessing other skills such as typing. The corollary is that it is the quality of training that individuals receive, rather than their experience alone, that may influence the level at which their performance plateaus.
Ericsson and colleagues20 have explored which activities are most associated with optimal learning and improvement in performance and have referred to these actions as “deliberate practice.” They have characterized a number of features of such deliberate practice. First, individuals must be motivated to improve some aspect of their performance in a well-defined task. Second, detailed and immediate feedback should be provided on their performance. Finally, there must be ample opportunity to perform the same or similar tasks repeatedly. Ericsson first demonstrated the importance of deliberate practice in attaining expert performance in a landmark study on musicians studying at a famous music academy in Berlin. He found that although all musicians spent a similar amount of time practicing when all music-related activities were combined, the best group of experts consistently spent more time practicing by themselves, concentrating on improving a specific aspect of their performance, thus meeting the criteria for deliberate practice.
Applying the theoretical framework of deliberate practice to the traditional surgical apprenticeship model highlights a number of important factors limiting neurosurgical trainees. First, the costs of mistakes or failures in neurosurgery are very high (death or serious morbidity), which encourages trainees to maintain an acceptable and reliable performance rather than experimenting with new and possibly better operative techniques. Second, although surgical operations inherently provide a great deal of immediate natural feedback, once trainees attain an acceptable level of performance, they are often left to perform such cases without direct supervision by an expert surgeon. Finally, the opportunities to perform and repeat index neurosurgical procedures are often unpredictable, reflecting the time at which patients present, the urgency of the intervention, and the availability of resources such as anesthetic and operating room staff.
Simulation in Neurosurgery
The use of simulation-based learning may provide a method for neurosurgical trainees to circumvent these barriers to deliberate practice. First, simulated operations allow trainees to practice and improve their technical skills in a safe environment, without fear of harming their patient. Second, the use of simulated operations may allow improved quality and detail of feedback. Tools such as the Imperial College Surgical Assessment Device may be used to provide trainees with a quantitative evaluation of their dexterity when performing core surgical skills (Figure 2).21 Video recordings of trainee performances can also be analyzed retrospectively by surgical masters to identify aspects that can be improved in the simulator. Finally, surgical simulators may permit surgeons to practice an operation repeatedly on their own time and to address particularly challenging parts of procedures in a systematic way.
Evidence for the Efficacy of Simulation-Based Learning With Deliberate Practice
Although Ericsson provides a sound theoretical basis for the value of deliberate practice using simulators to acquire and maintain operative neurosurgical expertise, the cost of implementing high-fidelity simulators calls for more rigorous scientific evidence. To this end, although no study has yet provided empirical data to support the role of simulation-based learning in neurosurgery per se, a number of investigators have provided substantial evidence for its utility in related fields.22-27
A meta-analysis of the evidence for simulation-based medical education with deliberate practice in 14 studies (6 randomized controlled trials) found simulation-based learning with deliberate practice to be better than traditional clinical education in terms of technical skill acquisition and maintenance for a range of clinical skills28; such skills included advanced cardiac life support, laparoscopic surgery, cardiac auscultation, hemodialysis catheter insertion, thoracocentesis, and central venous catheter insertion.
A recent study evaluated the use of virtual reality simulation of laparoscopic cholecystectomy (LC) in surgical education.27 Twenty-six inexperienced surgeons were recruited and randomized into 2 groups and attended 10 virtual LC sessions over a 6-week period. In each session, surgeons in the control group performed 2 virtual LCs unsupervised, separated by a 30-minute surgical tutorial on a topic unrelated to laparoscopy or cholecystectomy; surgeons in the deliberate practice group were given immediate expert feedback after their first virtual LC and assigned a 30-minute drill during the interim to address identified weaknesses. After completion of the training sessions, surgeons in both groups performed 2 LCs on a porcine model, and their performance was assessed by the use of motion tracking with synchronous video capture.
Although the performance of the surgeons in both the control and deliberate practice groups greatly improved over the course of the training sessions, the nature of these improvements varied considerably. Surgeons in the control group completed the procedures in a shorter amount of time and with fewer movements than the deliberate practice group. Conversely, surgeons in the deliberate practice group were consistently rated higher by experts on the video-based rating scales, which are a measure of quality of performance. The authors speculate that surgeons in the study who were participating in deliberate practice took more care and precision when performing the LC at the expense of speed but that further practice beyond the duration of the study would have led to improvements in speed and economy of movement toward the level of the control group.
It is important to note that the number of studies assessing the efficacy of deliberate practice in surgery remains relatively small, and many are cohort or case-control studies; none specifically addresses operative neurosurgery. Nonetheless, the strikingly consistent and positive effect of deliberate practice on the acquisition and maintenance of expertise strongly supports the use of medical simulators in the neurosurgical setting.
Future Perspectives on Simulation in Neurosurgery
Currently, a range of simulators are available to neurosurgical educators, including low-tech physical models such as part-task trainers used to practice suturing, animals models, and human cadavers and recently high-tech virtual reality and haptic simulators (Table). The most notable example of the latter category is NeuroTouch (National Research Council, Canada), a virtual reality neurosurgery simulator that provides haptic feedback with the aim of assisting in the training and assessment of technical skills requiring the use of tactile and visual cues.29 It currently incorporates 2 training tasks, a tumor debulking task and a tumor cauterization task, using 3 different surgical tools (suction, ultrasonic aspirator, and bipolar). Prototypes of NeuroTouch are currently being deployed in 7 Canadian teaching hospitals, and the initial results of its effect on surgical education are greatly anticipated.
SCRIPT-BASED MENTAL REHEARSAL
Although a growing evidence base now supports the use of surgical simulators in the education of novice surgeons, because of cost and resource implications, they are not widely implemented. An educational method is therefore needed that allows learners to develop surgical skills for a wide range of operations in an environment that ensures the safety of patients and facilitates learning for the trainee. This method should also be easy and cost-effective to implement without the need for major infrastructure such as laparoscopic training laboratories. One such method is script-based mental rehearsal. This has been defined as “the cognitive rehearsal of a task in the absence of overt physical movement”30 in which trainee surgeons are given scripts specially formulated by experts in the respective specialties providing detailed explanations of the procedure. The descriptions use a wide range of imagery surrounding visual, tactile, acoustic, olfactory, and kinesthetic cues that aid factual recall. Over and above the detailed descriptions, imagery cues are thought to enhance the memory of important procedural steps in the surgeon’s “mind’s eye,” allowing the surgeon to visualize the operation before performing it. Trainees are therefore given an initial “gold standard” way of performing the procedure, removing the variability and potential bad habits picked up from observing or assisting different surgeons.
Mental Rehearsal Theory
Mental rehearsal is a well-established technique used in a variety of sports to enhance the performance of repeated and accurate physical movements. Many techniques have been proposed and tested, the most common of which include the schema theory and staged motor learning. Schema theory emphasizes the need to develop a well-rehearsed plan of the individual movements that make up an action such as a tennis serve or golf swing so that it can be performed smoothly and efficiently without inaccuracy from hesitation in individual steps. Indeed, in laparoscopic surgical procedures, economy of movement and accuracy of individual steps can be assessed and quantified with modern simulators. Studies that have compared experienced senior and inexperienced novice surgeons have highlighted that economy and accuracy of definite movements are key distinguishing features.31,32 If this could therefore be enhanced in the initial training phase of surgeons, the transition to competent surgeon may be more rapid.
Staged motor learning is a concept whereby the initial learning or “cognitive” phase of mental rehearsal is followed by an “associative” phase in which the movement is practiced, akin to a physical representation of the mental thought process. In sport, this method allows athletes to make variations to the planned movements to improve it based on their own physical features. For example, a taller tennis player may hold the racquet at a more acute angle during a serve or rally to place the ball in a desired location. In surgical training, this phase is likely to be of varied duration depending on the amount of experience and confidence of the trainee, but this concept highlights the importance of changing one’s practice in different situations. Patients present different challenges to surgeons such as a large body habitus or variant anatomy that may require a different or modified approach. Variations on the mental thought process must also be practiced physically so that the surgeon can modify the procedure for surgeon- or patient-specific needs. The final phase in this process is the “autonomous” phase in which the motor movements have been performed repeatedly until they occur with efficiency and accuracy each time almost subconsciously. This occurs in experienced surgeons who undertake a series of complex maneuvers, each smoothly and efficiently leading on to the next, resulting in seamless completion of the whole procedure.
The Neurobiology of Mental Rehearsal
To determine an underlying neurobiological explanation for the difference in mental rehearsal of motor tasks in novice and experienced athletes, a recent study compared functional magnetic resonance imaging mapping between elite and novice archers.33 Archers were asked to mentally rehearse performing archery and nonmotor tasks while in an functional magnetic resonance imaging scanner. Novice archers showed increased activity in the premotor, supplementary motor, and inferior frontal regions, as well as the basal ganglia and cerebellum, whereas experienced archers showed activation of primarily the supplementary motor area. This suggests that during the learning phase a significant increase in cortical activity is required to rehearse a task, especially in the cerebellum. The authors of this study suggest that this economy of cortical processing in elite archers somehow leads to greater consistency and accuracy of the given motor task.
The Evidence for Mental Rehearsal
The effects of mental rehearsal on the acquisition of basic surgical skills in medical students has been assessed in 2 randomized studies, demonstrating an improvement in suturing skills after mental rehearsal compared with textbook study30 and showing that mental rehearsal is as efficacious as physical practice of basic surgical skills.34 The authors therefore conclude that mental rehearsal may even provide a substitute for physical practice. This benefit of mental rehearsal appears to extend to more complex procedures. In simulated LC, a randomized study found mental practice to be statistically superior in enhancing the technical ability of both senior and novice surgeons, starting from as early as the first procedure.14
The evidence base in both surgical and nonsurgical disciplines suggests that mental practice may be a cost-effective and safe way of training novice surgeons. To date, no studies in mental rehearsal have been conducted in neurosurgery, but the outcomes of studies in laparoscopic surgery are encouraging. If mental rehearsal can demonstrably improve technical skills in a specialty as technically challenging as neurosurgery, it is likely that it will play a pivotal role in the future neurosurgery curriculum.
Surgical education in the United Kingdom and elsewhere is undergoing overwhelming change, in part as a result of changes in the economic, political, social, cultural, and technological climates in which it operates. Shortened training, reductions in the working week, economic constraints, and increasing emphasis on patient safety have required surgical educators to radically rethink the way in which surgical education is delivered. This has resulted in the development of simulation technology, mental script-based rehearsal, and simulation-based deliberate practice. Although these tools and techniques are garnering increasing evidence for their efficacy, their evidence as applied to neurosurgery is somewhat more limited. Even though there is much to learn from other diverse fields, further research into the utility of these tools and techniques in improving the acquisition of technical skills in neurosurgery is vital in a field in which technical error can result in grave consequences.
The authors have no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
We would like to thank David Riley, MSc, at the Education Development Unit of Imperial College London for his assistance in identifying citations from the educational literature for this review.
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