In other cases, simulators designed for simple and widely performed procedures such as lumbar puncture may be adapted for more complex and specialty specific procedures such as lumbar drain placement. During a pilot course undertaken for boot camp curricular development, lumbar drain placement safety was taught by reviewing the anatomic landmarks used for the procedure and the proper sequencing and connecting of the various insertion kit components, which were reviewed and physically handled (Figure 4). By the time the national courses were initiated, lumbar drain placement teaching used a commercially available lower-torso lumbar spinal surgery model, which was designed for teaching surgical anatomy but not for lumbar puncture. Subsequently, the courses have used a commercially available lumbar puncture model (Kyoto Kagaku Co, Ltd, Kyoto, Japan) that provides flow of artificial cerebrospinal fluid after the interlaminar space is successfully entered and allows threading the lumbar catheter through the needle into the model thecal sac. The learner can perform the procedure while visualizing the internal bony anatomic landmarks or, as in the live clinical environment, with those landmarks hidden from view by artificial skin.
Similarly, components of model-based simulations used for entirely different purposes may also be adapted to create a simple neurosurgical procedural simulator. During the initial boot camp courses, the ventriculoperitoneal shunt tap procedure was taught by reviewing the typical location of shunt valves relative to anatomic landmarks and tapping a naked shunt reservoir with attached tubing and saline flow (Medtronic, Inc, Minneapolis, Minnesota; Figure 5). Subsequently, a shunt system with continuous flow of saline has been used, with the valve covered by artificial scalp (Ethicon, Inc). Learners can palpate and tap the valve with proprioceptive feedback similar to that of the actual clinical procedure and visualize the relationship between palpated landmarks and the orientation and components of the valve and reservoir.
At the time the boot camp pilot and subsequent national courses were developed, sophisticated, computer-controlled, and haptic ventriculostomy placement simulators were commercially available but too expensive for use in these resident courses. Therefore, during the pilot course, ventriculostomy placement teaching involved reviewing anatomic landmarks with a skull model and teaching the proper sequencing and connecting of the various insertion kit components (Figure 6). By the time the national courses were initiated, ventriculostomy teaching stations used a frameless navigation system with electromagnetic tracking (Stealth Station S7 with AxiEM, Medtronic Inc), preloaded with computed tomographic imaging of “normal” and “large” ventricles, plus a hollow skull model created by resin stereolithography (Medtronic, Inc). Although frameless navigation systems are also expensive technology, they are nearly universally available in the academic hospitals and surgical teaching centers at which resident courses are taught and have been loaned free of cost by surgical technology vendors.20
Furthermore, iterative improvement of ventriculostomy placement simulation has been possible within the structure of the boot camp courses each year. Currently, the station uses a more refined stereolithography-generated resin skull model with a polished and clear-coated surface that is compatible with a dry erase marker (Medical Modeling, Inc, Golden, Colorado), so each learner can be tested on anatomic landmarks for burr hole placement before catheter passage. The model has a built-in electromagnetic fiducial to interact with the AxiEM tracking system. The resin skull model itself is lined with a 3-mm-thick silicone sheet to simulate dural puncture and filled with 5-mm-diameter BBs (Crosman Airsoft BBs, Crosman, Inc, Bloomfield, New York), re-creating the consistency of brain tissue, to simulate catheter passage with higher fidelity (Figure 6).
The ICP monitor placement procedural simulation uses a plastic skull or skull cap, access drill, and clinically available ICP bolt monitoring system (Camino; Integra LifeSciences Corp, Plainsboro, New Jersey) to train residents to insert, secure, and “zero” the monitoring system. There have not been major changes to this simulation during the courses.
Decision-making and Behavioral Simulation
Early learners in surgical training are likely to be supervised initially for most procedural and all operative interventions.27 In contrast, these early learners may face a need for critical decision making about important clinical events very early in training. In the SNS boot camp courses, clinical models have also been used to support critical decision-making and behavioral simulation (Figure 7). Various commercial systems enable simulation of critical decision making with assessment of trainee knowledge and behavior in response to purpose-designed clinical scenarios. The boot camp courses have used a scenario involving sudden neurological deterioration in the emergency department caused by a rapidly expanding epidural hematoma. PGY1 surgical residents were provided a brief history of a patient who fell off a ladder sustaining a head injury. Each learner was expected to develop a differential diagnosis related to a traumatic closed-head injury, to recognize the development of elevated ICP, and to suggest management strategies related to the airway/circulation, reduction of ICP, and calling for supervisor/attending help. Commercially available manikin simulators used for this teaching are capable of modeling verbal, physiological, and even some neurological responses (eg, pupillary dilatation; Sim Man, Laerdal Medical, Wappinger Falls, New York). Thus, simulators initially designed to teach more universal skills such as resuscitation and endotracheal intubation have been adapted for training neurosurgical residents.
Immediate postcourse surveys were answered by nearly all resident attendees (186 of 186 in 2010, 100%; 187 of 201 in 2011, 93%; 164 of 206 in 2012, 80%). The percentage of resident attendee respondents who described the model-based simulation hands-on materials for each surgical or procedural skills station as “excellent” is given for each of the 3 course years in the Table. Those procedural and surgical skills stations that underwent specific iterative improvements in their model-based simulations between 2010 and 2012 showed improvement in rankings, including the dural and skin closure surgical skills simulations and the ventriculoperitoneal shunt tap, lumbar drain, external ventricular drain, and central line placement procedural skills simulations, whereas other stations did not [analysis of variance F(2,18) = 5.567; P < .02]. The average magnitude of improvement in “excellent” ratings for simulation model hands-on materials was 15% for those stations undergoing iterative improvement and no change (0%) for other stations (P < .01).
The value of model-based simulation in PGY1 neurosurgical residents was assessed by surveys of resident learners and faculty attending the 2010 boot camp courses.20,21 Residents most highly valued those simulations of procedures that they were called on more frequently to perform during their PGY1 year.21 All simulations, but particularly those related to neurosurgical operative interventions and neurosurgery-specific intensive care unit procedures, were highly valued by resident learners.20
Validated assessments of procedural simulation are important to assess the pedagogy itself, to gauge the performance of the resident, and to assess the resident's ability to progress to subsequent training stages.28,29 In general, validated assessments are often lacking from surgical simulation models. In 2012, the SNS boot camp courses introduced pilot, checklist-based technical assessments for 3 course procedural stations: ventriculostomy, ICP monitor, and lumbar drain placement. As part of the ongoing process of iterative course improvement, these assessments are being validated and broadened to additional course components.
Simulation training in neurosurgery is particularly challenging because of the wide variety of anatomic approaches and pathology routinely dealt with in the field.30,31 Nevertheless, early learners appear to particularly benefit from model-based simulation designed to teach common neurosurgical procedures or narrow skills components of more complex operative interventions that are commonly performed by residents in their initial clinical years.
Model-based simulation for early neurosurgical learners benefits from a defined curriculum, within which each technical or procedural skill gains relevance. For example, in the approach used by the SNS boot camp courses, each PGY1 resident is exposed to a simulated manikin patient that experiences sudden deterioration in the emergency department resulting from an expanding traumatic intracranial hematoma. In the skills laboratory, the resident is tasked with practicing and then performing the various component skills of a standard hemispheric craniotomy for traumatic extra-axial hematoma evacuation, including bone drilling, craniotomy formation, dural tack-up placement and closure, and skin closure.
The boot camp courses effort has produced significant positive results in its first 3 years of national attendance.20,21 Despite these successes, further work is necessary to ensure a fully robust educational process. Although challenging and time intensive, the creation of validated assessments for each fundamental skill must be undertaken. This complexity and effort are justified by the scale of the enterprise and its reach across the breadth of US residency training.
Various other educational organizations that include early learners use simulation in neurosurgical teaching. The Congress of Neurological Surgeons simulation initiative has created, refined, or adopted the use of various procedural and surgical simulators and aggregated their use into simulation courses for neurosurgical residents, allowing intensive experience relevant to multiple procedures during attendance at national neurosurgical meetings. An important component of simulator development by this program has been the creation of validated assessment instruments.32 The American Association of Neurological Surgeons has created a recurring competitive event for residents using ventriculostomy and pedicle screw placement simulations, the “Top Gun” program, which also generates numeric accuracy assessments for each resident performing these simulated procedures.33
Procedural simulation for early learners is particularly useful as part of an overarching and validated residency curriculum, with explicit tracking of educational outcomes. In this context, the SNS, on behalf of residency program directors and in collaboration with the neurosurgery Residency Review Committee and ACGME, has formulated a “Matrix” curriculum for US neurosurgery residency training. The SNS is currently working to coordinate that curriculum, including its simulated and live procedural components, with the ACGME milestones instrument, which is required for educational outcomes aggregation and reporting.34,35
More synthetic simulation of complex neurosurgical procedures will continue to benefit from recent advances in computational processing.30,36 In some cases, simulation can re-create the normal and pathological anatomy of individual patients using their preoperative, 3-dimensional imaging, allowing experienced neurosurgeons to plan or practice complex cases in advance of performing them in the operative environment.37
Several simulation modules have been used in endovascular neurosurgery, which is particularly suited to the use of high-fidelity simulators with haptic feedback capability and visual interfaces.38 These systems enable realistic simulation of intracranial and extracranial aneurysm coiling, stent placement, liquid embolization, and stroke thrombolysis.39 Training with endovascular simulators improves subsequent simulator-based skills testing.40-42 Simulator-trained residents may also perform better in the live clinical environment, for example, scoring significantly higher on a validated rating scale than nontrained residents while performing a pair of supervised endovascular procedures for occlusive vascular disease.43
Simulators are now becoming available in various subspecialty areas of neurosurgical practice. Spinal neurosurgeons have developed various model-based simulations of bony anatomy for the placement of pedicle screws and other spinal instrumentation. Virtual reality simulators are also used for 3-dimensional reconstruction of spinal anatomy when simulating or planning actual pedicle screw placement.44-46 More recently, simulators have been developed for laminoplasty and dural repair.47 Model-based simulators for more complex spinal pathology, including scoliosis, degenerative disease, spinal stenosis, and deformity, are in development.32
Many lesions of the cranial base demand complex surgical approaches involving intricate anatomy comprising various delicate, vulnerable structures such as vasculature and cranial nerves. Three-dimensional cranial base models are now available for both simulation and teaching of these approaches.48 Additional simulators for cranial base surgery, currently under development, will include haptic feedback for drilling and soft tissue manipulation, as well as endoscopic approaches.49
There are a number of additional benefits of developing relevant neurosurgical simulation models. First, particularly simple and inexpensive model-based simulation methods may be accessible and scalable to international training programs in less resource-rich countries. Thus, simulation development in North America may aid the growth and development of endogenous training mechanisms in areas of the world currently with inadequate access to neurosurgical care. In addition, model-based simulation in North American residency programs, if offered to medical students, may increase their interest in surgical careers.50
Early neurosurgical learners benefit from procedural and surgical skills simulations, including those based on relatively simple model systems using available materials and technology. Simulation is most effective when used to accomplish specific goals within a larger, validated curriculum. The development of relevant model-based simulators has been possible using an iterative improvement process in the context of national boot camp courses for residents entering neurosurgical training in the United States, as well as in a number of related settings. Validation of simulation assessment measures is a principal ongoing challenge for continued development of simulation in neurosurgical education. Validated assessments will also assist in more accurately evaluating the impact of iterative simulation model improvements.
A podcast related to this article can be accessed online (http://links.lww.com/NEU/A573).
Dr Selden is chair of the Committee on Resident Education of the SNS and a member of the executive committee of the Congress of Neurological Surgeons. Dr Origitano serves as a member of the Committee on Resident Education Subcommittee on Resident Courses, SNS. Dr Hadjipanayis is codirector of the Southeast Region SNS boot camp course. Dr Byrne is chair of the Committee on Resident Education Subcommittee on Resident Courses and a member of the executive committee of the Congress of Neurological Surgeons. No author has any financial or proprietary interest in the courses or any course materials. The SNS resident courses are sponsored by educational grants to the SNS from Stryker, Integra, and Synthes, plus additional in-kind donations from Medtronic, Ethicon, Teleflex, and Zeiss. The Congress of Neurological Surgeons and American Association of Neurological Surgeons serve as administrative sponsors for the SNS boot camp and SNS junior resident course, respectively. No financial or material support is given to any SNS resident course directors or faculty. Only funds necessary for the direct administration of the courses and expense reimbursements are distributed or retained.
We thank Shirley McCartney, PhD, for assistance with the manuscript and Andrew Rekito, MS, for assistance with the figures. We thank the leadership and membership of the SNS for sponsorship of the boot camp courses and the 6 dozen or so course directors and faculty who participate each year. We acknowledge assistance with development and provision of certain materials for the external ventricular drain and lumbar drain model simulations of Andrew Koert and Tom Poss (Medtronic, Inc). We also acknowledge the important contributions to the early development and curriculum of the boot camp courses by the late Dr Christopher Getch.
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Early learners; Models; Neurosurgery; Residency; Simulation
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