Development and initial evaluation of a novel simulation model for comprehensive brain tumor surgery training.

BACKGROUND: Increasing technico-manual complexity of procedures and time constraints necessitates effective neurosurgical training. For this purpose, both screen- and model-based simulations are under investigation. Approaches including 3D printed brains, gelatin composite models, and virtual environments have already been published. However, quality of brain surgery simulation is limited due to discrepancies in visual and haptic experience. Similarly, virtual training scenarios are still lacking sufficient real-world resemblance. In this study, we introduce a novel simulator for realistic neurosurgical training that combines real brain tissue with 3D printing and augmented reality. METHODS: Based on a human CT scan, a skull base and skullcap were 3D printed and equipped with an artificial dura mater. The cerebral hemispheres of a calf's brain were placed in the convexity of the skullcap and tumor masses composed of aspic, water, and fluorescein were injected in the brain. The skullcap and skull base were placed on each other, glued together, and filled up with an aspic water solution for brain fixation. Then, four surgical scenarios were performed in the operating room as follows: (1) simple tumor resection, (2) complex tumor resection, (3) navigated biopsy via burr hole trepanation, and (4) retrosigmoidal craniotomy. Neuronavigation, augmented reality, fluorescence, and ocular-as well as screen-based (exoscopic)-surgery were available for the simulator training. A total of 29 participants performed at least one training scenario of the simulator and completed a 5-item Likert-like questionnaire as well as qualitative interviews. The questionnaire assessed the realism of the tumor model, skull, and brain tissue as well as the capability for training purposes. RESULTS: Visual and sensory realism of the skull and brain tissue were rated,"very good," while the sensory and visual realism of the tumor model were rated "good." Both overall satisfaction with the model and eligibility of the microscope and neurosurgical instruments for training purposes were rated with "very good." However, small size of the calf's brain, its limited shelf life, and the inability to simulate bleedings due to the lack of perfusion were significant drawbacks. CONCLUSION: The combination of 3D printing and real brain tissue provided surgical scenarios with very good real-life resemblance. This novel neurosurgical model features a versatile setup for surgical skill training and allows for efficient training of technological support like image and fluorescence guidance, exoscopic surgery, and robotic technology.

A neurosurgical phantom-based training system with ultrasound simulation.

BACKGROUND: Brain tumor surgeries are associated with a high technical and personal effort. The required interactions between the surgeon and the technical components, such as neuronavigation, surgical instruments and intraoperative imaging, are complex and demand innovative training solutions and standardized evaluation methods. Phantom-based training systems could be useful in complementing the existing surgical education and training. METHODS: A prototype of a phantom-based training system was developed, intended for standardized training of important aspects of brain tumor surgery based on real patient data. The head phantom consists of a three-part construction that includes a reusable base and adapter, as well as a changeable module for single use. Training covers surgical planning of the optimal access path, the setup of the navigation system including the registration of the head phantom, as well as the navigated craniotomy with real instruments. Tracked instruments during the simulation and predefined access paths constitute the basis for the essential objective training feedback. RESULTS: The prototype was evaluated in a pilot study by assistant physicians at different education levels. They performed a complete simulation and a final assessment using an evaluation questionnaire. The analysis of the questionnaire showed the evaluation result as "good" for the phantom construction and the used materials. The learning effect concerning the navigated planning was evaluated as "very good", as well as having the effect of increasing safety for the surgeon before planning and conducting craniotomies independently on patients. CONCLUSIONS: The training system represents a promising approach for the future training of neurosurgeons. It aims to improve surgical skill training by creating a more realistic simulation in a non-risk environment. Hence, it could help to bridge the gap between theoretical and practical training with the potential to benefit both physicians and patients.

Assessment of pedicle screw placement accuracy, procedure time, and radiation exposure using a miniature robotic guidance system.

STUDY DESIGN: Controlled, cadaveric implantation trial. OBJECTIVE: To evaluate the effect of a robotic guidance system on screw placement accuracy, amount of radiation exposure, and length of procedure time during percutaneous pedicle screw implantation. SUMMARY OF BACKGROUND DATA: Pedicle screws are associated with low complication rates, and several computer-assisted image guidance systems exist that facilitate accurate screw placement. However, these systems may represent substantial radiation exposure risk to patients and surgeons. METHODS: We implanted 234 pedicle screws in 12 cadavers (study group: 15 surgeons, 197 screws, and 10 specimens; control group: 2 surgeons, 37 screws, and 2 specimens). We measured procedure time, fluoroscopy time, and radiation exposure and evaluated screw placement accuracy with computed tomography scans. To evaluate the learning curve, we compared measurements with those of an experienced robotic guidance user through the 2-sample (heteroscedastic), 1-tail t test (P< 0.05). RESULTS: Relative to control, the study group had fewer screw placement deviations (average, 2.6±0.7 mm vs. 1.1±0.4 mm; P<0.0001), fewer pedicle wall breaches of 4 mm or greater (average, 5.4% vs. 1.5%), lower surgeon radiation exposure (average, 136 mrem vs. 4.2 mrem), lower fluoroscopy time per screw (average, 33.0 s vs. 0.9 s), and shorter procedure time (average, 1.98 h vs. 1.23 h). Use of robotic guidance increased the accuracy of percutaneous pedicle screw placement by 58%, thereby reducing the risk of neurologic injury (as measured by breaches >4 mm), new-user radiation exposure (by 98.2%), and procedure time (by 36%). CONCLUSIONS: The advantages associated with a robotic guidance system may make the surgeon more at ease about offering minimally invasive or percutaneous surgical options to patients and more comfortable about implementing pedicle-based fixation in general. This advanced technology may also allow inclusion of patients with complicated anatomic deformities, who are often excluded from pedicle screw-based surgery options.

Contribution of technological progress, inter-operator difference and experience of operators in Gamma Knife radiosurgery for arteriovenous malformation.

BACKGROUND: Outcomes of microsurgical resection for cerebral arteriovenous malformation (AVM) largely depend on the skill and experience of the operator, but it is still unknown whether such individual differences similarly exists in stereotactic radiosurgery (SRS) for AVM. The purpose of this study was to assess the influence of the inter-operator difference and technological progress in SRS for AVM. METHODS: During the past 20 years, 514 patients with AVM were treated by SRS by four neurosurgeons. Until 1992, angiography was solely used for dose planning, and computed tomography (CT) or magnetic resonance imaging (MRI) was jointly used thereafter. In the early years, dose planning was calculated with the first-generation computer system, KULA, and manually superimposed on the radiographical images. After 1998, treatment planning was made on the computer monitor with sophisticated dose-planning software, GammaPlan. The influence of inter-operator difference, the operator's experience, and radiographical or radiosurgical technologies on the rates of obliteration and morbidity was assessed by multivariate analyses. RESULTS: The factors associated with higher obliteration rates were higher margin dose (p = 0.003) and the presence of hemorrhagic event before SRS (p = 0.002). There was no significant difference in either obliteration rate or morbidity among the five operators. However, after introduction of CT and MRI on dose planning, the risk of adverse events was significantly decreased. Especially for AVM larger than 3 cm in maximum diameter, each operator's experience (p = 0.040) and use of GammaPlan (p = 0.015) reduced morbidity. CONCLUSIONS: Inter-operator difference was not a significant factor associated with the rates of obliteration and the risk of adverse events after SRS for AVM in the multivariate analyses. Progress of the sophisticated planning software and the experience of the operator were associated with lower morbidity for larger lesions.

Frameless image-guided neuroendoscopy training in real simulators.

BACKGROUND: Over the last decade, neuroendoscopy has re-emerged as an interesting option in the management of intraventricular lesions in both children and adults. Nonetheless, as it has become more difficult to use cadaveric specimens in training, the development of alternative methods was vital. The aim of this study was to analyze the performance of a real simulator, in association with image-guided navigation, as a teaching tool for the training of intraventricular endoscopic procedures. METHODS: 3 real simulators were built using a special type of resin. 1 was designed to represent the abnormally enlarged ventricles, making it possible for a third ventriculostomy to be performed. The remaining 2 were designed to simulate a person's skull and brain bearing intraventricular lesions, which were placed as follows: in the foramen of Monro region, in the frontal and occipital horns of the lateral ventricles and within the third ventricle. In all models, MRI images were obtained for navigation guidance. Within the ventricles, the relevant anatomic structures and the lesions were identified through the endoscope and compared with the position given by the navigation device. The next step consisted of manipulating the lesions, using standard endoscopic techniques. RESULTS: We observed that the models were MRI compatible, easy and safe to handle. They nicely reproduced the intraventricular anatomy and brain consistence, as well as simulated intraventricular lesions. The image-based navigation was efficient in guiding the surgeon through the endoscopic procedure, allowing the selection of the best approach as well as defining the relevant surgical landmarks for each ventricular compartment. Nonetheless, as expected, navigation inaccuracies occurred. After the training sessions the surgeons felt they had gained valued experience by dealing with intraventricular lesions employing endoscopic techniques. CONCLUSION: The use of real simulators in association with image-guided navigation proved to be an effective tool in training for neuroendoscopy.

Virtual ventriculostomy with 'shifted ventricle': neurosurgery resident surgical skill assessment using a high-fidelity haptic/graphic virtual reality simulator.

Based on a study of 48 neurological residents using a high fidelity haptic/graphic virtual reality simulator to perform ventricular cannulation, we recorded absolute Euclidean distance from the catheter tip to the foramen of Monroe within the ventricle. The data suggest that as expected, successful first attempts to cannulate the virtual 'shifted ventricle' are much less frequent than previous assessments with normal virtual ventricular anatomy. Furthermore, the significant improvement observed by the second attempt implies that the learning curve has been affected and the process 'jump started'.

Development of a brain simulator for intracranial targeting: Technical note.

Learning and enhancing of manual skills in the field of neurosurgery requires an intensive training which can be maintained by using virtual reality (VR)-based or physical model (PM)-based simulators. However, both simulator types are limited to one specific intracranial procedure, e.g. the application of an external ventricular drainage (EVD), and they do not provide any accuracy verification. We present a brain simulator which consists of a 3D human skull model having five electroconductive balls in its interior. The installed balls represent intracranial target points providing various accuracy problems in neuronavigation. They are electrically contacted to lamps getting an optical signal by touching them with a current-carrying target tool. The simulator fulfills two requirements: First, it can prove the accuracy of navigation systems and algorithms. Second, it allows becoming familiar with a navigation system's application in an ex vivo setting. It could be a helpful device in neurosurgical skills labs.

Current status of training environments in neuro-interventional practice: are animal models still contemporary?

PURPOSE: Several different training environments for practicing neurointerventional procedures have been realized in silico, in vitro, and in vivo. We seek to replace animal-based training with suitable alternatives. In an effort to determine present training model distribution and preferences, we interviewed interventional neuroradiologists from 25 different countries about their experience in distinct training environments. METHODS: A voluntary online survey comprising 24 questions concerning the different training facilities was designed and electronically conducted with the members of the European Society for Minimally Invasive Neurological Therapy. RESULTS: Seventy-one physicians with an average experience of 11.8 (±8.7) years completed the survey. The majority of participants had experience with animal-based training (eg, stroke intervention: 36; 50.7%). Overall, animal-based training was rated as the most suitable environment to practice coil embolization (20 (±6)), flow diverter placement (13 (±7)), and stroke intervention (13.5 (±9)). In-vitro training before using a new device in patients was supported by most participants (35; 49.3%). Additionally, preference for certain training models was related to the years of experience. CONCLUSION: This survey discloses the preferred training modalities in European neurointerventional centers with the majority of physicians supporting the general concept of in-vitro training, concomitantly lacking a standardized curriculum for educating neurointerventional physicians. Most suitable training modalities appeared to be dependent on procedure and experience. As animal-based training is still common, alternate artificial environments meeting these demands must be further developed.

The Barrow Innovation Center Case Series: A Novel 3-Dimensional-Printed Retractor for Use with Electromagnetic Neuronavigation Systems.

OBJECTIVE: The Barrow Innovation Center consists of an educational program that promotes interdisciplinary collaboration among neurosurgery, legal, and engineering professionals to foster the development of new medical devices. This report describes a common issue faced during the placement of ventricular shunts for the treatment of hydrocephalus and the solution to this problem that was developed through the Barrow Innovation Center. METHODS: Neurosurgery residents involved in the Barrow Innovation Center presented the problem of ferromagnetic retractors interfering with pinless image-guidance systems at a monthly meeting. Potential solutions were openly discussed by an interdisciplinary committee of neurosurgeons, patent lawyers, and biomedical engineers. The committee decided to pursue development of a novel self-retaining retractor made of nonferromagnetic material as a solution to the problem. RESULTS: Each retractor design was tested in the cadaver laboratory for size and functionality. A final design was chosen and used in a surgical case requiring ventriculoperitoneal shunt placement. The new retractor successfully retracted the scalp without interfering with the electromagnetic image-guidance system. CONCLUSIONS: Through the interdisciplinary Barrow Innovation Center program, a newly designed, 3-dimensional-printed skin and soft-tissue retractor was created, along with an innovative universal shunt retainer. Through this integrated program dedicated to surgical innovation (i.e., the Barrow Innovation Center), the process of developing and implementing new technology at our institution has been streamlined, creating a culture of innovation within the neurosurgery training program.

Accuracy of ventriculostomy catheter placement using a head- and hand-tracked high-resolution virtual reality simulator with haptic feedback.

OBJECT: The purpose of this study was to evaluate the accuracy of ventriculostomy catheter placement on a head- and hand-tracked high-resolution and high-performance virtual reality and haptic technology workstation. METHODS: Seventy-eight fellows and residents performed simulated ventriculostomy catheter placement on an ImmersiveTouch system. The virtual catheter was placed into a virtual patient's head derived from a computed tomography data set. Participants were allowed one attempt each. The distance from the tip of the catheter to the Monro foramen was measured. RESULTS: The mean distance (+/- standard deviation) from the final position of the catheter tip to the Monro foramen was 16.09 mm (+/- 7.85 mm). CONCLUSIONS: The accuracy of virtual ventriculostomy catheter placement achieved by participants using the simulator is comparable to the accuracy reported in a recent retrospective evaluation of free-hand ventriculostomy placements in which the mean distance from the catheter tip to the Monro foramen was 16 mm (+/- 9.6 mm).

Navigation-Guided Endoscopic Intraventricular Injectable Tumor Model: Cadaveric Tumor Resection Model for Neurosurgical Training.

BACKGROUND: Intraventricular tumors present difficult challenges to the neurosurgeon. Neurosurgeons have begun to explore the possibilities of using the endoscope in the radical resection of solid intraventricular lesions. There is a steep learning curve when dealing with such lesions with an endoscope. OBJECTIVE: The aim of this study was to create a laboratory training model for neuroendoscopic surgery of intraventricular lesions guided by the navigation system. We believe this technique is more reliable than the traditional approach using contrast injection with C-arm x-ray guidance. MATERIALS AND METHODS: Five formalin-fixated, latex-injected cadaveric heads were used. The arterial system was injected with red latex through the common carotid arteries, and the venous system was injected with blue latex through the internal jugular veins at the C6 vertebral level. The contrast-enhancing tumor polymer, Stratathane resin ST-504-derived polymer (SRSDP), was injected into the lateral ventricle via Frazier's point under direct endoscopic visualization and real-time neuronavigation guidance. When navigation was used for trajectory planning, the peel-away sheath was registered using a frameless navigational system (BrainLAB, Feldkirchen, Germany). A questionnaire was distributed to all participants in an endoscopic cadaveric course in which the models were used to evaluate the endoscopic tumor model. RESULTS: Neurosurgeons participating in the course performed an endoscopic approach to resect the intraventricular tumor model through an ipsilateral frontal burr hole. The properties of the SRSDP mixture could be manipulated through varying concentrations of the materials used, in order to reach the desired consistency of a nodular solid lesion and possibility for piecemeal resection. The tumor model allowed participants to compare between normal and pathologic endoscopic anatomy in the same cadaveric head. CONCLUSION: This injectable tumor model with the combination of neuroendoscopy and navigation can improve the accuracy of the endoscopic approach and minimize the risk of cadaveric brain specimen damage that in return augments the feeling of lifelike conditions. Using this endoscopic injectable tumor model technique can assist neurosurgeons' preparation for the challenges associated with an endoscopic piecemeal resection of a solid lesion in the lateral or third ventricle.

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.

Cerebrospinal fluid reconstitution via a perfusion-based cadaveric model: feasibility study demonstrating surgical simulation of neuroendoscopic procedures.

Cadaveric surgical simulation carries the advantage of realistic anatomy and haptic feedback but has been historically difficult to model for intraventricular approaches given the need for active flow of CSF. This feasibility study was designed to simulate intraventricular neuroendoscopic approaches and techniques by reconstituting natural CSF flow in a cadaveric model. In 10 fresh human cadavers, a simple cervical laminectomy and dural opening were made, and a 12-gauge arterial catheter was introduced. Saline was continuously perfused at physiological CSF pressures to reconstitute the subarachnoid space and ventricles. A neuroendoscope was subsequently inserted via a standard right frontal bur hole. In 8 of the 10 cadavers, adequate reconstitution and endoscopic access of the lateral and third ventricles were achieved. In 2 cadavers, ventricular access was not feasible, perhaps because of a small ventricle size and/or deteriorated tissue quality. In all 8 cadavers with successful CSF flow reconstitution and endoscopic access, identifying the foramen of Monro was possible, as was performing septum pellucidotomy and endoscopic third ventriculostomy. Furthermore, navigation of the cerebral aqueduct, fourth ventricle, prepontine cistern, and suprasellar cistern via the lamina terminalis was possible, providing a complementary educational paradigm for resident education that cannot typically be performed in live surgery. Surgical simulation plays a critical and increasingly prominent role in surgical education, particularly for techniques with steep learning curves including intraventricular neuroendoscopic procedures. This novel model provides feasible and realistic surgical simulation of neuroendoscopic intraventricular procedures and approaches.

Real-time soft tissue modelling for web-based surgical simulation: SurfaceChainMail.

The Web provides a useful environment for simple surgical training simulations. A combination of VRML for 3D rendering, and Java code for the simulation engine, has been used for a range of simple neurosurgical demonstrators. However the elements in these simulators are rigid, to avoid the computational complexity of deformable modelling. In this paper we describe a variation of the ChainMail technique that allows us to provide real-time deformable modelling, even in a Web browser environment on a PC. Our new algorithm, SurfaceChainMail, has been used to develop a simulator for the cutting of two layers of tissue, and separating the layers by pulling them apart.

The value of neurosurgical and intraoperative magnetic resonance imaging and diffusion tensor imaging tractography in clinically integrated neuroanatomy modules: a cross-sectional study.

Neuroanatomy is considered to be one of the most difficult anatomical subjects for students. To provide motivation and improve learning outcomes in this area, clinical cases and neurosurgical images from diffusion tensor imaging (DTI) tractographies produced using an intraoperative magnetic resonance imaging apparatus (MRI/DTI) were presented and discussed during integrated second-year neuroanatomy, neuroradiology, and neurosurgery lectures over the 2008-2011 period. Anonymous questionnaires, evaluated according to the Likert scale, demonstrated that students appreciated this teaching procedure. Academic performance (examination grades for neuroanatomy) of the students who attended all integrated lectures of neuroanatomy, was slightly though significantly higher compared to that of students who attended these lectures only occasionally or not at all (P=0.04). Significantly better results were obtained during the national progress test (focusing on morphology) by students who attended the MRI/DTI-assisted lectures, compared to those who did so only in part or not at all, compared to the average student participating in the national test. These results were obtained by students attending the second, third and, in particular, the fourth year (P≤0.0001) courses during the three academic years mentioned earlier. This integrated neuroanatomy model can positively direct students in the direction of their future professional careers without any extra expense to the university. In conclusion, interactive learning tools, such as lectures integrated with intraoperative MRI/DTI images, motivate students to study and enhance their neuroanatomy education.

Three-dimensional anatomical accuracy of cranial models created by rapid prototyping techniques validated using a neuronavigation station.

In neurosurgery and ear, nose and throat surgery the application of computerised navigation systems for guiding operations has been expanding rapidly. However, suitable models to train surgeons in using navigation systems are not yet available. We have developed a technique using an industrial, rapid prototyping process from which accurate spatial models of the cranium, its contents and pathology can be reproduced for teaching. We were able to register, validate and navigate using these models with common available navigation systems such as the Medtronic StealthStation S7®.

Informatic surgery: the union of surgeon and machine.

OBJECTIVE: Surgical robotics present new and unique opportunities for the training and practice of neurosurgery, beyond the promise of the minimally invasive paradigm. METHODS: Robotic systems have been developed that simulate the sight, sound, and touch of surgery allowing surgical training to evolve past an apprenticeship and patient-based model towards standardization and virtual training. RESULTS: The development of data-driven surgery, incorporating all information available to the human senses and advanced imaging modalities, give the modern surgeon an abundance of knowledge of the operative objectives and surgical site. Notwithstanding the automation of computers, the surgeon must not be excluded from this feedback loop as computer hardware and software is as-yet unable to compare to human data synthesis and decision making. CONCLUSIONS: It is this union of surgeon and machine and the continued evolution of surgery toward a data-driven science rather than an experiential art that are required for the definitive advancement of patient outcomes.

[Computer-assisted intraoperative navigation at the anterior skull base]. / Computerassistierte intraoperative navigation an der vorderen schädelbasis.

Intraoperative 3D-navigation at the anterior skull base has become a very valuable tool in the last years. For a successful use the clinical pathways need a slight adaptation only to provide the radiologic imagery to the system. Established algorithms and standardized protocols have proven 3D-navigation systems as a valuable clinical tool, when used in conjunction with appropriate intraoperative quality assurance. Ease-of-use and reliable intraoperative quality assurance is an active area of research that, combined with adequate strategies for referencing the patient to preoperative high-resolution radiologic data, will make 3D-navigation at the lateral skull base a successful clinical tool as well.