Low-flow and high-flow neurosurgical bypass and anastomosis training models using human and bovine placental vessels: a histological analysis and validation study

Neurosurgical Microvascular Anastomosis: Systematic Review of the Existing Simulators and Proposal of a New Training Classification System

BACKGROUND

The literature lacks a combined analysis of neurosurgical microvascular anastomosis training models. We performed a systematic literature search to provide an overview of the existing models and proposed a classification system based on the level of simulation and reproducibility of the microvascular anastomosis.

METHODS

The systematic literature search followed the PRISMA guidelines. We consulted MEDLINE, Web of Knowledge, and EMBASE independently for papers about bypass training models. Every training model was analyzed according to six tasks supposed to esteem their fidelity to the real operative setting by using a scoring system from zero to two. Finally, authors classified the models into five classes, from A to E, by summing the individual scores.

RESULTS

This study included 109 papers for analysis. Training models were grouped into synthetic tubes, ex vivo models (animal vessels, fresh human cadavers, human placentas) and in vivo simulators (live animals-rats, rabbits, pigs). By applying the proposed classification system, live animals and placentas obtained the highest scores, falling into class A (excellent simulators). Human cadavers and animal vessels (ex vivo) were categorized in class B (good simulators), followed by synthetic tubes (class C, reasonable simulators).

CONCLUSIONS

The proposed classification system helps the neurosurgeon to analyze the available training models for microvascular anastomosis critically, and to choose the most appropriate one according to the skills they need to improve.

Validation of a dynamic 4D microsurgical bypass simulator for training and teaching microvascular anastomosis techniques with blood flow and fluorescence imaging

Objective

Microvascular anastomosis is challenging, and training surgeons to develop and maintain skills is imperative. Current training models either miss the simulation of the surgical workflow, lack 3D key-hole space, need ethical approval, require special preparation, or lack realism. To circumvent these issues, this study describes the use of a mixed reality 3D printed model with integrated blood flow for training cerebral anastomosis and assesses its validity.

Methods

Different-sized 3D-printed artificial micro artery models in a 3D brain space with a keyhole opening were used. The model was connected to a 4D simulator to induce pulsatile blood flow. Neurosurgical microscopes and exoscopes were used for visualization. Nine participants (n = 6 board-certified cerebrovascular neurosurgeons; n = 3 in-training) participated in the study and practiced anastomosis techniques with the simulator. Two senior, experienced vascular neurosurgeons mentored live teaching activity on the simulator. Participants completed a survey to score the face and content validity of the simulation on a 5-point Likert scale. Simulation time and anastomosis score differences between in-training and board-certified participants were compared for construct validity.

Results

Participants scored the simulation difficulty similar to actual surgery, proving face validity. All participants agreed that practice on the provided simulator models would improve bypass techniques (μ = 4.67/5 ± 0.47) and instrument handling (μ = 4.56/5 ± 0.68). Board-certified participants had better anastomosis scores than in-training participants (non-significant difference).

Conclusions

The 4D simulator and the high-fidelity artificial 3D printed model effectively simulated actual bypass surgery in a key-hole fashion with blood flow abilities. Limited resources and preparation time are needed for the training setup. The model provides benefits in learning and maintaining anastomosis skills and allows for easy adaptation to different microanatomical scenarios.

Synthetic Simulators for Microsurgery Training: A Systematic Review

Background

Microsurgery has a steep learning curve. Synthetic simulators have proven to be useful training tools for the initial learning stages, as well as being ethically sound, viable, safe, and cost-effective. The objective of this review was to determine the quality, effectiveness, and validity of these simulators as well as to assess their ability to evaluate microsurgical skills.

Methods

A systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines was performed. We searched databases (Web of Science, Scopus, and PubMed) to identify original articles describing synthetic training models for microsurgery. Three reviewers evaluated articles for inclusion following predefined selection criteria. Data were extracted from full-texts of included articles.

Results

Thirty-nine studies met the inclusion criteria. A total of 38 different devices have been recorded. Microsurgical training devices offer a low-cost, fast, and consistent method to concretely quantify and assess the initial microsurgical skills of trainees using standardized exercises that can be scored by the examiner. According to the authors, the outcomes were satisfactory, with a tangible improvement in microsurgical abilities, despite the lack of a common comparison scale.

Conclusions

Thanks to their availability, cost, and effectiveness, synthetic models are the recommended option to train basic, intermediate and advanced procedures before executing them on in vivo models.

Three-Vessel Anastomosis for Direct Multiterritory Cerebral Revascularization: Case Series

BACKGROUND AND OBJECTIVE

Cerebral revascularization of multiple territories traditionally requires multiple constructs, serial anastomoses, or a combination of direct and indirect approaches. A novel 3-vessel anastomosis technique allows for direct, simultaneous multiterritory cerebral revascularization using a single interposition graft. We herein present our experience with this approach.

METHODS

Retrospective review of perioperative data and outcomes for patients undergoing multiterritory cerebral revascularization using a 3-vessel anastomosis from 2019 to 2023.

RESULTS

Five patients met inclusion criteria (median age 53 years [range 12-73]). Three patients with complex middle cerebral artery aneurysms (1 ruptured) were treated with proximal ligation or partial/complete clip trapping and multiterritory external carotid artery-M2-M2 revascularization using a saphenous vein interposition graft. Two patients with moyamoya disease, prior strokes, and predominately bilateral anterior cerebral artery hypoperfusion were treated with proximal superficial temporal artery-A3-A3 revascularization using a radial artery or radial artery fascial flow-through free flap graft. No patients experienced significant surgery-related ischemia. Bypass patency was 100%. One patient had new strokes from vasospasm after subarachnoid hemorrhage. One patient required a revision surgery for subdural hematoma evacuation and radial artery fascial flow-through free flap debridement, without affecting bypass patency or neurologic outcome. On hospital discharge, median Glasgow Outcome Scale and modified Rankin Scale scores were 4 (range 3-5) and 2 (range 0-5), respectively. On follow-up, 1 patient died from medical complications of their presenting stroke; Glasgow Outcome Scale and modified Rankin Scale scores were otherwise stable or improved.

CONCLUSION

The 3-vessel anastomosis technique can be considered for simultaneous revascularization of multiple intracranial territories.

Dye-Perfused Human Placenta for Simulation in a Microsurgery Laboratory for Plastic Surgeons

In recent decades, a number of simulation models for microsurgical training have been published. The human placenta has received extensive validation in microneurosurgery and is a useful instrument to facilitate learning in microvascular repair techniques as an alternative to using live animals. This study uses a straightforward, step-by-step procedure for instructing the creation of simulators with dynamic flow to characterize the placental vascular tree and assess its relevance for plastic surgery departments. Measurements of the placental vasculature and morphological characterization of 18 placentas were made. After the model was used in a basic microsurgery training laboratory session, a survey was given to nine plastic surgery residents, two microsurgeons, and one hand surgeon. In all divisions, venous diameters were larger than arterial diameters, with minimum diameters of 0.8 and 0.6 mm, respectively. The majority of the participants considered that the model faithfully reproduces a real microsurgical scenario; the consistency of the vessels and their dissection are similar in in vivo tissue. Furthermore, all the participants considered that this model could improve their surgical technique and would propose it for microsurgical training. As some of the model's disadvantages, an abundantly thick adventitia, a thin tunica media, and higher adherence to the underlying tissue were identified. The color-perfused placenta is an excellent tool for microsurgical training in plastic surgery. It can faithfully reproduce a microsurgical scenario, offering an abundance of vasculature with varying sizes similar to tissue in vivo, enhancing technical proficiency, and lowering patient error.

Key role of microsurgical dissections on cadaveric specimens in neurosurgical training: Setting up a new research anatomical laboratory and defining neuroanatomical milestones

Introduction

Neurosurgery is one of the most complex surgical disciplines where psychomotor skills and deep anatomical and neurological knowledge find their maximum expression. A long period of preparation is necessary to acquire a solid theoretical background and technical skills, improve manual dexterity and visuospatial ability, and try and refine surgical techniques. Moreover, both studying and surgical practice are necessary to deeply understand neuroanatomy, the relationships between structures, and the three-dimensional (3D) orientation that is the core of neurosurgeons' preparation. For all these reasons, a microsurgical neuroanatomy laboratory with human cadaveric specimens results in a unique and irreplaceable training tool that allows the reproduction of patients' positions, 3D anatomy, tissues' consistencies, and step-by-step surgical procedures almost identical to the real ones.

Methods

We describe our experience in setting up a new microsurgical neuroanatomy lab (IRCCS Neuromed, Pozzilli, Italy), focusing on the development of training activity programs and microsurgical milestones useful to train the next generation of surgeons. All the required materials and instruments were listed.

Results

Six competency levels were designed according to the year of residency, with training exercises and procedures defined for each competency level: (1) soft tissue dissections, bone drilling, and microsurgical suturing; (2) basic craniotomies and neurovascular anatomy; (3) white matter dissection; (4) skull base transcranial approaches; (5) endoscopic approaches; and (6) microanastomosis. A checklist with the milestones was provided.

Discussion

Microsurgical dissection of human cadaveric specimens is the optimal way to learn and train on neuroanatomy and neurosurgical procedures before performing them safely in the operating room. We provided a “neurosurgery booklet” with progressive milestones for neurosurgical residents. This step-by-step program may improve the quality of training and guarantee equal skill acquisition across countries. We believe that more efforts should be made to create new microsurgical laboratories, popularize the importance of body donation, and establish a network between universities and laboratories to introduce a compulsory operative training program.

Seven bypasses simulation set: description and validity assessment of novel models for microneurosurgical training

OBJECTIVE

Microsurgical training remains indispensable to master cerebrovascular bypass procedures, but simulation models for training that accurately replicate microanastomosis in narrow, deep-operating corridors are lacking. Seven simulation bypass scenarios were developed that included head models in various surgical positions with premade approaches, simulating the restrictions of the surgical corridors and hand positions for microvascular bypass training. This study describes these models and assesses their validity.

METHODS

Simulation models were created using 3D printing of the skull with a designed craniotomy. Brain and external soft tissues were cast using a silicone molding technique from the clay-sculptured prototypes. The 7 simulation scenarios included: 1) temporal craniotomy for a superficial temporal artery (STA)-middle cerebral artery (MCA) bypass using the M4 branch of the MCA; 2) pterional craniotomy and transsylvian approach for STA-M2 bypass; 3) bifrontal craniotomy and interhemispheric approach for side-to-side bypass using the A3 branches of the anterior cerebral artery; 4) far lateral craniotomy and transcerebellomedullary approach for a posterior inferior cerebellar artery (PICA)-PICA bypass or 5) PICA reanastomosis; 6) orbitozygomatic craniotomy and transsylvian-subtemporal approach for a posterior cerebral artery bypass; and 7) extended retrosigmoid craniotomy and transcerebellopontine approach for an occipital artery-anterior inferior cerebellar artery bypass. Experienced neurosurgeons evaluated each model by practicing the aforementioned bypasses on the models. Face and content validities were assessed using the bypass participant survey.

RESULTS

A workflow for model production was developed, and these models were used during microsurgical courses at 2 neurosurgical institutions. Each model is accompanied by a corresponding prototypical case and surgical video, creating a simulation scenario. Seven experienced cerebrovascular neurosurgeons practiced microvascular anastomoses on each of the models and completed surveys. They reported that actual anastomosis within a specific approach was well replicated by the models, and difficulty was comparable to that for real surgery, which confirms the face validity of the models. All experts stated that practice using these models may improve bypass technique, instrument handling, and surgical technique when applied to patients, confirming the content validity of the models.

CONCLUSIONS

The 7 bypasses simulation set includes novel models that effectively simulate surgical scenarios of a bypass within distinct deep anatomical corridors, as well as hand and operator positions. These models use artificial materials, are reusable, and can be implemented for personal training and during microsurgical courses.

A novel, reusable, realistic neurosurgical training simulator for cerebrovascular bypass surgery: Iatrotek® bypass simulator validation study and literature review

Background

Microanastomosis is a challenging technique requiring continuous training to be mastered. Several models have been proposed, but few effectively reflect a real bypass surgery; even fewer are reusable, most are not easily accessible, and the setting is often quite long. We aim to validate a simplified, ready-to-use, reusable, ergonomic bypass simulator.

Methods

Twelve novice and two expert neurosurgeons completed eight End-to-End (EE), eight End-to-Side (ES), and eight Side-to-Side (SS) microanastomoses using 2-mm synthetic vessels. Data on time to perform bypass (TPB), number of sutures and time required to stop potential leaks were collected. After the last training, participants completed a Likert Like Survey for bypass simulator evaluation. Each participant was assessed using the Northwestern Objective Microanastomosis Assessment Tool (NOMAT).

Results

When comparing the first and last attempts, an improvement of the mean TPB was registered in both groups for the three types of microanastomosis. The improvement was always statistically significant in the novice group, while in the expert group, it was only significant for ES bypass. The NOMAT score improved in both groups, displaying statistical significance in the novices for EE bypass. The mean number of leakages, and the relative time for their resolution, also tended to progressively reduce in both groups by increasing the attempts. The Likert score expressed by the experts was slightly higher (25 vs. 24.58 by the novices).

Conclusions

Our proposed bypass training model may represent a simplified, ready-to-use, reusable, ergonomic, and efficient system to improve eye-hand coordination and dexterity in performing microanastomoses.

From textbook to patient: a practical guide to train the end-to-side microvascular anastomosis

Microvascular anastomosis is one of the most challenging neurosurgical techniques. Mastering this technique allows to perform intracranial bypass with arteries of small caliber usually placed in deep narrow surgical fields. The aim of this paper is to describe step by step end-to-side microanastomosis training method by using polyvinyl alcohol (PVA) hydrogel tubing as it is easily reproducible. The tubing comes in sizes from 0.3 mm to 5 mm and has a texture and consistency similar to real vessels. This is based on the Teishinkai Hospital anastomosis technique. Continuous practice in microvascular anastomosis is of great importance in training vascular neurosurgeon. The PVA hydrogel tubing described in this article are useful and cost-effective material in the training of microvascular anastomosis. This practical guide model is easy to set up for repeated practice, and will contribute to facilitate 'off-the-job' training by young neurosurgeons and the development and maintenance of microsurgical skills in both resident neurosurgeons and experts who wish to master the various levels of anastomosis technique. There is no shortcut to master this technique, only hard work and perseverance.

Spotlight on clinical strategies of Chronic Internal Carotid Artery Occlusion: Endovascular interventions and external-intracarotid bypasses compared to conservative treatment

Chronic internal carotid artery occlusion (CICAO) has high prevalence and incidence rates, and patients with CICAO can be completely asymptomatic, experience a devastating stroke or die. It is important to note that CICAO causes cerebrovascular accidents. Currently, the external carotid-internal carotid (EC-IC) bypass technique is used to treat CICAO. However, many clinical studies showed that EC-IC bypass was not beneficial for many patients with CICAO. Meanwhile, endovascular intervention treatment options for CICAO are evolving, and an increasing number of patients are undergoing endovascular intervention therapy. Accordingly, a review comparing both techniques is warranted. For this review, we searched PubMed and collected relevant case study reports comparing endovascular interventional therapy and internal and external cervical bypass surgeries to provide strategies for clinical treatment.

The human placenta as a model for training and research in mechanical thrombectomy: Clarifications and use of the chorionic plate veins

Indications for mechanical thrombectomy in acute ischemic stroke are increasing, resulting in the continuous development of new devices and techniques. Therefore, there is a need for a realistic testing and training environment that offers the opportunity to practice different procedures and test the latest devices. Some authors have described the use of the human placenta as a model for neurointerventional surgery, with striking similarities to real-life conditions. This model has many advantages, including its relatively low cost and minimal infrastructure requirements, with fewer ethical concerns compared to animal models. So far, some preparation and set-up details were missing, and only arteries from the chorionic plate were used. This article provides the necessary clarifications and a mapping of the chorionic plate veins, so that the use of this model, which is particularly well suited for mechanical thrombectomy, can be as easy and wide as possible. A video explaining how to prepare the model is provided.

Evaluation of simulation models in neurosurgical training according to face, content, and construct validity: a systematic review

BACKGROUND

Neurosurgical training has been traditionally based on an apprenticeship model. However, restrictions on clinical exposure reduce trainees' operative experience. Simulation models may allow for a more efficient, feasible, and time-effective acquisition of skills. Our objectives were to use face, content, and construct validity to review the use of simulation models in neurosurgical education.

METHODS

PubMed, Web of Science, and Scopus were queried for eligible studies. After excluding duplicates, 1204 studies were screened. Eighteen studies were included in the final review.

RESULTS

Neurosurgical skills assessed included aneurysm clipping (n = 6), craniotomy and burr hole drilling (n = 2), tumour resection (n = 4), and vessel suturing (n = 3). All studies assessed face validity, 11 assessed content, and 6 assessed construct validity. Animal models (n = 5), synthetic models (n = 7), and VR models (n = 6) were assessed. In face validation, all studies rated visual realism favourably, but haptic realism was key limitation. The synthetic models ranked a high median tactile realism (4 out of 5) compared to other models. Assessment of content validity showed positive findings for anatomical and procedural education, but the models provided more benefit to the novice than the experienced group. The cadaver models were perceived to be the most anatomically realistic by study participants. Construct validity showed a statistically significant proficiency increase among the junior group compared to the senior group across all modalities.

CONCLUSION

Our review highlights evidence on the feasibility of implementing simulation models in neurosurgical training. Studies should include predictive validity to assess future skill on an individual on whom the same procedure will be administered. This study shows that future neurosurgical training systems call for surgical simulation and objectively validated models.

Novel System of Simulation Models for Aneurysm Clipping Training: Description of Models and Assessment of Face, Content, and Construct Validity

BACKGROUND

Aneurysm clipping simulation models are needed to provide tactile feedback of biological vessels in a nonhazardous but surgically relevant environment.

OBJECTIVE

To describe a novel system of simulation models for aneurysm clipping training and assess its validity.

METHODS

Craniotomy models were fabricated to mimic actual tissues and movement restrictions experienced during actual surgery. Turkey wing vessels were used to create aneurysm models with patient-specific geometry. Three simulation models (middle cerebral artery aneurysm clipping via a pterional approach, anterior cerebral artery aneurysm clipping via an interhemispheric approach, and basilar artery aneurysm clipping via an orbitozygomatic pretemporal approach) were subjected to face, content, and construct validity assessments by experienced neurosurgeons (n = 8) and neurosurgery trainees (n = 8).

RESULTS

Most participants scored the model as replicating actual aneurysm clipping well and scored the difficulty of clipping as being comparable to that of real surgery, confirming face validity. Most participants responded that the model could improve clip-applier-handling skills when working with patients, which confirms content validity. Experienced neurosurgeons performed significantly better than trainees on all 3 models based on subjective (P = .003) and objective (P < .01) ratings and on time to complete the task (P = .04), which confirms construct validity. Simulations were used to discuss clip application strategies and compare them to prototype clinical cases.

CONCLUSION

This novel aneurysm clipping model can be used safely outside the wet laboratory; it has high face, content, and construct validity; and it can be an effective training tool for microneurosurgery training during aneurysm surgery courses.

Microsurgical training: vascular control and intraoperative vessel rupture in the human placenta infusion model

BACKGROUND

Microsurgery is a challenging discipline. Regular lab training under the operating microscope has been the environment where most surgeons have mastered the skills and techniques inherent to most microneurosurgical procedures. However, some critical scenarios remain difficult to master or simulate. We describe a step-by-step method for how to build a low-cost, feasible, and widely available model that allows residents to familiarize themselves with demanding critical situations such as intraoperative rupture of major vessels.

METHODS

After delivery, nine fresh human placentas were transferred to the lab. The umbilical vein was cannulated for normal saline infusion. Several hands-on procedures were performed under direct microscope vision. Operating microscope setup, allantoic membrane splitting, vascular dissection and vessel injury, and repair exercises were simulated and video recorded. Indocyanine green was administered to simulate intraoperative angiography.

RESULTS

The model can be setup in less than 15 min, with minimal cost and infrastructure requirements. All the exercises described above can be conducted with a single placenta. Umbilical vein cannulation adds realism and allows quantification of the volume of saline required to complete the exercise. The final check with indocyanine green simulates intraoperative angiography and allows the assessment of distal vessel patency.

CONCLUSIONS

Minimal infrastructure requirements, simplicity, and easy setup models provide a suitable environment for regular training. The human placenta is inexpensive and widely available, making it a feasible model for residents training. Neurosurgery residents may benefit from this model to familiarize with microsurgery and critical scenarios in a risk-free environment without time or resource constraints.

Development and Validation of a Low-Cost Endoscopic Spine Surgery Simulator

Background

Minimally invasive endoscopic techniques in spine surgery continue to gain in popularity. Unfortunately, there is a long learning period for novice endoscope users to acquire basic skills, and complex training simulators are frequently cost-prohibitive. This paper describes the development and validation of a low-cost endoscopic spine training simulator.

Methodology

A low-cost endoscopic spine training model was created utilizing a budget of less than 65 USD. Afterward, a training curriculum consisting of five tasks was designed to mimic standard techniques frequently utilized in endoscopic spine surgery. This curriculum was tested on a cohort of surgical trainees. The initial time to completion as well as errors made during the tasks and repeat trials were recorded. A composite score was generated to quantify the overall scores which included both time and errors in each task.

Results

In total, 11 students and surgical residents completed the curriculum. The first attempt required an average of 622 seconds for the completion of the curriculum compared to 283 seconds in the second trial (p < 0.001; SD = 36.75). In regards to trials in which errors were counted, fewer errors occurred during the second attempt (2.55 vs. 1.53); however, this difference was not statistically significant (p > 0.05). In regards to the composite score, the composite score of the intern group demonstrated an average improvement of 0.345 compared to an average improvement of 0.47 in the resident group.

Conclusions

Our study demonstrates the feasibility of a low-cost endoscopic spine trainer as well as its efficacy in improving basic endoscopic skills in trainees.

3D-printed cranial models simulating operative field depth for microvascular training in neurosurgery

BACKGROUND

The skills required for neurosurgical operations using microsurgical techniques in a deep operating field are difficult to master in the operating room without risk to patients. Although there are many microsurgical training models, most do not use a skull model to simulate a deep field. To solve this problem, 3D models were created to provide increased training in the laboratory before the operating room, improving patient safety.

METHODS

A patient's head was scanned using computed tomography. The data were reconstructed and converted into a standard 3D printing file. The skull was printed with several openings to simulate common surgical approaches. These models were then used to create a deep operating field while practicing on a chicken thigh (femoral artery anastomosis) and on a rat (abdominal aortic anastomosis).

RESULTS

The advantages of practicing with the 3D printed models were clearly demonstrated by our trainees, including appropriate hand position on the skull, becoming comfortable with the depth of the anastomosis, and simulating proper skull angle and rigid fixation. One limitation is the absence of intracranial structures, which is being explored in future work.

CONCLUSION

This neurosurgical model can improve microsurgery training by recapitulating the depth of a real operating field. Improved training can lead to increased accuracy and efficiency of surgical procedures, thereby minimizing the risk to patients.

Augmentation of Chicken Thigh Model with Fluorescence Imaging Allows for Real-Time, High Fidelity Assessment in Supermicrosurgery Training

BACKGROUND

 The skills required for supermicrosurgery are hard-earned and difficult to master. The University of Wisconsin "blue-blood" chicken thigh model incorporates perfusion of the thigh vessels with a blue liquid solution, allowing users to visualize flow across their anastomoses. This model has proven to be an excellent source of small vessels (down to 0.3 mm) but assessing the quality of anastomoses at this spatial scale has proven difficult. We evaluated whether fluorescent imaging with indocyanine green (ICG) in this realistic training model would enhance the assessment of supermicrosurgical anastomoses, and therefore improve real-time feedback to trainees.

METHODS

 Anastomoses of vessels ranging from 0.35 to 0.55mm in diameter were performed followed by the capture of white light with and without fluorescence imaging overlay during infusion of "blue-blood" and ICG. Videos were randomized and shown to seven fellowship-trained microsurgeons at the University of Wisconsin-Madison who rated each anastomosis as "patent," "not patent," or "unsure." Surgeon accuracy, uncertainty, and inter-rater agreement were measured for each imaging modality.

RESULTS

 Use of fluorescence significantly increased surgeon accuracy to 91% compared with 47% with white light alone (p = 0.015), decreased surgeon uncertainty to 4% compared with 41% with white light alone (p = 0.011), and improved inter-rater agreement from 53.1% with white light alone to 91.8% (p = 0.016).

CONCLUSION

 Augmentation of the University of Wisconsin "blue-blood" chicken thigh model with ICG fluorescence improves accuracy, decreases uncertainty, and improves inter-rater agreement when assessing supermicrosurgical anastomoses in a training setting. This improved, real-time feedback enhances this model's value as a supermicrosurgical training tool.

A novel, low-cost, reusable, high-fidelity neurosurgical training simulator for cerebrovascular bypass surgery

OBJECTIVE

Cerebrovascular bypass surgery is a challenging yet important neurosurgical procedure that is performed to restore circulation in the treatment of carotid occlusive diseases, giant/complex aneurysms, and skull base tumors. It requires advanced microsurgical skills and dedicated training in microsurgical techniques. Most available training tools, however, either lack the realism of the actual bypass surgery (e.g., artificial vessel, chicken wing models) or require special facilities and regulations (e.g., cadaver, live animal, placenta models). The aim of the present study was to design a readily accessible, realistic, easy-to-build, reusable, and high-fidelity simulator to train neurosurgeons or trainees on vascular anastomosis techniques even in the operating room.

METHODS

The authors used an anatomical skull and brain model, artificial vessels, and a water pump to simulate both extracranial and intracranial circulations. They demonstrated the step-by-step preparation of the bypass simulator using readily available and affordable equipment and consumables.

RESULTS

All necessary steps of a superficial temporal artery-middle cerebral artery bypass surgery (from skin opening to skin closure) were performed on the simulator under a surgical microscope. The simulator was used by both experienced neurosurgeons and trainees. Feedback survey results from the participants of the microsurgery course suggested that the model is superior to existing microanastomosis training kits in simulating real surgery conditions (e.g., depth, blood flow, anatomical constraints) and holds promise for widespread use in neurosurgical training.

CONCLUSIONS

With no requirement for specialized laboratory facilities and regulations, this novel, low-cost, reusable, high-fidelity simulator can be readily constructed and used for neurosurgical training with various scenarios and modifications.

Microvascular anastomosis under 3D exoscope or endoscope magnification: A proof-of-concept study

Background:

Extracranial–intracranial bypass is a challenging procedure that requires special microsurgical skills and an operative microscope. The exoscope is a tool for neurosurgical visualization that provides view on a heads-up display similar to an endoscope, but positioned external to the operating field, like a microscope. The authors carried out a proof-of-concept study evaluating the feasibility and effectiveness of performing microvascular bypass using various new exoscopic tools.

Methods:

We evaluated microsurgical procedures using a three-dimensional (3D) endoscope, hands-free robotic automated positioning two-dimensional (2D) exoscope, and an ocular-free 3D exoscope, including surgical gauze knot tying, surgical glove cutting, placental vessel anastomoses, and rat vessel anastomoses. Image quality, effectiveness, and feasibility of each technique were compared among different visualization tools and to a standard operative microscope.

Results:

3D endoscopy produced relatively unsatisfactory resolution imaging. It was shown to be sufficient for knot tying and anastomosis of a placental artery, but was not suitable for anastomosis in rats. The 2D exoscope provided higher resolution imaging, but was not adequate for all maneuvers because of lack of depth perception. The 3D exoscope was shown to be functional to complete all maneuvers because of its depth perception and higher resolution.

Conclusion:

Depth perception and high resolution at highest magnification are required for microvascular bypass procedures. Execution of standard microanastomosis techniques was unsuccessful using 2D imaging modalities because of depth-perception-related constraints. Microvascular anastomosis is feasible under 3D exoscopic visualization; however, at highest magnification, the depth perception is inferior to that provided by a standard operative microscope, which impedes the procedure.

Microvascular Anastomosis Training in Neurosurgery: A Review

Cerebrovascular diseases are among the most widespread diseases in the world, which largely determine the structure of morbidity and mortality rates. Microvascular anastomosis techniques are important for revascularization surgeries on brachiocephalic and carotid arteries and complex cerebral aneurysms and even during resection of brain tumors that obstruct major cerebral arteries. Training in microvascular surgery became even more difficult with less case exposure and growth of the use of endovascular techniques. In this text we will briefly discuss the history of microvascular surgery, review current literature on simulation models with the emphasis on their merits and shortcomings, and describe the views and opinions on the future of the microvascular training in neurosurgery. In "dry" microsurgical training, various models created from artificial materials that simulate biological tissues are used. The next stage in training more experienced surgeons is to work with nonliving tissue models. Microvascular training using live models is considered to be the most relevant due to presence of the blood flow. Training on laboratory animals has high indicators of face and constructive validity. One of the future directions in the development of microsurgical techniques is the use of robotic systems. Robotic systems may play a role in teaching future generations of microsurgeons. Modern technologies allow access to highly accurate learning environments that are extremely similar to real environment. Additionally, assessment of microsurgical skills should become a fundamental part of the current evaluation of competence within a microneurosurgical training program. Such an assessment tool could be utilized to ensure a constant level of surgical competence within the recertification process. It is important that this evaluation be based on validated models.

Systematic Review of Factors Influencing Surgical Performance: Practical Recommendations for Microsurgical Procedures in Neurosurgery

BACKGROUND

Microneurosurgical techniques involve complex manual skills and hand-eye coordination that require substantial training. Many factors affect microneurosurgical skills. The goal of this study was to use a systematic evidence-based approach to analyze the quality of evidence for intrinsic and extrinsic factors that influence microneurosurgical performance and to make weighted practical recommendations.

METHODS

A literature search of factors that may affect microsurgical performance was conducted using PubMed and Embase. The criteria for inclusion were established in accordance with the PRISMA-P (Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols) statement.

RESULTS

Forty-eight studies were included in the analysis. Most of the studies used surgeons as participants. Most used endoscopic surgery simulators to assess skills, and only 12 studies focused on microsurgery. This review provides 18 practical recommendations based on a systematic literature analysis of the following 8 domains: 1) listening to music before and during microsurgery, 2) caffeine consumption, 3) β-blocker use, 4) physical exercise, 5) sleep deprivation, 6) alcohol consumption before performing surgery, 7) duration of the operation, and 8) the ergonomic position of the surgeon.

CONCLUSIONS

Despite the clear value of determining the effects of various factors on surgical performance, the available body of literature is limited, and it is not possible to determine standards for each surgical field. These recommendations may be used by neurosurgical trainees and practicing neurosurgeons to improve microsurgical performance and acquisition of microsurgical skills. Randomized studies assessing the factors that influence microsurgical performance are required.

The Role of Simulation in Microsurgical Training

Simulation has been established as an integral part of microsurgical training. The aim of this study was to assess and categorize the various simulation models in relation to the complexity of the microsurgical skill being taught and analyze the assessment methods commonly employed in microsurgical simulation training. Numerous courses have been established using simulation models. These models can be categorized, according to the level of complexity of the skill being taught, into basic, intermediate, and advanced. Microsurgical simulation training should be assessed using validated assessment methods. Assessment methods vary significantly from subjective expert opinions to self-assessment questionnaires and validated global rating scales. The appropriate assessment method should carefully be chosen based on the simulation modality. Simulation models should be validated, and a model with appropriate fidelity should be chosen according to the microsurgical skill being taught. Assessment should move from traditional simple subjective evaluations of trainee performance to validated tools. Future studies should assess the transferability of skills gained during simulation training to the real-life setting.