Surgical training technology for cerebrovascular anastomosis

Advancing Neurosurgical Skills: A Comparative Study of Training Models for Intra-Extracranial Cerebral Bypass

BACKGROUND

Training in anastomosis is fundamental in neurosurgery due to the precision and dexterity required. Biological models, although realistic, present limitations such as availability, ethical concerns, and the risk of biological contamination. Synthetic models, on the other hand, offer durability and standardized conditions, although they sometimes lack anatomical realism. This study aims to evaluate and compare the efficiency of anastomosis training models in the intra-extracranial cerebral bypass procedure, identifying those characteristics that enhance optimal microsurgical skill development and participant experience.

METHODS

A neurosurgery workshop was held from March 2024 to June 2024 with 5 vascular techniques and the participation of 22 surgeons. The models tested were the human placenta, the Wistar rat, the chicken wing artery, the nasogastric feeding tube, and the UpSurgeOn Mycro simulator. The scales used to measure these models were the Main Characteristics Score and the Evaluation Score. These scores allowed us to measure, qualitatively and quantitatively, durability, anatomical similarity, variety of simulation scenarios, risk of biological contamination, ethical considerations and disadvantages with specific infrastructure.

RESULTS

The human placenta model, Wistar rat model, and UpSurgeOn model were identified as the most effective for training. The human placenta and Wistar rat models were highly regarded for anatomical realism, while the UpSurgeOn model excelled in durability and advanced simulation scenarios. Ethical and cost implications were also considered.

CONCLUSIONS

The study identifies the human placenta and UpSurgeOn models as optimal for training in intra-extracranial bypass procedures, emphasizing the need for diverse and effective training models in neurosurgery.

Assessing textbook outcomes following major liver surgery in association with obesity at a referral academic center

INTRODUCTION

Outcomes of major surgeries in tertiary educational hospitals have been complicated by the referral of high-risk patients and the participation of trainees in surgical procedures. We analyzed outcomes of major hepatectomies in a tertiary academic setting emphasizing the role of training and obesity on textbook outcomes (TO).

MATERIALS AND METHODS

971 adult patients who underwent open major hepatectomy (Mesohepatectomy [n = 111], hemihepatectomy [n = 610], and extended hepatectomy [n = 250]) were evaluated. A TO was defined as: a negative resection margin, no grade B/C bile leak, no major complications, no in-hospital mortality, and no 30-day readmission. TOs were compared following operations performed by senior surgeons and those performed by junior surgeons under the supervision of senior surgeons and between patients with and without obesity.

RESULTS

TO was achieved in 70.1% of patients overall (78.4% in mesohepatectomy, 73.1% in hemihepatectomy, and 59.2% in extended hepatectomy). The rate of TO was similar following operations performed by and supervised by a senior surgeon (69.3% vs 71.0%, p = 0.570). The rate of TO was significantly lower in patients with obesity (41.5% vs 74.6%, p < 0.001). Factors including increased age (odds ratio [OR] for 10-year increase = 0.83, 95% confidence interval [CI]: 0.73-0.96, p = 0.009), obesity (OR = 0.25, 95%CI: 0.16-0.37, p < 0.001), biliodigestive anastomosis (OR = 0.27, 95%CI: 0.19-0.40, p < 0.001), and portal vein resection (OR = 0.49, 95%CI: 0.28-0.87, p = 0.014) lower the rate of TO.

CONCLUSION

Promising outcomes are possible after major hepatectomy in an academic setting. Obese patients and those undergoing more complex surgeries had a higher risk of poor postoperative outcomes.

The Hibiscus Model: A Feasible Cadaveric Model Using Continuous Arterial Circulation for Intracranial Bypass Training and Its Validation

OBJECTIVE

The frequency of intracranial bypass procedures has declined. Thus it is difficult for neurosurgeons to develop the necessary skills for this complex procedure. We present a perfusion-based cadaveric model to provide a realistic training experience with high anatomic and physiological fidelity, as well as instantaneous assessment of bypass patency. Validation was assessed by evaluating the educational impact and skill improvement of the participants.

METHODS

Fourteen participants attended a hands-on revascularization course with 7 cadaveric models connected to a continuous arterial circulation system pumping a red-colored solution through the entire cranial vasculature, mimicking blood circulation. The ability to perform a vascular anastomosis was evaluated initially. Further, a questionnaire on prior experience was provided. At the end of the 36-hour course, the ability to perform an intracranial bypass was reexamined and the participants completed a self-assessment questionnaire.

RESULTS

Initially, only 3 attendees were able to perform an end-to-end anastomosis within the time limit, and only 2 of these anastomoses showed adequate patency. After having accomplished the course, all participants were able to complete a patent end-to-end anastomosis within the time limit, thus demonstrating a significant improvement. Further, both overall educational gain and surgical skills were regarded as remarkable (n = 11 and n = 9).

CONCLUSIONS

Simulation-based education is considered an important aspect of medical and surgical development. The presented model is a feasible and accessible alternative to the prior models used for cerebral bypass training. This training may serve as a helpful and widely available tool to improve neurosurgeons' development irrespective of financial resources.

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.

Introducing a Realistic, Low-Cost Simulation Model for Clipping of Brain Aneurysms

BACKGROUND

The current trend toward endovascular treatment of brain aneurysms may have a negative impact on young neurosurgeons who are less exposed to these lesions, thus affecting the acquisition of surgical skills in the field. Different training models have emerged to help cope with this issue, but these have specific pitfalls. Training models based on live animals or cadaveric specimens face increasing restrictions as regulations become a barrier in accessibility for everyday skills development. We introduce a novel, realistic, and inexpensive simulation model using a fresh bovine brain, and we assess its face and content validity as a training tool.

METHODS

A fresh bovine brain is used to simulate microsurgical fissure dissection. Arterial and aneurysmal components are created with arteries and veins harvested from chicken thigh. A 12-item questionnaire using the Likert numeric scale (grades 1 - 5) was used to assess the validity of model in 10 surgeons.

RESULTS

Ten neurosurgeons performed the simulated clipping of the aneurysm and completed a questionnaire. All surgeons surveyed responded "agree" or "strongly agree" that the simulator, and the skills trained with it, are comparable to clipping brain aneurysms. All respondents believed that this simulator could improve patient safety.

CONCLUSIONS

We present a novel, realistic, and inexpensive simulation model for the clipping of brain aneurysms. This model was partially validated by the opinion of field experts. We believe this model has the potential to become a useful training tool for young neurosurgeons who have little exposure to real aneurysm cases.

Best Practices Using Ex Vivo Animal Brain Models in Neurosurgical Education to Assess Surgical Expertise

BACKGROUND

Ex vivo animal brain simulation models are being increasingly used for neurosurgical training because these models can replicate human brain conditions. The goal of the present report is to provide the neurosurgical community interested in using ex vivo animal brain simulation models with guidelines for comprehensively and rigorously conducting, documenting, and assessing this type of research.

METHODS

In consultation with an interdisciplinary group of physicians and researchers involved in ex vivo models and a review of the literature on the best practices guidelines for simulation research, we developed the "ex vivo brain model to assess surgical expertise" (EVBMASE) checklist. The EVBMASE checklist provides a comprehensive quantitative framework for analyzing and reporting studies involving these models. We applied The EVBMASE checklist to the studies reported of ex vivo animal brain models to document how current ex vivo brain simulation models are used to train surgical expertise.

RESULTS

The EVBMASE checklist includes defined subsections and a total score of 20, which can help investigators improve studies and provide readers with techniques to better assess the quality and any deficiencies of the research. We classified 18 published ex vivo brain models into modified (group 1) and nonmodified (group 2) models. The mean total EVBMASE score was 11 (55%) for group 1 and 4.8 (24.2%) for group 2, a statistically significant difference (P = 0.006) mainly attributed to differences in the simulation study design section (P = 0.003).

CONCLUSIONS

The present findings should help contribute to more rigorous application, documentation, and assessment of ex vivo brain simulation research.

Dye-Perfused Human Placenta for Vascular Microneurosurgery Training: Preparation Protocol and Validation Testing

BACKGROUND

Human placenta is recognized as a valuable vascular microneurosurgery training model because of its abundant availability, ethical acceptance, and analogous vasculature with other vessels of the human body; however, human placenta laboratory preparation techniques are not well described in the literature. This study outlines a detailed and standardized laboratory protocol for preparation of a color-perfused human placenta model. Survey-based validation of the model is also reported herein.

METHODS

The protocol involved cleaning and cannulation of the umbilical vein and arteries, irrigation with heparin, and storage at 3°C or freezing at -18°C. Before use, arteries were perfused with carmine/cochineal, and veins were perfused with methylthioninium chloride. A questionnaire with 5 questions was administered to 40 participants among attending or resident neurosurgeons, otolaryngologists, and maxillofacial surgeons on 4 consecutive microsurgical courses to assess the reliability of the placenta model. Trainees were divided into 3 groups based on their experience. A χ² test was used to identify differences between groups.

RESULTS

Forty-two placentas were considered appropriate for training and were successfully perfused with dyes. Thirty-three participants completed the questionnaire, of which most, especially advanced and intermediate participants, indicated the placenta as a valuable, accurate, and reproducible model. No differences were observed among the groups.

CONCLUSIONS

The human placenta is an excellent tool for vascular microneurosurgery laboratory training. Color perfusion enhances the reliability of this model, which was validated by most surgeons, regardless of their experience.

Comparison of Conventional Microscopic and Exoscopic Experimental Bypass Anastomosis: A Technical Analysis

BACKGROUND

Recently, the use of digital exoscopes has been increasingly promoted as an alternative to microscopes. The aim of this study is to compare experimental bypass quality in both visualization methods.

METHODS

This study used two hundred 1-mm chicken wing vessels, which were used for either exoscopic or microscopic (100 samples each) bypass procedures. All procedures were recorded between July 2018 and September 2018. The bypass quality was evaluated according to our published practical scale (time, stitch distribution, intima-intima attachment, and orifice size).

RESULTS

Both methods are effective in doing bypass suturing (practical scale score was good, 86% vs. 85%; P = 0.84). There were no significant differences regarding intima-intima attachment (P = 0.26) and orifice size (P = 0.25). However, suturing time (P < 0.001) was less using the microscope, whereas stitch distribution (P = 0.001) was better using the exoscope. Different suturing techniques (interrupted vs. continuous) had overall comparable results (P = 0.55).

CONCLUSIONS

Both methods produced equally satisfactory results in experimental bypass procedures. The exoscope has the potential for better 3-dimensional visualization and sharing the surgeon's view with others for teaching purposes.

The Role of Low-Cost Microsurgical Training Models and Experience with Exercises Based on a Bovine Heart

BACKGROUND

Microscopic training is essential for development of neurosurgical skills. A range of models is reported in the literature for this purpose, including live animals, exvivo, and synthetic material. Among the factors involved in selection and development of a training station, cost is a decisive one.

METHODS

We present a low-cost model to practice microvascular anastomoses using a bovine heart and an artificial perfusion system. We also present a brief review of laboratory models for microsurgical training, focusing on the costs and reproducibility of the different options.

RESULTS

Exvivo models are a great bridging point between nonbiologic and living animal training models. These models have major similarities to human vessels, such as lumen size and malleability of the arteries. The bovine heart model allowed the residents to gain confidence in handling vascular tissue in a microscopic environment.

CONCLUSIONS

Although these models do not resemble anatomic landmarks in the human brain, the bovine heart model allowed the residents to gain confidence in handling vascular tissue in a microscopic environment.

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.

A Practical Cadaveric Model for Intracranial Bypass Training

BACKGROUND

Intracranial bypass is technically challenging and difficult to learn owing to its relative rarity and complexity. Although multiple training models for intracranial bypass exist, a detailed depiction of the use and fidelity of cadaveric specimens for bypass training is lacking in the literature. This study describes use of preserved cadaveric specimens as a practical training model for performance of multiple intracranial bypasses and discusses the surgical setup for a cadaveric bypass laboratory.

METHODS

Using a cadaveric specimen and basic microneurosurgical instruments and supplies, 5 intracranial bypasses were performed (superficial temporal artery [STA]-to-middle cerebral artery [MCA], MCA-to-MCA, STA-to-posterior cerebral artery [PCA], anterior cerebral artery-to-anterior cerebral artery, and posterior inferior cerebellar artery-to-posterior inferior cerebellar artery) using pterional, subtemporal, interhemispheric, and suboccipital approach. Bypass integrity was assessed by direct fluid injection into the adjacent vessel segment. All procedures were recorded.

RESULTS

Procedural steps mirrored actual bypass surgery and included vessel marking, performance of arteriotomy, and completion of an end-to-end, end-to-side, or side-to-side anastomosis. Simulations included anatomically appropriate exposures of common intracranial (MCA, PCA, posterior inferior cerebellar artery, anterior cerebral artery) and extracranial (STA) vessels encountered during cerebral bypass surgery and high-fidelity recreations of the operative corridors associated with deeper anastomoses, such as STA-to-PCA bypass. Vessel diameters were 1.5-2.1 mm, and anastomosis times were 20-40 minutes. Immediate feedback on anastomotic integrity was achieved via direct fluid injection adjacent to the anastomosis site.

CONCLUSIONS

The cadaveric specimen trainee model is a relatively simple yet high-fidelity approach for learning intracranial bypass.

The Identification of Factors That Influence the Quality of Bypass Anastomosis and an Evaluation of the Usefulness of an Experimental Practical Scale in This Regard

BACKGROUND

Several factors associated with interrupted and continuous suturing techniques affect the quality of bypass anastomosis. It is difficult to determine the impact of these factors during surgery. The primary objective of this study was to evaluate factors with the potential to influence the quality of bypass anastomosis using either interrupted or continuous suturing. A secondary objective was to evaluate the usefulness of a practical scale when comparing interrupted and continuous suturing techniques to improve bypass anastomosis.

METHODS

Interrupted (n = 100) and continuous (n = 100) suturing techniques were used in 200 end-to-side bypasses to a depth of 3 cm and were assessed by 5 neurosurgeons.

RESULTS

Vessel closing time (P < 0.001), stitch distribution (P < 0.001), intima-intima attachment (P < 0.001), and size of the orifice (P < 0.001) had a significant impact on the quality of the bypass regardless of the suturing technique used. The suturing technique used (interrupted or continuous) and positioning of the recipient vessel (vertical or horizontal) did not significantly influence the quality of anastomosis. Using multivariate analysis, the highest statistical significance with regard to bypass quality was attributed to the large size of the orifice and intimal attachment.

CONCLUSIONS

There were advantages and disadvantages to both suturing techniques. The scale was a practical way to measure and improve performance.

The impact of neurosurgical procedure on cognitive resources: Results of bypass training

Background:

Neurosurgeons are exposed to unavoidable distractions in their natural operating environment. Distractions can affect both the surgeon's concentration and the safety and duration of the surgery. Such distraction can be studied by applying a simultaneous cognitive task during a surgical procedure.

Methods:

We used a previously described cognitive task: a forward (DF) and backward digit (DB) repetition task to interfere with the surgeon's attention during a training bypass. A pilot study was performed to find suitable digit repetition lengths. For the main experiment, we used four-digit strings. The test task was alternated across two consecutive sutures (n = 153, 8 bypasses), followed by two consecutive control sutures without digit repetition. The duration and the number of correct answers for the digit repetition task were compared to a baseline digit repetition without simultaneous surgery.

Results:

During the bypass surgery, digit repetitions (especially DB) became slower (P < 0.0001). More errors were made during DB compared to DF only during simultaneous bypass (P < 0.0001). However, we found no effect of digit repetition tasks on individual suture times (P = 0.823).

Conclusions:

The ability to engage in simultaneous tasks while performing surgery is diminished. A surgeon with extensive training can withstand external distraction without an effect on performance; however, this is achieved by partially ignoring the simultaneous task. Our data support that during surgery other cognitive tasks should be avoided to ensure safety.

The role of simulation in neurosurgery

PURPOSE

In an era of residency duty-hour restrictions, there has been a recent effort to implement simulation-based training methods in neurosurgery teaching institutions. Several surgical simulators have been developed, ranging from physical models to sophisticated virtual reality systems. To date, there is a paucity of information describing the clinical benefits of existing simulators and the assessment strategies to help implement them into neurosurgical curricula. Here, we present a systematic review of the current models of simulation and discuss the state-of-the-art and future directions for simulation in neurosurgery.

METHODS

Retrospective literature review.

RESULTS

Multiple simulators have been developed for neurosurgical training, including those for minimally invasive procedures, vascular, skull base, pediatric, tumor resection, functional neurosurgery, and spine surgery. The pros and cons of existing systems are reviewed.

CONCLUSION

Advances in imaging and computer technology have led to the development of different simulation models to complement traditional surgical training. Sophisticated virtual reality (VR) simulators with haptic feedback and impressive imaging technology have provided novel options for training in neurosurgery. Breakthrough training simulation using 3D printing technology holds promise for future simulation practice, proving high-fidelity patient-specific models to complement residency surgical learning.