Feasibility of ovine and porcine models for simulation training in parotid surgery and facial nerve dissection

An ex vivo model for education and training of unilateral cleft lip surgery

BACKGROUND

Unilateral cleft lip surgery is a complex procedure, and the outcome depends highly on the surgeon's experience. Digital simulations and low-fidelity models seem inadequate for effective surgical education and training. There are only few realistic models for haptic simulation of cleft surgery, which are all based on synthetic materials that are costly and complex to produce. Hence, they are not fully available to train and educate surgical trainees. This study aims to develop an inexpensive, widely available, high-fidelity, ex vivo model of a unilateral cleft lip using a porcine snout disc.

METHODS

A foil template was manufactured combining anatomical landmarks of the porcine snout disc and the anatomical situation of a child with a unilateral cleft. This template was used to create an ex vivo model of a unilateral cleft lip from the snout disc. Millard II technique was applied on the model to proof its suitability. The individual steps of the surgical cleft closure were photo-documented and three-dimensional scans of the model were analysed digitally. Sixteen surgical trainees were instructed to create a unilateral cleft model and perform a unilateral lip plasty. Their self-assessment was evaluated by means of a questionnaire.

RESULTS

The porcine snout disc proved highly suitable to serve as a simulation model for unilateral cleft lip surgery. Millard II technique was successfully performed as we were able to perform all steps of unilateral cleft surgery, including muscle suturing. The developed foil-template is reusable on any porcine snout disc. The creation of the ex vivo model is simple and inexpensive. Self-assessment of the participants showed a strong increase in comprehension and an eagerness to use the model for surgical training.

CONCLUSIONS

A porcine snout disc ex vivo model of unilateral cleft lips was developed successfully. It shows many advantages, including a haptic close to human tissue, multiple layers, low cost, and wide and rapid availability. It is therefore very suitable for teaching and training beginners in cleft surgery and subsequently improving surgical skills and knowledge. Further research is needed to finally assess the ex vivo model's value in different stages of the curriculum of surgical residency.

An ex vivo model for education and training of bilateral cleft lip surgery

BACKGROUND

Bilateral cleft lip surgery is very challenging and requires a high level of skill, knowledge and experience. Existing high-fidelity simulation models that can be used by novice cleft surgeons to gain experience and expand their knowledge are rare and expensive. In this study, we developed a bilateral cleft lip model using porcine snout discs, which are available anywhere and inexpensive.

METHODS

Anatomic reference points of a patient with a bilateral cleft lip were superimposed with landmarks of the porcine snout disc on a foil template. The template was used to construct an ex vivo bilateral cleft lip model. Surgery was performed on the model according to Millard and the surgical steps were photodocumented analogous to two clinical cases of bilateral cleft lip surgery. The suitability of the model was further tested by twelve participants and evaluated using self-assessment questionnaires.

RESULTS

The bilateral cleft lip ex vivo model made of a porcine snout disc proved to be a suitable model with very low cost and ease of fabrication, as the template is reusable on any snout disc. The Millard procedure was successfully performed and the surgical steps of the lip plasty were simulated close to the clinical situation. Regarding the nasal reconstruction, the model lacks three-dimensionality. As a training model, it enhanced the participants comprehension of cleft surgery as well as their surgical skills. All participants rated the model as valuable for teaching and training.

CONCLUSIONS

The porcine snout discs can be used as a useful ex vivo model for bilateral cleft lip surgery with limitations in the construction of the nose, which cannot be realistically performed with the model due to anatomical differences with humans. Benefits include a realistic tissue feel, the simulation of a multi-layered lip construction, a wide and rapid availability and low cost. This allows the model to be used by novice surgeons also in low-income countries. It is therefore useful as a training model for gaining experience, but also as a model for refining, testing and evaluating surgical techniques for bilateral lip plasty.

Detailed anatomical study of the peripheral motor branches of the facial nerve in the swine model: A novel investigative approach for facial paralysis research

INTRODUCTION

Large animal models aid in innovating surgical approaches and developing medical devices for the treatment of facial paralysis. However, there is a lack of information on facial nerve anatomy in swine. This study aimed to investigate the branching pattern and histologic characteristics of the swine facial nerve, thereby establishing the anatomical patterns of preclinical models in facial paralysis research.

MATERIAL AND METHODS

The five peripheral motor branches of the facial nerve were dissected in 30 hemifaces of fresh swine cadavers. Starting at the stylomastoid foramen, the course, branching pattern, and diameter of each motor branch was recorded. Samples were taken at the start of each branch for epoxy embedding, toluidine blue staining, and histomorphologic analysis.

RESULTS

The dissections demonstrated consistent anatomy of the buccal and marginal mandibular branches in contrast to the temporal and zygomatic branches, which showed more variation in branching patterns. The buccal branch had the largest mean diameter of 1.34 mm (± 0.26 mm), whereas the marginal mandibular branch had the largest fascicular area of 0.558 mm² (± 0.12 mm²) and highest axon count of 3636.35 (± 526.36). The zygomatic branch had both the smallest diameter of 0.74 mm (± 0.25 mm) and fascicular area of 0.187 mm² (± 0.14 mm²).

CONCLUSIONS

The swine facial nerve is anatomically similar to the human facial nerve, making the pig a suitable large animal model. Detailed anatomical and histological information is crucial for developing preclinical models of novel facial nerve reconstruction approaches.

Thinking Beyond the Temporal Bone Lab: A Systematic Process for Expanding Surgical Simulation in Otolaryngology Training

The COVID-19 pandemic led to a temporary lapse in the development of otolaryngology trainee operative skills due to the cancellation of elective procedures and redeployment of trainees and attendings to COVID-19 units. Although transient, this disruption provided an opportunity for otolaryngology programs to develop contingency plans and formalize nascent simulation training curricula. Integration of formal simulation training alongside current didactic and surgical education may offset lost exposure during surgically lean times while providing the framework and resources for enhanced baseline training. Here, we provide an up-to-date overview of surgical simulation models in otolaryngology and identify easily implementable, low-cost, low fidelity models for junior trainees. By taking advantage of rapid advancements in technology and a paradigm shift to a more hands-on approach in medical education, formal simulation training may prove to be a beneficial tool at all stages of residency training, allowing for expanded peer-mentored skill development and providing a safe haven during unforeseen disruptions in surgical case volume.

Surgical Training on Ex Vivo Ovine Model in Otolaryngology Head and Neck Surgery: A Comprehensive Review

Background: Nowadays, head and neck surgical approaches need an increased level of anatomical knowledge and practical skills; therefore, the related learning curve is both flat and long. On such procedures, surgeons must decrease operating time as much as possible to reduce the time of general anesthesia and related stress factors for patients. Consequently, little time can be dedicated for training skills of students and young residents in the operating theater. Fresh human cadavers offer the most obvious surrogate for living patients, but they have several limitations, such as cost, availability, and local regulations. Recently, the feasibility of using ex vivo animal models, in particular ovine ones, have been considered as high-fidelity alternatives to cadaveric specimens. Methods: This comprehensive review explores all of head and neck otolaryngology applications with this sample. We analyzed studies about ear surgery, orbital procedures, parotid gland and facial nerve reanimation, open laryngeal and tracheal surgery, microlaryngoscopy procedures, laryngotracheal stenosis treatment, and diagnostic/operative pediatric endoscopy. For each different procedure, we underline the main applications, similarities, and limitations to human procedures so as to improve the knowledge of this model as a useful tool for surgical training. Results: An ovine model is easily available and relatively inexpensive, it has no limitations associated with religious or animal ethical issues, and it is reliable for head and neck surgery due to similar consistencies tissues and neurovascular structures with respect to humans. However, some other issues should be considered, such as differences about some anatomical features, the risk of zoonotic diseases, and the absence of bleeding during training. Conclusion: This comprehensive review highlights the potentials of an ex vivo ovine model and aims to stimulate the scientific and academic community to further develop it for other applications in surgical education.

Repairing whole facial nerve defects with xenogeneic acellular nerve grafts in rhesus monkeys

Acellular nerve allografts conducted via chemical extraction have achieved satisfactory results in bridging whole facial nerve defects clinically, both in terms of branching a single trunk and in connecting multiple branches of an extratemporal segment. However, in the clinical treatment of facial nerve defects, allogeneic donors are limited. In this experiment, we exposed the left trunk and multiple branches of the extratemporal segment in six rhesus monkeys and dissected a gap of 25 mm to construct a monkey model of a whole left nerve defect. Six monkeys were randomly assigned to an autograft group or a xenogeneic acellular nerve graft group. In the autograft group, the 25-mm whole facial nerve defect was immediately bridged using an autogenous ipsilateral great auricular nerve, and in the xenogeneic acellular nerve graft group, this was done using a xenogeneic acellular nerve graft with trunk-branches. Examinations of facial symmetry, nerve-muscle electrophysiology, retrograde transport of labeled neuronal tracers, and morphology of the regenerated nerve and target muscle at 8 months postoperatively showed that the faces of the monkey appeared to be symmetrical in the static state and slightly asymmetrical during facial movement, and that they could actively close their eyelids completely. The degree of recovery from facial paralysis reached House-Brackmann grade II in both groups. Compound muscle action potentials were recorded and orbicularis oris muscles responded to electro-stimuli on the surgical side in each monkey. FluoroGold-labeled neurons could be detected in the facial nuclei on the injured side. Immunohistochemical staining showed abundant neurofilament-200-positive axons and soluble protein-100-positive Schwann cells in the regenerated nerves. A large number of mid-graft myelinated axons were observed via methylene blue staining and a transmission electron microscope. Taken together, our data indicate that xenogeneic acellular nerve grafts from minipigs are safe and effective for repairing whole facial nerve defects in rhesus monkeys, with an effect similar to that of autologous nerve transplantation. Thus, a xenogeneic acellular nerve graft may be a suitable choice for bridging a whole facial nerve defect if no other method is available. The study was approved by the Laboratory Animal Management Committee and the Ethics Review Committee of the Affiliated Wuxi No. 2 People's Hospital of Nanjing Medical University, China (approval No. 2018-D-1) on March 15, 2018.

Ex Vivo Ovine Model for Surgical and Microsurgical Training on Parotidectomy and Facial Nerve Reanimation: Proposal of Structured Training Program

INTRODUCTION

 Facial nerve palsy has a great physical and psychological impact on patients, so the avoidance of facial nerve damage during surgery and its reanimation are important for Otolaryngologists and head and neck surgeons. The acquisition of anatomical knowledge and surgical training regarding the parotid surgery and facial nerve is mandatory, but not easy to achieve. Surgical simulation is a reliable alternative to the on-the-job learning. In the study, we tested an ex vivo animal model to obtain the basic and advanced skills of parotid gland surgery and facial nerve reconstruction/reanimation.

MATERIALS AND METHODS

 A prospective cohort study has been conducted on ovine head and neck specimen. A junior resident, a senior resident, and an expert surgeon were involved in a step-by-step preplanned dissection, divided in macroscopic and microscopic. Each procedure was recorded and evaluated by an expert surgeon following an adapted rating scale.

RESULTS

 A statistically significant improvement in terms of execution times and quality of the work was show in most of the surgical steps and for many quality items by the junior and senior residents, while the expert surgeon, as expected, did not show any improvement.

DISCUSSION

 Our ex vivo ovine model provided the trainee with close-to-real tissues in term of elastic resistance and consistency, to learn the skills requested in a head and neck surgery, on a reproducible environment. It is mandatory to have a feedback, which focuses on the quality of the work through valid and reliable assessment of technical skills. The judgment parameters should be reproducible and focused on the specific surgical procedure. Some limitations to this study are present, such as anatomical differences between ovine and human and the limited number of study participants.

CONCLUSION

 This proposal of training program on the ex vivo ovine model for the acquisition of skills needed in head and neck surgery proved to be feasible, effective, repeatable, and cheap.

Surgical simulation supplements reproductive endocrinology and infertility fellowship training

Objective

To assess if a surgical boot camp improves laparoscopic skill among reproduction endocrinology and infertility (REI) fellows and increases fellow desire to incorporate surgical skills into practice and to examine whether fellowship in vitro fertilization (IVF) volume correlates with surgical efficiency.

Design

Prospective evaluation.

Setting

Simulation Center.

Patients

Forty REI fellows.

Interventions

Fellows were timed before and after training in laparoscopic suturing and knot tying and while using virtual simulators. Fellows were surveyed before boot camp on prior experience with IVF and reproductive surgery, and immediately and 1 month after boot camp on their desire to incorporate surgical skills into practice.

Main Outcome Measures

Efficiency of laparoscopic suturing and knot tying before and after boot camp; likelihood and persistence of incorporating surgical skills into practice immediately and 1 month after boot camp; and correlation between fellowship IVF volume and fellow surgical efficiency.

Results

Fellows experienced significant improvement in laparoscopic suturing (44 sec), intracorporeal knot tying (82 sec), and extracorporeal knot tying (71 sec). Fellows reported being more likely to incorporate operative hysteroscopy (89%), operative laparoscopy (87%), and laparoscopic suturing (84%) into practice immediately following boot camp with no difference 1 month later. Fifty-four percent of fellows reported being more likely to perform robotic surgery after the boot camp, increasing to 70% 1 month later. There were weak correlations between IVF case volume and efficiency in laparoscopic suturing or hysteroscopic polypectomy (Spearman correlation coefficients, -0.14 and -0.03).

Conclusions

An intensive surgical boot camp enhances surgical skill among REI fellows.