A Simple and Innovative Simulator Model for Sialendoscopy Basket Stone Retrieval Training

Abstract

We present a simple and innovative sialendoscopy basket stone retrieval (BSR) simulator model composed mainly of a 1.0-mL insulin syringe with detachable needle whose lumen mimics a dilated salivary duct. Dried Guava seeds are used to imitate small-sized floating sialoliths. The BSR simulator is evaluated by sialendoscopy trainees to ensure its realism and efficiency. Laryngoscope, 2025 Sialendoscopy requires the use of fine delicate instruments and is mastered by relatively few surgeons worldwide.1 One of the key components that can facilitate the learning process is the use of simulator models in training courses or for self-directed practice.2 Currently, pig heads are the most commonly used models for sialendoscopy training, as they allow for practice on the salivary duct papillae. However, these models do not provide adequate training for manipulating sialolithiasis. In some countries, sanitation laws may prohibit the use of such animals for training, presenting additional ethical limitations. Human cadaveric heads are difficult to acquire, maintain, and work with, and they are expensive. Additionally, the mandible's postmortem rigor complicates dissection in both porcine and human cadavers.3 To overcome these challenges, it is imperative to develop a low-cost, easily constructed, and reproducible training model that can be applied to any setup (laboratory or operative) and that complies with existing sanitary and ethical guidelines. Such a model could help educate and train novice practitioners, allowing them to gain proficiency in handling delicate surgical instruments before using them in real-life surgeries. In this article, we describe a simple and innovative sialendoscopy basket stone retrieval (BSR) simulator model that we developed and employed in our training courses over the past few years. Preliminary evaluation data obtained from both trainee and instructor participants are also discussed. Our sialendoscopy BSR simulator was designed to mimic the real experience of grasping floating stones from the lumen of the natural major salivary gland ducts. A 1.0-mL plastic insulin syringe with a detachable needle (inner barrel diameter, 4 mm; length, 6.0 cm) is used to simulate a dilated salivary duct. The syringe needle adaptor, consisting of the plain tip of syringe barrel (inner diameter: 2 mm; length: 8 mm), accommodates the outer diameter of the sialendoscope and mimics the narrow entrance to the salivary papilla after dilatation (Fig. 1). The syringe barrel is uniformly wrapped with red-colored plastic adhesive tape to mimic the coloration inside the ductal system and provide lumen opacity. Dried guava fruit seeds, which imitate real sialoliths in both consistency and morphology, are inserted into the syringe lumen after filling it with saline solution ensuring the elimination of air bubbles. The prepared insulin syringe simulator is securely fixed to a flat working table edge using an opaque wide adhesive surgical tape, aligning the syringe tip with the table edge (Fig. 2). The trainees worked in pairs, with one trainee passing a 1.6-mm semirigid all-in-one miniature sialendoscope with an angled tip (model 11583A; Karl Storz® GmbH & Co., Tuttlingen, Germany) attached to an endoscopic camera, to visualize the floating seeds within the syringe lumen. The second trainee used various salivary stone extractor wire baskets (3, 4, and 6 wires), developed by Karl Storz® (Tuttlingen, Germany) and NCircle® and NGage® by Cook Medical Inc® (Bloomington, IN, USA), inside the scope's working channel to practice the refined skills needed for BSR (Fig. 3). Other interventional sialendoscope models may be used depending on availability and preference. To enhance the realism of the training, pulsed saline injection was administered using a 10-mL syringe attached by an extension tube to the sialendoscope's irrigation channel. Trainee roles were alternated to allow practice of all required skills and to foster a harmonious training environment (Video 1). Consenting participants of the Egyptian Sialendoscopy Hands-on/Live Surgery course and the Alexandria Sialendoscopy (AlexSIAL) International Clinical/Surgical Fellowship program courses from 2023 to 2024 participated in the evaluation of the BSR simulator. These participants were all certified medical practitioners of various nationalities, subspecialties, medical qualifications, and pretraining experiences. After completing the BSR simulator training sessions, each participant answered a predesigned anonymous web-based questionnaire within 1 to 2 weeks. The questionnaire included five questions on participant data, five questions evaluating simulator realism, and five questions assessing the usefulness of the training process. The responses were rated on a 5-point Likert scale (Strongly Agree, Agree, Neutral, Disagree, and Strongly Disagree). A footnote was added to collect personal impressions and suggestions. The full questionnaire form is included in Supplementary Material S1. All 38 consenting participants detected the dried guava seeds (imitating sialoliths) and successfully performed interventional sialendoscopy retrieval using different wire baskets. Only one untoward effect occurred in the form of one wire basket breakage during training (which was replaced by another), with no sialendoscope damage encountered in any training session. Table I summarizes the data of the participants. Twenty-eight participants (74%) “strongly agreed” that the simulator setup met their training objectives, while 9 (24%) “agreed.” Thirty-seven out of 38 participants (97%) rated the simulator model as “strongly agree” or “agree” in terms of its reproducibility (replicability) in their own training settings. Regarding the use of an insulin syringe lumen and dried guava seeds, 26 participants (68%) “strongly agreed” that the simulator components allowed procedural training for floating stone retrieval, and 24 participants (63%) “strongly agreed” that dried guava seeds mimicked real sialoliths. Overall, 25 participants (66%) “strongly agreed” that the training improved their manual dexterity for BSR, whether as a surgeon or as an assistant. Twenty-seven participants (71%) replied “strongly agree” that the training enhanced the surgeon/assistant teamwork and facilitated role switching. Additionally, 28 participants (74%) “strongly agreed” that they would recommend this BSR simulator training before beginning a career in sialendoscopy (Table II). The development of training models and simulators in the medical field is limited only by imagination and innovation. Simulators provide a low-stress environment for trainees, allowing them to practice without risking real patient morbidity and offering opportunities for pauses, reflection, and discussion. Sialendoscopy is a relatively new procedure that requires specific training with delicate instruments to facilitate the learning curve before performing real-life surgeries. Simulation models are crucial in this context. In 2008, Fritsch3 introduced a salivary duct-and-gland teaching model using standard plastic intravenous fluid tubing (9 cm in length), which was inlaid and glued into a cleaning sponge to imitate the natural duct and gland. Rice grains were used to replicate stones, and their extraction was performed using sialendoscopic forceps and wire baskets, though no irrigation fluid was employed. In 2015, Geisthoff et al.2 proposed a model in which a 5- to 10-mm hole was made in a paprika (pepper) to attempt seed extraction as a sialendoscopy model. They also utilized the hilar, venous, and arterial blood duct systems of a cleaned pig kidney, inserting millet and rice grains as artificial stones. Although these models are innovative, we believe that the training model presented herein is simpler to set up and provides a more realistic training experience for sialendoscopy BSR. Dried guava fruit seeds replicate the texture, consistency, and color of real small-sized sialoliths more closely than any other previously used material. The pig head has been the most widely used model for training sialendoscopy techniques, especially papilla cannulation and ductal navigation.2 Borner et al.4 recently evaluated the use of the ovine head model, comparing its salivary ducts with human anatomy. However, both models still have limitations in terms of availability and ethical concerns surrounding the use of animals in various parts of the world. Several alternatives have been proposed to avoid the limitations associated with animal models and to achieve a more realistic training experience for sialendoscopy. Pascoto et al.5 introduced a full human head anatomical replica model made from a synthetic thermo-retractile and thermo-sensible rubber called Neoderma® (ProDelphus, Olinda, Brazil), specifically designed for sialendoscopy training. Canzi et al.1 also explored the use of 3D printed salivary duct models reconstructed from 3 Tesla magnetic resonance sialography data obtained from healthy volunteers and patients with salivary duct obstruction. Although both models offer significant advancements in sialendoscopy training, their high cost and complexity hinder their widespread use and accessibility. It is important to note that our sialendoscopy BSR simulator is a very simple method and can be considered the first step of the training curve. Moreover, this simulator is not intended to replace existing training models but to complement them. Sialendoscopy is a procedure that can be broken down into several independent steps, including papillary identification and dilatation, ductal system navigation, and basket stone extraction. Each of these steps requires specific training objectives that can be acquired individually and later integrated into the trainee's overall sialendoscopy learning process. In this regard, our BSR simulator could aid in developing skills such as endoscope handling, irrigation amplitude and timing, wire basket stone engagement maneuvers, manual dexterity, and teamwork between the surgeon and assistant. The simplicity, ease of reproducibility, and minimal cost make it suitable not only for inclusion in sialendoscopy courses but also for local implementation, allowing trainees to continue their practice with their own operating teams. Preliminary evaluation results indicate that most participants found the sialendoscopy BSR training model beneficial. Further studies involving a broader range of trainees are necessary to confirm its wider acceptance within the growing sialendoscopy community. The authors would like to express their sincere appreciation to all the 38 medical practitioners who provided their insightful evaluation of the sialendoscopy BSR simulator used. The authors also extend their thanks and gratitude to Miss Rabab Osman (Registered Nurse) and Mr. Hossam Ragab for their valuable help in the production and professional editing, respectively, of the video demonstrating the sialendoscopy BSR simulator training model provided in this article. Permission to conduct the evaluation for the purposes of this research was obtained by all respondents, who were fully informed about the purposes of this research and how their responses in the supplemented questionnaire would be used and stored. Participant Consent to publish was granted. Supplementary Material S1 Sialendoscopy BSR simulator training questionnaire web-based form. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.