Through the Eustachian Tube and Beyond: A New Miniature Robotic Endoscope to See Into The Middle Ear

Coupling Analysis of Compound Continuum Robots for Surgery: Another Line of Thought

The compound continuum robot employs both concentric tube components and cable-driven continuum components to achieve its complex motions. Nevertheless, the interaction between these components causes coupling, which inevitably leads to reduced accuracy. Consequently, researchers have been striving to mitigate and compensate for this coupling-induced error in order to enhance the overall performance of the robot. This paper leverages the coupling between the components of the compound continuum robot to accomplish specific surgical procedures. Specifically, the internal concentric tube component is utilized to induce motion in the cable-driven external component, which generates coupled motion under the constraints of the cable. This approach enables the realization of high-precision surgical operations. Specifically, a kinematic model for the proposed robot is established, and an inverse kinematic algorithm is developed. In this inverse kinematic algorithm, the solution of a highly nonlinear system of equations is simplified into the solution of a single nonlinear equation. To demonstrate the effectiveness of the proposed approach, simulations are conducted to evaluate the efficiency of the algorithm. The simulations conducted in this study indicate that the proposed inverse kinematic (IK) algorithm improves computational speed by a significant margin. Specifically, it achieves a speedup of 2.8 × 10³ over the Levenberg-Marquardt (LM) method. In addition, experimental results demonstrate that the coupled-motion system achieves high levels of accuracy. Specifically, the repetitive positioning accuracy is measured to be 0.9 mm, and the tracking accuracy is 1.5 mm. This paper is significant for dealing with the coupling of the compound continuum robot.

Benefits of Side-Firing Optical Fibers in Endoscopic Laser Treatment of the Larynx

OBJECTIVE

To elucidate potential tissue coverage of side-firing optical fibers in office-based endoscopic laser treatment of larynx, as well as to demonstrate their enhanced ability to address challenging anatomic areas.

METHOD

We performed a comparative study of four different fiber designs: a traditional forward-facing fiber, and three side-firing fibers that emit light at an angle of 45°, 70°, and 90°, respectively. The study was conducted in simulation, using eight three-dimensional models of the human larynx generated from microtomography x-ray scans. A computer program simulated the insertion of the endoscope into the larynx, and the Möller-Trumbore algorithm was used to simulate the application of laser light.

RESULTS

Side-firing laser fibers increased potential tissue coverage by a mean of 50.2 (standard deviation [SD] 25.8), 73.8 (SD 41.3), and 84.0 (SD 47.6) percent for angles of 45°, 70°, and 90°, respectively, compared to forward-facing fibers. Angled fibers provided access to areas of the larynx considered difficult to address by traditional methods, including the infraglottis, laryngeal ventricle, and right vocal fold.

CONCLUSION

Simulation results suggest that side-firing optical fibers have the potential to enhance anatomical access during in-office endoscopic laser procedures in the larynx. Further research is needed to better understand the benefits and any potential risks or contraindications of side-firing optical fibers.

LEVEL OF EVIDENCE

NA Laryngoscope, 133:1205-1210, 2023.

Management of retraction pockets: historic and novel approaches

Background

Retraction pockets are collapsed segments of the tympanic membrane. Their formation is associated with a disruption in middle-ear ventilation pathways, leading to the loss of organised collagen of the tympanic membrane. There are several approaches in treating retraction pockets, which aim either to improve ventilation or repair the retraction pockets themselves.

Methods

A review of the literature regarding the classification and associated management of retraction pockets was conducted, using Medline and Cochrane Library databases, with the addition of our institution's experience in undertaking novel techniques.

Results

All the current classification systems fail to guide treatment or prognosticate the disease. Commonly, an initial conservative approach is suggested for early stages, with no clear indication regarding when a surgical solution should be offered. There are conflicting data concerning the effectiveness of these treatments in terms of disease prevention, recurrence and hearing outcomes.

Conclusion

Minimally invasive approaches utilising novel techniques may be key to reducing peri-operative morbidity and improving the overall patient experience.

Magnetic concentric tube robots: introduction and analysis

In this paper, we propose a new type of continuum robot, referred to as a magnetic concentric tube robot (M-CTR), for performing minimally invasive surgery in narrow and difficult-to-access areas. The robot combines concentric tubes and magnetic actuation to benefit from the ‘follow the leader’ behaviour, the dexterity and stability of existing robots, while targeting millimetre-sized external diameters. These three kinematic properties are assessed through numerical and experimental studies performed on a prototype of a M-CTR. They are performed with general forward and inverse kineto-static models of the robot, continuation and bifurcation analysis, and a specific experimental setup. The prototype presents unique capabilities in terms of deployment and active stability management, while its dexterity in terms of tip orientability is also among the best reported for other robots at its scale.

MR-Tracked Deflectable Stylet for Gynecologic Brachytherapy

Brachytherapy is a radiation based treatment that is implemented by precisely placing focused radiation sources into tumors. In advanced interstitial cervical cancer bracytherapy treatment, this is performed by placing a metallic rod ("stylet") inside a hollow cylindrical tube ("catheter") and advancing the pair to the desired target. The stylet is removed once the target is reached, followed by the insertion of radiation sources into the catheter. However, manually advancing an initially straight stylet into the tumor with millimeter spatial accuracy has been a long-standing challenge, which requires multiple insertions and retractions, due to the unforeseen stylet deflection caused by the stiff muscle tissue that is traversed. In this paper, we develop a novel tendon-actuated deflectable stylet equipped with MR active-tracking coils that may enhance brachytherapy treatment outcomes by allowing accurate stylet trajectory control. Herein we present the design concept and fabrication method, followed by the kinematic and mechanics models of the deflectable stylet. The hardware and theoretical models are extensively validated via benchtop and MRI-guided characterization. At insertion depths of 60 mm, benchtop phantom targeting tests provided a targeting error of 1. 23 ± 0. 47 mm, and porcine tissue targeting tests provided a targeting error of 1. 65 ± 0. 64 mm, after only a single insertion. MR-guided experiments indicate that the stylet can be safely and accurately located within the MRI environment.

Transeustachian Middle Ear Endoscopy Using a Steerable Distal-Camera Tipped Endoscope

OBJECTIVE

Demonstrate the ability of a novel steerable distal chip endoscope to traverse the Eustachian tube and provide diagnostic quality images of the human middle ear.

PATIENTS

Three cadaveric temporal bone specimens were used in this work.

INTERVENTION

Diagnostic transeustachian endoscopy of the middle ear was performed.

MAIN OUTCOME MEASURE

Diagnostic image quality.

RESULTS

A novel 1.62 mm steerable endoscope successfully cannulated the Eustachian tube of three human cadaveric temporal bone specimens to reveal intact middle ear anatomy with high optical clarity.

CONCLUSIONS

A steerable endoscope can be designed to traverse the human Eustachian tube and provide diagnostic quality images of middle ear anatomy.

Literature Review on Endoscopic Robotic Systems in Ear and Sinus Surgery

In otolaryngologic surgery, endoscopy is increasingly used to provide a better view of hard-to-reach areas and to promote minimally invasive surgery. However, the need to manipulate the endoscope limits the surgeon's ability to operate with only one instrument at a time. Currently, several robotic systems are being developed, demonstrating the value of robotic assistance in microsurgery. The aim of this literature review is to present and classify current robotic systems that are used for otological and endonasal applications. For these solutions, an analysis of the functionalities in relation to the surgeon's needs will be carried out to produce a set of specifications for the creation of new robots.

Functional aspects of the Eustachian tube by means of 3D-modeling

The extent of dysfunction of the Eustachian tube (ET) is relevant in understanding the pathogenesis of secondary otological diseases such as acute or chronic otitis media. The underlying mechanism of ET dysfunction remains poorly understood except for an apparent genesis such as a nasopharyngeal tumor or cleft palate. To better describe the ET, its functional anatomy, and the biomechanical valve mechanism and subsequent development of diagnostic and interventional tools, a three-dimensional model based on thin-layer histology was created from an ET in this study. Blackface sheep was chosen as a donor. The 3-D model was generated by the coherent alignment of the sections. It was then compared with the cone-beam computed tomography dataset of the complete embedded specimen taken before slicing. The model shows the topographic relation of the individual components, such as the bone and cartilage, the muscles and connective tissue, as well as the lining epithelium with the lumen. It indicates a limited spiraling rotation of the cartilaginous tube over its length and relevant positional relationships of the tensor and levator veli palatine muscles.

Beyond Constant Curvature: A New Mechanics Model for Unidirectional Notched-Tube Continuum Wrists

This paper presents a new mechanics model for unidirectional notched-tube continuum wrists, a class of mechanisms frequently used to implement distal steering in needle-sized surgical robotic instruments. Existing kinematic models available for these devices are based on the simplifying assumption that, during actuation, all the notches undergo the same amount of deflection, so that the shape of a wrist can be approximated by an arc of constant curvature. This approach is analytically attractive, but, as we show in this paper, it can sometimes fail to provide good tracking accuracy. In this article, we provide a new model that relaxes the assumption above, and we report experimental evidence showing its superior accuracy. We model wrist deflection using Castigliano's second theorem, with the addition of a capstan friction term that accounts for frictional losses on the actuation tendon. Because notched-tube wrists are typically made of Nickel-Titanium (Nitinol), which has nonlinear stress-strain characteristics, we use a technique to obtain a local linearized approximation of the material modulus, suitable for use in the deflection model. The result of our modeling is a system of nonlinear equations that can be solved numerically to predict the wrist configuration based on the applied actuation force. Experimental results on physical specimens show that this improved model provides a more accurate estimate of wrist kinematics than prior models assuming constant curvature bending.

Eyes in Ears: A Miniature Steerable Digital Endoscope for Trans-Nasal Diagnosis of Middle Ear Disease

The aim of this work is to design, fabricate and experimentally validate a miniature steerable digital endoscope that can provide comprehensive, high-resolution imaging of the middle ear using a trans-nasal approach. The motivation for this work comes from the high incidence of middle ear diseases, and the current reliance on invasive surgery to diagnose and survey these diseases which typically consists of the eardrum being lifted surgically to directly visualize the middle ear using a trans-canal approach. To enable less-invasive diagnosis and surveillance of middle ear disease, we propose an endoscope that is small enough to pass into the middle ear through the Eustachian tube, with a steerable tip that carries a 1 Megapixel image sensor and fiber-optic illumination to provide high-resolution visualization of critical middle ear structures. The proposed endoscope would enable physicians to diagnose middle ear disease using a non-surgical trans-nasal approach instead, enabling such procedures to be performed in an office setting and greatly reducing invasiveness for the patient. In this work, the computational design of the steerable tip based on computed tomography models of real human middle ear anatomy is presented, and these results informed the fabrication of a clinical-scale steerable endoscope prototype. The prototype was used in a pilot study in three cadaveric temporal bone specimens, where high-quality middle ear visualization was achieved as determined by an unbiased cohort of otolaryngologists. This is the first paper to demonstrate cadaveric validation of a digital, steerable, clinical-scale endoscope for middle ear disease diagnosis, and the experimental results illustrate that the endoscope enables the visualization of critical middle ear structures (such as the epitympanum or sinus tympani) that were seldom or never visualized in prior published trans-Eustachian tube endoscopy feasibility studies.

Design, prototype development and pre-clinical validation of a novel instrument with a compliant steerable tip to facilitate endoscopic ear surgery

This work presents the design of a novel compliant steerable tip (CST) instrument to facilitate transcanal (or totally) endoscopic ear surgery (TEES). The evolution of the instrument's design is shown, where prototypes were evaluated by surgeons and their feedback was used to inform the design changes for the next prototype iteration. The final prototype enables the surgeon to articulate the compliant tip to achieve the desired bending curvature while automatically locking in place and providing dissection and suction capabilities. Pre-clinical validation testing was performed in goat and human cadaver models by two surgeons who successfully removed an allograft from the middle ear. Time and the number of blockages while suctioning saline in both cadaver models were measured and compared with current instruments used during TEES. The CST took significantly less time to suction saline within a flooded middle ear compared to the Panetti suction dissector (PSD) for atticus and underwent less blockages than the PSD for atticus, ear drum and sinus tympani instruments, Wilcoxon Method p < .05. Our study demonstrates the development and successful clinical evaluation of a minimally invasive surgical instrument designed to facilitate endoscopic approaches to the ear.

Computational Optimization of Notch Spacing for a Transnasal Ear Endoscopy Continuum Robot

This paper presents a computational framework to optimize the visual coverage attainable by a notched-tube continuum robotic endoscope inside the middle ear cavity. Our framework combines anatomically-accurate geometric (mesh) models of the middle ear with a sampling-based motion planning algorithm (RRT) and a ray-casting procedure to quantify what regions of the middle ear can be accessed and visualized by the endoscope. To demonstrate the use of this framework, we run computer simulations to investigate the effect of varying the distance between each pair of consecutive flexure elements (i.e., notches) in our robotic endoscope.

Artificial intelligence and robotics: a combination that is changing the operating room

PURPOSE

The aim of the current narrative review was to summarize the available evidence in the literature on artificial intelligence (AI) methods that have been applied during robotic surgery.

METHODS

A narrative review of the literature was performed on MEDLINE/Pubmed and Scopus database on the topics of artificial intelligence, autonomous surgery, machine learning, robotic surgery, and surgical navigation, focusing on articles published between January 2015 and June 2019. All available evidences were analyzed and summarized herein after an interactive peer-review process of the panel.

LITERATURE REVIEW

The preliminary results of the implementation of AI in clinical setting are encouraging. By providing a readout of the full telemetry and a sophisticated viewing console, robot-assisted surgery can be used to study and refine the application of AI in surgical practice. Machine learning approaches strengthen the feedback regarding surgical skills acquisition, efficiency of the surgical process, surgical guidance and prediction of postoperative outcomes. Tension-sensors on the robotic arms and the integration of augmented reality methods can help enhance the surgical experience and monitor organ movements.

CONCLUSIONS

The use of AI in robotic surgery is expected to have a significant impact on future surgical training as well as enhance the surgical experience during a procedure. Both aim to realize precision surgery and thus to increase the quality of the surgical care. Implementation of AI in master-slave robotic surgery may allow for the careful, step-by-step consideration of autonomous robotic surgery.

Investigating variability in cochlear implant electrode array alignment and the potential of visualization guidance

Background Internal cochlear anatomy is difficult to discern from external inspection, hindering cochlear implant electrode insertion. Methods A user study characterized the repeatability of standard surgical technique and examined the role of visual inspection and guidance cues in reducing electrode array insertion misalignment. Results Without guidance, a large spread in angles of insertion, up to 30°, was observed, highlighting the need for intraoperative guidance. Visual inspection did not significantly improve overall orientation, suggesting the need for alternate intracochlear visualization methods and/or increased training to effectively improve surgeon understanding of the visualized images. Visual cues and guidance software increased repeatability of surgeon performance, reducing one metric of repeatability to ±2°. Conclusions This study establishes a baseline for surgeon variability in cochlear implant insertion and supports the need and lays the groundwork for future intraoperative guidance techniques.

Design, Modelling and Teleoperation of a 2 mm Diameter Compliant Instrument for the da Vinci Platform

This work explores the feasibility of creating and accurately controlling an instrument for robotic surgery with a 2 mm diameter and a three degree-of-freedom (DoF) wrist which is compatible with the da Vinci platform. The instrument's wrist is composed of a two DoF bending notched-nitinol tube pattern, for which a kinematic model has been developed. A base mechanism for controlling the wrist is designed for integration with the da Vinci Research Kit. A basic teleoperation task is successfully performed using two of the miniature instruments. The performance and accuracy of the instrument suggest that creating and accurately controlling a 2 mm diameter instrument is feasible and the design and modelling proposed in this work provide a basis for future miniature instrument development.

Planning nonlinear access paths for temporal bone surgery

PURPOSE

Interventions at the otobasis operate in the narrow region of the temporal bone where several highly sensitive organs define obstacles with minimal clearance for surgical instruments. Nonlinear trajectories for potential minimally invasive interventions can provide larger distances to risk structures and optimized orientations of surgical instruments, thus improving clinical outcomes when compared to existing linear approaches. In this paper, we present fast and accurate planning methods for such nonlinear access paths.

METHODS

We define a specific motion planning problem in [Formula: see text] with notable constraints in computation time and goal pose that reflect the requirements of temporal bone surgery. We then present [Formula: see text]-RRT-Connect: two suitable motion planners based on bidirectional Rapidly exploring Random Tree (RRT) to solve this problem efficiently.

RESULTS

The benefits of [Formula: see text]-RRT-Connect are demonstrated on real CT data of patients. Their general performance is shown on a large set of realistic synthetic anatomies. We also show that these new algorithms outperform state-of-the-art methods based on circular arcs or Bézier-Splines when applied to this specific problem.

CONCLUSION

With this work, we demonstrate that preoperative and intra-operative planning of nonlinear access paths is possible for minimally invasive surgeries at the otobasis.

Review on Otological Robotic Systems: Toward Microrobot-Assisted Cholesteatoma Surgery

Otologic surgical procedures over time have become minimally invasive due to the development of medicine, microtechniques, and robotics. This trend then provides an expected reduction in the patient's recovery time and improvement in the accuracy of diagnosis and treatment. One of the most challenging difficulties that such techniques face are precise control of the instrument and supply of an ergonomic system to the surgeon. The objective of this literature review is to present requirements and guidelines for a surgical robotic system dedicated to middle ear surgery. This review is particularly focused on cholesteatoma surgery (diagnosis and surgical tools), which is one of the most frequent pathologies that urge for an enhanced treatment. This review also presents the current robotic systems that are implemented for otologic applications.