Lukas Anschuetz

Robotic cochlear implantation: surgical procedure and first clinical experience

Abstract Conclusion: A system for robotic cochlear implantation (rCI) has been developed and a corresponding surgical workflow has been described. The clinical feasibility was demonstrated through the conduction of a safe and effective rCI procedure. Objectives: To define a clinical workflow for rCI and demonstrate its feasibility, safety, and effectiveness within a clinical setting. Method: A clinical workflow for use of a previously described image guided surgical robot system for rCI was developed. Based on pre-operative images, a safe drilling tunnel targeting the round window was planned and drilled by the robotic system. Intra-operatively the drill path was assessed using imaging and sensor-based data to confirm the proximity of the facial nerve. Electrode array insertion was manually achieved under microscope visualization. Electrode array placement, structure preservation, and the accuracy of the drilling and of the safety mechanisms were assessed on post-operative CT images. Results: Robotic drilling was conducted with an accuracy of 0.2 mm and safety mechanisms predicted proximity of the nerves to within 0.1 mm. The approach resulted in a minimal mastoidectomy and minimal incisions. Manual electrode array insertion was successfully performed through the robotically drilled tunnel. The procedure was performed without complications, and all surrounding structures were preserved.

Population Statistics Approach for Safety Assessment in Robotic Cochlear Implantation.

HYPOTHESIS Descriptive statistics with respect to patient anatomy and image guidance accuracy can be used to assess the effectiveness of any system for minimally invasive cochlear implantation, on both an individual patient and wider population level. BACKGROUND Minimally invasive cochlear implantation involves the drilling of a tunnel from the surface of the mastoid to cochlea, with the trajectory passing through the facial recess. The facial recess anatomy constrains the drilling path and places prohibitive accuracy requirements on the used system. Existing single thresholds are insufficient for assessing the effectiveness of these systems. METHODS A statistical model of the anatomical situation encountered during minimally invasive drilling of the mastoid for cochlear implantation was developed. A literature review was performed to determine the statistical distribution of facial recess width; these values were confirmed through facial recess measurements on computed tomography (CT) data. Based on the accuracy of a robotic system developed by the authors, the effect of variation of system accuracy, precision, and tunnel diameter examined with respect to the potential treatable portion of the population. RESULTS A facial recess diameter of 2.54 ± 0.51 mm (n = 74) was determined from a review of existing literature; subsequent measurements on CT data revealed a facial recess diameter of 2.54 ± 0.5 mm (n = 23). The developed model demonstrated the effects of varying accuracy on the treatable portion of the population. CONCLUSIONS The presented model allows the assessment of the applicability of a system on a wider population scale beyond examining only the systems ability to reach an arbitrary threshold accuracy.

Expanded transcanal transpromontorial approach to the internal auditory canal: Pilot clinical experience

The aim of this study was to describe and evaluate the feasibility of an expanded transcanal transpromontorial approach, developed from the exclusive endoscopic transcanal transpromontorial approach.

Management of Bleeding in Exclusive Endoscopic Ear Surgery: Pilot Clinical Experience.

Objective Transcanal exclusive endoscopic ear surgery requires the management of the endoscope and the surgical instruments in the external auditory canal. Bleeding in this narrow space is one of the most challenging issues, especially for novice endoscopic ear surgeons. We aim to assess the severity and occurrence of bleeding and describe strategies to control the bleeding during endoscopic ear surgery. We hypothesize that bleeding is reasonably controllable in endoscopic ear surgery. Study Design Case series with chart review. Setting Tertiary referral center. Subjects and Methods We retrospectively assessed 104 consecutive cases of exclusive endoscopic ear surgery at the University Hospital of Modena, Italy. The surgical videos and the patient charts were carefully investigated and analyzed. Results Hemostatic agents included injection of diluted epinephrine (1:200,000, 2% mepivacaine), cottonoids soaked with epinephrine (1:1000), mono- or bipolar cautery, washing with hydrogen peroxide, and self-suctioning instruments. The localization of bleeding in the external auditory canal was most frequently the posterior superior part, and inside of the middle ear, it was the pathology itself. Statistical analysis revealed significant differences comparing the mean arterial pressure and the type of intervention among bleeding scores. Conclusion The management of bleeding in endoscopic ear surgery is feasible through widely available hemostatic agents in reasonable frequency. This study gives an instructive overview on how to manage the bleeding in the exclusive endoscopic technique. Even the highest bleeding scores could be managed in an exclusively endoscopic technique.

An Ovine Model for Exclusive Endoscopic Ear Surgery

Importance With the international spread of exclusive transcanal endoscopic ear surgery, the need for a suitable and affordable surgical training model has grown during the past years. Objective To develop and validate an ex vivo animal model for exclusive endoscopic ear surgery. Design, Setting, and Animal Models In an experimental study, we compared ovine and human middle ear anatomy in 4 specimens and assessed the lamb as a model for endoscopic ear surgery. After confirming its suitability, we developed a surgical training program for canaloplasty, myringoplasty, and ossiculoplasty. From March 1 to May 31, 2016, the ex vivo model was tested, assessing the time needed for dissection and complications. Each experience was subjectively validated on a scale from 1 (very poor) to 10 (excellent). Main Outcomes and Measures Suitability of the lamb model for training in exclusive endoscopic ear surgery. Results We assessed the suitability of our novel lamb model on 20 ovine middle ears. All interventions could be performed in a satisfactory manner. The mean (SD) time required to perform canaloplasty was 29.7 (13.2) minutes, for middle ear dissection was 7.7 (2.6) minutes, for myringoplasty was 7.7 (4.3) minutes, and for ossiculoplasty was 10.4 (2.7) minutes. The time required for canaloplasty and tympano-meatal flap elevation during dissection decreased from 46.4 minutes in the first 5 cases to 16.2 minutes in the last 5 cases, representing an absolute difference of 30.2 minutes (95% CI, 22.28-38.12). Subjective ratings revealed excellent values for tissue quality (8.9 points of 10), overall satisfaction (8.3 points), and the learning experience (8.8 points). Conclusions and Relevance The ovine model is suitable for endoscopic ear surgery. We describe a novel, exclusively endoscopic approach in an ex vivo animal model for middle ear surgery. The proposed surgical program leads the trainee step by step through the main otologic procedures and is able to enhance his or her surgical skills.

Minimally Invasive Lateral Endoscopic Multiport Approach to the Infratemporal Fossa: A Cadaveric Study

BACKGROUND Expanded endoscopic endonasal approaches to the infratemporal fossa (ITF) are increasingly performed owing to improved visualization and less morbidity compared with classic open approaches. Only a few studies in the literature investigated lateral endoscopic access to the ITF. The aim of this study was to examine the ITF with the minimally invasive endoscopically assisted Gillies approach with a trial of its expansion through a double port technique. METHODS The ITF was examined in 10 sides of 5 cadaveric heads using a lateral endoscopic assisted approach. A double portal technique was developed to allow bimanual dissection. Specific long angled skull base instruments were used for dissection under stereotactic guidance. RESULTS The endoscopic assisted Gillies approach permitted minimally invasive access to the complete anteroposterior extension of the ITF with sufficient mobility of surgical instruments. A new anatomic classification for the ITF from a lateral endoscopic perspective was introduced. The addition of the second port allowed bimanual dissection. CONCLUSIONS This cadaveric study shows the feasibility of an endoscopically assisted lateral approach to the ITF. The addition of a posterior port expands the approach through increasing the working area and enabling a bimanual dissection technique. Performed alone or combined with an anterior endoscopic transnasal approach, this technique offers minimally invasive access to the ITF. The development of specifically designed instruments would further improve this promising approach.

Unilateral and Bilateral Audiological Benefit With an Adhesively Attached, Noninvasive Bone Conduction Hearing System

OBJECTIVE To assess the audiological benefit of a noninvasive, adhesively attached bone conduction device (BCD1) in subjects with induced bilateral conductive hearing loss. Secondary objectives were to evaluate the additional benefit of bilateral fitting compared with unilateral fitting and to compare the outcomes with bone conduction devices attached to a softband (BCD2). STUDY DESIGN Prospective nonrandomized crossover study. SETTING Tertiary referral center. PATIENTS Fifteen subjects with induced bilateral conductive hearing loss. MAIN OUTCOME MEASURES Sound field thresholds, speech understanding in quiet and in multinoise were assessed in unaided, unilateral, and bilateral treatment conditions. In addition, sound localization was evaluated in uni- and bilateral treatment conditions. RESULTS The outcomes of BCD1 and BCD2 were comparable. Sound field thresholds improved by 24.6 dB (BCD1) and 24.8 dB (BCD2) in the unilateral and 26.8 dB (BCD1) and 25.1 dB (BCD2) in the bilateral treatment condition. Speech reception thresholds (SRTs) in quiet improved by 20.0 dB (BCD1) and 21.7 dB (BCD2) in the unilateral and by 22.7 dB (BCD1) and 21.5 dB (BCD2) in the bilateral condition. If speech was presented from the front, SRTs in noise were improved by 3.6 dB and 4.2 dB (unilateral) and by 4.5 dB and 4.4 dB (bilateral) for BCD1 and BCD2, respectively. With speech presented from the unilateral side, SRTs were improved by 4.0 dB and 4.7 dB (unilateral) and 3.8 dB and 4.8 dB (bilateral) compared with the unaided situation. If noise was presented from the contralateral side, small differences (-0.6 dB and -0.1 dB) were observed. Bilateral fitting brought additional benefits for speech understanding in noise and sound localization. CONCLUSIONS Both bone conduction devices seem to be a valid treatment for patients with conductive hearing loss and minor sensorineural hearing loss component.

Discovering Middle Ear Anatomy by Transcanal Endoscopic Ear Surgery: A Dissection Manual

The middle ear is located in the center of the temporal bone and bears a highly complex anatomy. The recently introduced exclusively endoscopic transcanal approach to the middle ear is a minimally invasive technique sparing the bone and mucosa of the mastoid bone, since the middle ear is accessed through the external auditory canal. This emerging method has several advantages over the traditional (microscopic) approaches to the middle ear such as the panoramic wide-angle views of the anatomy, the possibility to approach and magnify tiny structures, and the possibility of looking around the corner using angled endoscopes. The cadaveric dissection method presented here consists of an overview on the technical requirements and a precise description of a step-by-step protocol to discover the anatomy of the middle ear. Each step and anatomical structure is carefully described in order to provide a comprehensive guide to endoscopic ear anatomy. In our opinion, this is particularly important to any novice in endoscopic ear surgery as it provides thorough anatomical knowledge and may improve surgical skills.

Novel Dissection Station for Endolaryngeal Microsurgery and Laser Surgery: Development and Dissection Course Experience.

Objective We aimed to develop and validate an ex vivo dissection station for endolaryngeal surgery suitable for different kinds of laryngeal specimen and any type of operating technique (CO2 laser, cold instruments by endoscopic or microscopic techniques). Study Design Experimental construction and validation of a highly specialized dissection station. Setting Laboratory and international dissection course. Methods We designed a lightweight dissection station made of polycarbonate resin approved for use with a CO2 laser. The cylindrical box hosts an articulated laryngeal support. The laryngoscope is positioned on an articulated arm, which is fixed on the construction’s footplate. Validation of the larynx box was performed during an international dissection course on laryngeal surgery held in January 2016. Results We assessed the suitability of our novel dissection station among specialized laryngologists with a mean experience of 14 years. Feedback from the participants was very positive, with a mean general impression of 9.5 (out of 10 points) and a recommendation score of 9.6 for further use. Its utility in transforming the taught surgical steps into daily practice has been highly recognized, with a score of 9.5. Conclusion The lightweight and transparent larynx box is suitable for any kind of laryngeal specimen, and any surgical intervention can be taught at reasonable cost. It is safe and suitable for use with CO2 lasers. Validation among experienced surgeons revealed its suitability in the teaching of endolaryngeal microsurgery and laser surgery.

Letter to the Editor “Is endoscopic ear surgery an alternative to the modified Bondy technique for limited epitympanic cholesteatoma?” by Prasad et al.

We carefully read the interesting article by Prasad et al., recently published on your journal [1]. In their paper, the authors address the issue of epitympanic cholesteatoma surgery by presenting their retrospective case series of 269 ears treated by the modified Bondy technique and by discussing the role of the endoscopy in treating this kind of pathology. Although the paper represents an important contribution to this specific subject, several considerations must be made. Starting from the ‘‘Materials and methods’’ subheading of the paper, it is honestly mentioned that few patients (not specifying how many) were contacted telephonically to gather the latest records: this method of assessing results is quite inaccurate, and those patients should have been excluded from the analyses or at least censored. In fact it is obviously very difficult to assess a recurrence or a residual only by asking the patients. Moreover, out of 362 patients, 59 were lost at follow-up (16 %). In the present case series the patients, which did not have an adequate follow-up (because made by phone, or because of the drop-out) is quite high and could represent a bias. In this perspective, the presented results could have underestimated recurrences, residuals, discharging ear and all other end-points analyzed. About the comparison of the results of the paper to those of the endoscopic literature, there would be several points to argue. First of all, the case series presented by Prasad et al. [1] deals with ‘‘limited’’ attic cholesteatoma with preoperative intact ossicles, in 76.2 % of cases laying laterally to the ossicular chain and in 24.1 % with a limited extension medial to the incus. These results are compared to very different endoscopic case series from literature, in which not only ‘‘limited’’ attic cholesteatomas are included, but also extended attic pathologies involving anterior epitympanum, posterior epitympanum, laying medial to the ossicles, or with preoperative erosion of the ossicular chain. In conclusion, the results cannot be compared, due to completely different anatomical extension and pathologic stages. Second, the comparison of the results was made using an incomplete literature review, because other papers than those mentioned by Prasad et al. dealing with endoscopic technique results are present in literature [2]. Always commenting the results of Prasad et al. it is very surprising that only 1.5 % of their case series had a postoperative discharging ear. It is a fact in our daily clinical practice, that patients with open cavities (regardless the surgeon or the hospital where they were operated) present in a relevant percentage of cases the necessity of periodic toileting, and quite often with a ‘‘wet’’ ear. Moreover, since it is said that most of their patients have been able to perform underwater activities, it would be also interesting to know how and in how many patients Prasad This comment refers to the article available at doi:10.1007/s00405015-3883-3.