Measurement of the Pediatric and Adult Osseous External Auditory Canal: Implications for Transcanal Endoscopic Ear Surgery

Recent advances in Otology: Current landscape and future direction

Hearing is an essential sensation, and its deterioration leads to a significant decrease in the quality of life. Thus, great efforts have been made by otologists to preserve and recover hearing. Our knowledge regarding the field of otology has progressed with advances in technology, and otologists have sought to develop novel approaches in the field of otologic surgery to achieve higher hearing recovery or preservation rates. This requires knowledge regarding the anatomy of the temporal bone and the physiology of hearing. Basic research in the field of otology has progressed with advances in molecular biology and genetics. This review summarizes the current views and recent advances in the field of otology and otologic surgery, especially from the viewpoint of young Japanese clinician-scientists, and presents the perspectives and future directions for several topics in the field of otology. This review will aid next-generation researchers in understanding the recent advances and future challenges in the field of otology.

Treatment of congenital middle ear cholesteatoma in children using endoscopic and microscopic ear surgeries: a case series

Introduction

Surgical removal is widely employed in children with congenital middle ear cholesteatoma (CMEC). Here, we report the surgical outcomes of CMEC removal via endoscopic ear surgery (EES) and microscopic ear surgery (MES) in children.

Methods

Children with CMEC who underwent preoperative medical history inquiry, hearing test, endoscopic evaluation, and radiology imaging before receiving EES or MES were included. Postoperative audiological outcomes and recurrence rates were collected.

Results

Seventeen children (20 ears) with stage II-IV CMEC were included. Of those, 11 ears (55.0%) underwent EES, and 9 ears (45.0%) underwent MES. The follow-up time was 35 ± 13.5 months. One child in the EES group with stage III CMEC had a recurrence during the follow-up period. In the EES group, the average minimum diameter of the external auditory canal on the affected side was 5.8 mm (4.3-8.0 mm). No linear association was found between age and the minimum diameter of the external auditory canal.

Discussion

EES is a promising treatment option for children with early-stage CMEC because of its low recurrence rate and minimally invasive nature. The minimum diameter of the external auditory canal on the affected side should be meticulously examined when performing EES in children.

External Auditory Canal: Computed Tomography Analysis and Classification

Introduction  Computed tomography (CT) details of the external auditory canal (EAC) are not fully covered in the literature, so building up base for the CT evaluation and description is important. Preoperative details of the EAC are mandatory before any approach or procedure involving the canal. Objective  To determine the different dimensions, measurements, and grading of the EAC by CT scan that were not previously published. Methods  The CT scans of 100 temporal bones (200 sides) were included. Axial images were acquired with multiplanar reformates to obtain delicate details in coronal and sagittal planes for all subjects. Results  At the EAC entry, the mean vertical length (height) was 7.75 ± 1 mm, and its mean horizontal length (width) was 6.1 ± 0.8. At the bony cartilaginous junction of the EAC, the mean vertical length was 7.88 ± 1 mm, and its mean horizontal length was 6.22 ± 0.9. At the EAC isthmus, the mean vertical length was 6.8 ± 0.97 mm, and its mean horizontal length was 5.2 ± 0.76. At the medial end of the EAC, the mean vertical length was 7.1 ± 0.9 mm, and its mean horizontal length was 5.4 ± 0.85. There were no reported significant differences between right and left sides in all dimensions. Males showed significantly longer vertical and horizontal dimensions of the EAC entry, vertical dimension of the isthmus, and vertical dimension of the medial end of the EAC than females. Conclusion  This study improves otologists and radiologists' awareness of EAC variations in the ear field and can be of help to residents in training.

Updates in paediatric cholesteatoma

PURPOSE OF REVIEW

The management of paediatric patients with cholesteatoma is complex, as the disease process is more aggressive in children than adults. New technologies and practice adaptations currently help optimize the surgical management and monitoring of these challenging patients.

RECENT FINDINGS

Several options of surgical management are available and are associated with equal if not improved outcomes. Technologic advancements in endoscopic ear surgery, the discovery of chemical-assisted dissection of cholesteatoma and advanced imaging protocols have enabled surgeons to better care for patients with this complex disease process.

SUMMARY

The advances in endoscopic ear surgery, the discovery of Mesna as a chemically assisted dissection agent to improve recidivism rates and the use of specific diffusion-weighted MRI protocols enable the otologic surgeon to better care for these paediatric patients.

Endoscopic vs. microscopic stapes surgery: An anatomical feasibility study

Objectives

To investigate the feasibility of the endoscopic approach vs. microscopic approach during stapes surgery, focusing on the visualization of the important anatomical structures of the middle ear, the volume of the resected scutum and chorda tympani (CT) injury.

Methods

Fresh frozen human cadaveric heads underwent two stapes surgeries using an operating microscope on one ear and an endoscope on the other ear. The surgeon documented the visualization of critical landmarks, as well as exposure and injury of the CT. The volume of resected scutum was evaluated using cone beam computed tomography scanning and three-dimensional imaging.

Results

We performed endoscopic stapes surgery in 10 ears and microscopic stapes surgery in 11 ears. A stapes prosthesis was placed in all ears. The volume of bony scutum resection was significantly lower in the endoscopic group (median = 2.20 mm³, IQR = 4.17) than in the microscopic group (median 13.25 mm³, IQR = 8.71). No scutum was removed in two endoscopic ears, while scutum was removed in all microscopic ears. The endoscopic and microscopic group had similar CT injury.

Conclusions

This study showed that the endoscopic stapes surgery procedure is feasible and might be less invasive than microscopic stapes surgery. Future clinical prospective and functional studies will be needed to support our findings.

Thermal Safety of Endoscopic Usage in Robot-Assisted Middle Ear Surgery: An Experimental Study

Objectives: The widespread application of endoscopic ear surgery (EES), performed through the external auditory canal, has revealed the limitations of the one-handed technique. The RobOtol® (Collin ORL, Bagneux, France) otological robotic system has been introduced to enable two-handed procedures; however, the thermal properties of dedicated endoscopes, which are usually used in neurosurgery, called "neuro-endoscopes," have not yet been clarified for the robotic systems. In this study, we aimed to profile the thermal characteristics of two dedicated neuro-endoscopes, as compared to endoscopes used routinely in manual EES, called "oto-endoscopes," and defined by a smaller diameter and shorter length, and to discuss the safe application of robotic assistance in EES. Methods: Two neuro-endoscopes (3.3 mm, 25 cm, 0°/30°) were studied using two routine light sources (LED/xenon), and two routine oto-endoscopes (3 mm, 14 cm, 0°/30°) were initially measured to provide a comprehensive comparison. Light intensities and temperatures were measured at different power settings. The thermal distributions were measured in an open environment and a human temporal bone model of EES. The cooling measures were also studied. Results: Light intensity was correlated with stabilized tip temperatures (P < 0.01, R ² = 0.8719). Under 100% xenon power, the stabilized temperatures at the tips of 0°, 30° neuro-endoscopes, and 0°, 30° oto-endoscopes were 96.1, 60.1, 67.8, and 56.4°C, respectively. With 100% LED power, the temperatures decreased by about 10°C, respectively. For the 0° neuro-endoscope, the illuminated area far away 1cm from the tip was below 37°C when using more than 50% both power, while this distance for 30° neuro-endoscope was 0.5 cm. In the EES temporal bone model, the round window area could reach 59.3°C with the 0° neuro-endoscope under 100% xenon power. Suction resulted in a ~1-2°C temperature drop, while a 10 mL saline rinse gave a baseline temperature which lasted for 2.5 min. Conclusion: Neuro-endoscope causes higher thermal releasing in the surgical cavity of ESS, which should be especially cautious in the robotic system usage. Applying submaximal light intensity, a LED source and intermittent rinsing should be considered for the safer robot-assisted EES using a neuro-endoscope that allows a two-handed surgical procedure.

Multicenter Study of Congenital Middle Ear Anomalies. Report on 246 Ears

OBJECTIVES/HYPOTHESIS

Congenital middle ear anomalies represent a relatively rare condition. This study aimed to describe the characteristics and the surgical outcomes for patients with middle ear anomalies.

METHODS

A multicenter study was conducted of consecutive patients with congenital middle ear anomalies who underwent primary surgical treatment between January 2008 and December 2017. Demographics, surgical procedures, and audiometric data were registered into the institutional database. Hearing changes and postoperative air-bone gap (ABG) were evaluated 1 year after surgery.

RESULTS

A total of 246 patients (246 ears) (median age: 14 years, range: 4-75 years old) were included in this study. Anomalies were subdivided using the Teunissen and Cremers classification: 53 ears (22%) were categorized as class I, comprising only stapes ankylosis; 35 ears (14%) as class II, having ossicular chain anomalies with stapes ankylosis; 139 ears (57%) as class III, having ossicular chain anomalies with a mobile stapes-footplate; and 19 ears (8%) as class IV, with aplasia of the oval window. Evaluation of hearing outcomes for 198 ears with more than 1 year of follow-up revealed that good postoperative ABG (≤20 dB) was achieved in 82% of class I, 68% of class II, 74% of class III, and 23% of class IV anomalies. The postoperative ABG in class IV was significantly worse than in class I (P < .001) or class III (P < .01).

CONCLUSIONS

This study demonstrated that class III anomalies comprised the majority of middle ear anomalies and surgical outcomes for class IV anomalies are unfavorable.

LEVEL OF EVIDENCE

4 Laryngoscope, 131:E2323-E2328, 2021.