Endoscopic classification of the external auditory canal for transcanal endoscopic ear surgery

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.

Lexicon for classifying ear-canal shapes

The ear canal is usually described as an S-shaped funnel. In attempting to classify ear-canal shapes obtained from point clouds digitized from molds of 300 ears, the problem of designing criteria for distinguishing and organizing the canal shapes arose. In this work, we extracted features inspired by the S-shape characteristic (critical point, maximum, minimum, twist, writhe, translation, rotation) and, through them, introduced 14 types of ear-canal shapes. This classification allowed comparison of ears within a type and of ears between different types. It expanded our range of descriptors of canal shapes and unlocked perspectives for applications.

External Auditory Canal Cholesteatoma after Radiation Therapy for Nasopharyngeal Cancer: Case Series and Systematic Review

The authors performed a systematic review, in accordance with the PRISMA guidelines, across multiple databases, including all original studies published until November 2022, focusing on External auditory canal cholesteatoma (EACC) after radiation therapy (RT) for nasopharyngeal cancer (NC). Inclusion criteria were original articles reporting on secondary EACC after RT for NC. Articles were critically appraised to assess level of evidence using the Oxford Center for Evidence-Based Medicine criteria. Overall, 138 papers were identified and after duplicate removal (34 papers) and excluding papers not in English, 93 papers were assessed for eligibility; finally, only five papers were included and summarized with the three cases coming from our institution. These mainly involved the anterior and the inferior part of the EAC. The mean time of diagnosis after RT was the largest series of 6.5 years (with a range from 0.5 to 15.4 years). Patients undergoing RT for NC have 18 times a higher risk of developing EACC compared to the normal population. EACC is probably one of the most underreported side effects, because patients may present variable clinical findings, which could lead to misdiagnosis. Early diagnosis of RT related EACC is advised to enable conservative treatment.

Endoscopic transcanal transtympanic myringoplasty vs. endoscopic transcanal tympanoplasty: 1-year follow-up study

BACKGROUND

Endoscopic transcanal transtympanic myringoplasty (ETTM) is a relatively easier technique than endoscopic transcanal tympanoplasty (ETT) for repairing tympanic membrane perforations. No studies have compared the outcomes of these two procedures with tragal perichondrium after 1-year. Furthermore, there is no evidence-based stratification according to variations in perforation size in endoscopic ear surgery. Therefore, we compared the 1-year outcomes of ETTM and ETT stratified according to perforation size.

METHODS

Patients who underwent ETT and ETTM to repair eardrum perforations with a tragal perichondrium graft were identified. Pure-tone audiometric tests and otoscopic examination were performed to assess hearing outcomes and perforation sizes both preoperatively and at least 1 year postoperatively.

RESULTS

In total, 158 patients (159 ears) were included. ETT was performed on 83 ears, and ETTM was performed on 76 ears. The ETTM procedure time was 10-minutes shorter than that for ETT ( p < 0.001). Perforation size was significantly correlated with graft take-rate. For large perforations, the ETT success rate was significantly higher than that of ETTM (91.7% vs. 78.9%). Success rates for small-medium perforations were comparable for both methods ( p > 0.05). However, for medium perforations, the graft take-rate of ETT reached a plateau after 6 months, while that of ETTM gradually declined during the 12-month follow-up. Both groups had a comparable mean postoperative air-bone gap gain ( p = 0.666).

CONCLUSION

ETTM is suitable for repairing small perforations, whereas ETT is preferred for large perforations. Both methods, and particularly ETTM, should be employed cautiously for medium perforations.

Canalplasty using underwater bone drilling in transcanal endoscopic myringoplasty for patients with a narrow external auditory canal

BACKGROUND

Canalplasty is important in microscopic ear surgery, but it has rarely been studied in otoendoscopic surgery.

OBJECTIVES

The aim of this study was to investigate the application of canalplasty due to external auditory canal stenosis caused by bony bulges in endoscopic myringoplasty.

MATERIALS AND METHODS

The procedures and effects of canalplasties and myringoplasties were analysed. During the canalplasties, depending on the location of the bulges, the meatal skin flaps were elevated in different manners, and the underwater bone drilling technique was adopted to remove the bulges to enlarge the osseous canals.

RESULTS

Canalplasties were performed in 18.5% (33/178) of myringoplasties. All surgeries were completed exclusively via the transcanal endoscopic approach. No iatrogenic injuries were found. Most of the canalplasties required drilling off bulges on multiple walls. The mean total duration of the canalplasties and myringoplasties was 76.6 ± 4.5 min, and the proportion of time required for the canalplasties was 47.3 ± 2.4%.

CONCLUSION

Only approximately one in five endoscopic myringoplasties require antecedent canalplasties due to concurrent canal stenosis. With the underwater bone drilling technique, transcanal endoscopic canalplasty can be safely and efficiently conducted.

Totally endoscopic tympanic membrane repair

BACKGROUND

Transcanal totally endoscopic ear surgery (TEES) has become increasingly popular internationally; however, for surgeons trained with a two-handed microscope-guided approach, the potential challenges of adopting TEES can appear off-putting.

OBJECTIVES

This article outlines the pros and cons of TEES for tympanic membrane repair and describes aspects of surgical technique relevant to those who might adopt this approach.

MATERIALS AND METHODS

Data are provided from the author's experience along with a review of relevant literature, including several meta-analyses of tympanoplasty outcome.

RESULTS

Meta-analyses show that TEES tympanoplasty is as effective at closing tympanic membrane perforations and improving hearing as microscope-guided surgery. Yet patients benefit from avoidance of a skin incision and faster recovery.

CONCLUSION

Repair of the tympanic membrane with TEES is feasible and effective. This minimally invasive approach is very appealing to patients.

Developing a novel meatal areolar tissue autograft for minimally invasive tympanoplasty

BACKGROUND

We developed an easy and minimally invasive method of transmeatal tympanoplasty using meatal areolar tissue (MAT) grafts to achieve less postoperative morbidity or surgical scarring. We compared the functional and anatomical results of the developed method with conventional endaural tympanoplasty with a temporalis fascia (TF) graft.

METHODS

In this retrospective cohort study, 58 patients (59 ears) with simple chronic otitis media who underwent type I tympanoplasty between January 2016 and August 2018 were included. All surgeries were performed in a tertiary referral hospital and by the same senior surgeon. The tympanic membrane (TM) was repaired with either a TF or an MAT graft.

RESULTS

Healing of the perforated TM and improvement in a hearing test by air-bone gap (ABG) closure were identified. Postoperative wound conditions were also evaluated. Twenty-eight ears were grafted with MAT, and 31 ears were grafted with TF. Graft success was observed in 26 patients (92.9%) in the MAT group and 28 patients (90.3%) in the TF group. Both groups showed functional improvement compared with the preoperative measurements. The postoperative pure tone audiogram (p = 0.737), ABG closure (p = 0.547), and graft success rate (p = 0.726) were not significantly different between the two groups. Neither wound dehiscence nor keloid formation was observed in our patients.

CONCLUSION

Both MAT and TF grafts revealed satisfactory surgical and functional results. Compared with the conventional endaural approach with TF grafts, the new transmeatal approach method with an MAT graft causes relatively minimal trauma and results in better wound cosmetics. This method represents an easy, minimally invasive surgery and shows comparatively good results.

COVID-19 and ear endoscopy in otologic practices

Purpose

Otolaryngologists have had to postpone the majority of surgical procedures in the current COVID-19 pandemic. Airborne transmission, beyond the projection of droplets from upper airways, expose healthcare workers to a risk of viral infection. Aerosol generating procedures (AGP) increase the risk of viral transmission to staff within the operating room.

Methods

Surgery of middle ear and mastoid is also considered an AGP, particularly mastoidectomy performed using a high-speed drill. The authors report their experience in endoscopic ear surgery as an alternative technique to reduce AGP in otologic procedures.

Results

Transcanal endoscopic ear surgery is a reliable technique used to manage many otologic conditions.

Conclusion

The endoscopic approach may reduce the risk of viral transmission to operating room staff by reducing the need for mastoidectomy.

[External ear canal parameters and endoscopic otosurgery in children]

INTRODUCTION

Main difficulties of endoscopic ear surgery in children could be connected with width of external ear canal (EEC) and endoscope diameter discrepancy.

OBJECTIVE

To investigate EEC parameters in children, to determine cross section and to develop the recommendations whenever possible of endootosurgery performance in children.

MATERIAL AND METHODS

Research included two stages. First - average values determination of narrowest site EEC in children according to computer tomograms. Second - determination of age of the patient and the amount of acoustical pass at which there are specifications for performance of interventions endoscopic.

RESULTS

EEC square: 1-3 years - 12.6±1.91 mm², diameter is 4.01±0.59 mm; 4-7 years - 16.8±1.34 mm², diameter is 5.34±0.43 mm; 8-11 years - 21.7±1.38 mm², diameter is 6.9±0.45 mm; 12-18 years - 31.3±4.27 mm², diameter is 9.96±1.4 mm. The difference between parameters at each of age groups was statistically reliable. Comfortable work endoscopically is possible with EEC square 20.4±3.19 mm² and more. This corresponds to average value of EEC in 8-18 years.

CONCLUSIONS

Endoscopic ear surgery is inexpedient in children up to 4 years. It is necessary to expect that intervention will be exigeant and transition to the microscopic equipment is required in case of 4-7 years old patients. Endoscopic ear surgery can be used with success to performance of various manipulations and surgical interventions on a middle ear in patients 8-18 years old.

Transcanal Computed Tomography Views for Transcanal Endoscopic Lateral Skull Base Surgery: Pilot Cadaveric Study

Objective  Transcanal endoscopic operative approaches provide for a minimally invasive surgical portal to the lateral skull base. Traditional preoperative imaging evaluation involves computed tomography (CT) acquisition in the axial and coronal planes that are not optimized for the transcanal surgical corridor. Herein, we describe a novel CT-based "transcanal view" for preoperative surgical planning and intraoperative navigation. Study Design  Present study is a cadaveric imaging study. Methods  Cadaveric temporal bones ( n  = 6) from three specimens underwent high-resolution CT (0.625 mm slice thickness). Using three-dimensional (3D) Slicer 4.8, reformatted "transcanal" views in the plane of the external auditory canal (EAC) were created. Axial and coronal reformats were used to compare and measure distances between anatomic structures in the plane of the EAC. Results  The degree of oblique tilt for transcanal CT reformats was 6.67 ± 1.78 degrees to align the EAC in axial and coronal planes. Anticipated critical landmarks were identified easily using the transcanal view. Mean values were 8.68 ± 0.38 mm for annulus diameter, 9.5 ± 0.93 mm for isthmus diameter, 10.27 ± 0.73 mm for distance between annulus and isthmus, 2.95 ± 0.13 mm for distance between annulus and stapes capitulum, 5.12 ± 0.35 mm for distance between annulus and mastoid facial nerve, and 19.54 ± 1.22 mm for EAC length. Conclusion  This study is the first to illustrate a novel "transcanal" CT sequence intended for endoscopic lateral skull base surgery. Future studies may address how incorporation of a transcanal CT reformat may influence surgical decision making.