Applied anatomy of round window and adjacent structures of tympanum related to cochlear implantation / Anatomia aplicada da janela redonda e estruturas adjacentes relacionadas ao implante coclear

Abstract Introduction: Various aspects of the round window anatomy and anatomy of posterior tympanum have relevant implications for designing cochlear implant electrodes and visualizing the round window through facial recess. Preoperative information about possible anatomical variations of the round window and its relationships to the adjacent neurovascular structures can help reduce complications in cochlear implant surgery. Objective: The present study was undertaken to assess the common variations in round window anatomy and the relationships to structures of the tympanum that may be relevant for cochlear implant surgery. Methods: Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of round window and its relation to facial nerve, carotid canal, jugular fossa and other structures of posterior tympanum. The dissected bones were photographed by a digital camera of 18 megapixels, which were then imported to a computer to determine various parameters using ScopyDoc 8.0.0.22 version software, after proper calibration and at 1× magnification. Results: When the round window niche is placed posteriorly and inferiorly, the distance between round window and vertical facial nerve decreases, whereas that with horizontal facial nerve increases. In such cases, the distance between oval window and round window also increases. Maximum height of the round window in our study ranged from 0.51-1.27 mm (mean of 0.69 ± 0.25 mm). Maximum width of round window ranged from 0.51 to 2.04 mm (mean of 1.16 ± 0.47 mm). Average minimum distance between round window and carotid canal was 3.71 ± 0.88 mm (range of 2.79-5.34 mm) and that between round window and jugular fossa was 2.47 ± 0.9 mm (range of 1.24-4.3 mm). Conclusion: The distances from the round window to the oval window and facial nerve are important parameters in identifying a difficult round window niche. Modification of the electrode may be a better option than drilling off the round window margins for insertion of cochlear implant electrodes.

Resumo Introdução: Vários aspectos da anatomia da janela redonda e da anatomia da caixa timpânica posterior são relevantes, devido a suas implicações no desenho dos eletrodos para o implante coclear e na visibilidade da janela redonda através do recesso facial. Informações prévias sobre possíveis variações anatômicas da janela redonda e suas relações com as estruturas neurovasculares adjacentes podem ajudar a reduzir as complicações dessa cirurgia. Objetivo: O presente estudo foi realizado para avaliar as diversas variações da anatomia da janela redonda e sua relação com as estruturas adjacentes, o que pode ser relevante para a cirurgia de implante coclear. Método: Trinta e cinco ossos temporais normais de cadáveres humanos frescos foram dissecados para avaliação da anatomia da janela redonda e sua relação com o nervo facial, canal carotídeo, fossa jugular e outras estruturas da caixa timpânica posterior. Os ossos dissecados foram fotografados com uma câmera digital de 18 megapixels e as imagens importadas para um computador para determinar diversos parâmetros, utilizando-se o software ScopyDoc versão 8.0.0.22, após a calibração adequada e com ampliação de 1×. Resultados: Quando o nicho da janela redonda se encontra posicionado posteriormente e inferiormente, a distância entre a janela redonda e o nervo facial vertical diminui, enquanto aquela com o nervo facial horizontal aumenta. Em tais casos, a distância entre a janela oval e a janela redonda também aumenta. A altura máxima da janela redonda em nosso estudo variou de 0,51 a 1,27 mm (média de 0,69 ± 0,25 mm). A largura máxima da janela redonda variou de 0,51 a 2,04 mm (média de 1,16 a 0,47 mm). A distância mínima média entre a janela redonda e o canal carotídeo foi de 3,71 ± 0,88 mm (variação de 2,79 a 5,34 mm) e entre a janela redonda e a fossa jugular, em nosso estudo, foi de 2,47 ± 0,9 mm (variação de 1,24 ± 4,3 mm). Conclusão: A distância da janela redonda a partir da janela oval e do nervo facial são parâmetros importantes para a identificação do difícil nicho da janela redonda. A modificação do desenho do eletrodo pode ser uma opção melhor do que o broqueamento das margens da janela redonda para a inserção dos eletrodos no implante coclear.

A Spatial Index Analysis for Decision on the First Opening of Facial Recess in Posterior Tympanotomy / 대한이비인후과학회지

BACKGROUND AND OBJECTIVES: Temporal bone is a complicated structure anatomically. Highresolution computed tomography (HRCT) provides a good method for examination of the middle ear, inner ear anatomy and pathologic changes in the temporal bones. The purpose of this study is to evaluate the relations of facial nerve and other structures in temporal bone and factors influencing access to posterior tympanotomy according to the age, sex and degree of temporal bone pneumatizaton. SUBJECTS AND METHOD: A total of 133 ears of temporal bone computer tomograph (TBCT) were analyzed. We measured the distances and angle between important surgical landmarks, and compared the data according to the age, sex and mastoid pneumatization. RESULTS: We presented the angle between the posterior wall of external auditory canal and the facial nerve with the index for facial nerve preservation in posterior tympanotomy. This angle is 10.05 degrees other indices are not related statistically. CONCLUSION: This results may enable preoperative assessment and provide background knowledge to prevent facial nerve injury when performing a posterior tympanotomy.

THIN SECTIONAL ANATOMY AND HRCT OF FACIAL RECESS AND ITS ADJACENT STRUCTURES / 解剖学报

0.05).Conclusion The thin section collodion anatomy of temporal bone area,combined with the images of HRCT can clearly delineate the details of facial recess and its relative structures.

Role of Measuring Facial Recess in Cochlear Implantation / 听力学及言语疾病杂志

Objective To introduce the development of facial recess of 210 cases who recieved cochlear implantation and experienced the opening of the facial recess under the direction of high resolation computed tomography(HRCT).Methods The facial recess was assessed and measured using the HRCT before cochlear implantation in 210 patients who suffered from severe and profound sensorineural hearing loss.A statistic analysis was performed according to the age group,and the findings during the operation were compared with that before the surgery.Results The facial recess of 13 cases (6%) did not developed.The mean volume of the rest facial recess was 4.26 mm3 in 197 cases,while in 12.0 years group(group C) it was 3.09 mm3.The differences among three groups were statistically significant. The findings during the operation was agreed with the assessment results prior to the surgery.Conclusion 94% facial recesses developed in all 210 cases.Employment of HRCT scan prior to the surgery allows auurate determination of the location of facial recess to ensure successful surgery.