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. 2020 Jan-Feb;86(1):74-82.
doi: 10.1016/j.bjorl.2018.10.002. Epub 2018 Nov 3.

Endoscopic evaluation of middle ear anatomic variations in autopsy series: analyses of 204 ears

Bayram Şahin  1 , Kadir Serkan Orhan  2 , Hızır Aslıyüksek  3 , Erdoğan Kara  3 , Yalçın Büyük  3 , Yahya Güldiken  2
Affiliations

Endoscopic evaluation of middle ear anatomic variations in autopsy series: analyses of 204 ears

Bayram Şahin et al. Braz J Otorhinolaryngol. 2020 Jan-Feb.

Abstract
in English, Portuguese

Introduction: Microsurgery of the ear requires complete evaluation of middle ear surgical anatomy, especially the posterior tympanic cavity anatomy. Preoperative assessment of the middle ear cavity is limited by the permeability of eardrum and temporal bone density. Therefore, middle ear exploration is an extremely useful method to identify structural abnormalities and anatomical variations.

Objective: The aim of this study is to determine anatomic variations of the middle ear in an autopsy series.

Methods: All evaluations were performed in the Forensic Medicine Institute Morgue Department. The cases over 18 years of age, with no temporal bone trauma and history of otologic surgery included in this study.

Results: One hundred and two cadavers were included in the study. The mean age was 49.08±17.76 years. Anterior wall prominence of the external auditory canal was present in 27 of all cadavers (26.4%). The tympanic membrane was normal in 192 ears (94%) while several eardrum pathologies were detected in 12 ears (6%). Agenesis of the pyramidal eminence and stapedial tendon was found in 3 ears. While the ponticulus was bony ridge-shaped in 156 of 204 ears (76.4%), it was bridge-shaped in 25 ears (12.3%). The ponticulus was absent in 23 ears (11.3%). While complete subiculum was present in 136 of all ears (66.7%), incomplete subiculum was present in 21 ears (10.3%). Subiculum was absent in 47 ears (23%). Facial dehiscence was found in 32 ears and the round window niche was covered by a pseudomembrane in 85 ears (41.6%). A fixed footplate was present in 7.4% of all ears, and no persistent stapedial artery was seen in any cases.

Conclusion: The pseudomembrane frequency covering the round window niche was found different from reports in the literature. In addition, the frequency of the external auditory canal wall prominence has been reported for the first time.

Introdução: A otomicrocirurgia requer avaliação completa da anatomia cirúrgica da orelha média, especialmente da anatomia da cavidade timpânica posterior. A avaliação pré-operatória da cavidade timpânica é limitada pela permeabilidade do tímpano e densidade do osso temporal. Portanto, a exploração da orelha média é um método extremamente útil para identificar anormalidades estruturais e variações anatômicas.

Objetivo: Determinar as variações anatômicas da orelha média em uma série de autópsias.

Método: Todas as avaliações foram realizadas no necrotério do Instituto Médico-Legal. Os casos com mais de 18 anos, sem trauma do osso temporal e história de cirurgia otológica foram incluídos neste estudo.

Resultados: Cento e dois cadáveres foram incluídos no estudo. A média de idade foi de 49,08 ± 17,76 anos. A proeminência da parede anterior do conduto auditivo externo estava presente em 27 de todos os cadáveres (26,4%). A membrana timpânica era normal em 192 orelhas (94%), enquanto várias alterações do tímpano foram detectadas em 12 orelhas (6%). Agenesia da eminência piramidal e do tendão do estapédio foi encontrada em 3 orelhas. Enquanto o pontículo tinha formato de crista óssea em 156 das 204 orelhas (76,4%), tinha o formato de ponte em 25 orelhas (12,3%). O pontículo estava ausente em 23 orelhas (11,3%). Enquanto o subículo completo estava presente em 136 de todas as orelhas (66,7%), encontrava-se incompleto em 21 orelhas (10,3%). O subículo estava ausente em 47 orelhas (23%). Deiscência facial foi encontrada em 32 orelhas e o nicho da janela redonda estava coberto por uma pseudomembrana em 85 orelhas (41,6%). A platina fixa foi observada em 7,4% de todas as orelhas e a artéria estapediana persistente não foi vista.

Conclusão: A frequência da pseudomembrana que cobre o nicho da janela redonda foi diferente daquela encontrada na literatura. Além disso, a frequência da proeminência da parede do canal auditivo externo foi relatada pela primeira vez.

Keywords: Anatomia da orelha média; Cirurgia endoscópica da orelha; Endoscopic ear surgery; Middle ear anatomy; Ponticulus; Pontículo; Retrotympanum; Retrotímpano; Subiculum; Subículo.

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Figures

Figure 1
Figure 1
Right ear. (A) Elevation of the tympanomeatal flap from external auditory canal. (B) Visualization of the middle ear cavity via transcanal endoscopic approach. (C) Disconnection of the incudostapedial joint by 90° curved pick. (D) Removing of the stapedial tendon by curved micro-scissors. (E) Separation of the stapes from the oval window as in one piece with footplate. (F) Evaluation of the facial nerve canal dehiscence by micro elevator.
Figure 2
Figure 2
Distribution of anterior wall prominence of the external auditory canal according to gender.
Figure 3
Figure 3
Agenesis of the pyramidal eminence and stapedius tendon. (A1) Case I right ear; (A2) Case I left ear; (B) Case II left ear (Black arrows: stapes).
Figure 4
Figure 4
Variations of the ponticulus. (A) Bridge shape (indicated by 90° curved pick). (B) Bony ridge shape (indicated by 90° curved pick). (C) Total absence. (D) Total absence of ponticulus and bony ridge shape subiculum (indicated by white arrow) (black arrow, pyramidal eminence; *, facial nerve).
Figure 5
Figure 5
Variations of the subiculum. (A) Bony ridge shape. (B and C) Bridge shape. (D) Total absence and dehiscence jugular bulb abnormality (black arrows: subiculum; *, facial nerve).
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