Artificial intelligence to detect tympanic membrane perforations.

OBJECTIVE: To explore the feasibility of constructing a proof-of-concept artificial intelligence algorithm to detect tympanic membrane perforations, for future application in under-resourced rural settings. METHODS: A retrospective review was conducted of otoscopic images analysed using transfer learning with Google's Inception-V3 convolutional neural network architecture. The 'gold standard' 'ground truth' was defined by otolaryngologists. Perforation size was categorised as less than one-third (small), one-third to two-thirds (medium), or more than two-thirds (large) of the total tympanic membrane diameter. RESULTS: A total of 233 tympanic membrane images were used (183 for training, 50 for testing). The algorithm correctly identified intact and perforated tympanic membranes (overall accuracy = 76.0 per cent, 95 per cent confidence interval = 62.1-86.0 per cent); the area under the curve was 0.867 (95 per cent confidence interval = 0.771-0.963). CONCLUSION: A proof-of-concept image-classification artificial intelligence algorithm can be used to detect tympanic membrane perforations and, with further development, may prove to be a valuable tool for ear disease screening. Future endeavours are warranted to develop a point-of-care tool for healthcare workers in areas distant from otolaryngology.

Tympanoplasty: factors associated with anatomical and audiometric results. / Timpanoplastias: factores asociados al resultado anatómico y auditivo.

INTRODUCTION: Tympanoplasty is a frequent surgery in otolaryngology. Its main indication is tympanic perforation, followed by adhesive otopathy. Its main and (or) anatomic objective is to restore the tympanic membrane's integrity, preventing infections, and its secondary or audiometric objective is to preserve or improve hearing. MATERIAL AND METHOD: Retrospective study of all patients submitted to tympanoplasty at our hospital. Biodemographic, ear pathology and surgery characteristics were registered, and anatomic and audiometric success rates were analyzed. RESULTS: A total of 182 patients were included, most female (57.1%), with average age of 36.1 years. The main surgical indication was tympanic perforation (89.0%), followed by adhesive otopathy (7.1%). Most tympanoplasties were primary surgeries (84.1%), type I (62.6%), performed by endoaural approach (83.5%) using medial or Austin technique (90.1%). Compound cartilage-perichondrium grafts were most frequently used (87.9%). The anatomic success rate was 84.6%, and the audiometric success rate was 66.8%. Patients who underwent myringoplasty (without raising of tympanomeatal flap) presented a better audiometric result (p=.003). No factors associated with better anatomical results were identified. CONCLUSIONS: Our anatomic and audiometric results are comparable to those previously published. Further prospective studies are required to define factors associated with improved anatomic and audiometric results.

Bilateral same-day endoscopic tympanoplasty.

PURPOSE: Although bilateral same-day tympanoplasty is a faster and more comfortable procedure for patients, it is rarely performed due to its theoretical risks. The present study aims to evaluate the results of patients who underwent bilateral same-day endoscopic tympanoplasty. MATERIALS AND METHODS: In this study, 26 patients and 52 ears were evaluated. Postoperative anatomic success rate, pre- and postoperative hearing test results, hearing gains and postoperative complications were recorded. RESULTS: Postoperative anatomic success rate was 92.3% (48/52). Audiological tests revealed the preoperative air-bone gap (ABG) as 19.1 ± 8.8 (7-35) dB and postoperative ABG as 9.8 ± 5.7 (5-25) dB. Postoperative ABG decreased significantly (p: <0.001) and 9.2 ± 4.6 (2-23) dB hearing gain was obtained. We did not observe any significant complications. CONCLUSION: Bilateral same-day endoscopic tympanoplasty is a feasible surgical procedure with good anatomic and functional outcomes, low complication rate and good postoperative patient comfort.

Endoscopic evaluation of middle ear anatomic variations in autopsy series: analyses of 204 ears / Avaliação endoscópica das variações anatômicas da orelha média em uma série de autópsias: análise de 204 orelhas

Abstract 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.

Resumo 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.

Imaging anatomy of the retrotympanum: variants and their surgical implications.

The retrotympanic anatomy is complex and variable but has received little attention in the radiological literature. With advances in CT technology and the application of cone beam CT to temporal bone imaging, there is now a detailed depiction of the retrotympanic bony structures.With the increasing use of endoscopes in middle ear surgery, it is important for the radiologist to appreciate the nomenclature of the retrotympanic compartments in order to aid communication with the surgeon. For instance, in the context of cholesteatoma, clear imaging descriptions of retrotympanic variability and pathological involvement are valuable in pre-operative planning.The endoscopic anatomy has recently been described and the variants classified. The retrotympanum is divided into medial and lateral compartments with multiple described potential sinuses separated by bony crests.This pictorial review will describe the complex anatomy and variants of the retrotympanum. We will describe optimum reformatting techniques to demonstrate the structures of the retrotympanum and illustrate the associated anatomical landmarks and variants with CT. The implications of anatomical variants with regards to otologic surgery will be discussed.

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

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.

Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature

Abstract Introduction Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR. Objective The present study was undertaken to assess the various parameters of FR and round window visibility, which may be of relevance for cochlear implant surgery. Methods Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of FR and posterior tympanum. Photographs were taken with an 18megapixels digital camera, which were then imported to a computer to determine various parameters. Results The mean distance from the take-off point/crotch of the chorda tympani nerve (CTN) to the stylomastoid foramen was 4.08 ± 0.8 mm(range of 2.06 - 5.5mm). The variations in the course of the CTN included origin at the level of the lateral semicircular canal. Themean chorda-facial angle in our study was 26.91° ± 1.19°, with a range of 25° to 28.69°. The mean FR length ranged between 9.4 mm and 18.56 mm (mean of 12.41 ± 2.91mm) and varied with the origin of the CTN and pneumatization of temporal bone. The average maximum width of the FR was 2.93 ± 0.4 mm (range 2.24-3.45 mm) and the mean width of the FR at the level of the round window was 2.65 ± 0.41 mm. Conclusion The FR approach provides good access to the round windowmembrane in all cases. In some cases, table adjustment is required.

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.

Pars tensa and tympanicomalleal joint: proposal for a new anatomic classification.

PURPOSE: The tympanic membrane (TM) belongs to the ear. Despite its place in the ear anatomy, can we give it also a different anatomic classification? The main objective is to clarify the nature of TM, tympanic bone and malleus to propose a new anatomic classification. METHODS: This cadaveric study was performed in two human heads and six fresh temporal bones. A study of the temporomandibular joint, external acoustic meatus (EAM), TM and middle ear structures was conducted. A medical literature review englobing anatomy, embryology, histology and phylogeny of the ear was performed and the results were compared with the results of the dissection. RESULTS: The external ear is constituted by the auricle and the EAM. This last segment is made by a cartilaginous and an osseous portion. The osseous portion of the EAM is constituted mainly by tympanic bone. The external ear is separated from the middle ear by the TM. Inside the middle ear, there are three ossicles: malleus, incus and stapes, which allow the conduction of sound to the cochlea. Based on the anatomic dissection and medical literature review of the tympanic bone, malleus and TM, we propose that these structures are interconnected like a joint, and named it "Tympanicomalleal joint". CONCLUSIONS: It seems that the TM can be part of a joint that evolved to improve sound transmission and middle ear protection. Thinking TM has part of a joint may help in the development of more efficient reconstructive surgical techniques.

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

OBJECTIVE: Evaluation of an endoscopic anatomic classification of the external auditory canal (EAC) for transcanal endoscopic ear surgery. MATERIALS AND METHOD: The EAC Canal Endoscopic Scale (CES) was initially defined according to total or partial EAC narrowing on 0° transcanal endoscopy. A retrospective study was then conducted between September 2013 and March 2015 in a series of consecutive patients fulfilling the study inclusion criteria. RESULTS: A total of 83% of 5000 patients (10000 ears) were classified as CES 0: i.e., total visualization of the tympanic membrane. Various kinds of EAC narrowing were described. Results were comparable between right and left ears. CONCLUSIONS: 0° endoscopy provided total visualization of the tympanic membrane in most cases, thanks to its magnified lateral view. Preoperative CES classification allows use of angled endoscopes, curved instruments or drilling for canalplasty to be planned in the first step of transcanal endoscopic ear surgery.

Applied anatomy of round window and adjacent structures of tympanum related to cochlear implantation.

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 0.51-1.27mm (mean of 0.69±0.25mm). Maximum width of round window ranged from 0.51 to 2.04mm (mean of 1.16±0.47mm). Average minimum distance between round window and carotid canal was 3.71±0.88mm (range of 2.79-5.34mm) and that between round window and jugular fossa was 2.47±0.9mm (range of 1.24-4.3mm). 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.

Anatomical and functional results of ossiculoplasty using titanium prosthesis.

Titanium ossicular chain replacement prosthesis is often used for rehabilitation of the columellar effect in otologic surgeries. This retrospective study aims to analyse the anatomical and functional results of surgeries in which a titanium prosthesis was used. Two hundred and eighty procedures in 256 patients operated on in a tertiary referral center were analysed. Aetiologies, preoperative audiograms, peroperative data and postoperative outcomes at 2 and 12 months postoperatively were reviewed. Chronic suppurative otitis media with or without cholesteatoma was the main aetiology (89%). There was no difference in anatomical results between partial and total ossicular replacement prosthesis, with an overall dislocation rate of 6%, and an overall extrusion rate of 3%. Regarding functional results, a postoperative air-bone gap ≤ 20 dB was achieved in 65% of cases, with a better result for partial compared to total ossiculoplasty (p = 0.02). A significant difference in air bone gap closure was found when comparing aetiologies, with a higher air-bone gap closure in malformation cases compared to chronic suppurative otitis media with cholesteatoma or retraction cases (p = 0.03). Ossiculoplasty using titanium prosthesis is a safe and effective procedure for rehabilitation of hearing loss, which allows reaching an air-bone gap ≤ 20 dB in the majority of patients.

The malleus cap: Anatomic description of cartilage of the lateral process of the malleus.

PURPOSE: To anatomically describe a cartilaginous cap attached to the lateral process of the malleus. STUDY DESIGN: Histologic and gross anatomic review. METHODS: Twenty temporal bones were histologically reviewed. The anatomical relationship between the tympanic membrane and malleus was then defined at the level of the lateral process of the malleus and the long process of the malleus. Separately, gross evaluation of these levels at the macroscopic level was undertaken through endoscopic imaging in five subjects. RESULTS: All temporal bones reviewed revealed the presence of a cartilaginous cap articulating between the tympanic membrane and the lateral process of the malleus. The cartilaginous cap was also readily identifiable in gross evaluation of the tympanic membrane from views lateral and medial to the tympanic membrane during endoscopic evaluation. CONCLUSION: The cartilaginous cap of the lateral process of the malleus is an important and reliable anatomical structure of the middle ear that has not previously been described. Through knowledge of the structure surgeons may exploit its presence by creating a cleavage plane between the cartilaginous cap and the malleus during tympanoplasty, possibly allowing for safer and more efficient surgery.

[CT study on the development of facial nerve canal in children].

Objective: To assess the characteristics of facial nerve canal between normal anatomy and dysplasia of children in different ages. Methods: A total of 492 health ears were divided into six groups, neonatal group (<1 m , n=42), infancy group(1 m-1 y, n=106), toddler group(1-3 y, n=102), preschool group (3-6 y, n=100), school group(6-10 y, n=60)and adolescent group (10-14 y, n=82). The length and diameter of facial nerve canal and that angles of first and second genu were measured with CT in each group. Results: ①The lengths of facial nerve canal in neonatal and infancy group were shorter than other four groups, especially in the mastoid segments of facial nerve canal. The lengths of mastoid segments in neonatal, infancy, toddler, preschool, school and adolescent groups were 5.03±0.84, 6.25±1.40, 8.34±1.38, 9.70±1.34, 10.84±1.41 and 12.17±1.83 mm, with P<0.05, respectively. After school age, the lengths of labyrinthine and tympanic segment grew slowly or developed completely (P>0.05). ② The diameter of labyrinth and tympanic segment in neonatal group were narrower than other five groups (P<0.05), but no significant difference among them in other groups (P>0.05). ③The dysplasia of facial nerve canal were occurred on 978 locations. Among them, the percentage of dehiscence, aberrance, partially expanding and bifurcation were 72.9%(713/978), 5.1%(50/978), 18.9%(185/978) and 3.1%(30/978) respectively. The percentage of dehiscence in geniculate fossa segment was decreased significantly with age (neonatal group 85.7%(36/42), infancy group 59.4%(63/106), toddler group 39.2%(40/102), preschool group 33%(33/100), school group 30%(18/60)and adolescent group 26.8%(22/82), with P<0.05). Except the dehiscence of geniculate fossa and mastoid segment, there was no significant difference in the occurrence rate of the other variants (P>O.05). Conclusions: The growth of length and dehiscence in labyrinth segment of facial nerve canal are significant in difference ages. The changes of diameter and angles of first and second genu in facial nerve canal, and the rate of other dysplasia are individual.

Development of an intelligent surgical instrument for otitis media with effusion.

To treat a worldwide common ear disease (OME), a device allowing fast grommet tube insertion has been designed in our earlier works (Gao et al., 2015 [1] and Liang et al., 2013 [2]). However, the instrument has to be manually placed as close as to the Tympanic Membrane before the insertion procedures. To realize a fully automated surgical process, the instrument shall be automatically manipulated to align to the axial direction of ear canal and proceed to complete the surgery. A vision-based servomechanism is proposed to solve the path planning problem. A fuzzy-gain-scheduled controller is proposed to minimize the projection error based on the image detection and the proximity measurement. The proposed controller is proven to outperform the traditional PI controller in pre-clinical trials.

Technical note for post-auricular route surgery in Mongolian gerbil.

The Mongolian gerbil (Meriones unguiculatus) is commonly used in hearing research because the hearing frequency spectrum of the gerbil is rather similar to that of the human being. However, a precise description of the surgical post-auricular route has not been reported. The aim of this technical note is to provide details on the procedure and the surgical anatomy of the post-auricular route in the Mongolian gerbil. Surgery was performed under general anesthesia on eight (2 males and 6 females) adult Mongolian gerbils. All steps of the post-auricular route were detailed. This surgery provided an access to the following structures: the semi-circular posterior and lateral canals, the external auditory meatus, the tympanic membrane, the round window, the stapes, the stapedial artery and the reliefs of the cochlea. No anatomic variation was noticed among the 8 animals. This post-auricular route in the Mongolian gerbil defines a brief and simple surgery, overall standardized as a consequence of the absence of common anatomic variation, with painless and uncomplicated post-operative stage.

Intraoperative assessment of ossicular fixation.

Determining the degree of ossicular fixation is a difficult task, with the final assessment often being made with manual palpation during exploratory tympanotomy. A more objective method to evaluate ossicular fixation would be valuable. In this paper we describe a new method which makes use of a magnet and coil to measure ossicular motion through the ear canal with an elevated tympanic membrane. We report measurements of the vibration response at the umbo, the tip of the incus long process and the lateral posterior crus of the stapes before and after artificially fixing the stapes footplate and anterior mallear ligament with luting cement. Results were obtained on temporal bones, but the practicality of the method allows easy clinical implementation. Velocity ratios between different measurement points along the ossicular chain may provide a quantitative indication of the degree of stapes fixation. Isolated anterior mallear ligament fixation was not distinguishable from the unfixed condition.

Subannular tube insertion: anatomical considerations.

OBJECTIVES: To assess the distance between the bony groove created during subannular tubes placement and the chorda tympani, and examine the depth of the hypotympanum and retrotympanum. METHOD: Grooves drilled in cadaver temporal bones at two levels were imaged to measure: the distance between the chorda tympani nerve and the tympanic sulcus, and the depth of the hypotympanum and the retrotympanum relative to the annulus. RESULTS: The chorda tympani was between 0 and 5 mm from the groove cut across the annulus. The hypotympanum average depth was 2 mm (0.44-6.40 mm) and the retrotympanum average depth was 1 mm (0-2.53 mm). CONCLUSION: Grooves drilled across the tympanic sulcus should be placed at a point 20 per cent of the height of the tympanic membrane or lower; this will ensure least risk of injury to the chorda tympani nerve. The depth of the hypotympanum and retrotympanum dictates that the posteroinferior part of a subannular tube flange should be approximately 2 × 1 mm.

Restoration of middle-ear input in fluid-filled middle ears by controlled introduction of air or a novel air-filled implant.

The effect of small amounts of air on sound-induced umbo velocity in an otherwise saline-filled middle ear (ME) was investigated to examine the efficacy of a novel balloon-like air-filled ME implant suitable for patients with chronically non-aerated MEs. In this study, air bubbles or air-filled implants were introduced into saline-filled human cadaveric MEs. Umbo velocity, a convenient measure of ME response, served as an indicator of hearing sensitivity. Filling the ME with saline reduced umbo velocity by 25-30 dB at low frequencies and more at high frequencies, consistent with earlier work (Ravicz et al., Hear. Res. 195: 103-130 (2004)). Small amounts of air (∼30 µl) in the otherwise saline-filled ME increased umbo velocity substantially, to levels only 10-15 dB lower than in the dry ME, in a frequency- and location-dependent manner: air in contact with the tympanic membrane (TM) increased umbo velocity at all frequencies, while air located away from the TM increased umbo velocity only below about 500 Hz. The air-filled implant also affected umbo velocity in a manner similar to an air bubble of equivalent compliance. Inserting additional implants into the ME had the same effect as increasing air volume. These results suggest these middle-ear implants would significantly reduce conductive hearing loss in patients with chronically fluid-filled MEs.

Multiscale fabrication of biomimetic scaffolds for tympanic membrane tissue engineering.

The tympanic membrane (TM) is a thin tissue able to efficiently collect and transmit sound vibrations across the middle ear thanks to the particular orientation of its collagen fibers, radiate on one side and circular on the opposite side. Through the combination of advanced scaffolds and autologous cells, tissue engineering (TE) could offer valuable alternatives to autografting in major TM lesions. In this study, a multiscale approach based on electrospinning (ES) and additive manufacturing (AM) was investigated to fabricate scaffolds, based on FDA approved copolymers, resembling the anatomic features and collagen fiber arrangement of the human TM. A single scale TM scaffold was manufactured using a custom-made collector designed to confer a radial macro-arrangement to poly(lactic-co-glycolic acid) electrospun fibers during their deposition. Dual and triple scale scaffolds were fabricated combining conventional ES with AM to produce poly(ethylene oxide terephthalate)/poly(butylene terephthalate) block copolymer scaffolds with anatomic-like architecture. The processing parameters were optimized for each manufacturing method and copolymer. TM scaffolds were cultured in vitro with human mesenchymal stromal cells, which were viable, metabolically active and organized following the anisotropic character of the scaffolds. The highest viability, cell density and protein content were detected in dual and triple scale scaffolds. Our findings showed that these biomimetic micro-patterned substrates enabled cell disposal along architectural directions, thus appearing as promising substrates for developing functional TM replacements via TE.