Absent pyramidal eminence and stapedial tendon associated with congenital stapes footplate fixation: Intraoperative and radiographic findings.

OBJECTIVE: Report an association between congenital stapes footplate fixation (CSFF) and radiological absence of the pyramidal eminence and stapedial tendon. PATIENTS: Children and adults with intraoperatively confirmed CSFF and an absent stapedial tendon. INTERVENTIONS: Computed tomography (CT); exploratory tympanotomy with stapedotomy. MAIN OUTCOME MEASURES: Absence of a pyramidal eminence and stapedial tendon aperture identified on preoperative CT that was confirmed intraoperatively. RESULTS: Eight patients with intraoperative confirmation of CSFF and absent stapedial tendon were retrospectively identified. The average preoperative bone conduction and air conduction pure tone averages were 19.6 dB (SD 15.6 dB) and 55.9 dB (SD 23.6 dB), respectively. The average air-bone gap was 36.3 dB (SD 17.9 dB) preoperatively. In the seven patients who underwent preoperative CT, all were consistently identified to have an absent or hypoplastic pyramidal eminence and absent stapedial tendon aperture at the pyramidal eminence. In six cases, the stapedial footplate appeared normal, while in one case the footplate appeared abnormal which correlated with severe facial nerve prolapse observed intraoperatively. All eight cases underwent exploratory tympanotomy and demonstrated intraoperative stapes footplate fixation, absent stapedial tendon and either absent or hypoplastic pyramidal eminence, which correlated with preoperative CT findings. CONCLUSIONS: This study identifies a clinically pragmatic association between an absent pyramidal eminence identified on high-resolution CT and the diagnosis of CSFF. In a condition that otherwise generally lacks distinctive radiological features, the absence of a pyramidal eminence on CT in a patient with nonprogressive, congenital conductive hearing loss may strengthen clinical suspicion for CSFF.

Dyna-CT of the temporal bone for case-specific three-dimensional rendering of the stapedial muscle for planning of electrically evoked stapedius reflex threshold determination during cochlear implantation directly from the stapedius muscle via a retrofacial approach: a pilot study.

PURPOSE: Evaluation of 3D Dyna-CTs to improve cochlear implantation (CI) planning and intraoperative electrically elicited stapedius reflex threshold (ESRT) measurements. METHODS: A prospective observational cohort study was performed. Anonymized data collection of Dyna-CTs and CI surgeries in which a retrofacial approach was implemented to access the stapedius muscle. 3D Dyna-CTs of 30 patients and the intraoperative confirmation of the predication in 5/30 patients during CI surgery were evaluated. Inter-rater reliability was also analyzed along with the predictive value of this evaluation. RESULTS: 36 representative structures of the middle and inner ear and 3D renderings of the Dyna-CTs were evaluated by four otoneurological surgeons. Fleiss' kappa values for the evaluation of the visibility were high (> 0.7) for most of the anatomical structures. The stapedius muscle was visible in 90% of the cases. Using the 3D data, the retrofacial access to the stapedius muscles was estimated as feasible in 86.7%. Fleiss' kappa value of the evaluation of the accessibility was 0.942. The intraoperative exploration of the stapedius muscle confirmed the preoperative prediction in all five selected patients (four patients with predicted accessibility and one patient with predicted inaccessibility). CONCLUSIONS: The use of Dyna-CT and 3D rendering is a helpful tool for preoperative planning of cochlear implantations and ESRT measurements from the stapedius muscle via the retrofacial approach.

[Stapedoplasty in a HIV-infected patient].

This paper reports an observation illustrating the possibility of the successful surgical treatment of otosclerosis in a HIV-infected patient presenting with acquired immunodeficiency syndrome (AIDS) and positive response in the test for hepatitis C. The authors used the results of multispiral computed tomography (MSCT) of the temporal bones as a basis for the prediction of the outcome of the surgical intervention taking into consideration specific primary manifestations of HIV infection as well as immunological and virlogical responses to anti-retroviral therapy.

Stapedius muscle: Don't mistake it for a branch of the facial nerve in images.

OBJECTIVE: The relationship between the stapedius muscle and the vertical part of the facial nerve is important for surgery. The study aims to understand the spatial relationship between the stapedius muscle and the vertical part of the facial nerve in ultra-high-resolution computed tomography (U-HRCT) images. METHODS: A total of 105 ears from the heads of 54 human cadavers were analyzed using U-HRCT. The location and direction of the stapedius muscle were evaluated with the facial nerve as the reference. The integrity of the bony septum between the two structures and the distance between the transverse sections were examined. Paired Student's t-test and the nonparametric Wilcoxon test were applied. RESULTS: The lower end of the stapedius muscle emerged at the upper (45 ears), middle (40 ears), or lower (20 ears) level of the facial nerve and was positioned medial (32 ears), medial posterior (61 ears), posterior (11 ears), or lateral posterior (1 ear) to the facial nerve. The bony septum was not continuous in 99 ears. The distance between the midpoints of the two structures was 1.75 mm (IQR=1.55-2.16 mm). CONCLUSION: The spatial relationship between the stapedius muscle and the facial nerve was varied. They were close to each other and in most cases the bony septum was not intact. Preoperative familiarity with the relationship between the two structures is helpful for avoiding unwanted injury to the facial nerve in surgery.

The use of a surgical planning tool for evaluating the optimal surgical accessibility to the stapedius muscle via a retrofacial approach during cochlear implant surgery: a feasibility study.

PURPOSE: During cochlear implant (CI) surgery, visual detection of the stapedius reflex as movements of the stapes tendon, electrically elicited via the CI, is a standard measure to confirm the system's functionality. Direction visualization of the stapedius muscle (SM) movements might be more reliable, but a safe access to the small SM is not defined. A new surgical planning tool for pre-operative evaluation of the accessibility to the stapedius muscle (SM) during a cochlear implantation (CI) via a retrofacial approach was now evaluated. METHODS: A surgical planning tool was developed in MATLAB using an image processing algorithm to evaluate drilling feasibility. A flat-panel computed tomography (CT) combining a rotational angiographic C-arm units with flat-panel detectors (Dyna-CT) was used. In total, 30 3D Dyna-CT-based temporal bone reconstructions were evaluated by automatized algorithms, generating a series of trajectories and comparing their feasibility and safety to reach the SM via a retrofacial approach. The predictability of the surgical planning tool results was tested in 5 patients. RESULTS: The surgical planning tool showed that a retrofacial access to the SM would be feasible in 25/30 cases. Moreover, the evaluation of the predictability of the results obtained with the surgical planning tool conducted during 5 CI surgeries confirmed the results. Both the surgical planning tool and the results on SM accessibility via retrofacial approach during CI showed that this is safe and feasible only when the SM-exposed area was > 25% of its total, the distance between the SM and the facial nerve was > 0.8 mm, and the surgical corridor diameter was > 3 mm. CONCLUSION: The surgical planning tool seems to be useful for the pre-operative evaluation of the accessibility to the SM during a CI surgery via a retrofacial approach. Further prospective studies are needed to validate the results in larger cohorts.

Microtomographic morphometry of the stapedius muscle and its tendon.

The aim of this study was to evaluate the morphology of the stapedius muscle and its tendon with the use of microCT and to describe their anatomic relationship with facial nerve and incudostapedial joint. The study was performed on 16 fresh cadaveric temporal bones scanned in microtomography (microCT). Stapedius muscle and its tendon were identified in each set of images. The length of the medial and lateral border of the stapedius tendon (STL-med, STL-lat), width at the insertion to stapes (STW-s), at the point it emerges from the pyramidal eminence (STW-p) and in the half way from the pyramidal eminence to stapes (STW-m), and the length and the width of the belly of stapedius muscle (BSML and BSMW) were measured in modified axial plane. The shortest distance between the facial canal and incudostapedial joint (FN-isj), and between the facial canal and stapedius tendon (FN-st) were measured in the Pöschl plane. The average values of all distances measured were: STL-lat 1.29 ± 0.50 mm, STL-med 1.27 ± 0.44 mm, BSML 2.98 ± 0.51 mm, STW-s 0.47 ± 0.10 mm, STW-p 0.46 ± 0.12 mm, STW-m 0.35 ± 0.12 mm, BSMW 1.26 ± 0.29 mm, FN-isj 1.72 ± 0.33 mm, FN-st 1.35 ± 0.30 mm. The stapedius muscle complex consists of the tendon and the belly, and the border between them in microCT scans is not always evident. The distance between the facial nerve and the incudostapedial joint is greater than the distance between the facial nerve and the stapedius muscle tendon.

An atypical stapedial artery.

The persistence of the stapedial artery is a rare vascular anomaly. It is mostly asymptomatic but sometimes cause conductive hearing loss, pulsatile tinnitus, or vertigo. The estimated prevalence of this rare postembryonic persistence ranged from 0.02% to 0.48%. Four different anatomical forms have been identified, and their preoperative diagnostic is essential. We report the case of an incidental discovery of pharyngo-hyo-stapedial artery, the most uncommon form of persistent stapedial artery. Its per-operative finding has become rare because tomodensitometry is performed in case of conductive hearing loss. The continuous improvement of imagery resolution will probably help to revise the incidence of this malformation.

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.

Location of the stapedius muscle with reference to the facial nerve in patients with unilateral congenital aural atresia: implication for active middle ear implants surgery.

Background: Detailed investigations of the stapedial muscle (SM) in congenital aural atresia (CAA) patients have yet to be adequately conducted.Objectives: To assess image variations in the mastoid segment of the facial nerve (FN) and SM in CAA.Materials and methods: A total of nine patients comprising of 9 ears with unilateral CAA were studied. The courses of the FN and SM were evaluated from the basic point to 1 mm intervals between the mastoid portion of FN, and measured from the mean X and Y values in each group.Results: The atresia side of FN among the Y values showed significant differences compared to the contralateral side. In terms of the SM, there were no significant differences in both the X and Y values. The stapedial muscle of the CAA patients was located medially to the FN. Conversely, the distance from the PSC to the FN revealed no significant differences with regard to the X and Y values for each group.Conclusion: The current observations revealed that the SM is located more posterior to the FN in CAA patients, and this is mainly attributed to the laterally and anteriorly displaced FN.

Persistent stapedial artery in PHACE syndrome.

INTRODUCTION: PHACE syndrome is characterized by posterior fossa malformations, haemangioma, arterial anomalies, coarctation of the aorta, and eye abnormalities. CASE REPORT: We present the case of a 6-year-old girl followed since birth for PHACE syndrome and left hemifacial haemangioma, who presented with left hearing loss. Computed tomography scan showed left persistent stapedial artery (PSA). DISCUSSION: Two types of arterial anomalies may be observed in PHACE syndrome: persistence of embryonic arteries and anomalies of cerebral arteries. PSA can be observed in the context of PHACE syndrome. Children with PHACE syndrome require regular audiometric follow-up to detect hearing loss and avoid its consequences on speech and language development.

Detectability of minute temporal bone structures with ultra-high resolution CT.

OBJECTIVE: Computed tomography (CT) is the imaging tool of choice in the diagnosis of temporal bone lesions. With the recent progress in imaging technology, CT with higher spatial resolution (Ultra-high resolution CT) has become available in the clinical setting. The purpose of this study is to evaluate the visibility of small temporal bone structures using ultra-high resolution CT. MATERIAL AND METHODS: The visibility of 27 minute temporal bone structures on ultra-high resolution CT images was evaluated. Non-helical axial scans were performed in 18 normal hearing ears without previous otologic diseases. Visibility was scored by an experienced radiologist and otologist. RESULTS: Minute temporal bone structures including the ossicular chain, the crus of the stapes, the greater superficial petrosal nerve, and the anterior malleolar ligament were clearly visualized on ultra-high resolution CT. The stapedius muscle tendon and the chorda tympani exiting the posterior canaliculus and coursing medial to the malleus could be visualized. CONCLUSION: Ultra-high resolution CT provides good visualization of small temporal bone structures in normal subjects.

Vibrant Soundbridge implantation via a retrofacial approach in a patient with congenital aural atresia.

OBJECTIVE: A method of Vibrant Soundbridge (VSB) placement to the round window (RW) via the retrofacial approach with preoperative evaluation of the relationship between the facial nerve (FN) and RW by 3D-CT reconstruction was proposed for the treatment of congenital aural atresia (CAA) patient. METHODS: A fenestration to the mesotympanum was made mastoid portion of the FN. During the approach, part of the stapedial muscle was encountered and removed. The RW niche was identified, and the floating mass transducer was placed from an inferior approach into the RW niche. RESULTS: There were no intra-operative or post-operative surgical complications. CONCLUSION: The VSB placement to the RW via the retrofacial approach with partial removal of the stapedial muscle can be feasible alternative in CAA cases associated with an anteriorly and laterally positioned aberrant FN. Preoperative assessment using 3D CT may facilitate in assessing the feasibility of the approach and implantation of VSB.

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.

CT of the normal suspensory ligaments of the ossicles in the middle ear.

PURPOSE: To establish the range of normal variation in the CT appearance of the middle ear ligaments and the stapedius tendon as an aid in detecting abnormal changes in these structures. METHODS: CT scans of the temporal bone in 75 normal middle ears, obtained with 1-mm-thick sections, were reviewed by two observers, who rated the visibility of the structures of interest on a scale of 1 to 5. RESULTS: The anterior, superior, and lateral malleal ligaments and the medial and lateral parts of the posterior incudal ligament were seen in 68%, 46%, 95%, 26%, and 34% of the ears, respectively. The stapedius tendon was seen in 27% of the cases. When visible, the ligaments were judged to be complete in 90% to 100% of the ears and the stapedius tendon was complete in 65% of cases. Their width varied considerably. Interobserver variability was high for most observations. CONCLUSION: CT scans are more likely to show the malleal than the incudal ligaments. Although the interobserver agreement was statistically significant for most study parameters, the percentage of agreement above that expected by chance was low. When seen, the ligaments usually appeared complete. Understanding the normal range of appearance may help identify abnormalities of the ligaments and tendons of the middle ear.

CT of ear structures: a tailored approach.

A major advance in imaging of the ear structures has occurred with the development of high-resolution, thin-section computed tomography. The purpose of this article is to explain a technique tailored to the CT evaluation of specific anatomic structures. The normal CT anatomy of the ear is demonstrated.

The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia.

CONCLUSION: The extent of inferior displacement of the mastoid tegmen is related to the severity of congenital aural atresia (CAA). OBJECTIVE: To analyze anatomic variations observed on high-resolution temporal bone computed tomography (TBCT) in patients with CAA, the extent of inferior displacement of the mastoid tegmen and the size of the incudo-stapedial (IS) joint angle were compared with surgical parameters for atresiaplasty, such as Jahrsdoerfer score and hearing acuity. METHODS: Sixty-one patients with unilateral CAA underwent high-resolution TBCT and hearing tests. We evaluated TBCTs in terms of Jahrsdoerfer criteria and analyzed the relationships among the inferior displacement of the mastoid tegmen, size of the IS joint angle, hearing acuity, and the Jahrsdoerfer score on the atretic side. RESULTS: IS joint angle on the atretic side was found to be 120.6 ± 11°, which was significantly greater than the corresponding value of 103.4 ± 5.4° on the normal side. Cholesteatoma occurred significantly more often in CAA patients with narrow external auditory canals (EACs) (9/27; 33.3%), compared with CAA patients with no EAC opening (2/34; 5.9%). There was a significant relation between the extent of inferior displacement of the mastoid tegmen (28.9% in the atretic side and 17.3% in the normal side) and the Jahrsdoerfer score (p < 0.0001).

Persistent stapedial artery: a congenital anomaly to know.

Persistent stapedial artery, one of the rare arterial congenital anomalies of the middle ear, is important to know due to its possible clinical repercussions. Ignoring its existence may lead to complications during surgery of the middle ear (notably hemorrhage). Exploration of the vascular malformation is rendered possible via high-definition computed tomography (CT) imaging of the petrous bones, which reveals the frequent bilaterality of this anatomical variation as well as the presence of associated anomalies. We report on two cases of persistent stapedial artery discovered during CT scan explorations.

High-resolution computed tomographic features of the stapedius muscle and facial nerve in chronic otitis media.

OBJECTIVE: To improve preoperative recognition of the morphologic features of stapedius muscle and facial nerve in cases of chronic otitis media by providing a systemized description using temporal bone high-resolution computed tomography (HRCT). STUDY DESIGN: Retrospective review of HRCT scans from 212 patients. SETTING: Tertiary hospital affiliated to Fudan University. PATIENTS: Men and women undergoing surgery for chronic otitis media. No preference for demographics or side presenting otitis media. INTERVENTION: Therapeutic surgery. MAIN OUTCOME MEASURE: Location and morphology of stapedius muscle and facial nerve. RESULTS: The stapedius muscle was encountered in 90.5% of axial (n = 181) and 87% of coronal sections (n = 174), and differences between sides and genders were not significant (p > 0.05). Five categories of anomalies or pathologic features were identified in axial layers, and 3 categories were identified in coronal layers. Two axial and 2 coronal CT planes were found to be especially significant in imaging the facial nerve and its morphology (p < 0.001), whereas axial planes were more apt to show stapedius muscle features. Other pathologic features were also observed significantly more from specific CT imaging planes. CONCLUSION: The presence the stapedius muscle and the morphology between the stapedius muscle and the facial nerve vary between different observation areas, and some CT planes provide more useful information than others. The imaging planes outlined in this study can be used to systematically and correctly identify certain facial nerve and stapedius muscle features and clarify unfamiliar pathologic anatomy in preoperative planning.

Realistic 3D computer model of the gerbil middle ear, featuring accurate morphology of bone and soft tissue structures.

In order to improve realism in middle ear (ME) finite-element modeling (FEM), comprehensive and precise morphological data are needed. To date, micro-scale X-ray computed tomography (µCT) recordings have been used as geometric input data for FEM models of the ME ossicles. Previously, attempts were made to obtain these data on ME soft tissue structures as well. However, due to low X-ray absorption of soft tissue, quality of these images is limited. Another popular approach is using histological sections as data for 3D models, delivering high in-plane resolution for the sections, but the technique is destructive in nature and registration of the sections is difficult. We combine data from high-resolution µCT recordings with data from high-resolution orthogonal-plane fluorescence optical-sectioning microscopy (OPFOS), both obtained on the same gerbil specimen. State-of-the-art µCT delivers high-resolution data on the 3D shape of ossicles and other ME bony structures, while the OPFOS setup generates data of unprecedented quality both on bone and soft tissue ME structures. Each of these techniques is tomographic and non-destructive and delivers sets of automatically aligned virtual sections. The datasets coming from different techniques need to be registered with respect to each other. By combining both datasets, we obtain a complete high-resolution morphological model of all functional components in the gerbil ME. The resulting 3D model can be readily imported in FEM software and is made freely available to the research community. In this paper, we discuss the methods used, present the resulting merged model, and discuss the morphological properties of the soft tissue structures, such as muscles and ligaments.