The effects of mass loading the ossicles with a floating mass transducer on middle ear transfer function

Hypothesis: The aim of this study was to measure the mass loading effect of an active middle-ear implant (the Vibrant Soundbridge) in cadaver temporal bones. Background: Implantable middle ear hearing devices such as Vibrant Soundbridge have been used as an alternative to conventional hearing aids for the rehabilitation of sensorineural hearing loss. Other than the obvious disadvantage of requiring implantation middle ear surgery, it also applies a direct weight on the ossicular chain which, in turn, may have an impact on residual hearing. Previous studies have shown that applying a mass directly on the ossicular chain has a damping effect on its response to sound. However, little has been done to investigate the magnitude and the frequency characteristics of the mass loading effect in devices such as the Vibrant Soundbridge. Methods: Five fresh cadaver temporal bones were used. The stapes displacement was measured using laser Doppler vibrometry before and after the placement of a Vibrant Sound-bridge floating mass transducer. The effects of mass and attachment site were compared with the unloaded response. Measurements were obtained at frequencies between 0.1 and 10 kHz and at acoustic input levels of 100 dB sound pressure level. Each temporal bone acted as its own control. Results: Placement of the floating mass transducer caused a reduction of the stapes displacement. There were variations between the bones. The change of the stapes displacement varied from 0 dB to 28 dB. The effect was more prominent at frequencies above 1,000 Hz. Placing the floating mass transducer close to the incudostapedial joint reduced the mass loading effect. Conclusion: The floating mass transducer produces a measurable reduction of the stapes displacement in the temporal bone model. The effect is more prominent at high frequencies.

Contribution of the study of the styloid prominence in the posterior tympanic cavity

70 human temporal bones were analyzed with the aid of an otologic microscope. The styloid prominence was found to be extremely variable in shape, location and occurrence. Depending on the degree of development, the prominence establishes important relationships with the sinus tympani, with the fossula of the cochlear fenestra, and with the suprapyramidal recess. Serial sections were used to study the relationship of the styloid process with the facial nerve inside the bony mass of the mastoid portion of the temporal bone.

MORFOLOGIA DOS RECESSOS TIMPANICOS POSTERIORES

The sinuses of the posterior wall of the tympanic cavity are formed between the bony ridges, bridges and other osseous prominences, remnants of the tympanum widening process. Anatomical limits and relationships of these sinuses were observed in 100 human temporal bones. Many morphological variabilities were found due to different levels of development of the middle ear posterior wall. The most important sinuses of this complex are the Sinus tympani and the Facial Sinus (Facial recess) seen in all cases. The Lateral tympanic sinus is well-formed in 83% of the cases and the Posterior tympanic sinus in 20% of our series.

O forame de Huschke e suas implicações clínicas

During temporal bone development and formation it is noted the presence of a foramen in the medial portion of the external auditory canal (foramen of Huschke). This foramen is normally present until the age of 4 or 5 years old, but in some people it persists throughout life. The persistence of this foramen and its clinical implications related to the temporomandibular joint, ear and nearby structures has been reported by many authors. Therefore, it is important that dentists, otorhinolaryngologists, speech pathologist and physiotherapists have a wide knowledge about the consequences of the presence and persistence of the foramen of Huschke.

Anatomic and radiograph study of the persistence of Foramen of Huschke

Aim: the aim of this study is to assess and locate the Foramen of Huschke. Study design: anatomical. Material and Method: using contrast material like gutta-percha and barium sulfate, through extraoral radiographs, such as panoramic, submental vertex and corrected saggital linear Temporal Mandibular Joint tomograms in four skulls where we clinically checked the existence of foramen of Huschke. Results: The results proved that the foramen of Huschke can be observed in skulls submitted to contrast using radiographic techniques.

Persistência do forame de Huschke: Um estudo tomográfico

OBJECTIVE: To evaluate the persistency of foramen of Huschke by means of computed tomography study of the ear region and approaching important clinical aspects related to the presence of this anatomical anomaly. MATERIALS AND METHODS: Two examiners have analyzed the whole tympanic portion of temporal bone in 150 bilateral computed tomography studies of the ear region, searching for foramen of Huschke presence or absence. RESULTS: The mentioned anatomical anomaly was found in 17 cases (11.3%), 13 patients (76.5%) being female and four (23.5%) male. This higher female incidence is statistically confirmed. CONCLUSION: Ear and/or temporomandibular joint specialists should turn their attention to the persistency of foramen of Huschke.

Anatomia macroscópica e ultraestrutural da orelha da paca (Cuniculus paca, Linnaeus, 1766)

Pós-graduação em Cirurgia Veterinária - FCAV

Ultrassonografia transcraniana em cães hígidos: padronização da técnica e descrição anatômica

The study of the nervous system is increasing in Veterinary Medicine. Transcranial ultrasonography (TCUS) has the advantage of being a non-invasive and low cost method compared to computerized tomography (CT) and Magnetic Resonance Imaging (MRI). The temporal bone has been used as an acoustic window in TCUS in humans. This study aimed to correlate transcranial ultrasonographic images obtained through the temporal and occipital window with healthy dog's encephalic anatomy, and to standardize the technique. 37 adult mongrel dogs were used: 30 animals in vivo, in order to perform USTC screening and seven dog corpses for brain section as well as USTC planes. Data analysis was accomplished by the non parametric Wilcoxon test. Results obtained indicate that TCUS (in dorsal and oblique planes) is a viable method for brain evaluation in dogs weighting up to 10kg without anesthesia.

Estudo anátomo antropológico do processo mastóideo e suas relações musculares

Os processos mastóideos de 305 crânios humanos identificados foram estudados com a finalidade de melhor compreender suas características morfológicas básicas, bem como suas relações com outras formações ósseas da área mastóidea. Foram mensuradas, além das várias medidas gerais do crânio, a altura e a largura dos processos mastôideos, a distância bimastóidea e bi-supramastóidea. Foram estudados: a incidência e a forma do processo paramastóideo, do sulco do processo mastóideo e da rugosidade da superfície lateral do processo mastóideo. Todos os resultados ósseos foram submetidos à análise estatística, relacionando-os ao sexo, grupo étnico e forma do crânio. Objetivando um melhor entendimento das formações anatómicas que se relacionam com os processos mastóideos, foram dissecados, em vinte cabeças humanas (quarenta lados), os músculos estemocleidomastóideo, esplênio da cabeça, longo da cabeça e ventre posterior do digástrico. As inserções destes músculos foram mensuradas, tendo-se como referência o plano aurículo-orbital. As áreas de fixação no osso foram medidas através de um analisador de imagens. De maneira geral as características ósseas estudadas mostraram que existem diferenças estatísticas significantes nos grupos formados por sexo e forma do crânio. Os caracteres estudados para a determinação do sexo dos crânios mostraram-se estatisticamente confiáveis, indicando a possibilidade da utilização do processo mastóideo para a determinação do sexo de crânios humanos. As dissecções realizadas mostraram que há relação funcional entre os músculos e as formações ósseas da área mastóidea, principalmente entre o ventre posterior do músculo digástrico e o processo paramastóideo

Anatomical, Clinical and Radiographic Characteristics of Styloid Syndrome (Eagle Syndrome): a Case Report

Styloid syndrome is characterized by an elongated styloid process or calcification of the stylomandibular and stylohyoid ligament. This study describes a case of a 65-year-old woman who presented to the Stomatology Clinic, University of Marilia with temporomandibular joint pain, ear ringing and a reduced ability to open the mouth. Panoramic and posteroanterior digital radiographs showed bilateral elongation of the styloid processes, especially of the right side, whose length extended beyond the mandible angle. The diagnosis was confirmed with the association of clinical data and image examinations. The treatment options for styloid Syndrome include clinical follow-up, surgical removal of the styloid process or fracture of the elongated process. The case was managed by providing prosthetic rehabilitation and clinical follow-up, observing the level of discomfort and the benefit that could be achieved by the therapy, and avoiding surgical intervention.

Anatomical study of the human middle ear for the design of implantable hearing aids

OBJECTIVE: To generate anatomical data on the human middle ear and adjacent structures to serve as a base for the development and optimization of new implantable hearing aid transducers. Implantable middle ear hearing aid transducers, i.e. the equivalent to the loudspeaker in conventional hearing aids, should ideally fit into the majority of adult middle ears and should utilize the limited space optimally to achieve sufficiently high maximal output levels. For several designs, more anatomical data are needed. METHODS: Twenty temporal bones of 10 formalin-fixed adult human heads were scanned by a computed tomography system (CT) using a slide thickness of 0.63 mm. Twelve landmarks were defined and 24 different distances were calculated for each temporal bone. RESULTS: A statistical description of 24 distances in the adult human middle ear which may limit or influence the design of middle ear transducers is presented. Significant inter-individual differences but no significant differences for gender, side, age or degree of pneumatization of the mastoid were found. Distances, which were not analyzed for the first time in this study, were found to be in good agreement with the results of earlier studies. CONCLUSION: A data set describing the adult human middle ear anatomy quantitatively from the point of view of designers of new implantable hearing aid transducers has been generated. In principle, the method employed in this study using standard CT scans could also be used preoperatively to rule out exclusion criteria.

Mastoiditis in children: a prospective, observational study comparing clinical presentation, microbiology, computed tomography, surgical findings and histology

The aim of this study was to obtain comprehensive data on clinical presentation, microbiology, computed tomography, surgical findings and histology in acute, sub-acute and chronic mastoiditis. We performed a prospective, observational study in children under 16 years of age presenting to our institution during the 2-year period beginning in April 2000. The children were examined and their condition treated in accordance with a standardized protocol elaborated by the paediatric, otolaryngology (ORL) and radiology departments. Thirty-eight patients were hospitalized (22 with acute mastoiditis, seven with sub-acute mastoiditis, nine with chronic mastoiditis). There were 30 complications present in 21 patients (55%). Streptococcus pyogenes was the most common pathogen (7/24 cases), followed by Streptococcus pneumoniae (4/24 cases). Mastoid surgery was performed in 29 patients. Histology of mastoid tissue revealed predominantly acute inflammation in two cases, mixed acute/chronic inflammation in 19 cases and predominantly chronic inflammation in seven cases. Radiologic data were evaluated retrospectively. Spiral, volume-based high-resolution (HR) computed tomography (CT) of the temporal bone had a sensitivity of 100%, specificity of 38%, positive predictive value (PPV) of 50% and negative predictive value (NPV) of 100% in detecting coalescence of mastoid trabeculae. Cranial CT with contrast had a sensitivity of 80%, specificity of 94%, PPV of 80% and NPV of 94% in identifying intra-cranial extension. Conclusion: histological evidence suggests that sub-acute/chronic infection underlies not only sub-acute and chronic mastoiditis, but most cases of acute mastoiditis as well. HR-CT of the temporal bone is effective in ruling out coalescence. Cranial CT is valuable in identifying intra-cranial extension. Cranial and HR-CT are recommended in the examination of children with mastoiditis.

Cholesteatoma triggering squamous cell carcinoma: case report and literature review of a rare tumor

BACKGROUND: The aim of this study was to report a case of squamous cell carcinoma of the petrous part of the temporal bone associated with a long history of secondary acquired cholesteatoma in a 71-year-old man. PATIENTS AND METHODS: We present the case of a 71-year-old man diagnosed with secondary acquired cholesteatoma in 1950. Treatments consisted of repetitive surgery owing to several relapses. In 2004, he presented with progressive fetid otorrhea. Clinical and computed tomography findings were indicative for relapsing cholesteatoma and a subtotal petrosectomy was performed. RESULTS: Histologic work-up demonstrated a moderately differentiated squamous cell carcinoma. The staging revealed stadium pT3 cN0 cM0. Postoperative treatment consisted of local radiation therapy with intensity-modulated beam geometry with a total of 64.2 Gy in 30 fractions using a simultaneous integrated boost. CONCLUSION: Middle ear carcinoma can arise from acquired cholesteatoma. The pathogenesis of squamous cell carcinoma associated with cholesteatoma has not been elucidated satisfactorily. Due to the complex anatomic features, intensity-modulated radiation therapy is the technique of choice for postoperative radiotherapy.

Cone Beam and Micro-Computed Tomography Validation of Manual Array Insertion for Minimally Invasive Cochlear Implantation

Delivering cochlear implants through a minimally invasive tunnel (1.8 mm in diameter) from the mastoid surface to the inner ear is referred to as direct cochlear access (DCA). Based on cone beam as well as micro-computed tomography imaging, this in vitro study evaluates the feasibility and efficacy of manual cochlear electrode array insertions via DCA. Free-fitting electrode arrays were inserted in 8 temporal bone specimens with previously drilled DCA tunnels. The insertion depth angle, procedural time, tunnel alignment as well as the inserted scala and intracochlear trauma were assessed. Seven of the 8 insertions were full insertions, with insertion depth angles higher than 520°. Three cases of atraumatic scala tympani insertion, 3 cases of probable basilar membrane rupture and 1 case of dislocation into the scala vestibuli were observed (1 specimen was damaged during extraction). Manual electrode array insertion following a DCA procedure seems to be feasible and safe and is a further step toward clinical application of image-guided otological microsurgery.

Radiation dose reduction in postoperative computed position control of cochlear implant electrodes in lambs - An experimental study

OBJECTIVE Cochlear implants (CI) are standard treatment for prelingually deafened children and postlingually deafened adults. Computed tomography (CT) is the standard method for postoperative imaging of the electrode position. CT scans accurately reflect electrode depth and position, which is essential prior to use. However, routine CT examinations expose patients to radiation, which is especially problematic in children. We examined whether new CT protocols could reduce radiation doses while preserving diagnostic accuracy. METHODS To investigate whether electrode position can be assessed by low-dose CT protocols, a cadaveric lamb model was used because the inner ear morphology is similar to humans. The scans were performed at various volumetric CT dose-indexes CTDIvol)/kV combinations. For each constant CTDIvol the tube voltage was varied (i.e., 80, 100, 120 and 140kV). This procedure was repeated at different CTDIvol values (21mGy, 11mGy, 5.5mGy, 2.8mGy and 1.8mGy). To keep the CTDIvol constant at different tube voltages, the tube current values were adjusted. Independent evaluations of the images were performed by two experienced and blinded neuroradiologists. The criteria diagnostic usefulness, image quality and artifacts (scaled 1-4) were assessed in 14 cochlear-implanted cadaveric lamb heads with variable tube voltages. RESULTS Results showed that the standard CT dose could be substantially reduced without sacrificing diagnostic accuracy of electrode position. The assessment of the CI electrode position was feasible in almost all cases up to a CTDIvol of 2-3mGy. The number of artifacts did not increase for images within this dose range as compared to higher dosages. The extent of the artifacts caused by the implanted metal-containing CI electrode does not depend on the radiation dose and is not perceptibly influenced by changes in the tube voltage. Summarizing the evaluation of the CI electrode position is possible even at a very low radiation dose. CONCLUSIONS CT imaging of the temporal bone for postoperative electrode position control of the CI is possible with a very low and significantly radiation dose. The tube current-time product and voltage can be reduced by 50% without increasing artifacts. Low-dose postoperative CT scans are sufficient for localizing the CI electrode.