Classification, registration and segmentation of ear canal impressions using convolutional neural networks.

Today, fitting bespoke hearing aids involves injecting silicone into patients' ears to produce ear canal molds. These are subsequently 3D scanned to create digital ear canal impressions. However, before digital impressions can be used they require a substantial amount of effort in manual 3D editing. In this article, we present computational methods to pre-process ear canal impressions. The aim is to create automation tools to assist the hearing aid design, manufacturing and fitting processes as well as normalizing anatomical data to assist the study of the outer ear canal's morphology. The methods include classifying the handedness of the impression into left and right ear types, orienting the geometries onto the same coordinate system sense, and removing extraneous artifacts introduced by the silicone mold. We investigate the use of convolutional neural networks for performing these semantic tasks and evaluate their accuracy using a dataset of 3000 ear canal impressions. The neural networks proved highly effective at performing these tasks with 95.8% adjusted accuracy in classification, 92.3% within 20° angular error in registration and 93.4% intersection over union in segmentation.

Morphological relationships between external auditory canal and vital structures of tympanic cavity.

PURPOSE: We aimed to evaluate the morphology of the external auditory canal (EAC) using a three-dimensional (3D) reconstruction of computed tomography (CT) scans of the temporal bone to corroborate and predict important anatomical structures involved in middle ear surgery based on the EAC morphology. METHODS: Temporal bone CT from 62 patients (120 ears) was used to perform 3D reconstruction (maximum intensity projection), of which 32 patients (60 ears) had chronic otitis media and 30 patients (60 ears) had normal temporal bones. The anatomical morphology of the EAC, tympanic sinus, vertical portion of the facial nerve, and jugular bulb were measured, and the anatomical relationship between the EAC morphology and important structures of the middle ear was analyzed. RESULTS: In ears with chronic otitis media, the overhang of the inferior wall of the EAC was significantly more than that in normal ears, and the antero-posterior length of the bony tympanic ring was short. Furthermore, the tympanic sinus was shallow, and vertical portion of the facial nerve tended to run outward. The EAC morphology correlated with the tympanic sinus depth and outward orientation of the vertical portion of the facial nerve. CONCLUSION: A severe overhang of the inferior wall of the EAC and short antero-posterior length of the bony tympanic ring indicates a higher possibility of a shallow tympanic sinus and an outward orientation of the vertical portion of the facial nerve. These findings aid in predicting the difficulty of tympanic sinus operation and reducing facial nerve damage risk during EAC excision.

Extracranial landmarks for surgical skull base approaches / Puntos de referencia extracraneales para abordajes quirúrgicos de la base del cráneo

SUMMARY: Surgical operations regarding to skull base are challenging and reliable anatomical landmarks are required. There is a lack of knowledge on anatomical variations in this region. The aim of this study was to determine the safe extracranial landmarks for surgical approach to the skull base. In this study, 23 adult dry skulls were evaluated: the age and sex of the specimens were unknown. All measurements were taken from external surface of inferior aspect of the skull by using digital calipers accurate to 0.01 mm. In right and left sides; the distances between the external acoustic meatus (EAM) and the following anatomical landmarks were measured: articular tubercle (AT); anterior margin of squamous suture (ASS); superior margin of squamous suture (SSS); posterior margin of squamous suture (PSS); end point of styloid process (SP); midpoints of pterygomaxillary fissure (PMF); foramen ovale (FO); foramen spinosum (FS); and of carotid canal (CC).The distances of the external acoustic meatus to the anatomical structures on the right and left sides were: EAM-SP; 24.24±3.19 mm, 23.16±3.17 mm; EAM-PMF; 46.56±4.51mm, 46.25±3.96 mm; EAM-FO; 27.57±2.87 mm, 28.70±2.85 mm; EAM-FS; 22.53±3.19 mm, 22.72±3.47 mm; EAM-CC; 17.35±3.56 mm, 17.19±3.39 mm; EAM-AT; 19.31±3.79 mm, 18.95±3.42 mm; EAM-ASS; 43.14±4.80 mm, 46.82±4.61 mm; EAM-SSS; 49.17±4.74 mm, 48.83±3.34 mm and EAM-PSS; 36.15±4.24 mm, 35.39±4.25 mm, respectively. We think that the findings obtained from this study related to external acoustic meatus can be an important reference for surgical anatomy and surgical procedures in skull base.

RESUMEN: Las cirugías relacionadas con la base del cráneo son un desafío, las cuales requieren puntos de referencia anatómicos confiables. Existe una falta de conocimiento sobre las variaciones anatómicas en esta región. El objetivo de este estudio fue determinar los puntos de referencia extracraneales seguros para el abordaje quirúrgico de la base del cráneo. En este estudio se evaluaron 23 cráneos secos adultos: se desconocía la edad y el sexo de los ejemplares. Las medidas se tomaron de la superficie externa de la cara inferior del cráneo utilizando calibradores digitales con una precisión de 0,01 mm. En lados derecho e izquierdo se midieron las distancias entre el meato acústico externo (MAE) y los siguientes puntos de referencia anatómicos: tubérculo articular (TA); margen anterior de la sutura escamosa (MASE); margen superior de sutura escamosa (MSSE); margen posterior de sutura escamosa (MPSE); punto final del proceso estiloides (PFPE); puntos medios de la fisura pterigomaxilar (PMFP); foramen oval (FO); foramen espinoso (FE); y del canal carotídeo (CC). Las distancias del meato acústico externo a las estructuras anatómicas de los lados derecho e izquierdo fue- ron: MAE-PFPE; 24,24 ± 3,19 mm, 23,16 ± 3,17 mm; MAE-PMFP; 46,56 ± 4,51 mm, 46,25 ± 3,96 mm; MAE-FO; 27,57 ± 2,87 mm, 28,70 ± 2,85 mm; MAE-FE; 22,53 ± 3,19 mm, 22,72 ± 3,47 mm; MAE-CC; 17,35 ± 3,56 mm, 17,19 ± 3,39 mm; MAE-TA; 19,31 ± 3,79 mm, 18,95 ± 3,42 mm; MAE-MASE; 43,14 ± 4,80 mm, 46,82 ± 4,61 mm; MAE-MSSE; 49,17 ± 4,74 mm, 48,83 ± 3,34 mm y MAE-MPSE; 36,15 ± 4,24 mm, 35,39 ± 4,25 mm, respectivamente. Creemos que los hallazgos obtenidos de este estudio relacionados con el meato acústico externo pueden ser una referencia importante para la anatomía quirúrgica y los procedimientos quirúrgicos en la base del cráneo.

A narrow ear canal reduces sound velocity to create additional acoustic inputs in a microscale insect ear.

Located in the forelegs, katydid ears are unique among arthropods in having outer, middle, and inner components, analogous to the mammalian ear. Unlike mammals, sound is received externally via two tympanic membranes in each ear and internally via a narrow ear canal (EC) derived from the respiratory tracheal system. Inside the EC, sound travels slower than in free air, causing temporal and pressure differences between external and internal inputs. The delay was suspected to arise as a consequence of the narrowing EC geometry. If true, a reduction in sound velocity should persist independently of the gas composition in the EC (e.g., air, [Formula: see text]). Integrating laser Doppler vibrometry, microcomputed tomography, and numerical analysis on precise three-dimensional geometries of each experimental animal EC, we demonstrate that the narrowing radius of the EC is the main factor reducing sound velocity. Both experimental and numerical data also show that sound velocity is reduced further when excess [Formula: see text] fills the EC. Likewise, the EC bifurcates at the tympanal level (one branch for each tympanic membrane), creating two additional narrow internal sound paths and imposing different sound velocities for each tympanic membrane. Therefore, external and internal inputs total to four sound paths for each ear (only one for the human ear). Research paths and implication of findings in avian directional hearing are discussed.

Intraspecies variation in ectotympanic tube length and orientation among humans.

Ectotympanic bone morphology is commonly used as a large-scale phylogenetic indicator across primates. Less well-understood is the intraspecies variation in this characteristic and the dynamic ways in which it affects and is affected by overall basicranial shape. This study attempts to clarify relationships between the external ear canal and basicranial shape among humans in a sample of archaeological human crania. The ectotympanic length and orientation were hypothesized to correlate with the shape of the cranial base and particularly with shape variables associated with relative brachycephaly. Basicranial shape in 80 computed tomography (CT) scans of adult humans were quantified using landmark coordinate data, with particular emphasis on the cranial base and auditory structures. Scaled ectotympanic lengths were taken from interlandmark distances and then compared to shape variation of the whole basicranium as summarized by procrustes shape variables and principal components analysis (PCA). The length of the ectotympanic bone was correlated with total cranial base variation. Long ectotympanic bones were found to be associated with brachycephalic individuals and less flexed basicrania. Additionally, long ectotympanic bones were found to be more horizontally oriented, as opposed to inferiorly sloped. We suggest that as brachycephaly increases the distance between the otic capsule and the pinna, the ectotympanic bone lengthens in response.

Estudio anatómico de la dehiscencia timpánica (foramen de Huschke) en la población arqueológica de Tutuquén, Región del Maule, Chile / Anatomical study of tympanic dehiscence (foramen of Huschke) in the archaeological population of Tutuquén, Maule Region, Chile

RESUMEN: La dehiscencia timpánica o Foramen de Huschke (FH) se considera un rasgo craneal morfológico menor, hipostósico, no estocástico, transitorio, ubicado en laplaca timpánica del hueso temporal, cuya expresión se considera fisiológica hasta los 5 años de edad, denominándose como persistente su presencia a mayor edad. La mención de este rasgo en la literatura anatómica se presenta de manera escasa, debido a una muy baja presencia en poblaciones modernas, situación que cambia al estudiar poblaciones arqueológicas. El propósito de este estudio es describir la expresión del foramen de Huschke en una población arqueológica de Chile central. Fueron analizados 27 huesos temporales obtenidos de los restos óseos de la población del Monumento Arqueológico Cementerio Tutuquén, los cuales están depositados en el Museo Regional de Rancagua, Chile. Se evaluó presencia y ubicación del foramen, sexo, temporalidad y rango etáreo para cada muestra incluida. El FH se presentó en un 77,78% de los temporales, siendo 47,62% restos masculinos, 28,57% femeninos y 23,81% de sexo indeterminado. La totalidad de los restos de niños y subadultos presentaron FH, mientras que en adultos su expresión disminuye hasta un 68,42%. La ubicación fue un 38,10% en cuadrante inferomedial, 33,33% superolateral, 23,81% superomedial, 4,71% central. No se encontraron FH de ubicación inferolateral. El único temporal observable del período 10.000 AP (antes del presente, 1950) presentó FH, mientras que, en el período 7.000 AP se presentó en 6/7 temporales y en 14/19 temporales del período 1.000 AP. Los datos aportados complementan el conocimiento anatómico del proceso de osificación del hueso timpánico y la expresión de la dehiscencia timpánica como rasgo morfológico menor desde el estudio de poblaciones arqueológicas.

SUMMARY: The tympanic dehiscence or Foramen of Huschke (FH) is considered a transient minor, hypostosic, non-stochastic cranial feature, located in the tympanic plate of the temporal bone. Its expression is considered physiological until the age of five, and its presence is constant after that. This characteristic is seldom mentioned in anatomical literature since it is infrequent in modern populations. However, there is a difference when archaeological populations are studied. The purpose of this study is to describe the expression of the Huschke foramen in an archaeological population of central Chile. For this analysis, 27 temporal bones were obtained from human skeletal remains of the Tutuquén Cemetery Archaeological Monument. Presence and location of the foramen, sex, time period and age range were evaluated for each sample. The FH occurred in 77.78% of the temporal bones, with 47.62% male, 28.57% female and 23.81% of undetermined sex. All children and subadults presented FH, while in adults it decreased to 68.42%. The location was 38.10% in the inferomedial quadrant, 33.33 % superolateral, 23.81% superomedial, 4.71% central, and no FH was found at the inferolateral position. The only temporal bone identified in the 10,000 BP (before the present 1950) presented FH, while in the 7,000 BP period, it presented in 6/7 temporal bones and in the 1000 BP period, it was found in 14/ 19 temporal bones. The data provided complements anatomical knowledge of the tympanic bone ossification process, and in archaeological population studies, tympanic dehiscence presents as a lesser morphological characteristic.

Safe Zones for Temporal Muscle Hook Retraction: A Technical Note.

BACKGROUND: The temporal muscle (TM) needs to be dissected and reflected downward in some anterolateral cranial approaches, and failing to preserve its integrity could have severe functional and cosmetic consequences. Most articles focus on techniques to prevent vascular injury during retrograde dissection or techniques to preserve the facial nerve; however, information on how to take care of the muscle during hook retraction is limited. We presented an anatomic study of vascularization of the TM, and we established safe areas for muscular hook retraction. METHODS: We dissected 16 TMs in 8 cadaveric heads. The TM was reflected downward, and we measured the distance between the anterior branch of the posterior deep temporal artery (PDTA) and the frontozygomatic suture and the distance between the posterior branch of the PDTA and the external auditory meatus projection. RESULTS: The average distance between the anterior branch of the PDTA and the frontozygomatic suture was 19.5 mm (range, 14-26 mm). The average distance between the posterior branch of the PDTA and the external auditory canal was 37.1 mm (range, 31-43 mm). We established 2 safe zones for hook placement: an anterior safe zone 14 mm posterior to the frontozygomatic suture and a posterior safe zone 30 mm anterior to the external auditory meatus. CONCLUSIONS: We delimited 2 safe zones for hook placement during TM retraction aiming to avoid direct vascular damage in anterolateral cranial approaches.

Positional relationship between the external acoustic meatus and sigmoid sinus: an MRI study.

PURPOSE: There is no study exploring the positional relationship between the external acoustic meatus (EAM) and the sigmoid sinus (SS) in detail. The present study aimed to characterize the relationship using contrast magnetic resonance imaging (MRI). METHODS: In total, 85 patients with an intact EAM, SS, and surrounding structures underwent thin-sliced, contrast MRI. Imaging data were transferred to a workstation for analysis. RESULTS: In all patients, the EAM and SS were well depicted on both the sagittal and axial images. The relationships and distances between the EAM and SS, in addition to the shape of cross sections of the EAM, were highly variable with left-right asymmetry. The positional relationships between the EAM and the anterior edge of the SS were classified into superior, intervening, and inferior types. The intervening type was the most predominant, accounting for 85%. The shortest distance between the posterior wall of the EAM and the anterior margin of the SS was 12.3 ± 3.9 mm on the right side and 13.0 ± 2.9 mm on the left. In three women, the distance was less than 5 mm on the right side. CONCLUSIONS: The positional relationship between the EAM and SS is highly variable and inconsistent. These structures may be adjacent, especially on the right side, and presurgical contrast MRI should be included when planning surgeries around the EAM.

Infrasonic hearing in birds: a review of audiometry and hypothesized structure-function relationships.

The perception of airborne infrasound (sounds below 20 Hz, inaudible to humans except at very high levels) has been documented in a handful of mammals and birds. While animals that produce vocalizations with infrasonic components (e.g. elephants) present conspicuous examples of potential use of infrasound in the context of communication, the extent to which airborne infrasound perception exists among terrestrial animals is unclear. Given that most infrasound in the environment arises from geophysical sources, many of which could be ecologically relevant, communication might not be the only use of infrasound by animals. Therefore, infrasound perception could be more common than currently realized. At least three bird species, each of which do not communicate using infrasound, are capable of detecting infrasound, but the associated auditory mechanisms are not well understood. Here we combine an evaluation of hearing measurements with anatomical observations to propose and evaluate hypotheses supporting avian infrasound detection. Environmental infrasound is mixed with non-acoustic pressure fluctuations that also occur at infrasonic frequencies. The ear can detect such non-acoustic pressure perturbations and therefore, distinguishing responses to infrasound from responses to non-acoustic perturbations presents a great challenge. Our review shows that infrasound could stimulate the ear through the middle ear (tympanic) route and by extratympanic routes bypassing the middle ear. While vibration velocities of the middle ear decline towards infrasonic frequencies, whole-body vibrations - which are normally much lower amplitude than that those of the middle ear in the 'audible' range (i.e. >20 Hz) - do not exhibit a similar decline and therefore may reach vibration magnitudes comparable to the middle ear at infrasonic frequencies. Low stiffness in the middle and inner ear is expected to aid infrasound transmission. In the middle ear, this could be achieved by large air cavities in the skull connected to the middle ear and low stiffness of middle ear structures; in the inner ear, the stiffness of round windows and cochlear partitions are key factors. Within the inner ear, the sizes of the helicotrema and cochlear aqueduct are expected to play important roles in shunting low-frequency vibrations away from low-frequency hair-cell sensors in the cochlea. The basilar papilla, the auditory organ in birds, responds to infrasound in some species, and in pigeons, infrasonic-sensitive neurons were traced back to the apical, abneural end of the basilar papilla. Vestibular organs and the paratympanic organ, a hair cell organ outside of the inner ear, are additional untested candidates for infrasound detection in birds. In summary, this review brings together evidence to create a hypothetical framework for infrasonic hearing mechanisms in birds and other animals.

Skill Transference of a Probe-Tube Placement Training Simulator.

BACKGROUND: Probe-tube placement is a necessary step in hearing aid verification which needs ample hands-on experience and confidence before performing in clinic. To improve the methods of training in probe-tube placement, a manikin-based training simulator was developed consisting of a 3D-printed head, a flexible silicone ear, and a mounted optical tracking system. The system is designed to provide feedback to the user on the depth and orientation of the probe tube, and the time required to finish the task. Although a previous validation study was performed to determine its realism and teachability with experts, further validation is required before implementation into educational settings. PURPOSE: This study aimed to examine the skill transference of a newly updated probe-tube placement training simulator to determine if skills learned on this simulator successfully translate to clinical scenarios. RESEARCH DESIGN: All participants underwent a pretest in which they were evaluated while performing a probe-tube placement and real-ear-to-coupler difference (RECD) measurement on a volunteer. Participants were randomized into one of two groups: the simulator group or the control group. During a two-week training period, all participants practiced their probe-tube placement according to their randomly assigned group. After two weeks, each participant completed a probe-tube placement on the same volunteer as a posttest scenario. STUDY SAMPLE: Twenty-five novice graduate-level student clinicians. DATA COLLECTION AND ANALYSIS: Participants completed a self-efficacy questionnaire and an expert observer completed a questionnaire evaluating each participant's performance during the pre- and posttest sessions. RECD measurements were taken after placing the probe tube and foam tip in the volunteer's ear. Questionnaire results were analyzed through nonparametric t-tests and analysis of variance, whereas RECD results were analyzed using a nonlinear mixed model method. RESULTS: Results suggested students in the simulator group were less likely to contact the tympanic membrane when placing a probe tube, appeared more confident, and had better use of the occluding foam tip, resulting in more improved RECD measurements. CONCLUSIONS: The improved outcomes for trainees in the simulator group suggest that supplementing traditional training with the simulator provides useful benefits for the trainees, thereby encouraging its usage and implementation in educational settings.

Does tranexamic acid improve intra-operative visualisation in endoscopic ear surgery? A double-blind, randomised, controlled trial.

OBJECTIVE: To assess the effect of tranexamic acid on intra-operative bleeding and surgical field visualisation. METHODS: Fifty patients undergoing various endoscopic ear surgical procedures, including endoscopic tympanoplasty, endoscopic atticotomy or mastoidectomy, endoscopic ossiculoplasty, and endoscopic stapedotomy, were randomly assigned to: a study group that received tranexamic acid or a control group which received normal saline. The intra-operative bleeding and operative field visualisation was graded using the Das and Mitra endoscopic ear surgery bleeding and field visibility score, which was separately analysed for the external auditory canal and the middle ear. RESULTS: The Das and Mitra score was better (p < 0.05) in the group that received tranexamic acid as a haemostat when working in the external auditory canal; with respect to the middle ear, no statistically significant difference was found between the two agents. Mean values for mean arterial pressure, heart rate and surgical time were comparable in both groups, with no statistically significant differences. CONCLUSION: Tranexamic acid appears to be an effective haemostat in endoscopic ear surgery, thus improving surgical field visualisation, especially during manipulation of the external auditory canal soft tissues.

Surgically-Relevant Anatomy of the External Auditory Canal Bulge and Scutum.

HYPOTHESIS: Anatomic study of the external auditory canal's (EAC) anterior bulge, scutum, and ossicular chain will generate knowledge applicable to safe ear surgery and instrument design. BACKGROUND: The EAC contains two structures that obscure view of the middle ear: the anterior bulge and the scutum. The dimensions of these structures and their relationships to the ossicular chain have not been previously described. METHODS: Cadaveric temporal bones underwent computed tomography scanning, and three-dimensional reconstructions were created. Dimensions and angles of the EAC, its anterior bulge and scutum were measured. Distances to ossicular landmarks and the facial nerve were examined. RESULTS: The anterior EAC had a swan-neck shape. The thinnest portion was located medially and correlated with the canal thickness at the anterior bulge. However the thickness of the anterior bulge was not correlated with its angulation. The scutum averaged 3.8 mm long with a base thickness of 2.3 mm and a mean tip angle of 33 degrees. The short process of the incus was significantly closer to the scutum than other ossicular landmarks. CONCLUSION: Prominent anterior canal bulges are formed by posterior temporomandibular joints, not thicker bone. The scutum has asymmetric distances to various portions of the ossicles with the incus short process sometimes as close as 0.2 mm, placing it at risk of injury.

A comparison of ear-canal-reflectance measurement methods in an ear simulator.

Ear-canal reflectance has been researched extensively for diagnosing conductive hearing disorders and compensating for the ear-canal acoustics in non-invasive measurements of the auditory system. Little emphasis, however, has been placed on assessing measurement accuracy and variability. In this paper, a number of ear-canal-reflectance measurement methods reported in the literature are utilized and compared. Measurement variation seems to arise chiefly from three factors: the residual ear-canal length, the ear-probe insertion angle, and the measurement frequency bandwidth. Calculation of the ear-canal reflectance from the measured ear-canal impedance requires estimating the ear-canal characteristic impedance in situ. The variability in ear-canal estimated characteristic impedance and reflectance due to these principal factors is assessed in an idealized controlled setup using a uniform occluded-ear simulator. In addition, the influence of this measurement variability on reflectance-based methods for calibrating stimulus levels is evaluated and, by operating the condenser microphone of the occluded-ear simulator as an electro-static speaker, the variability in estimating the emitted pressure from the ear is determined. The various measurement methods differ widely in their robustness to variations in the three principal factors influencing the accuracy and variability of ear-canal reflectance.

On the calculation of reflectance in non-uniform ear canals.

Ear-canal reflectance is useful for quantifying the conductive status of the middle ear because it can be measured non-invasively at a distance from the tympanic membrane. Deriving the ear-canal reflectance requires decomposing the total acoustic pressure into its forward- and reverse-propagating components. This decomposition is conveniently achieved using formulas that involve the input and characteristic impedances of the ear canal. The characteristic impedance is defined as the ratio of sound pressure to volume flow of a propagating wave and, for uniform waveguides, the plane-wave characteristic impedance is a real-valued constant. However, in non-uniform waveguides, the characteristic impedances are complex-valued quantities, depend on the direction of propagation, and more accurately characterize a propagating wave in a non-uniform ear canal. In this paper, relevant properties of the plane-wave and spherical-wave characteristic impedances are reviewed. In addition, the utility of the plane-wave and spherical-wave reflectances in representing the reflection occurring due to the middle ear, calibrating stimulus levels, and characterizing the emitted pressure in simulated non-uniform ear canals is investigated and compared.

Anatomy of the Intertragic Notch of the Auricle May Protect the Ear Canal from Fluids as a Built-In Overflow Spout at an Appropriate Position.

To observe the utility of the intertragic notch during rain showers, an anatomic replica of the human auricle was studied under an artificial shower system with a video recorder. During the shower, water trickled out through the intertragic notch naturally, avoiding the ear canal. This study finds one utility of the intertragic notch may be the prevention of water flowing into the ear canal during rain showers.

Clinical benefit of wideband-tympanometry: a pediatric audiology clinical study.

PURPOSE: Wideband-tympanometry (WBT) could give more informative data about the tympanic condition than the conventional tympanometry. In the actual literature, the clinical profit of wideband-tympanometry in pediatric audiological settings is not well evaluated. The aim of this study was to analyze the additional clinical benefit. METHODS: 150 children (281 ears) with normal hearing, at the age from 11 days up to 14;10 years, checked with pure tone audiometry or auditory brainstem responses (ABR) participated in this retrospective study. We divided in four age ranges (≤ 6 month; > 6 month ≤ 3 years; > 3 years ≤ 11 years; > 11 years). All children were evaluated with ENT examination including ear microscopy, conventional 226-Hz or 1000-Hz tympanometry and WBT. Ear canal volumes were determined. RESULTS: Compared with literature data, our patients aged ≤ 3 years showed smaller mean ear canal volumes (≤ 4 ml). We found a good statistical correlation between the WBT-results and 1000-Hz tympanometry but a rare correlation between WBT-results and ear microscopic findings. In the patients with pathologic ear microscopic results in all groups of age, a significant reduction of WBT-absorbance in 1000 Hz and 2000 Hz was found. CONCLUSIONS: This study confirms that WBT collects additive data to detect the correct middle ear status. In pediatric audiology, WBT is an additional useful method to value middle ear problems and to analyze the character of infantile hearing loss. Standard guidelines for the interpretation of the pediatric population are needed. Hence, it will be necessary to determine these findings in a larger number of infantile ears.

Feasibility of High-Resolution Computed Tomography Imaging for Obtaining Ear Impressions for Hearing Aid Fitting.

OBJECTIVE: This study investigated the feasibility of obtaining ear impressions for hearing aids by using 3-dimensional high-resolution computed tomography (HRCT) images. STUDY DESIGN: Case series. SETTING: One referral tertiary center. SUBJECTS AND METHODS: Hearing-impaired adults who were fitted with 1 or 2 behind-the-ear hearing aid(s) and had undergone temporal bone HRCT for various ear pathologies were enrolled in this study. Earmolds were fabricated from the impressions obtained using the conventional ear canal silicone injection technique and the HRCT reconstructed technique. Outer ear canal resonance frequencies and amplitude in open ears and those measured with silicon and HRCT reconstructed earmolds were determined through real-ear gain measurements, including real-ear unaided gain (REUG) and real-ear occluded gain (REOG), for comparison. RESULTS: A total of 50 HRCT reconstructed earmolds were compared with 50 conventional silicon injection earmolds. The average value of open ear canal resonance amplitude (REUG) for each ear was 0.41 to 16.76 dB. No statistically significant difference in resonance amplitude (REOG) was observed between silicon and reconstructed earmolds (paired t test, P > .05). The mean insertion loss (REOG-REUG) at all frequencies also did not differ significantly between the two earmolds (paired t test, P > .05). CONCLUSION: According to our real-ear measurements, acoustic characteristics of the HRCT reconstructed earmolds were compatible with those of the silicone injection earmolds. Despite concerns about increased cost and radiation exposure, the HRCT reconstructed technique is a clinically useful and applicable method and can reduce potential safety complications for difficult cases.

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.

Predictors of round window membrane visibility in pediatric cochlear implant surgery using temporal bone HRCT: A retrospective study.

OBJECTIVE: To predict round window membrane (RWM) visibility and electrode insertion sites using high-resolution computed tomography (HRCT) in pediatric cochlear implant surgery. MATERIALS AND METHODS: Sixty-two ears of 36 infants less than 1 year old were included in our study. Intraoperative RWM visibility was classified into three types corresponding to three different surgical approaches. Radiologic parameters were measured on preoperative axial temporal HRCT images and correlated with RWM visibility and surgical approaches. RESULTS: A significant correlation was found between the degree of RWM visibility and the following two parameters: 1) a line (lw) was drawn from the posterior margin of the RWM to the intersection point of the posterior wall of the external auditory canal (EAC) and mastoid cortex. Another line (lf) was drawn between the posterior margin of the RWM and the lateral margin of the FN. The angle between lw and lf was measured as angle A, P < 0.01, R2 = -0.809; 2) a line (lm) was drawn from the anterior to posterior margin of the RWM, and the angle between lm and lf was measured as angle B, P < 0.01, R2 = -0.850. A nonsignificant correlation was found between the degree of RWM visibility and the facial recess width, p > 0.05, R2 = -0.00015. CONCLUSION: RWM visibility showed a high correlation with the two angular measurements (angle A and angle B) and was associated with electrode insertion sites. In children less than one year old, surgeons can depend on those two parameters in predicting the RWM visibility.

The anatomical and radiological evaluation of the Vidian canal on cone-beam computed tomography images.

INTRODUCTION: The aim of this study is to explore the anatomy of the Vidian nerve to elucidate the appropriate surgical approach based on preoperative cone-beam computed tomography (CBCT) images. MATERIALS AND METHODS: The Vidian canal and its surrounding structures were morphometrically evaluated retrospectively in CBCT images of 400 cases by the Planmeca Romexis program. The types of the Vidian canal were determined and seven parameters were measured from the images. RESULTS: Three types of the Vidian canal according to the relationship with the sphenoid bone were found as follows: the Vidian canal totally protruded into the sphenoid sinus (19.75%), partially protruded into sphenoid sinus (44.37%) and embedded inside bony tissue of the body of sphenoid bone (35.87%). The position of the Vidian canal was medial (34.62%), on the same line (55.12%) and lateral (10.25%) to the medial plate of the pterygoid process. The distance between the Vidian canal and the vomerine crest, the mid-sagittal plane, the round foramen, the palatovaginal canal, and the superior wall of the sphenoid sinus, the length of the Vidian canal and the angle between the Vidian canal and the sagittal plane was found to be 16.69 ± 2.14, 13.80 ± 2.00, 8.88 ± 1.60, 5.83 ± 1.37, 23.98 ± 2.68, 13.29 ± 1.71 mm and 25.78° ± 3.68° in males, 14.62 ± 1.66, 11.43 ± 1.28, 8.51 ± 1.63, 5.78 ± 0.57, 22.37 ± 2.07, 12.91 ± 1.26 mm and 23.43° ± 3.07° in females, respectively. CONCLUSIONS: Our results may assist with proper treatment for surgical procedures around the Vidian canal with a high success rate and minimal complications. Therefore, the results obtained in this study contribute to the literature.