Numerical simulations to determine the stimulation of the crista ampullaris during the Head Impulse Test.

The Head Impulse Test, the most widely accept test to assess the vestibular function, comprises rotations of the head based on idealized orientations of the semicircular canals, instead of their individual arrangement specific for each patient. In this study, we show how computational modelling can help personalize the diagnosis of vestibular diseases. Based on a micro-computed tomography reconstruction of the human membranous labyrinth and their simulation using Computational Fluid Dynamics and Fluid-Solid Interaction techniques, we evaluated the stimulus experienced by the six cristae ampullaris under different rotational conditions mimicking the Head Impulse Test. The results show that the maximum stimulation of the crista ampullaris occurs for directions of rotation that are more aligned with the orientation of the cupulae (average deviation from alignment of 4.7°, 9.8°, and 19.4° for the horizontal, posterior, and superior maxima, respectively) than with the planes of the semicircular canals (average deviation from alignment of 32.4°, 70.5°, and 67.8° for the horizontal, posterior, and superior maxima, respectively). A plausible explanation is that when rotations are applied with respect to the center of the head, the inertial forces acting directly over the cupula become dominant over the endolymphatic fluid forces generated in the semicircular canals. Our results indicate that it is necessary to consider cupulae orientation to ensure optimal conditions for testing the vestibular function.

Adding Kinetic Energy Does Not Further Improve Treatment Outcomes With a Mechanical Reposition Chair: A Randomized Controlled Trial.

OBJECTIVE: To test if the addition of abrupt deaccelerations (kinetic energy) during treatment with a mechanical repositional chair (MRC) provides improved treatment efficacy with treatment of posterior benign paroxysmal positional vertigo (BPPV). STUDY DESIGN: Randomized two-armed parallel open-labeled clinical trial. SETTING: Tertiary referral center. PATIENTS: Seventy patients diagnosed with posterior canalolithiasis BPPV were included. INTERVENTIONS: All patients underwent diagnostics and treatment with an MRC. Patients were randomized to either a traditional Epley maneuver or a potentiated version of the Epley maneuver where kinetic energy was applied in five positions with 45-degree turns between each step. MAIN OUTCOME MEASURES: Primary endpoint was the number of treatments needed before complete resolution of both subjective symptoms and objective signs of BPPV within the semicircular canal of interest. Secondary endpoints included the following: 1) number of patients requiring more than 10 treatments, 2) length of treatment in days before treatment(s) were successful, and 3) changes in total Dizziness Handicap Inventory scores before and after treatment. RESULTS: No significant difference in the number of required treatments between the two treatment arms was found. Approximately three of four subjects were cured after two repositional maneuvers regardless of type of treatment. An equal length of treatment was seen with both groups, and the Dizziness Handicap Inventory scores were significantly lowered after treatment with no significant differences between the two types of treatment. CONCLUSIONS: Both the traditional and the potentiated Epley maneuver are efficient in treatment of canalolithiasis of the posterior semicircular canals with MRC. Addition of kinetic energy with this subgroup of BPPV patients does not seem to add further efficacy to the treatment.

Inner ear biomechanics reveals a Late Triassic origin for mammalian endothermy.

Endothermy underpins the ecological dominance of mammals and birds in diverse environmental settings1,2. However, it is unclear when this crucial feature emerged during mammalian evolutionary history, as most of the fossil evidence is ambiguous3-17. Here we show that this key evolutionary transition can be investigated using the morphology of the endolymph-filled semicircular ducts of the inner ear, which monitor head rotations and are essential for motor coordination, navigation and spatial awareness18-22. Increased body temperatures during the ectotherm-endotherm transition of mammal ancestors would decrease endolymph viscosity, negatively affecting semicircular duct biomechanics23,24, while simultaneously increasing behavioural activity25,26 probably required improved performance27. Morphological changes to the membranous ducts and enclosing bony canals would have been necessary to maintain optimal functionality during this transition. To track these morphofunctional changes in 56 extinct synapsid species, we developed the thermo-motility index, a proxy based on bony canal morphology. The results suggest that endothermy evolved abruptly during the Late Triassic period in Mammaliamorpha, correlated with a sharp increase in body temperature (5-9 °C) and an expansion of aerobic and anaerobic capacities. Contrary to previous suggestions3-14, all stem mammaliamorphs were most probably ectotherms. Endothermy, as a crucial physiological characteristic, joins other distinctive mammalian features that arose during this period of climatic instability28.

[Frequency characteristics of horizontal semicircular canals damage and the ultrastructure analysis of crista ampullaris in patients with Meniere's disease].

Objective: To investigate the frequency characteristics and the pathological characteristics of the horizontal crista ampullaris in patients with Meniere's disease,and to analyse its structural basis. Methods: Between March, 2019 and November, 2019, seventy-two patients diagnosed as Meniere's disease (27 males and 45 females, aged from 13 to 74 years, with a course of disease ranging from 4 months to 32 years)in Shandong Provincial ENT Hospital were included.Caloric test, sinusoidal harmonic acceleration test (SHA), video-head impulse test (v-HIT), Gadolinium-enhanced inner-ear 3D-FLAIR MRI and pure tone audiometry were conducted in the patients. The function of the horizontal semicircular canal in these patients were analysed as well as its relationship with the degree of endolymphatic hydrops,clinical stage and duration. Light microscopy and transmission electron microscopy were used to observe the ultrastructure of horizontal semicircular canal crista ampullaris from six patients with refractory Meniere's disease who underwent labyrinthectomy. The number of type Ⅰ and type Ⅱ vestibular hair cells, the common pathophysiological changes of horizontal semicircular canal crista ampullaris were investigated in these patients. Statistical analysis was performed using SPSS 19.0. Results: With the increase of detection frequency, the abnormal rate decreased gradually. The abnormal rate of caloric test was 69.4% (50/72), SHA 51.4% (37/72), V-HIT 36.1% (26/72), comparation of the positive rate among the three tests showed statistically significant differences(P<0.05).Neither caloric test nor SHA had correlation with the degree of hydrops(P>0.05), but v-HIT(r=0.434,P<0.01).There was correlation with clinical stage to SHA and v-HIT(r=0.338,0.462,P<0.01), except caloric test(P>0.05).No significant relation was found with caloric test, SHA, v-HIT and course of disease(P>0.05).Morphological observation found abnormal monolayer epithelialization of the horizontal semicircular canal crista ampullaris significantly decreased number of type Ⅱ hair cells compared with type Ⅰhair cells. Hair cells showed perinuclear vacuolization, cytoplasmic vacuoles, mitochondrial electron density increasement and loss of stereocilia. Conclusions: The horizontal semicircular canal damage in the patients with Meniere's disease has a frequency-dependent characteristic, mainly occurres in low frequency area. With progress of the disease, the high frequency area of ampulla will be impaired gradually, and it is related to the degree of endolymphatic hydrops and hearing level. Hair cell injury would be observed,the frequency characteristics may be more associated with the disorder of type Ⅱ hair cells.

Novel cell types and developmental lineages revealed by single-cell RNA-seq analysis of the mouse crista ampullaris.

This study provides transcriptomic characterization of the cells of the crista ampullaris, sensory structures at the base of the semicircular canals that are critical for vestibular function. We performed single-cell RNA-seq on ampullae microdissected from E16, E18, P3, and P7 mice. Cluster analysis identified the hair cells, support cells and glia of the crista as well as dark cells and other nonsensory epithelial cells of the ampulla, mesenchymal cells, vascular cells, macrophages, and melanocytes. Cluster-specific expression of genes predicted their spatially restricted domains of gene expression in the crista and ampulla. Analysis of cellular proportions across developmental time showed dynamics in cellular composition. The new cell types revealed by single-cell RNA-seq could be important for understanding crista function and the markers identified in this study will enable the examination of their dynamics during development and disease.

Frequency characteristics of horizontal semicircular canals damage and the ultrastructure analysis of crista ampullaris in patients with Meniere's disease / 中华耳鼻咽喉头颈外科杂志

Objective: To investigate the frequency characteristics and the pathological characteristics of the horizontal crista ampullaris in patients with Meniere's disease,and to analyse its structural basis. Methods: Between March, 2019 and November, 2019, seventy-two patients diagnosed as Meniere's disease (27 males and 45 females, aged from 13 to 74 years, with a course of disease ranging from 4 months to 32 years)in Shandong Provincial ENT Hospital were included.Caloric test, sinusoidal harmonic acceleration test (SHA), video-head impulse test (v-HIT), Gadolinium-enhanced inner-ear 3D-FLAIR MRI and pure tone audiometry were conducted in the patients. The function of the horizontal semicircular canal in these patients were analysed as well as its relationship with the degree of endolymphatic hydrops,clinical stage and duration. Light microscopy and transmission electron microscopy were used to observe the ultrastructure of horizontal semicircular canal crista ampullaris from six patients with refractory Meniere's disease who underwent labyrinthectomy. The number of type Ⅰ and type Ⅱ vestibular hair cells, the common pathophysiological changes of horizontal semicircular canal crista ampullaris were investigated in these patients. Statistical analysis was performed using SPSS 19.0. Results: With the increase of detection frequency, the abnormal rate decreased gradually. The abnormal rate of caloric test was 69.4% (50/72), SHA 51.4% (37/72), V-HIT 36.1% (26/72), comparation of the positive rate among the three tests showed statistically significant differences(P<0.05).Neither caloric test nor SHA had correlation with the degree of hydrops(P>0.05), but v-HIT(r=0.434,P<0.01).There was correlation with clinical stage to SHA and v-HIT(r=0.338,0.462,P<0.01), except caloric test(P>0.05).No significant relation was found with caloric test, SHA, v-HIT and course of disease(P>0.05).Morphological observation found abnormal monolayer epithelialization of the horizontal semicircular canal crista ampullaris significantly decreased number of type Ⅱ hair cells compared with type Ⅰhair cells. Hair cells showed perinuclear vacuolization, cytoplasmic vacuoles, mitochondrial electron density increasement and loss of stereocilia. Conclusions: The horizontal semicircular canal damage in the patients with Meniere's disease has a frequency-dependent characteristic, mainly occurres in low frequency area. With progress of the disease, the high frequency area of ampulla will be impaired gradually, and it is related to the degree of endolymphatic hydrops and hearing level. Hair cell injury would be observed,the frequency characteristics may be more associated with the disorder of type Ⅱ hair cells.

Mechanical aspects of the semicircular ducts in the vestibular system.

The semicircular ducts (SCDs) of the vestibular system play an instrumental role in equilibration and rotation perception of vertebrates. The present paper is a review of quantitative approaches and shows how SCDs function. It consists of three parts. First, the biophysical mechanisms of an SCD system composed of three mutually connected ducts, allowing endolymph to flow from one duct into another one, are analysed. The flow is quantified by solving the continuity equations in conjunction with the equations of motion of the SCD hydrodynamics. This leads to mathematical expressions that are suitable for further analytical and numerical analysis. Second, analytical solutions are derived through four simplifying steps while keeping the essentials of the coupled system intact. Some examples of flow distributions for different rotations are given. Third, the focus is on the transducer function of the SCDs. The complex structure of the mechano-electrical transduction apparatus inside the ampullae is described, and the consequences for sensitivity and frequency response are evaluated. Furthermore, both the contributions of the different terms of the equations of motion and the influence of Brownian motion are analysed. Finally, size limitations, allometry and evolutionary aspects are taken into account.

[Ultrastructural study of ampulla of mouse inner ear].

Objective: To observe the ultrastructure of the ampulla, and analyze its physiological and pathological significance. Methods: In this study, 20 Kunming mice were used, and scanning electron microscopy was used to observe the ultrastructure of the ampulla of inner ear. Results: Otoconia was found among the cilia bundles of different haircell(intercilla otoconia of ampulla). The cupula was attached to the lateral wall of the ampulla, and easily to be separated; after separated, a kind of slender crystal(surface otoconia of ampulla) could be seen between the cupula and lateral wall of the ampulla, both sides of ampullary crest were covered with slender crystals too. On the canal side of the ampulla wall, there was more particulate matter attached to the wall near the bottom of ampullary crest, partially embedded in the wall, and less on the utricle side of the ampulla wall. Conclusions: The observation of the ultrastructure of the ampulla is helpful for better understanding the physiological functions of the semicircular canals and the ampulla, and better understanding the pathogenesis and solution of some vertigo diseases.

Vertical Nystagmus in the Bow and Lean Test may Indicate Hidden Posterior Semicircular Canal Benign Paroxysmal Positional Vertigo: Hypothesis of the Location of Otoconia.

The 'Bow and Lean Test' (BLT) was developed for proper diagnosis of horizontal semicircular canal benign paroxysmal positional vertigo (HSC-BPPV). Occasionally, down- and/or up-beating vertical nystagmus is observed during the BLT. This study analyzed patients who exhibited vertical nystagmus in the BLT to comprehend the clinical significance of this sign. Of 2872 patients with vertigo between 2010 and 2015, 225 patients who showed vertical nystagmus in the BLT were enrolled. All patterns of vertical nystagmus were described based on their types of BPPV. After performing therapeutic maneuvers for BPPV, remnant symptoms in the BLT findings were investigated. Of the 225 patients with vertical nystagmus, 163 were posterior semicircular canal BPPV (PSC-BPPV). Down-beating in the bowing position and no nystagmus in the leaning position ('Down/-') was the most common type (190 of 225 patients). In addition, the nystagmus occurred in the form of '-/Up', 'Down/Up', and '-/Down'. The pattern of vertical nystagmus may be related to the position of otoconia in the canals. The location of the otoconia enables the diagnosis of hidden PSC-BPPV. Even after treatment for BPPV, patients with vertical nystagmus in the BLT tended to complain remnant vertigo symptoms (44.8% vs. 23.9%, P = 0.022, in PSC-BPPV; 70.0% vs. 24.0%, P = 0.020, in HSC-BPPV). We thought that they actually had hidden PSC-BPPV and the otoconial debris may still in the PSC; this untreated PSC-BPPV might cause the remnant symptoms. In conclusion, vertical nystagmus in the BLT may indicate the presence of PSC-BPPV. Moreover, vertical nystagmus during the BLT may occur in patients with hidden PSC-BPPV who complain of remnant vertigo symptoms. Vertical nystagmus shown in the BLT may not include the possibility of central vertigo.

A possible mechanism of the formation of endolymphatic hydrops and its associated inner ear disorders.

The pathology of Meniere's disease (MD) is well established to be endolymphatic hydrops. However, the mechanism underlying deafness and vertigo of MD or idiopathic endolymphatic hydrops is still unknown. In order to evaluate the pathogenesis of deafness and vertigo in MD, it seems to be rational to investigate the interrelationship between hydrops and inner ear disorders using animals with experimentally-induced endolymphatic hydrops. In spite of intense efforts by many researchers, the mechanism of vertiginous attack has been unexplained, because animals with experimental hydrops usually did not show vertiginous attack. Recently, there are two reports to succeed to evoke vertiginous attack in animals with experimental hydrops. In the present paper were first surveyed past proposals about underlying mechanism of the development of hydrops and inner ear disorders associated with hydrops, and were discussed the pathogenetic mechanism of vertiginous attack in hydrops. In conclusion, abrupt development of hydrops was thought to play a pivotal role in the onset of vertiginous seizure.

Growth and cellular patterning during fetal human inner ear development studied by a correlative imaging approach.

BACKGROUND: Progressive transformation of the otic placode into the functional inner ear during gestational development in humans leads to the acquisition of hearing perception via the cochlea and balance and spatial orientation via the vestibular organ. RESULTS: Using a correlative approach involving micro-computerized tomography (micro-CT), transmission electron microscopy and histological techniques we were able to examine both the morphological and cellular changes associated with human inner ear development. Such an evaluation allowed for the examination of 3D geometry with high spatial and temporal resolution. In concert with gestational progression and growth of the cochlear duct, an increase in the distance between some of the Crista ampullaris is evident in all the specimens examined from GW12 to GW36. A parallel increase in the distances between the macular organs - fetal utricle and saccule - is also evident across the gestational stages examined. The distances between both the utricle and saccule to the three cristae ampullares also increased across the stages examined. A gradient in hair cell differentiation is apparent from apex to base of the fetal cochlea even at GW14. CONCLUSION: We present structural information on human inner ear development across multiple levels of biological organization, including gross-morphology of the inner ear, cellular and subcellular details of hearing and vestibular organs, as well as ultrastructural details in the developing sensory epithelia. This enabled the gathering of detailed information regarding morphometric changes as well in realizing the complex developmental patterns of the human inner ear. We were able to quantify the volumetric and linear aspects of selected gestational inner ear specimens enabling a better understanding of the cellular changes across the fetal gestational timeline. Moreover, these data could serve as a reference for better understanding disorders that arise during inner ear development.

Focal Degeneration of Vestibular Neuroepithelium in the Cristae Ampullares of Three Human Subjects.

BACKGROUND: We report a unique pattern of focal degeneration of the neuroepithelium of cristae ampullares, thick subepithelial extracellular deposits, and neural degeneration in three humans. OBJECTIVE: To characterize the pattern of vestibular degeneration and measure the thickness of subepithelial deposits in these three cases and controls. METHODS: The subepithelial deposits of vestibular end organs in three subject cases and controls were studied using hematoxylin and eosin, periotic acid-Schiff, Gomori trichrome staining, and immunostaining for antineurofilament, antimyosin VIIa, and anticollagen 4a1. The thickness of deposit as measured by light microscopy was compared with that of control groups (age-matched controls, patients with unilateral Menière's disease, vestibular neuritis, cupulolithiasis, severe nonfocal degeneration of the vestibular neuroepithelium, and Alport syndrome). The correlation of thickness of deposits with age from 0 to 100 years was also investigated. RESULTS: Focal loss of hair cells in the neuroepithelium, thick subepithelial deposits, and degeneration of subepithelial dendrites and Scarpa's ganglion were found in all three cristae of three subject cases. Immunostaining demonstrated a decrease of afferent neural fibers in the cristae and focal fragmentation of the basement membrane adjacent to the deposits. The thickness of the subepithelial deposits in three cristae of three subject cases was significantly greater than that of all controls. In the three cristae of normal controls, the thickness of deposits demonstrated a positive correlation with age. CONCLUSION: Although both age and degeneration of the vestibular neuroepithelium may be associated with the thickness of the subepithelial deposits, in this unique pattern of degeneration, the thickness of the subepithelial deposits was significantly greater than that in all controls.

Síndrome de Alagille: hipoplasia de canales semicirculares posteriores / Alagille's syndrome: Hypoplasia of posterior semicircular canals

No disponible

[The exploration on optimization of two alternatives between roll test and Dix-Hallpike test in benign paroxysmal positional vertigo].

Objective: To analyze the objective characteristics of roll test and Dix-Hallpike test in benign paroxysmal positional vertigo(BPPV)patients, discussing the premier solution of positional test. Methods: A total of 230 patients with BPPV, whereas 170 posterior semicircular canal canalithiasis (PSC-Can) BPPV and 60 horizontal semicircular canal canalithiasis (HSC-Can) BPPV were involved respectively. The induced nystagmus in roll test and Dix-Hallpike test was recorded by video nystagmuo graph (VNG), and the direction, intensity and time characteristics of nystagmus were compared in various BPPV.SPSS19.0 software was used for statistical analysis. Results: Vertically upward nystagmus was induced by hanging in 170 PSC-Can Dix-Hallpike test, and the nystagmus reversed and turned weaker when the subjects came to sit. The intensity of nystagmus at turning to lesion side by hanging and sitting were (30.3±14.1)°/s and (12.6±7.5)°/s respectively, the difference was statistically significant (t=20.153, P<0.05). However, no nystagmus was induced in PSC-Can roll test. Horizontal nystagmus in the same direction with turning was induced in 60 HSC-Can roll test. The intensity of nystagmus at turning to lesion side and normal side was (42.0±18.0)°/s and (20.3±8.7)°/s respectively, the difference was statistically significant (t=12.731, P<0.05). Furthermore, horizontal nystagmus in the same direction with turning was induced in 57 HSC-Can Dix-Hallpike. The coherence was 95% with the results of roll test. Conclusions: Dix-Hallpike test can not only be used to diagnose PSC-Can, but also induce nystagmus in HSC-Can effectively. Whereas the roll test only show significance in diagnosing HSC-Can. To avoid uncomfortable stimulation to patients as much as possible, we suggest to use Dix-Hallpike test at first, and to judge whether using roll test based on the result of the horizontal nystagmus.

Morphological basis for a tonotopic design of an insect ear.

The tonotopically organized hearing organs of bushcrickets provide the opportunity for a detailed correlation of morphological and structural properties within hearing organs that are needed to establish tonotopic gradients. In the present study of a tonotopic insect hearing organ, we combine mechanical measurements of sound-induced hearing organ motion and detailed anatomical investigations to explore the anatomical basis of tonotopy. We compare mechanical data of frequency responses along the auditory organ to several anatomical parameters. Low frequency responses are related to larger organ and cap cell size in the proximal part of the hearing organ while in the distal part of the organ, small organ and cap cell size is related to high-frequency representation. However, the correlation between organ and cap cell size with continuous frequency representation along the organ is not very tight. Instead, the height of the organ and the corresponding length of the sensory dendrites are best correlated to tonotopic frequency representation. The sensory dendrite contains a ciliary root with a pronounced cross-banding of electron-dense material that should be important for the stiffness of the dendrite. The geometry of surrounding structures like the hemolymph channel and the acoustic trachea as well as the extension of the tectorial membrane are not correlated to the tonotopy. We provide evidence that tonotopy in the bushcricket hearing organ may depend on the size of ciliary structures. In particular, the ciliary root of the sensory cells is a likely cellular basis of tonotopy.

Compliance and outcomes of concurrent Chemo-radiation in patients with peri-ampullary cancer undergoing curative resections.

OBJECTIVES: We aimed to study the compliance and treatment outcome of patients who received adjuvant treatment following curative resection for periampullary cancers periampullary cancers. MATERIALS AND METHODS: Institute medical records of PAC treated during 2007-2014 were retrieved. Demographics, treatment, and outcome in patients who were intended to receive adjuvant chemoradiation after curative resection were analyzed. Patients received first cycle chemotherapy with 5-fluorouracil folinic acid/capecitabine, followed by external radiotherapy 45 Gy/25 fractions/5 weeks and second and third cycle concurrent chemotherapy. Fourth and fifth cycle chemotherapy were administered after radiotherapy). Various prognostic factors, disease-free survival (DFS), and overall survival (OS) were evaluated. RESULTS: Sixty-five patients were evaluated. Median age was 50 years. 96.9% patients completed the intended course of radiation and overall adherence to chemotherapy was 86.2%. Median follow-up and DFS were 20 and 29.64 months, respectively (range: 1.9-97.3 months). Estimated 1-, 2-, 5-year DFS was 77.8%, 59.3%, and 37.6%, respectively. One-year estimated OS was 92.7%. Median DFS for node-negative and node-positive patients was 88.6 and 24.33 months (P = 0.06). Grade ≥III hematological toxicity was 20%. CONCLUSION: Positive node indicated a trend toward poor survival. The study highlights high compliance to multimodal management of PAC with acceptable toxicity in and out of clinical trial setting in a tertiary cancer center in India.

[VESTIBULAR PROSTHETICS: CONCEPT, APPROACHES, RESULTS].

Unlike prosthetic hearing, which develops technology for more than 30 years, the problem of the vestibular prosthesis developed a little more than one and half decades. Meanwhile, the involvement of the vestibular system in ensuring the normal functioning of the visual, motor and other systems of the body determines its decisive contribution to the spatial orientation of humans and animals. In case of damage of the vestibular apparatus (the labyrinth), there are serious violations of posture control, stabilization of sight, spatial orientation, psychological status, that is, in the aggregate quality of human life deteriorates. At present, on the animals developed technology of prosthetic semicircular canals, sensing angular acceleration, and control eye movements in dynamic situations. New approaches based on the replacement of the lost natural vestibular afferent impulses by electrical stimulation through multichannel vestibular prosthesis, are successfully introducing into the clinic.

The difference in endolymphatic hydrostatic pressure elevation induced by isoproterenol between the ampulla and the cochlea.

OBJECTIVE: The purpose of the study was to investigate the difference in the responses of endolymphatic hydrostatic pressure to isoproterenol, ß-adrenergic receptor agonist, between pars superior and pars inferior. METHODS: The hydrostatic pressure of endolymph and perilymph and endolymphatic potential in the ampulla and the cochlea during the intravenous administration of isoproterenol were recorded using a servo-null system in guinea pigs. RESULTS: The hydrostatic pressure of endolymph and perilymph in the ampulla and cochlea was similar in magnitude. Isoproterenol significantly increased hydrostatic pressure of ampullar and cochlear endolymph and perilymph with no change in the ampullar endolymphatic potential and endocochlear potential, respectively. The isoproterenol-induced maximum change of endolymphatic hydrostatic pressure in ampulla was significantly (p<0.01) smaller than that in the cochlea. In ears with an obstructed endolymphatic sac, the action of isoproterenol on endolymphatic hydrostatic pressure in the ampulla disappeared like that in the cochlea. CONCLUSION: Isoproterenol elevates endolymphatic hydrostatic pressure in different manner between the vestibule and the cochlea.

Assessing morphology and function of the semicircular duct system: introducing new in-situ visualization and software toolbox.

The semicircular duct system is part of the sensory organ of balance and essential for navigation and spatial awareness in vertebrates. Its function in detecting head rotations has been modelled with increasing sophistication, but the biomechanics of actual semicircular duct systems has rarely been analyzed, foremost because the fragile membranous structures in the inner ear are hard to visualize undistorted and in full. Here we present a new, easy-to-apply and non-invasive method for three-dimensional in-situ visualization and quantification of the semicircular duct system, using X-ray micro tomography and tissue staining with phosphotungstic acid. Moreover, we introduce Ariadne, a software toolbox which provides comprehensive and improved morphological and functional analysis of any visualized duct system. We demonstrate the potential of these methods by presenting results for the duct system of humans, the squirrel monkey and the rhesus macaque, making comparisons with past results from neurophysiological, oculometric and biomechanical studies. Ariadne is freely available at http://www.earbank.org.

Explicación ontogénica para la asociación entre dehiscencia del tegmen tympani y dehiscencia del canal semicircular superior / Ontogenetic explanation for tegmen tympani dehiscence and superior semicircular canal dehiscence association

Objetivos: Analizar la ontogenia del canal semicircular superior y del tegmen tympani y determinar si hay factores embriológicos comunes que expliquen la dehiscencia asociada de ambos. Métodos: Se han analizado 77 series embriológicas humanas de edades comprendidas entre las 6 semanas y recién nacidos. Las preparaciones estaban cortadas en serie y teñidas con la técnica de tricrómico de Martins. Resultados: La prolongación tegmentaria del tegmen tympani y el canal semicircular superior se originan de la misma estructura, la cápsula ótica, y poseen el mismo tipo de osificación endocondral; mientras que la prolongación escamosa del tegmen tympani se desarrolla desde la escama del temporal y su osificación es de tipo directa o intramembranosa. En la osificación de la prolongación tegmentaria colaboran los núcleos de osificación de los canales semicirculares superior, externo y accesorio del tegmen, los cuales por crecimiento se extienden hasta la prolongación tegmentaria, este hecho sumado a que ambas estructuras comparten una capa común de periostio externo podría explicar la coexistencia de falta de cobertura ósea en el tegmen y en el canal. Conclusión: El desarrollo del canal semicircular y tegmen tympani podrían explicar las causas de la asociación de ambas dehiscencias (AU)

Objectives: To analyze the ontogeny of the superior semicircular canal and tegmen tympani and determine if there are common embryological factors explaining both associated dehiscence. Methods: We analyzed 77 human embryological series aged between 6 weeks and newborn. Preparations were serially cut and stained with Masson's trichrome technique. Results: The tegmental prolongation of tegmen tympani and superior semicircular canal originate from the same structure, the otic capsule, and have the same type of endochondral ossification; while the extension of the squamous prolongation of tegmen tympani runs from the temporal squama and ossification is directly of intramembranous type. The nuclei of ossification of the superior and external semicircular canals and accessory of tegmen collaborate in the ossification of the tegmental extension and by growth extend to the tegmental prolongation. This fact plus the fact that both structures share a common layer of external periosteum could explain the coexistence of lack of bone coverage in tegmen and superior semicircular canal. Conclusion: The development of the semicircular canal and tegmen tympani could explain the causes of the association of both dehiscences (AU)