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BMC Research Notes Apr 2010The ionic composition of the luminal fluid in the vestibular labyrinth is maintained within tight limits by the many types of epithelial cells bounding the lumen....
BACKGROUND
The ionic composition of the luminal fluid in the vestibular labyrinth is maintained within tight limits by the many types of epithelial cells bounding the lumen. Regulatory mechanisms include systemic, paracrine and autocrine hormones along with their associated intracellular signal pathways. The epithelium lining the semicircular canal duct (SCCD) is a tissue that is known to absorb sodium and calcium and to secrete chloride.
FINDINGS
Transport function was assessed by measurements of short circuit current (Isc) and gene transcript expression was evaluated by microarray. Neither ATP nor UTP (100 microM) on the apical side of the epithelium had any effect on Isc. By contrast, basolateral ATP transiently increased Isc and transepithelial resistance dropped significantly after basolateral ATP and UTP. P2Y2 was the sole UTP-sensitive purinergic receptor expressed. Isc was reduced by 42%, 50% and 63% after knockdown of alpha-ENaC, stimulation of PKC and inhibition of PI3-K, while the latter two increased the transepithelial resistance. PKCdelta, PKCgamma and PI3-K were found to be expressed.
CONCLUSIONS
These observations demonstrate that ion transport by the SCCD is regulated by P2Y2 purinergic receptors on the basolateral membrane that may respond to systemic or local agonists, such as ATP and/or UTP. The sodium absorption from endolymph mediated by ENaC in SCCD is regulated by signal pathways that include the kinases PKC and PI3-K. These three newly-identified regulatory components may prove to be valuable drug targets in the control of pathologic vestibular conditions involving dysfunction of transport homeostasis in the ear, such as Meniere's disease.
PubMed: 20398257
DOI: 10.1186/1756-0500-3-100 -
Frontiers in Neurology 2016The purpose of this exploratory study was to investigate whether a quantitative image analysis of the labyrinth in conventional magnetic resonance imaging (MRI) scans...
OBJECTIVE
The purpose of this exploratory study was to investigate whether a quantitative image analysis of the labyrinth in conventional magnetic resonance imaging (MRI) scans using a radiomics approach showed differences between patients with Ménière's disease (MD) and the control group.
MATERIALS AND METHODS
In this retrospective study, MRI scans of the affected labyrinths of 24 patients with MD were compared to the MRI scans of labyrinths of 29 patients with an idiopathic asymmetrical sensorineural hearing loss. The 1.5- and 3-T MRI scans had been previously made in a clinical setting between 2008 and 2015. 3D Slicer 4.4 was used to extract several substructures of the labyrinth. A quantitative analysis of the normalized radiomic image features was performed in Mathematica 10. The image features of the two groups were statistically compared.
RESULTS
For numerous image features, there was a statistically significant difference (-value <0.05) between the MD group and the control group. The statistically significant differences in image features were localized in all the substructures of the labyrinth: 43 in the anterior semicircular canal, 10 in the vestibule, 22 in the cochlea, 12 in the posterior semicircular canal, 24 in the horizontal semicircular canal, 11 in the common crus, and 44 in the volume containing the reuniting duct. Furthermore, some figures contain vertical or horizontal bands (three or more statistically significant image features in the same image feature). Several bands were seen: 9 bands in the anterior semicircular canal, 1 band in the vestibule, 3 bands in the cochlea, 0 bands in the posterior semicircular canal, 5 bands in the horizontal semicircular canal, 3 bands in the common crus, and 10 bands in the volume containing the reuniting duct.
CONCLUSION
In this exploratory study, several differences were found in image features between the MD group and the control group by using a quantitative radiomics approach on high resolution T2-weighted MRI scans of the labyrinth. Further research should be aimed at validating these results and translating them in a potential clinical diagnostic method to detect MD in MRI scans.
PubMed: 27872606
DOI: 10.3389/fneur.2016.00190 -
Anatomical Record (Hoboken, N.J. : 2007) Apr 2021Three vascular routes to the inner ear are known: (a) through the internal acoustic meatus with the vestibulocochlear nerve; (b) from the endolymphatic duct aperture;...
The third vascular route of the inner ear or the canal of Cotugno: Its topographical anatomy, fetal development, and contribution to ossification of the otic capsule cartilage.
Three vascular routes to the inner ear are known: (a) through the internal acoustic meatus with the vestibulocochlear nerve; (b) from the endolymphatic duct aperture; and (c) along the canal of Cotugno (CC) inserted into the vestibular part of the ear from the superior or brain side. The third is believed to contain only veins. Examinations of 33 human embryos and fetuses at 6-40 weeks demonstrated that (a) the CC appeared as a recess of epidural mesenchymal tissues at the superior aspect of the otic capsule cartilage in embryos and it was inserted deeply to issue multiple peripheral divisions inferolaterally and posteriorly at midterm; (b) the CC consistently passed through a ring of the superior or anterior semicircular canal and contained both, the arteries from the vestibulocochlear nerve origin at the midbrain and the vein draining into the sigmoid sinus or petrosal sinuses; and (c) the CC appeared not to contribute to ossification of the otic capsule cartilage but, after endochondral ossification of the internal ear, woven bone development occurred along a smooth interface of the CC with the ossified ear. In contrast, another interface between the developing bone and the residual cartilage of the otic capsule was rough and wavy with many short bony columns, called osseous globules. In addition, the endolymphatic duct accompanied veins but no arteries. Our results show that the CC is a major vascular route to the vestibular part of the otic capsule cartilage, but its role appears to be limited after ossification.
Topics: Cartilage; Ear, Inner; Fetal Development; Humans; Ossification, Heterotopic; Osteogenesis
PubMed: 32865892
DOI: 10.1002/ar.24508 -
Scientific Reports Jan 2022Nodosauridae is a group of thyreophoran dinosaurs characterized by a collar of prominent osteoderms. In comparison to its sister group, the often club-tailed...
Nodosauridae is a group of thyreophoran dinosaurs characterized by a collar of prominent osteoderms. In comparison to its sister group, the often club-tailed ankylosaurids, a different lifestyle of nodosaurids could be assumed based on their neuroanatomy and weaponry, e.g., regarding applied defensive strategies. The holotype of the nodosaurid Struthiosaurus austriacus consists of a single partial braincase from the Late Cretaceous of Austria. Since neuroanatomy is considered to be associated with ecological tendencies, we created digital models of the braincase based on micro-CT data. The cranial endocast of S. austriacus generally resembles those of its relatives. A network of vascular canals surrounding the brain cavity further supports special thermoregulatory adaptations within Ankylosauria. The horizontal orientation of the lateral semicircular canal independently confirms previous appraisals of head posture for S. austriacus and, hence, strengthens the usage of the LSC as proxy for habitual head posture in fossil tetrapods. The short anterior and angular lateral semicircular canals, combined with the relatively shortest dinosaurian cochlear duct known so far and the lack of a floccular recess suggest a rather inert lifestyle without the necessity of sophisticated senses for equilibrium and hearing in S. austriacus. These observations agree with an animal that adapted to a comparatively inactive lifestyle with limited social interactions.
Topics: Animals; Behavior, Animal; Biological Evolution; Brain; Dinosaurs; Ecosystem; Fossils; Head Movements; Neuroanatomy; Paleontology; Posture; Sedentary Behavior; Semicircular Canals; Skull; Social Interaction; Species Specificity; X-Ray Microtomography
PubMed: 34996895
DOI: 10.1038/s41598-021-03599-9 -
PloS One 2013Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this...
Previous investigations have correlated vestibular function to locomotion in vertebrates by scaling semicircular duct radius of curvature to body mass. However, this method fails to discriminate bipedal from quadrupedal non-avian dinosaurs. Because they exhibit a broad range of relative head sizes, we use dinosaurs to test the hypothesis that semicircular ducts scale more closely with head size. Comparing the area enclosed by each semicircular canal to estimated body mass and to two different measures of head size, skull length and estimated head mass, reveals significant patterns that corroborate a connection between physical parameters of the head and semicircular canal morphology. Head mass more strongly correlates with anterior semicircular canal size than does body mass and statistically separates bipedal from quadrupedal taxa, with bipeds exhibiting relatively larger canals. This morphologic dichotomy likely reflects adaptations of the vestibular system to stability demands associated with terrestrial locomotion on two, versus four, feet. This new method has implications for reinterpreting previous studies and informing future studies on the connection between locomotion type and vestibular function.
Topics: Animals; Body Size; Dinosaurs; Head; Locomotion; Tomography, X-Ray Computed; Vestibular Function Tests
PubMed: 23516495
DOI: 10.1371/journal.pone.0058517 -
Anatomical Record (Hoboken, N.J. : 2007) Oct 2022Thalattosuchians represent one of the several independent transitions into the marine realm among crocodylomorphs. The extent of their aquatic adaptations ranges from...
Thalattosuchians represent one of the several independent transitions into the marine realm among crocodylomorphs. The extent of their aquatic adaptations ranges from the semiaquatic teleosauroids, superficially resembling extant gharials, to the almost cetacean-like pelagic metriorhynchids. Understanding the suite of osteological, physiological, and sensory changes that accompanied this major transition has received increased attention, but is somewhat hindered by a dearth of complete three-dimensionally preserved crania. Here, we describe the cranial and endocranial anatomy of a well-preserved three-dimensional specimen of Macrospondylus bollensis from the Toarcian of Yorkshire, UK. The trigeminal fossa contains two similar-sized openings separated by a thin lamina of prootic, a configuration that appears unique to a subset of teleosauroids. Macrospondylus bollensis resembles other thalattosuchians in having pyramidal semicircular canals with elongate cochlear ducts, enlarged carotid canals leading to an enlarged pituitary fossa, enlarged orbital arteries, enlarged endocranial venous sinuses, reduced pharyngotympanic sinuses, and a relatively straight brain with a hemispherical cerebral expansion. We describe for the first time the olfactory region and paranasal sinuses of a teleosauroid. A relatively large olfactory region suggests greater capacity for airborne olfaction in teleosauroids than in the more aquatically adapted metriorhynchoids. Additionally, slight swellings in the olfactory region suggest the presence of small salt glands of lower secretory capacity than those of metriorhynchoids. The presence of osteological correlates for salt glands in a teleosauroid corroborates previous hypotheses that these glands originated in the common ancestor of Thalattosuchia, facilitating their rapid radiation into the marine realm.
Topics: Animals; Brain; Cetacea; Fossils; Head; Skull
PubMed: 34259385
DOI: 10.1002/ar.24704 -
World Journal of Otorhinolaryngology -... Mar 2016To develop a three-dimensional study tool of the membranous labyrinth in order to study the pathophysiology, diagnostic workup and treatment of benign paroxysmal...
OBJECTIVE
To develop a three-dimensional study tool of the membranous labyrinth in order to study the pathophysiology, diagnostic workup and treatment of benign paroxysmal positional vertigo (BPPV). BPPV is the most common cause of peripheral vertigo. Its diagnosis and treatment depend on an understanding of the anatomy of the vestibular labyrinth and its position relative to the head. To date, many illustrations have been made to explain principals of diagnosis and treatment of BPPV, but few have been based on anatomical studies of the membranous labyrinth.
METHODS
A cadaveric human membranous labyrinth was axially sectioned at 20 μm resolution, stained and segmented to create a high-resolution digital model. The model was cloned to create an enantiomeric pair of labyrinths. These were associated a 3D model of a human skull, segmented from MRI data, and were oriented according to established anatomic norms. Canal markers representing otoliths were created to mark canalith position during movement of the model within the 3D environment.
RESULTS
The model allows visualization of true membranous labyrinth anatomy in both ears simultaneously. The dependent portion of each semicircular duct and of the utricle can easily be visualized in any head position. Moveable markers can mark the expected progress of otolith debris with changes in head position and images can be captured to document simulations. The model can be used to simulate pathology as well as diagnostic maneuvers and treatment procedures used for BPPV. The model has great potential as a teaching tool.
CONCLUSION
A simple model based on human anatomy has been created to allow careful study of BPPV pathophysiology and treatment. Going forward, this tool could offer insights that may lead to more accurate diagnosis and treatment of BPPV.
PubMed: 29204541
DOI: 10.1016/j.wjorl.2016.02.002 -
Journal of Neurophysiology Aug 1999Mechanical occlusion of one or more of the semicircular canals is a surgical procedure performed clinically to treat certain vestibular disorders and used experimentally...
Mechanical occlusion of one or more of the semicircular canals is a surgical procedure performed clinically to treat certain vestibular disorders and used experimentally to assess individual contributions of separate canals and/or otoliths to vestibular neural pathways. The present experiments were designed to determine if semicircular canal afferent nerve modulation to angular head acceleration is blocked by occlusion of the endolymphatic duct, and if not, what mechanism(s) might account for a persistent afferent response. The perilymphatic space was opened to gain acute access to the horizontal canal (HC) in the oyster toadfish, Opsanus tau. Firing rate responses of HC afferents to sinusoidal whole-body rotation were recorded in the unoccluded control condition, during the process of duct occlusion, and in the plugged condition. The results show that complete occlusion of the duct did not block horizontal canal sensitivity; individual afferents often exhibited a robust firing rate modulation in response to whole-body rotation in the plugged condition. At high stimulus frequencies (about >8 Hz) the average sensitivity (afferent gain; spikes/s per degrees /s of head velocity) in the plugged condition was nearly equal to that observed for unoccluded controls in the same animals. At low stimulus frequencies (about <0.1 Hz), the average sensitivity in the plugged condition was attenuated by more than two orders of magnitude relative to unoccluded controls. The peak afferent firing rate for sinusoidal stimuli was phase advanced approximately 90 degrees in plugged canals relative to their control counterparts for stimulus frequencies approximately 0.1-2 Hz. Data indicate that afferents normally sensitive to angular velocity in the control condition became sensitive to angular acceleration in the plugged condition, whereas afferents sensitive to angular acceleration in the control condition became sensitive to the derivative of acceleration or angular jerk in the plugged condition. At higher frequencies (>8 Hz), the phase of afferents in the plugged condition became nearly equal, on average, to that observed in controls. A three-dimensional biomechanical model of the HC was developed to interpret the residual response in the plugged condition. Labyrinthine fluids were modeled as incompressible and Newtonian; the membranous duct, osseous canal and temporal bone were modeled as visco-elastic materials. The predicted attenuation and phase shift in cupular responses were in close agreement with the observed changes in afferent response dynamics after canal plugging. The model attributes the response of plugged canals to labyrinthine fluid pressure gradients that lead to membranous duct deformation, a spatial redistribution of labyrinthine fluids and cupular displacement. Validity of the model was established through its ability to predict: the relationship between plugged canal responses and unoccluded controls (present study), the relationship between afferent responses recorded during mechanical indentation of the membranous duct and physiological head rotation, the magnitude and phase of endolymphatic pressure generated during HC duct indentation, and previous model results for cupular gain and phase in the rigid-duct case. The same model was adjusted to conform to the morphology of the squirrel monkey and of the human to investigate the possible influence of canal plugging in primates. Membranous duct stiffness and perilymphatic cavity stiffness were identified as the most salient model parameters. Simulations indicate that canal plugging may be the most effective in relatively small species having small labyrinths, stiff round windows, and stiff bony perilymphatic enclosures.
Topics: Afferent Pathways; Animals; Biomechanical Phenomena; Female; Fishes; Humans; Male; Pressure; Rotation; Saimiri; Semicircular Canals; Surgical Instruments; Vestibular Diseases
PubMed: 10444695
DOI: 10.1152/jn.1999.82.2.1033 -
AJNR. American Journal of Neuroradiology Sep 1999Large endolymphatic duct and sac (LEDS) is one of the most common anomalies seen in patients with congenital sensorineural hearing loss (SNHL), and is known to occur...
BACKGROUND AND PURPOSE
Large endolymphatic duct and sac (LEDS) is one of the most common anomalies seen in patients with congenital sensorineural hearing loss (SNHL), and is known to occur with other inner ear findings. Our purpose was to use high-resolution T2-weighted fast spin-echo (FSE) MR imaging to describe the features and prevalence of specific anomalies that occur in association with LEDS.
METHODS
We retrospectively reviewed MR images of the inner ear obtained in 63 patients with LEDS and in 60 control subjects. We evaluated each image for features of cochlear and vestibular dysplasia, including deficiency of the cochlear modiolus, gross cochlear dysmorphism, asymmetry of the cochlear scalar chambers, enlargement of the membranous vestibule, gross vestibular dysmorphism, and abnormality of the semicircular canals (SCC).
RESULTS
Cochlear anomalies were present in 76% of ears with LEDS. Modiolar deficiency, gross dysmorphism, and scalar asymmetry were seen in 94%, 71%, and 65% of abnormal cochleas, respectively. Vestibular abnormalities were present in 40% of ears with LEDS. Simple enlargement, gross dysmorphism, and distortion of the lateral SCC were seen in 84%, 16%, and 32% of abnormal vestibules, respectively.
CONCLUSION
Coexistent cochlear anomalies, vestibular anomalies, or both are present in most ears with LEDS, and appear as a spectrum of lesions, ranging from subtle dymorphism to overt dysplasia. The presence of coexistent anomalies in LEDS affects treatment decisions and prognosis. Newer techniques of high-resolution FSE MR imaging provide a means of exquisite characterization of LEDS, as well as more sensitive detection of associated vestibulocochlear anomalies.
Topics: Cochlea; Deafness; Endolymphatic Duct; Endolymphatic Sac; Hearing Loss, Sensorineural; Humans; Magnetic Resonance Imaging; Reference Values; Retrospective Studies; Vestibule, Labyrinth
PubMed: 10512225
DOI: No ID Found -
Laryngoscope Investigative... Dec 2018To investigate the temporal bone histopathology of vasculitis, especially in the vestibular organs, in granulomatosis with polyangitis (GPA).
OBJECTIVE
To investigate the temporal bone histopathology of vasculitis, especially in the vestibular organs, in granulomatosis with polyangitis (GPA).
METHODS
Using light and differential interference contrast microscopy, we examined 12 human temporal bones from six deceased GPA patients and 12 histopathologically normal human temporal bones from six deceased age-matched patients.
RESULTS
In the GPA group, three patients had undergone tympanostomy tube placement. Two of them had suffered mixed hearing loss; one, sensorineural hearing loss; and one, conductive hearing loss. Of the 12 specimens in the GPA group, the granulation tissue invaded the round window niche in seven; cochlear hair cells were not preserved in five. Hemosiderin was deposited in the stria vascularis in eight specimens, in the ampulla or semicircular duct in 10, and in the vestibule in three. The spiral ligament showed severe loss of cellularity in two specimens. In the GPA group, type I vestibular hair cell density was significantly decreased; however, type II vestibular hair cell density did not significantly differ between the GPA group and the control group.
CONCLUSION
Our histopathologic findings in human temporal bone specimens of GPA patients delineated changes in the tympanic membrane, middle ear cavity, round window membrane, organ of Corti, stria vascularis, spiral ligament, ampulla, semicircular duct, and vestibule. Type I vestibular hair cell density significantly decreased in the GPA group, as compared with the control group.
LEVEL OF EVIDENCE
N/A.
PubMed: 30599032
DOI: 10.1002/lio2.182