Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “LABYRINTH”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11Linked to original sources
PubMed2005

Volume of components of labyrinth: magnetic resonance imaging study.

OBJECTIVE: To determine total inner ear fluid volume and cochlear and semicircular canal/vestibule volumes of a normal population to form a base for dimensional abnormalities of inner ear structures. STUDY DESIGN: Cross-sectional. SETTING: Academic otology and radiology practices. PATIENTS: Twenty-nine healthy volunteers (13 male patients and 16 female patients with an average age of 31 yr) without any known history of intrauterine infection or any exposure to ototoxic agents and no abnormality at physical examination from the standpoint of hearing loss were included. INTERVENTIONS: Twenty-nine volunteers underwent magnetic resonance imaging of the temporal region by means of thin-section T2-weighted sequences. The images were evaluated by the radiologist for the presence of any gross configurational abnormality. Fluid volume of each inner ear and components of labyrinth (cochlea, semicircular canals/vestibule) were calculated with the help of an online work station. MAIN OUTCOME MEASURE: To determine the volume of components of the labyrinth and total inner ear fluid, which may form a base for future studies about sensorineural hearing loss. RESULTS: The volumes of total inner ear fluid, cochlea, and semicircular canals/vestibule were calculated. The mean and standard deviation of total inner ear fluid volume, cochlear volume, and semicircular canal/vestibule volume were obtained for each volunteer. Results were assessed with the help of statistical tests. CONCLUSION: There was no statistically significant difference between right and left inner ear fluid volumes of male and female subjects. There was also no statistical difference between right and left inner ear volumes when age and sex were not concerned. During evaluation of volumes according to sex, the difference between right and left inner ear fluid volumes was also assessed. Left semicircular canal/vestibule volume of female subjects were found to be higher than that of male subjects. The difference between right and left semicircular canal/vestibule volumes of female subjects was higher than the difference between right and left semicircular canal/vestibule volumes of male subjects.

Adult↗
PubMed1995

Mechanical indentation of the vestibular labyrinth and its relationship to head rotation in the toadfish, Opsanus tau.

1. In the present study we examine the response of the semicircular canal of the toadfish (Opsanus tau) to head rotation and to mechanical indentation of the membranous labyrinth. The relationship between the two stimuli is described by a new elastohydrodynamic model that delineates the three-dimensional (3-D) spatiotemporal distribution of endolymph pressure and flow. In vivo electrophysiological recordings of primary afferents supplying the horizontal canal (HC) were employed to validate the model predictions. Data were collected from 213 afferents in 18 fish during independent head rotation. HC indentation, utricle (U) indentation, and paired stimuli. To quantify the afferent response and the relationship between the applied sinusoidal stimuli, the magnitude (gain) and temporal relationship (phase) of the first harmonic of modulation were calculated and compared with theoretical predictions. 2. A mathematical based extensively on the 3-D morphology of a toadfish labyrinth and the physical properties of endolymph is presented to describe the relationship between head rotation and mechanical indentation. All model parameters specifying labyrinthine morphology and physical properties of endolymph are known; the model contains no free parameters. New results are independent of the structural properties of the cupula. The analysis employs an asymptotic solution of the Navier-Stokes equations in the three toroidal ducts that includes the 3-D fluid-structure interaction taking place within the enlarged ampulla. The solution addresses the differential pressure (delta P) acting across the cupula and the dilatational pressure acting on both sides of the cupula. The analysis quantifies the hydrodynamics of the HC for mechanical indentations of the long and slender portion of the canal duct (HC indentation) and the U (U indentation). Results specifically relate the indentation stimuli to head rotation. Linear commutations of HC indentation, U indentation, and rotation stimuli are analyzed by matching delta P acting across the cupula for the three stimulus modalities. 3. HC afferents show a linear correspondence between HC indentation, U indentation, and rotation stimuli. Specific experimental results for sinusoidal stimuli at frequencies < 2 Hz show 1) +/- 1 micron-HC indentation commutates with +/- 4 degrees/s rotation, 2) + 1-micron HC indentation commutates with -/+ 15-microns U indentation, and 3) -/+ 15-microns U indentation commutates with +/- 4 degrees/s rotation. These results were obtained by adjusting the relative amplitude and phase of two stimuli presented simultaneously to achieve destructive interaction that minimizes the afferent modulation (balanced). Equivalent results were obtained using afferent responses to the stimuli applied independently.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMedDate not supplied

Prospects for immunocytochemical studies of the labyrinth.

Immunocytochemistry, when used with traditional and other modern techniques, offers great promise as a tool for cytochemically characterizing cells and their processes in the normal and pathological labyrinth. The strength of assertions regarding results of such studies is proportional to the degree to which antibodies are characterized, a limitation that has often been neglected in studies of the labyrinth. Examples are given to demonstrate the degree of species variability of cytochemically distinct efferent fibers in the cochlea, and to demonstrate how readily new information can be obtained when appropriate antibodies are available.

Animals↗
PubMedDate not supplied

Viral labyrinthitis -- an experimental study.

Summary--An attempt was made to produce viral labyrinthitis in the rhesus monkey. Rhesus monkeys are susceptible to the mumps virus. Nine animals were used. After removal of the stapes, the left oval windows were plugged with Gelfoam soaked in a culture of live mumps virus; right oval windows were plugged with Gelfoam soaked in killed cultures. Animals were sacrificed at different time intervals, postinfection. In eight of the nine animals there was seroconversion from negative to positive; however, none of the animals developed the histologic changes of viral labyrinthitis.

Animals↗
PubMedDate not supplied

Action of glutamate in the cat labyrinth.

Glutamate solutions of either 50 mM applied on the membranous labyrinth or 1 mM perfused into the lateral canal in cats increased spontaneous and stimulus-evoked activity of vestibular neurons. Kainic acid (10(-4) M) perfused into the labyrinth produced a depolarizing action on vestibular afferents. These results indicate that glutamate could be an excitatory neurotransmitter at the synapse between vestibular hair cells and afferent nerve fibers in the cat.

Action Potentials↗
PubMedDate not supplied

Clinical and experimental studies on the incorporation of materials applied as covering for the labyrinth window.

From among the materials used for covering the labyrinth window, of the foreign materials gelfoam proved ideal from clinical and experimental points of view, while of the materials of interstitial origin, fascia, perichondrium, and periosteum seem to be suitable for covering the labyrinth window, resp. for transplantations in the tympanic cavity.

Adipose Tissue↗
PubMedDate not supplied

The effect of ultrasonic irradiation on the structural integrity of the inner ear labyrinth.

The histological appearance of the inner ear labyrinth was examined following ultrasonic irradiation of the vestibule and the cochlea in cats and guinea pigs. Directing ultrasound through the round window towards the ampulla of the superior semicircular canal produced severe balance dysfunction together with histological damage throughout the vestibular labyrinth. Cochlear damage was restricted to a small region of the basilar membrane proximal to the round window. When ultrasonic energy was directed into the cochlea cellular disruption extended over an area of at least two cochlear turns and included changes in the stria vascularis as well as to hair cells. The outer hair cells were found to be more sensitive than the inner hair cells to the damaging effects of ultrasound.

Animals↗
PubMedDate not supplied

Modulation by head and trunk positions of the vestibulo-spinal reflexes evoked by galvanic stimulation of the labyrinth. Observations by labyrinthine evoked EMG.

Modulation by head and trunk positions of the vestibulo-spinal reflexes was studied in the soleus muscle activities induced by galvanic stimulation of the labyrinth. The stimulation was applied using a bipolar-biaural method with the cathode on the right ear and the anode on the left ear. The intensity was 1 mA and duration 3 s. 1) When the labyrinth was stimulated with the head facing forward, soleus muscle activities increased on the right side and decreased on the left, with a latency of about 100 ms. In spite of the same stimulation, activities of the soleus muscle on both sides decreased with the head rotated to the right and increased with the head rotated to the left. 2) The responses in upper-body rotation were the same as in the case of head rotation. 3) In trunk rotation, some cases showed the same responses as with the trunk facing forward in rotation to the right and left, while others showed changes in muscular activities with the head rotation caused by rotating the trunk. 4) Changes in labyrinthine evoked EMG by head and trunk positions were considered to be due to interaction of vestibular and proprioceptive inputs on the interneurons of the spinal cord.

Ear, Inner↗
PubMed2002

Experimental autoimmune labyrinthitis: assessment of molecular size of autoantigens in fractions of inner ear proteins eluted on the Mini Whole Gel Eluter.

In order to determine the molecular size of the causative autoantigens of experimental autoimmune labyrinthitis, crude inner ear antigen was separated into 14 fractions and the constituent molecules were identified by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis using the Mini Whole Gel Eluter. The mean total protein recovery was approximately 66%. Sensitization with 55-65 kDa proteins induced the highest number of infiltrating cells among the fractions and sensitization with 38-45 kDa proteins induced the second highest number of inflammatory cells. These results suggest that 38-45 kDa and 55-65 kDa proteins are the causative autoantigens of experimental autoimmune labyrinthitis.

Animals↗
PubMed2005

[A case of labyrinthitis due to congenital cholesteatoma in a child].

A rare case of congenital cholesteatoma as a cause of acute labyrinthitis is presented in the report. 14-years old boy was operated due to labyrinthitis caused by a huge cholesteatoma discovered behind intact tympanic membrane. On the first examination the symptoms indicated lack of right inner ear function, so unfortunately the referral was to late and the patient resulted in the dead ear. The diagnosis of congenital cholesteatoma as well as treatment of the entity and its subsequent complications is discussed in the report.

Acute Disease↗
PubMed2006

[Expression of aquaporin-1 in a guinea pig model of labyrinth destruction].

OBJECTIVE: To study the expression of aquaporin-1(AQP-1) in the cochlea and endolymphatic sac in guinea pigs with labyrinth destruction. METHODS: Chloroform was injected into the tympanum to establish the animal model of labyrinth destruction in guinea pigs, and two-step immunohistochemical method was used to examine the expression of AQP-1 in the cochlea and endolymphatic sac at different time points. RESULTS: AQP-1 expression was fluctuant in accordance with the morphological changes of the spiral ligament fibrocytes in the cochlea: destruction of the spiral ligament cells was followed by AQP-1 expression down-regulation, and AQP-1 up-regulation occurred with the cell regeneration. But no such changes were observed in the endolymphatic sac. CONCLUSION: AQP-1 may take part in the maintenance of the structural stability of the spiral ligament.

Animals↗
PubMed1978

[Experience with using amedin in children with movement disorders of extrapyramidal and labyrinth origin].

Using previously obtained data concerning the effectivity of amedin in motor and speech disorders due to muscular dystonia the drug was used for the treatment of 50 children from 3.5 months to 18 years, with motor disorders of an extrapyramidal and labyrinth nature. A high therapeutical effectivity of amedin in an increased pathological activity of tonic cervical and labyrinth reflexes in infants and in torsion spasm of school age children is demonstrated.

Adolescent↗
PubMed1995

Spiral ganglion cell survival in labyrinthitis ossificans: computerized image analysis.

Obstruction of the cochlear scale by ossification and fibrosis, which can now be imaged by computed tomography, has been proposed as a predictor of ganglion cell survival. Subjects for this histopathologic temporal bone study were 12 profoundly deaf patients with labyrinthitis ossificans. Controls without ossification were 16 normal-hearing patients and 16 profoundly deaf patients. All temporal bones were graphically reconstructed. Computerized image analysis obtained the percentage of scalar obstruction in 12 temporal bones with labyrinthitis ossificans. Statistical analyses could demonstrate no relationship between spiral ganglion cell survival and obstruction. There was much interindividual variability in ganglion cell count among the 44 temporal bones. Ganglion cell survival was significantly less in the two deafness groups than in the normal group, but did not differ significantly between the two deafness groups. Therefore, cochlear labryinthitis ossificans is not a preditor of ganglion cell survival and should not be a contraindication to cochlear implantation.

Adolescent↗
PubMed2000

Syndecan-4 deficiency impairs the fetal vessels in the placental labyrinth.

Syndecan-4 is a transmembrane protein bearing heparan sulfate chains, involved in anticoagulation and focal adhesion formation. Here, we revealed that syndecan-4 was expressed in the fetal vessels in the placental labyrinth by in situ hybridization and immunohistochemical staining. At 17.5 gestational days, the area of degenerated fetal vessels in the placental labyrinth was more diffuse and larger in Synd4(-/-) embryos than wild-type controls. Calcium and fibrin(ogen) depositions in the degenerated vessels were also more extensive and more severe in the placentas of Synd4(-/-) embryos. These findings suggest that syndecan-4 deficiency impairs the fetal vessels in the placenta, probably due to a deficit in the anticoagulation mechanism. This article is the first report demonstrating that among a large number of core proteins of heparan sulfate proteoglycans, a defect of a single core protein caused impaired anticoagulation in a specific site.

Animals↗
PubMed1992

Extraembryonic tissue changes induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,4,7,8-pentachlorodibenzofuran with a note on direction of maternal blood flow in the labyrinth of C57BL/6N mice.

Histologic changes in extraembryonic and embryonic tissues induced by 3 or 6 micrograms 2,3,7,8-tetrachlorodibenzo-p-dioxin/kg (TCDD) or 80 micrograms 2,3,4,7,8-pentachlorodibenzofuran/kg/day (4-PeCDF) were studied 24 h after the last of four daily doses administered orally to C57BL/6N mice on days 10-13 of pregnancy. Both test compounds ruptured (1) the embryo-maternal vascular barrier in the labyrinth, which resulted in hemorrhage of embryonic blood into the maternal circulation, (2) the visceral yolk sac membrane with the embryonic blood from the vitelline vessels escaping into the uterine, exocelomic and amniotic cavities, and (3) the maternal vascular spaces of the placental periphery resulting in hemorrhages into the interconceptal space. The role of the hemorrhagic lesions in the induction of cleft palate and hydronephrosis by the two compounds remains to be investigated. The presence of embryonic nucleated erythroblasts that hemorrhaged into the maternal lacunar network allowed the identification of maternal venous channels in the placenta. It revealed that (1) the labyrinth could be tentatively divided into two caudocranially oriented zones, an arterial and a venous zone; (2) the maternal blood in the labyrinthine lacunae circulated from the arterial to the venous zone, somewhat parallel to the uterine axis; and (3) the largest maternal vessels in the center of the placenta hitherto named the "central maternal artery," was in fact, venous.

Animals↗
PubMed1990

Compensation of horizontal canal related activity in the medial vestibular nucleus following unilateral labyrinth ablation in the decerebrate gerbil. I. Type I neurons.

The spontaneous activity and dynamic responses to two frequencies (1.3 and 0.13 Hz) of sinusoidal angular horizontal head acceleration of type I neurons in the medial vestibular nucleus were recorded bilaterally in decerebrate Mongolian gerbils (Meriones unguiculatus) under three experimental conditions; normal labyrinth intact, acutely following unilateral labyrinthine lesion, and four to seven weeks following labyrinthine lesion. The mean spontaneous activity and number of detected type I neurons decreased immediately ipsilateral to the lesion but recovered significantly with time. In contrast, spontaneous activity on the contralateral side increased during compensation following hemilabyrinthectomy. The mean response gains at both frequencies of head oscillation were depressed bilaterally and asymmetrically acutely following the lesion such that the response gain of cells on the intact side exceeded that of the neurons recorded on the injured side. After compensation the number of detected type I neurons on the side ipsilateral to the injury increased but remained below normal levels. The mean gains remained depressed but became symmetric with compensation as a result of improvement in the response of ipsilateral neurons. The phase of responses were significantly advanced in the compensated animals. Although response gain is not fully restored, the linearity of the dynamic modulation in compensated animals is improved as evidenced by a continuous modulation of the increased spontaneous activity of neurons contralateral to the hemilabyrinthectomy. It is proposed that this effect is related to the concurrent improvement in the linearity of the horizontal vestibulo-ocular response. Electrical cathodal polarization of the vestibular nerve ipsilateral to the ablated labyrinth was utilized to investigate the relationship between recovery of spontaneous activity and dynamic function. Acutely following hemilabyrinthectomy, cathodal polarization restored activity in second-order type I neurons to near normal levels but their response gain to head rotation remained depressed. Similar galvanic stimulation in compensated animals also elevated ipsilateral spontaneous activity. As in the acute preparation, such stimulation did not modify the response gain or phase. Thus, the improvement in response of type I neurons in the compensated gerbil was not a direct consequence of restoration of spontaneous activity on the side of the injury.

Animals↗
PubMed1975

Neural pathways from the vestibular labyrinths to the flocculus in the cat.

In decerebrate, unanesthetized cats, responses in the flocculus were evoked by electric stimulation of the vestibular nerves and by natural stimulation of horizontal head angular acceleration. Field potentials in the flocculus and intracellular recording from Purkinje cells following vestibular nerve stimulation indicated that the responses were produced by mossy fiber inputs. Field potentials evoked from the contralateral labyrinth were as large as those from the ipsilateral one. There was considerable convergence of bilateral labyrinthine mossy fiber inputs to a Purkinje cell. In view of the effects of incision at the midline of the cerebellum and the brain stem, inputs from the contralateral labyrinth were mainly conveyed through the midline of the brain stem and partly through the midline of the cerebellum. Primary vestibular afferents were involved in the transcerebellar crossed pathway. Fibers of the secondary vestibular neurons projecting to the contralateral flocculus were implicated in the brain stem-mediated pathway and, in part, presumably in the transcerebellar crossed pathway. About one-third of the axon spikes examined in the flocculus responded to horizontal head angular acceleration. Commissural inhibition was observed in more than half of the axon spikes in the flocculus which were presumed to be mono- or polysynaptically activated from the vestibular nerve.

Animals↗
PubMed1995

Distribution of galanin-immunoreactive nerve fibers in the carotid labyrinth of the bullfrog, Rana catesbeiana: Comparison with substance P-immunoreactive fibers.

Immunoreactivity of galanin (GAL) was detected in the nerve fibers distributed within the intervascular stroma of the bullfrog carotid labyrinth. GAL-immunoreactive fibers are numerous, and some are close to the sinusoidal plexus. Most GAL fibers appear as thin processes with some varicosities. A combination of indirect double immunofluorescence labelling and image processing clearly demonstrated that the distribution pattern of GAL fibers is different from that of SP fibers. This indicates that GAL and SP do not coexist in the same nerve fibers. The role of GAL fibers may be different from that of previously reported neuropeptides (substance P, calcitonin gene-related peptide, vasoactive intestinal polypeptide, neuropeptide Y, and others) as a neuromodulator in controlling vascular tone of the labyrinth.

Animals↗