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At least 19 recordsLinked to original sources

PubMed1976

[Development of the internal ear in albino rat embryos subjected to transverse acceleration at + 3 G. Note 3: First observations on the ultrastructural picture of the labyrinth. 1st ultrastructural studies of the labyrinth].

Marked body size reduction (minus 50.5%), and delayed head and body skeletal development were noted in albino rat embryos following exposure of the mother to +/- 3 G acceleration for 3 hr/day between the 10th and 19th day of pregnancy. In addition, electron microscope examination of the inner ear showed signs of greater functional activity of the labyrinth, unaccompanied by reduction of development. Semicircular canal cells and size, in fact, were normal in the crests and at a distance from the latter. There was a marked increase in the number of mitochondria in the cells, in ER area and volume, and A and B glycogen granule richness compared with the controls, these being all signs of considerable activity. The findings substantiate prior histological and histochemical observations: the physiological stimulus offered by acceleration is highly specific for the inner ear structure, particularly that of the labyrinth, to the point where the handicap imposed by the circulatory hypoxia caused by such acceleration, by disturbing the mother-foetus circulation, is overcome.

Acceleration↗

PubMed1991

Histopathologic correlation of spiral ganglion cell count and new bone formation in the cochlea following meningogenic labyrinthitis and deafness.

Bacterial meningitis is a common cause of profound deafness and, hence, a common cause of deafness in published series of patients treated with a cochlear prosthesis. Labyrinthitis ossificans is a common finding in meningogenic labyrinthitis and has been considered a relative contraindication to cochlear implantation. In the present study, the numbers of remaining spiral ganglion cells in cases of meningogenic labyrinthitis were correlated with the severity of new bone formation within the inner ear. Six temporal bones in which profound sensorineural hearing loss occurred in life secondary to meningogenic labyrinthitis were studied by serial section light microscopy. Some degree of labyrinthitis ossificans was found in four of six. There was a moderately strong negative correlation between the number of years of total deafness and the percentage of normal of the remaining spiral ganglion cell count. There was a strong negative correlation between the degree of bony occlusion by labyrinthitis ossificans and the normality of the spiral ganglion cell count. The percentage of bony occlusion of the membranous labyrinth increased with the years of total deafness. The significance of these findings for cochlear implantation of individuals with meningogenic labyrinthitis is discussed.

Aged↗

PubMed1992

The significance for postoperative hearing of preserving the labyrinth in acoustic neurinoma surgery.

Among 186 patients with preoperative hearing, a total of 189 acoustic neurinomas were removed through a lateral suboccipital approach with anatomical preservation of the cochlear nerve. Functional hearing was preserved in 92 (49%) of these patients; despite anatomical preservation of the cochlear nerve, deafness was the result in 51% of the series. Many factors have been considered to cause hearing loss in patients whose cochlear nerve was intact after surgery; these include nerve retraction, nerve or cochlear ischemia, overheating and vibration damage to the nerve, and opening of the labyrinth. To evaluate the significance of injury to the labyrinth in postoperative hearing loss, a prospective study was undertaken. High-resolution computerized tomography studies through the inner ear with bone algorithm were performed pre- and postoperatively. The postoperative status of the labyrinth was classified into three patterns: intact, fenestrated, and widely opened. Injury to the labyrinth occurred in 30% of the cases. The most frequently injured labyrinth structures were the crus commune of the posterior and superior semicircular canals (52%), the posterior semicircular canal (23%), the vestibule (21%), and the superior semicircular canal (4%). A statistically significant relationship was found between injury to the labyrinth and deafness, elevated thresholds, and lower discrimination values at pure-tone audiograms and speech audiometry (p < 0.0001). The degree of the injury (comparison between fenestration and wide opening of the labyrinth) was also significantly related to postoperative deafness (p < 0.0001). Disturbance of the inner-ear fluids was considered to be the cause of the hearing loss. In 12 patients labyrinth injury was not associated with deafness. This finding may support the existence of mechanisms of cochlear protection. The homeostatic function of the endolymphatic sac was considered to play an important role in recovery of damaged hearing in these 12 cases.

Adolescent↗

PubMed1991

Morphogenesis of the carotid labyrinth in the bullfrog, Rana catesbeiana, during larval development and metamorphosis.

Morphogenesis of the carotid labyrinth in Rana catesbeiana during larval development and metamorphosis was studied using vascular corrosion casting and scanning electron microscopy. The carotid labyrinth was formed at the point where the carotid arch descends to the internal gills. The transformation of the appearance of the carotid labyrinth can be summarized in six phases. 1. Through the early stages of larval development (stages I-V), the slightly expanded region of the external carotid artery becomes closely connected with the carotid arch, and these two arteries are joined by small channels on their opposing faces. 2. By the last stage of foot stages (stage XVII), the expanded region becomes globular. 3. At the middle of the metamorphic stages (stage XXII), many protuberances appear on the surface of the globular expansion. 4. At stage XXIII, these form a rudimentary vascular maze. 5. At stage XXIV, this globular expansion is completely surrounded by a simple maze-like structure that resembles the carotid labyrinth in adults. The origin of the internal carotid artery is located within the vascular maze. 6. At the final stage of metamorphosis (stage XXV) the carotid labyrinth is nearly completed. The vascular ring and vascular routes found in the adult can be recognized at the proximal and distal end of the labyrinth, respectively. These findings suggest that the premetamorphic carotid labyrinth has a vascular regulatory function.

Animals↗

PubMed1977

On the vascular architecture of the carotid labyrinth in Cynops pyrrhogaster and Onychoactylus japonicus.

The fine vascular arrangement of the carotid labyrinth in two species of urodeles, Cynops pyrrhogaster and Onychodactylus japonicus was investigated. India ink-gelatin injected preparations were examined under the dissecting microscope. Resin casts of the blood vessels prepared using the method of MURAKAMI (1971) were observed in the scanning electron microscope. In both species, the common carotid artery terminated in the central chamber from which arose two retia mirabilia, i.e. an external carotid rete and an internal carotid rete. The external carotid artery arose recurrently from the external carotid rete, whereas the internal carotid artery received vessels from the internal carotid rete which apparently occupied more than two thirds of the carotid labyrinth. The present observations indicate that the previous descriptions of the urodele carotid labyrinth should be corrected: a vascular ring exists around the common carotid artery and the latter shows a corresponding narrowing at the entrance to the carotid labyrinth; the vascular ring forms the most proximal part of the external carotid rete; the central chamber occupies only a part of the proximal end of the carotid labyrinth; the internal carotid rete and the external carotid rete constitute a continuous rete mirabile; and a distinct furrow exists in the boundary between these two portions of the rete mirabile. Individual variations were frequently encountered, but were confined to the external carotid artery and its tributaries. The complicated and elaborate vascular architecture of the amphibian carotid labyrinth suggests that this organ should exert blood-flow regulating the probably other unknown functions as an effector organ in addition to its accepted activity as a chemo- and baro-receptor.

Ambystoma↗

PubMedDate not supplied

Radiologic diagnosis of labyrinthitis ossificans.

Labyrinthitis ossificans is the pathological ossification of the membranous labyrinthine spaces in response to processes which are destructive of the membranous labyrinth or the endosteum of the otic capsule. It has been primarily a histopathologic diagnosis. Complex motion tomography however, allows a detailed view of the osseous labyrinth and permits the diagnosis in the living state. Radiologic documentation of labyrinthitis ossificans is objective evidence of a process destructive of the membranous labyrinth. It supports the likelihood of an absence of cochlear and vestibular function. It alerts the surgeon to the possible obliteration of key inner ear anatomical landmarks.

Aged↗

PubMed1991

Labyrinthitis ossificans: histopathologic consideration for cochlear implantation.

Labyrinthitis ossificans may be a hindrance to cochlear implantation by making electrode insertion difficult. We performed a histopathologic study of 24 temporal bones with labyrinthitis ossificans from multiple causes. The organ of Corti was graphically reconstructed and the degree of obstruction was estimated for each millimeter of the cochlea. Correlations were calculated between the degree of new bone formation and the cause, patient's age and sex, and time from the original temporal bone insult. Our results demonstrate that complete cochlear ossification is rare. The scala tympani in the basal turn of the cochlea is the most frequent area of ossification, regardless of the cause of the labyrinthitis ossificans. Meningogenic labyrinthitis, usually a childhood disease, was associated with the greatest amount of ossification. When ossification resulted from tympanogenic labyrinthitis, the scala tympani was completely ossified near the round window niche in all temporal bones. Neo-ossification of the basal turn associated with otosclerosis was limited to the proximal 6 mm of the scala tympani in all cases. Three temporal bones had a patent round window niche and basal turn, but significant apical and middle-turn ossification. Peripheral sensorineural elements were severely degenerated in the region of the ossification in all specimens, and spiral ganglion cell counts were decreased.

Adolescent↗

PubMed1991

Localization of substance P, CGRP, VIP, neuropeptide Y, and somatostatin immunoreactive nerve fibers in the carotid labyrinths of some amphibian species.

Immunohistochemical localization of substance P (SP), CGRP, VIP, neuropeptide Y (NPY), and somatostatin (SOM) in the carotid labyrinth were compared in some species of amphibians using the peroxidase-antiperoxidase method. Immunoreactivity of SP, CGRP, VIP, and NPY was found in the nerve fibers distributed in the intervascular stroma of the carotid labyrinth. SP, CGRP, and VIP immunoreactive varicose fibers were densely distributed in the peripheral portion of the carotid labyrinth. Some SP-immunoreactive fibers were distributed similarly to CGRP-immunoreactive fibers. The density of NPY and SOM immunoreactive varicose fibers was low. No immunoreactivity of enkephalins was observed in the labyrinth. The intensities of these peptides were varied from species to species. No glomus cells showed immunoreactivity for any of the 7 peptides studied. These results suggest that the vascular regulatory function, which is one of the possible functions of the carotid labyrinth, is controlled by the peptidergic mechanisms in addition to regulation through intimate apposition of glomus and smooth muscle cells (g-s connection).

Ambystoma↗

PubMed1976

Asymmetric tonic labyrinth reflexes and their interaction with neck reflexes in the decerebrate cat.

1. Tonic labyrinth and neck reflexes were studied separately and in combination in the decerebrate cat with C1 and C2 spinal roots cut. Reflex effects were observed as changes in length of the isotonically loaded medial head of triceps. 2. The tonic labyrinth reflexes acted asymmetrically on the medial head of triceps. Side-down rotation of the head produced shortening in medial triceps, whereas side-up rotations of the head resulted in a lengthening. 3. The tonic neck reflexes acted asymmetrically on the medial head of triceps. Side-down rotations of the neck produced a lengthening of medial triceps, whereas side-up rotations of the neck resulted in shortening. 4. Labyrinth and neck reflexes produce opposite effects on the same limb extensor muscle so that, if the neck innervation is intact, head tilting produces no change in muscle length. 5. It is suggested that the interaction between the labyrinth and neck reflexes contributes to the stability of the trunk, allowing the head to move freely on the body without affecting this stability. Labyrinth and neck reflexes need therefore to be considered together as a single system.

Animals↗

PubMed1977

Quantitive studies of the reactions to horizontal angular accelerations in axolotls. II. head-turning reflexes in animals with a supernumerary pair of labyrinths.

In axolotls (Ambystoma mexicanun) the labyrinths and the associated parts of the medulla were doubled artificially. In these so-called tandem-heads the vestibular afferent fibres from both labyrinths on one side united within the medulla to form common bundles. The head-turning reflexes following impulse acceleration and during long-lasting acceleration were measured quantitatively and compared with those for normal animals. The form and the time-course of the reactions were almost identical in both groups. Tandem-heads showed a linear relationship between stimulus intensity and reaction strength, parallel to that in normal animals but with a greater reaction for a given stimulus. Consequent to this shift in the relationship, there was a significant decrease in the reaction threshold. The removal of one horizontal semicircular canal in tandem-heads proved that both pairs of labyrinths were functionally connected with the brain. It was suggested that during ontogenesis there exists a kind of specificity in the connexion of vestibular fibres. From the parallel shift of the intensity functions it was concluded that the input from both pairs of labyrinths in tandem-heads is not simply accumulate but compared with a reference parameter, which is also double in tandem-heads.

Ambystoma↗

PubMed1991

[Labyrinthitis ossificans after pneumococcal meningitis].

In labyrinthitis ossificans the membranous labyrinth and the endosteum are obliterated by pathological ossification. The pathogenesis, differential diagnosis and radiological findings of a case of labyrinthitis ossificans caused by pneumococcal meningitis are described. The destructive process in the membranous labyrinth can be shown by radiology. The importance of early diagnosis for rehabilitation of hearing loss after treatment is demonstrated.

Audiometry, Pure-Tone↗

PubMed1975

Spontaneous cerebrospinal fluid otorrhea. Congenital anomaly of bony labyrinth a possible cause.

A patient had recurrent meningitis as a result of a congenital anomaly of the bony labyrinth. As far as could be traced in the literature, this was the first time that an isolated congenital anomaly of the bony labyrinth could be shown to be the origin of spontaneous cerebrospinal fluid otorrhea and the resulting recurrent meningitis. In cerebrospinal fluid otorrhea of unknown origin, tomographic x-ray examination of the bony labyrinth is of utmost importance. For the detection of the finer details is the bony structure of the labyrinth, this tomography should be done according to one of the multidirectional techniques.

Adolescent↗

PubMed1976

EEG-studies on the phases of sleep and wakefulness after bilateral labyrinth destruction.

The dynamics of the state of wakefulness, slow and paradoxical sleep after labyrinth destruction was studied in chronic cats. The states were assessed according to the behaviour, EEG, myogram and eye movements. The labyrinth destruction was combined (chemical and mechanical). Bilateral labyrinth deafferentation results in a decrease in the duration of wakefulness from 30 to 17 per cent, p less than 0.001. At the same time paradoxical sleep increased from 4 to 8 per cent, p less than 0.001. This increase is due to both the greater average number of paradoxical sleep episodes and a higher average duration of the individual episode. The latency of the first appearance of a paradoxical sleep episode is considerably shortened after labyrinth destruction.

Animals↗

PubMed1991

Ganglion cell populations in labyrinthitis ossificans.

Ossification of the perilymphatic spaces of the inner ear is frequently found in patients with profound deafness who may be candidates for cochlear implantation. The ossification may be a hindrance in electrode insertion and has previously been considered a relative contraindication to implantation. The quantity of peripheral auditory elements remaining in a series of patients with labyrinthitis ossificans has not been reviewed. We performed a histopathologic study of 16 temporal bones with partial cochlear ossification of multiple etiologies. The organ of Corti and spiral ganglion were graphically reconstructed. The degree of obstruction was estimated for each millimeter of the scala tympani and scala vestibuli. A quantitative evaluation of the sensorineural elements of the inner ear (spiral ganglion cells, inner and outer hair cells, and peripheral auditory axons) was performed. The results were compared with 16 control patients with normal hearing and no evidence of cochlear ossification. Our results show that the greatest amount of damage is found in the organ of Corti with preservation of a significant number of spiral ganglion cells in most cases. A wide range of ganglion cells (6,310 to 28,196) was found in patients with labyrinthitis ossificans with the mean number of ganglion cells being 17,152. A profound sensorineural hearing loss was noted in all patients except one. Meningogenic labyrinthitis and otosclerosis were associated with the greatest loss of ganglion cells. The location of ossification could be correlated with the region showing loss of the organ of Corti. In the majority of patients, the location of ossification and fibrosis could not be correlated with the region of the spiral ganglion showing loss of ganglion cells. The implications of these findings for cochlear implantation is discussed.

Adolescent↗

PubMed1992

Bacterial tympanogenic labyrinthitis, meningitis, and sensorineural damage.

Pathologic changes (sensorineural hearing loss, labyrinthitis, meningitis) can follow otitis media. Various macromolecular substances demonstrably enter the inner ear via the round window membrane, but its permeability to bacteria is less known. We inoculated Streptococcus pneumoniae type 7F bilaterally into the middle ears of two groups of chinchillas, with and without grafted round window membranes. Inner ears of inoculated animals were observed by light and electron microscopy. None with continuous grafts had labyrinthitis. Bacteria penetrated all three layers of nongrafted round window membranes and into all cochlear turns, entering Schuknecht's channels and following neuronal pathways; nerves were often degenerated, hair cells were damaged or missing, and the stria vascularis was edematous and hemorrhagic. The neural damage suggests a mechanism for the hearing loss that can follow otitis media. Absence of labyrinthitis and meningitis in grafted animals suggests a tympanogenic pathway for the bacteria.

Animals↗

PubMed1992

"Floating" labyrinth. Pathophysiology and treatment of perilymph fistula.

Collapse of the membranous labyrinth of the pars superior is a morphological change observed in 50% of animals with experimentally produced perilymph fistula, although the extent and degree of the collapse may vary greatly. The moderately collapsed membranous labyrinth may drift with CSF and/or perilymph pressure changes and this may stimulate sensory cells of the utricle and/or semicircular canals if the sensory cells are intact and the collapsed wall is in contact with the otolithic membrane and/or cupula. This condition is termed "floating" labyrinth. Caloric irregularity is often observed in electronystagmograms recorded from animals with experimental perilymph fistula. This is also observed in patients with perilymph fistula. Partial destruction of the vestibular organs using argon laser was performed in a patient with perilymph fistula who was incapacitated because of persistent positional vertigo after closure of the oval window fistula. Irradiation of the argon laser beam was directed to the macula utriculi, utriculoampullary nerve and singular nerve. The hearing of the patient was maintained, and vertigo disappeared after laser labyrinthectomy.

Audiometry, Pure-Tone↗

PubMedDate not supplied

Contrast enhancement of the labyrinth on MR scans in patients with sudden hearing loss and vertigo: evidence of labyrinthine disease.

The sudden onset of hearing loss and vertigo presents a difficult diagnostic problem. We describe the finding of labyrinthine enhancement on MR images in five patients with sudden unilateral hearing loss or vertigo or both and correlate the MR findings with audiologic and electronystagmographic studies. All patients were studied with T2-weighted axial images through the whole brain, contrast-enhanced 3-mm axial T1-weighted images through the temporal bone, and enhanced T1-weighted sagittal images through the whole brain. Cochlear enhancement, on the side of hearing loss only, was found in all five patients. The presence of associated vestibular enhancement correlates with objective measures of vestibular function on the electronystagmogram. In two patients, the resolution of symptoms 4-6 months later correlated with resolution of the enhancement on gadopentetate dimeglumine-enhanced MR images. Two patients had luetic labyrinthitis. No labyrinthine enhancement was seen in a series of 30 control subjects studied with gadopentetate dimeglumine-enhanced MR using the same protocol. Labyrinthine enhancement in patients with auditory and vestibular symptoms is a new finding and is indicative of labyrinthine disease. While abnormalities on electronystagmograms and audiograms are nonspecific and indicate only a sensorineural problem, gadopentetate dimeglumine-enhanced MR may separate patients with retrocochlear lesions, such as acoustic neuromas, from those in whom the abnormal process is in the labyrinth or is intraaxial. This group of patients underscores the importance of identifying and commenting on the structures of the membranous labyrinth when evaluating MR studies of the internal auditory canal and the cerebellopontine angle in individuals with hearing loss.

Adult↗

PubMedDate not supplied

[Total sequestration of the labyrinth].

At present total sequestration of the labyrinth in the case of purulent epitympanitis and cholesteatoma is a rare pathology. This paper describes data from the literature and two observations by the present authors. They offer an efficient method for arresting labyrinthectomy-induced liquorrhea by means of a flap of the lip mucous membrane. They maintain that computer tomography combined with traditional tomography is an informative method for diagnosing labyrinth destruction. They assert that continuous destruction of the labyrinth during prolonged pyorrhea and progressive development of cholesteatoma can be stimulated by functional changes of the body, e.g. pregnancy. They also suggest that the vestibular apparatus has high compensatory potentials under the conditions of a complete destruction of the vestibule and semicircular canals as a result of extended inflammation of the middle and internal ear.

Cholesteatoma↗