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PubMed1975

Deformity of the labyrinth and internal auditory meatus in congenital deafness.

In congenital deafness it is important that the radiological examination should exclude any deformities of the bony labyrinth or internal auditory meatus as well as demonstrating lesions of the middle and external ears. Radiological assessment of inner ear abnormalities should be used as a guide both to the feasibility of reconstructive surgery to the middle and external ears and for the future training of the child. Inner ear abnormalities demonstrated by tomography in 56 patients are discussed in relation to the cochlea function. The importance of demonstrating the central bony spiral of the cochlea and of assessing the size and shape the internal auditory meatus is stressed.

Cochlea↗
PubMed1994

Computer generated three-dimensional reconstruction of the bony labyrinth in Mondini's dysplasia.

The bony labyrinth obtained at necropsy in four cases was studied by a new computer-generated three-dimensional (3-D) system. One case was normal (control) and the other three were histopathologically confirmed cases of Mondini's dysplasia. In case 1, the cochlea had only 2 turns and the lateral semicircular canal did not make a circle but appeared as a spherical mass projecting from the utricle even though the posterior semicircular canal made a normal circle. In case 2, there were no turns in the cochlea even though the semicircular canals and the vestibule appeared normal. In case 3, the cochlea showed 1 to 1 and 1/2 turns and the semicircular canals were premature showing only bud-like projections. This 3-D imaging system, which utilizes the toggling method, provides a way of obtaining satisfactory images without markers, and the time required to obtain these 3-D images was reduced by using a video camera instead of a digitizer. One of the problems associated with the use of 3-D imaging is the long processing time. We resolved this by inputting the section images with a video camera and by picking up structures using density segmentation instead of tracing with a digitizer.

Child, Preschool↗
PubMed1975

Simultaneous application of electronystagmography (ENG) and photoelectronystagmography (PENG) in the case of thermal labyrinth examination.

At examination of normal persons, the ENG registration method was compared with that of PENG. Special examinations were executed with regard to the behaviour of the beat rates during the culmination phase of thermal labyrinth reactions by using each of both registering methods. By synchronous recording of PENG and ENG, it was possible to settle the discrepancy of the greater number of beats in ENG compared with those of PENG, while the examinations were executed at different times. The PENG-method does not exclude an optical fixation due to the necessary interior illumination, and this results in a retarding of the reaction and smaller beat rates. This fact should be considered when comparing the results of ENG and PENG.

Ear, Inner↗
PubMedDate not supplied

Analysis of curves Na-24 efflux from membrane labyrinth containing stria vascularis.

The efflux of Na-24 was investigated in isolated labyrinths from a membrane section containing stria vascularis and spiral ligament in artificial endolymph medium. The efflux curves were calculated and compartmental analyses were made. The theoretical possibility of a exchange of sodium between compartments connected in different ways was considered. The calculated values of rate constant of transmembranal sodium fluxes are 0.0282+/-0.0052 min-1 and the half-time of the exchange of sodium between intracellular compartments is 24.27+/-4.53 min. The distribution of sodium in tissue with a commonly applied simplification gives 90% Na+ in the extracellular compartment and 3% Na+ in the intracellular compartment of the total tissue sodium content. The possibility of measuring the rate constant of transmembranal electrolyte fluxes in this tissue seems encouraging for future investigation of the mechanism by which they are transported.

Animals↗
PubMed1975

Experimental studies on the nerve--sensory cell relationship during degeneration and regeneration in ampullar nerves of the frog labyrinth.

The degeneration and regeneration of afferent and efferent nerves to the crista ampullaris in the frog were studied after transsection of the ampullar nerves. In some experiments one or both rostral ampullar nerves were simply divided and left in place. In other experiments the ampullar nerves to the horizontal and to the anterior vertical crista were divided and the branch to the former was brought into contact with the distal stump of the anterior vertical ampullar nerve. Sensory cells in the labyrinth survived total denervation for 1-2 weeks without regular signs of ultrastructural damage. The afferent synaptic structures in these cells were often preserved in the denervated stage. The afferent nerve fibres degenerated earlier than the efferent ones. Both type of fibres reinnervated the vestibular epithelium after division of the ampullar nerve. The fibres from a horizontal ampullar nerve could reinnervate a denervated anterior vertical crista, resulting in misdirected reflexes. About 40 days after division both function and morphological organization had been restored to normal.

Animals↗
PubMedDate not supplied

Ultrasonic irradiation of the guinea pig labyrinth. Correlation of morphology and intralabyrinthine temperature.

The effects of high frequency ultrasound on the inner ear structures after irradiation of the lateral semicircular canal have been analysed by means of light-and electronmicroscopy. Sudden as well as gradual morphological changes in the vestibular sensory epithelium are described. Damage to the connective tissue stroma, blood vessels and nerve fibres characterized the chronic phase. Both cochlear morphology and hearing remained normal after irradiation of some behaviorally conditioned animals. The temperature rise in the labyrinth during continuous irradiation was studied. The experiments indicated that the mechanical effects may be more significant than the thermal in explaining the structural changes of the inner ear of guinea pigs. The results are compared with previous extensive experience of ultrasound treatment of patients with Meniere's disease.

Animals↗
PubMedDate not supplied

The action of putative neurotransmitter substances in the cat labyrinth.

Possible neurotransmitter candidates were tested in the labyrinth of the cat with the aid of microiontophoretic techniques. Depending on the recording site, spontaneous regular or irregular fibre activity was obtained in the subsynaptic region of the macula sacculi. Ejection of GABA enhances the firing rate, whereas acetylcholine reduces the spontaneous activity. A similar application of glycine and proline produced no effect. The action of GABA was specifically blocked by the GABA antagonists bicuculline and picrotoxin. The alkaloids further induced a decrease in the spontaneous activity which lasted for several minutes.

Acetylcholine↗
PubMedDate not supplied

Effects of hypobaric pressure on the labyrinth. Cochlear aqueduct patent.

Cats with the cochlear aqueduct patent were placed in a pressure chamber and exposed for 10 min to hypobaric pressures of 5.1 and 6.8 kPa relative to atmospheric pressure. The experiments were designed according to a program used for treatment of Meniere's disease. The perilymph, middle ear, cerebrospinal fluid (CSF), venous, arterial and chamber pressures were recorded. The results demonstrated that hypobaric effects on the labyrinth were mediated via pressure changes in the middle ear and not via a systemic vascular or CSF influence. A reduction in chamber pressure induced a relative increase in middle ear pressure. It was the rate of the hypobaric change as well as the patency of the cochlear aqueduct and the Eustachian tube function that determined the magnitude of the initial perilymph peak pressure and the duration of this pressure increase. A rapid versus a slow rate induced an initial perilymph increase of 3.4 and 2.2 kPa, respectively. This relative pressure increase was eliminated within 1 min via the patent aqueduct. Thus, neither did a longstanding perilymph pressure increase occur during the hypobaric exposure, nor did a prolonged significant reduction in perilymph pressure occur after atmospheric pressure was restored.

Animals↗
PubMed1991

Anionic sites of the basement membrane of the labyrinth.

The presence of anionic sites in the labyrinth is demonstrated in this study, using polyethyleneimine as a cationic probe. Hartley-strain guinea pigs (200-300 g) with a normal Preyer's reflex were used. A 0.5% polyethyleneimine (PEI, MW 1,800) solution adjusted to pH 7.3 with HCl following Schurer's method was systemically administered through an axillary vein. In the cochlea, the presence of anionic sites was demonstrated on the basement membrane of the capillary wall in the stria vascularis. The presence of anionic sites was also confirmed on the basement membrane in Reissner's membrane but its density was much lower than that in the stria vascularis. In the ampulla and macula, the anionic sites were present on the basement membrane of the capillary wall and sensory epithelium.

Animals↗
PubMed1993

Catecholaminergic innervation in the vestibular labyrinth and vestibular nucleus of guinea pigs.

The vestibular sympathetic fibers of 20 guinea pigs were examined by immunohistochemical demonstration using tyrosine hydroxylase and dopamine B-hydroxylase. The vestibular sympathetics originated in the ipsilateral superior cervical ganglion and entered the internal auditory meatus along the labyrinthine artery. At the Schwann-glial border, some of the sympathetic fibers left the artery and went into the superior and inferior divisions of the vestibular nerve and made a loose meshwork among the Scarpa's ganglion cells, while other fibers kept following the labyrinthine artery. Both groups of fibers entered the cristae ampullaris and saccular and utricular maculas after several bifurcations in the cribrose areas and terminated either near the capillaries beneath the sensory epithelia, or among the vestibular nerve fibers. These fibers travelled freely in the vestibular labyrinth without being restricted to following blood vessels or vestibular nerve fibers. Some sympathetic fibers made direct contacts with the vestibular efferent fibers or the vestibular afferent fibers at the node of Ranvier. Sympathetic fibers were not observed in the sensory epithelia or semicircular canals, and were rarely found in the vicinity of the dark cells. The vestibular nucleus was also innervated by other catecholaminergic nerve fibers originating from the locus ceruleus, and the synaptic contacts were observed between the catecholaminergic nerve terminals and other neurons. These two peripheral and central catecholaminergic nervous systems were quite independent at the level of Schwann-glial border.

Animals↗
PubMed1995

Influence of changed blood pH on anionic sites in the labyrinth.

Using polyethyleneimine as a cationic probe, changes in the anionic sites of the labyrinthine basal laminae occurred during acidosis and alkalosis. Hartley-strain guinea pigs (200-300 g) with normal Preyer's reflex were injected i.v. with 0.5% polyethyleneimine (PEI, mol. wt 1800) solution adjusted to pH 7.3 with HCI via an axillary vein. The animals were divided into three groups: control, acidosis, and alkalosis. Acidosis was produced by inducing hypoxia, and alkalosis by injecting 7% NaHCO3. In controls, anionic sites were demonstrated on the basal laminae in the labyrinth. During both acidosis and alkalosis, a decreased number of anionic sites were observed on the basal laminae of the capillary walls in both stria vascularis and subepithelial layer of the vestibular sensory epithelium. However, an increase in anionic sites was observed on the basal lamina in Reissner's membrane during both acidosis and alkalosis.

Acidosis↗
PubMed1996

[A case of Paget's disease with progressive sensorineural hearing loss involved in the bilateral bony labyrinths].

Paget's disease of the bone is a chronic, progressive disease of unknown etiology characterized by abnormal bony resorption and deposition. It is a common skeletal disease in Europe and North America, while in Japan it is very rare. Paget's disease of the temporal bone has been reported to cause hearing loss frequently. We report a 50-year-old woman with Paget's disease who had progressive bilateral sensorineural hearing loss and right vestibular dysfunction. CT and 3 Dimensional CT (3D-CT) images demonstrated resorption of the entire bony labyrinth and its surroundings on both sides and that the temporal bone elsewhere remained intact. Bone scans revealed disease symmetrically in the bilateral otic capsules. Previous studies indicated that the bone changes in Paget's disease in the petrous pyramid begin in areas best supplied with marrow tissue and that the otic capsule is relatively spared until advanced changes are present in the remainder of the petrous pyramid. But, this patient mainly had foci in the bilateral otic capsules and the pattern was similar to cochlear otosclerosis. 3D-CT was useful for differentiation of Paget's disease and cochlear otosclerosis. The pattern of the affected areas indicated that this is a very rare situation even in the reports of Europe and North America, where the disease is rather common.

Diagnosis, Differential↗
PubMedDate not supplied

Bioethics, biotechnology products and humans: Europe between the skilled Theseus and the Labyrinth-Minotaur's syndrome.

Following the approval on May 1998 of the European Union Common position no. 19/98 regarding the legal protection of biotechnological inventions, the debate on bioethical aspects of biotechnologies is increased. The European Union document clearly protects the patentability of inventions (that concerns more than a particular plant or animal variety or a single procedure if they are of industrial interest), but not the finding or discovery of that is in the nature, e.g. a gene. Some safeguards (the dignity and integrity of the person and of the human embryo, the plant diversity, etc.) and exclusions from patentability (plant and animal varieties, processes for the production of plants or animals, the human body at any stage of growth, cloning of human beings, modifications of germ line, use of human embryos for industrial or commercial purposes as well as the inventions whose publication or exploitation would offend against public policy or morality, according to the Article 53a of the European Patenting Convention) are also indicated. Ethical issues discussed include the nature of human life and its protection, the safeguard of plant-animal biological diversity, the safeguard of human dignity and nature, whereas on several aspects (e. g. limits of the use of genetic material, xenotransplantation, etc.) the Parliament Assembly of the Council of Europe has requested a discussion or a moratorium (April, 1999). In this case an evaluation on the basis of the ethical beneficial principles should be performed and society should decide whether to master technologies and emulate the positive action of the hero Theseus against the Labyrinth-Minotaur syndrome or to renounce or "misuse" technologies like Daedalus and Icarus, who met a tragic end.

Bioethics↗
PubMed2000

Medicare, fee-for-service subsidies, and market outcomes: a partial description of Australia's health care financing labyrinth.

In Australia, both in-hospital and out-of-hospital services are subsidized via a national, social health insurance scheme, referred to as "Medicare." Revenue for the scheme is raised via general taxation and an earmarked "tax," which is presently 1.5 percent of taxable income. Members are entitled to the subsidized consumption of a broad range of medical practitioner services provided on both an in-hospital and an out-of-hospital basis, in both private and public facilities. Moreover, the range of services subsidized by the Australian scheme is broad, and includes the types of medical care that are available only to those U.S. Medicare patients who have opted for the Supplementary Medical Insurance Program. The purpose of this article is to provide a descriptive account of the Australian Medicare arrangements, particularly those that pertain to private, fee-for-service, medical practice. This article emphasizes the fact that, although the provisions are nationally uniform in application, these arrangements do not give rise to homogeneity of consumer payments and medical practitioner revenue. The article's theme is that, just as the simple terms "Medicare" and "Medicaid" belie the complexity of U.S. social health insurance, the Australian application of the term "Medicare" also describes a health care financing labyrinth.

Ambulatory Care↗
PubMed1975

[Morphofunctional characteristics of the microcirculatory bed of the cochlear portion of the otic labyrinth].

It has been shown that the microcirculatory system of the cohlear portion of the labyrinth is a complex of vessels adapted to the organ function. The analysis of the blood passages in the cochlear channel has shown that in accordance with the organ structure there occurs a spacious subdivision of the micrcirculatory bed into working units (segments) which are functionally integrated into a single microcirculatory system. Quantitative estimation of the microcirculatory system parameters has shown that 1) the blood volume which comes into the microcirculatory system is distributed between the vessels as following: 26%--arterioles: 8%--precapillaries; 29%--capillaries; 8%--postcapillaries and 29%--venules. 2) 639 capillaries fall on 1 mm-2 of the vascular strip and their diffuse surface is 1,3 mm-2.

Animals↗
PubMed2001

[Perilymphatic fistulas of the labyrinth: diagnostic problems].

Basic diagnostic criteria for perilymphatic fistulas of the labyrinth (PFL) comprise previous trauma or psychoemotional stress, unilateral acute affection of the acoustic and vestibular functions, severe noise in the ears, mixed hypoacusis, lower hearing thresholds in change of the head position, alteration of stabilogram parameters in rising pressure in the external acoustic meatus.

Ear, Inner↗
PubMedDate not supplied

[State of labyrinth tonic posture reflexes during administration to rabbits of microelements (copper, manganese and cobalt)].

The influence of varying doses of copper, manganese and cobalt chlorides on the labyrinthine tonic reflexes of rabbits was studied electromyographically. The presence and intensity of the reflexes were measured with respect to changes in the electric activity of muscles-extensors of forelimbs and occiput during the rotation of an animal along the bitemporal axis. Under the influence of cobalt (0.01 and 0.001 mg/kg), copper (0.1 mg/kg) and manganese (0.01 mg/kg) the threshold of adequate stimulation of the labyrinthine apparatus decreased and the time of the reflex response increased. This can be related to increased excitability of stem centers that are responsible for the realization of these reflexes. Larger doses of copper (1.0 mg/kg) and manganese (0.1 mg/kg) resulted in a significant and prolonged inhibition of tonic reflexes from the labyrinth to the limbs of rabbits. These data suggest an important role played by trace elements in the regulation and adjustment of the vestibular system.

Animals↗