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At least 667 records · Page 37Linked to original sources
PubMed1985

Endolymphatic sac surgery for Meniere's disease: a composite study of 339 cases.

This paper analyzes 339 consecutively performed endolymphatic mastoid sac shunts. Regardless of the method used, vertigo was controlled and hearing either improved or stabilized in approximately 70% of the cases. Overall, vertigo was controlled in approximately 80% of the cases. Similar results were obtained in cases of Meniere's syndrome and vestibular Meniere's disease. It is suggested here that, regardless of the method employed, there remains a high likelihood that the symptoms will recur, and the question is raised as to whether sac surgery may merely induce a temporary remission of the disease process. Consequently, it is hereby proposed that there is a need to devise a method to permanently drain the endolymph in order to more effectively control the disease on a permanent basis. Until this is achieved, however, sac surgery would appear to be the most appropriate surgical treatment for Meniere's disease.

Adolescent↗
PubMed1985

Horizontal canal BPV.

Benign paroxysmal vertigo (BPV) is generally attributed to a differential density condition in the posterior semicircular canal. Although the posterior canal is implicated because of its dependent position, the possibility exists that either the horizontal or superior canal could become involved. This paper reports on seven patients with a clinical picture consistent with horizontal canal BPV. The characteristic features are brief vertigo and horizontal nystagmus precipitated by head movement into or out of one of the lateral positions. Position change toward the left lateral position induces left beating nystagmus and vice versa for position change toward the right. The direction of the nystagmus indicates a utriculopetal "endolymph flow" when the affected horizontal canal is undermost. This could be explained by particle movement or a "viscous plug" in the posterior aspect of the canal.

Adult↗
PubMed1979

The mechanics of benign paroxysmal vertigo.

Benign paroxysmal vertigo (BPV) is a disorder of the vestibular labyrinth. The clinical features can be explained by an abnormality in the posterior semicircular canal. Under the influence of gravity, a density differential between the endolymph and the cupula will cause displacement of the cupula when changes in head position occur. The presence or absence of fatiguability is a useful test as it helps define etiology, prognosis, and therapy. At the risk of adding yet another classification of nystagmus to the literature, we submit that division of BPV into two types (fatiguable and nonfatiguable) will simplify and rationalize the management of this common complaint.

Adult↗
PubMed1978

The effects of indomethacin on inner ear fluids and morphology.

Metabolic disturbances may affect inner ear fluid homeostasis in various ways. The membrane sodium-potassium pump must play a role in this homeostasis, and as this pump derives energy from A.T.P. it may also depend somewhat on the presence of prostaglandins, through their stimulatory effect on the adenylate cyclase system. Salicylates suppress prostaglandins; and Indomethacin is even more potent in this respect. Could the temporary ototoxic effects of salicylates and Indomethacin be due to prostaglandin suppression? Further, could energy system problems involving prostaglandins be related to the development of endolymphatic hydrops? These questions prompted this study. Sublethal doses of Indomethacin were given to 14 guinea pigs in order to maximally suppress prostaglandins. Samples of perilymph and endolymph were analyzed for sodium and potassium concentrations and compared to normal controls. No significant differences were found in either acute (two to 24 hour) or chronic (three week) experiments. Light microscopic examination of serially sectioned cochleae in similarly treated animals showed, in a few cases, somewhat questionable distension of Reissner's membrane. Electron microscopy or the organ of Corti did not demonstrate any abnormalities. The study suggests that Indomethacin does not produce significant inner ear electrolyte shifts or endolymphatic distension, at least over the short term.

Animals↗
PubMed1983

Energy dispersive x-ray analysis of inner ear fluids and tissues during the ontogeny of cochlear function.

Energy dispersive x-ray analysis (EDXA) was used to characterize freeze-dried, microdissected samples of inner ear fluids and tissues from neonatal gerbils throughout the period of cochlear functional development, between 10 and 18 days after birth. EDXA spectra from endolymph residue demonstrated that the adult ionic composition of this fluid is established before functional onset, and before the appearance of the endocochlear potential. However, stria vascularis spectra showed substantial increases in relative phosphorus and sodium content during the period in which auditory thresholds improve by approximately 100 dB, in which the endocochlear potential appears and increases to its adult value, and in which the level of metabolism of the stria increases dramatically. The increase in relative phosphorus content of stria in particular occurred with a time course which was very similar to, though slightly earlier than, that of the developmental increase in the endocochlear potential. It is concluded that increases in the relative phosphorus content of stria may represent increases in inorganic phosphate associated with strial metabolism. Increases in relative sodium content may reflect the action of an ion transport system which directs this element into strial cells during generation of the endocochlear potential.

Aging↗
PubMed1981

[Physiopathology and clinical aspects of Menière's disease].

The most prominent changes in temporal bone histopathology of Menière's disease are hydrops-like extensions of the endolymphatic spaces. The endolymphatic hydrops seems to be the consequence of a diminished function or complete atrophy of the endolymphatic sac. The etiology or pathomechanism of perisaccular fibrosis or saccular degeneration is unknown. But as a consequence of experimental datas obtained by animal studies the pathogenesis of the endolymphatic hydrops can be explained by osmotic active forces which develope within the endolymphatic spaces after blockage of the endolymphatic aqueduct or sac: An increasing concentration of osmotic active endolymphatic components cause an influx of water from the perilymphatic (extracellular) environment so that the limiting membranes of the endolymphatic space have to extend (e.g. Reissner's membrane, saccular membrane). At any topographic location of the endolymphatic spaces these membranes can rupture followed by intermixing of potassium-rich endolymph with sodium rich perilymph. This leads to an acute or chronic intoxication of those sensory nerve elements which have close contact to perilymphatic fluid. The hypothesis of an osmotic induced accumulation of "water' during endolymphatic hydrops is supported by sometime striking results of the glycerol test. Nevertheless, the pathogenesis and etiology of Menière's disease remains obscure, as indicated by the diverging spectrum of the different conservative or surgical therapeutic methods in use.

Animals↗
PubMed1980

[Permeability barriers of the inner ear. Fine structure and function].

This paper summarizes the own electronmicroscopic studies on the inner ear fine structure (guinea pig) with the peroxidase tracer technique and mainly with the freeze-etch-technique. New findings are presented concerning the blood-perilymph-barrier, perilymph-endolymph-barrier as well as cell membrane differentiations of the stria vacularis cells and the sensory epithelia. The physiological and pathophysiological meaning is discussed in detail.

Animals↗
PubMedDate not supplied

Theoretical mechanical frequency response of the otolithic organs.

A distributed parameter model, which consisted of three coupled partial differential equations, describing the mechanical response of the otolithic organs, was used to develop a system mechanical transfer function. The equations were Laplace transformed and combined to yield a transfer function for otoconial layer displacement relative to an acceleration stimulus. Acceleration is either skull acceleration or gravity. In addition, transfer functions for the gel layer and endolymph fluid layer were also developed which included a spatial coordinate as a transfer function variable. Frequency response diagrams were constructed from the transfer functions, using numerical values of nondimensional parameters developed in an earlier study. The otoconial layer transfer function was compared to physiologic data on utricular primary afferent neurons and there was good agreement except at low frequencies. The discrepancy between the theoretical transfer function and the primary afferent response can be attributed to contributions of the spike encoder, which has been measured experimentally, additional non-mechanical components in the transduction process, and even non-linear elements in the mechanical system.

Animals↗
PubMed1993

Fine structure and development of ionocyte areas in the labyrinth of the trout (Salmo trutta fario).

The distribution of ionocyte areas in the trout labyrinth (in the semicircular canal ampullae, crus communis and utricular vesicle) is very similar to that of areas of dark cells in mammals. In all 3 regions, ionocytes begin to develop after hatching, and are cuboid at fry stages and prismatic in juveniles and adults. On electron microscopy, 3 types of cell can be seen in adult ionocyte areas: ionocytes, associate cells and basal cells. Ionocytes possess many mitochondria, occupying approximately 28% of the cytoplasmic volume, and a well-developed tubulomembranous system which opens on the basal surface at some points. These ultrastructural features, very similar to those of chloride cells, strongly suggest that ionocytes are involved in ion transport. Unlike mammalian dark cells, there are no basal or lateral infoldings of the plasma membrane in trout ionocytes. Trout associate cells have a well developed vacuolar system, few mitochondria and bundles of cytoplasmic filaments. Although less specialised than ionocytes, they may be involved in endolymph secretion.

Animals↗
PubMed1977

[The membranous labyrinth of the static organ in guinea pig (author's transl)].

The cristae ampullares of 16 guinea pigs were examined after their arrangements, weights and figures as after their relations to each other. It was noted that the size of the single crista increased from lateral to medial. They are inproportional to their related bony canals. Both the front cristae developed from the same basal plate and they are by the guinea pig less developed than the crista at the back. These different expansions of the cristae are considered in relation to the phylogenetical developement of the three canals. Where the size of the sensory cells by all the cristae ampullares are nearly the same, we fined that their number vary significantly. The expansions of the ampullares were we fined the cristae are confined to the membranous labyrinth. The bony labyrinth does not participate in that expansion. The supporting cells are of a great functional importance. Probably they transmit the required energy which they get from the lymph as well as the near by capillaris. Beyond that the sensory cells are able to support themselves directly with difinite nutriments from the endolymph.

Animals↗
PubMed1996

Update on posterior canal occlusion for benign paroxysmal positional vertigo.

Most, if not all, cases of BPPV appear to result from free-floating posterior semicircular canal endolymph particles. Particle repositioning alleviates symptoms and findings in the vast majority of patients. For the small intractable group of nonresponders, posterior semicircular canal occlusion remains a safe and highly efficacious procedure. This new technique has also paved the way for even newer and most invasive inner ear procedures.

Endolymph↗
PubMed1996

Dexamethasone perfusion of the labyrinth plus intravenous dexamethasone for Ménière's disease.

Recent clinical and laboratory evidence indicates that Meniere's disease is an immune-mediated disease. Dexamethasone perfusion of the inner ear through the round window plus intravenous dexamethasone often will stop the dizzy spells, reduce the fullness and low-frequency tinnitus, and sometimes improve the hearing in patients with Meniere's disease. The dexamethasone must act mostly on the endolymphatic sac and, to a lesser extent, on the stria vascularis and spiral ligament, the known targets of immune response in the inner ear, to reduce the endolymphatic hydrops and restore the fluid dynamics of the endolymph. Despite the good results with streptomycin perfusion, the number of patients with further hearing loss is large, so dexamethasone perfusion with intravenous dexamethasone should be tried first. The initial response to dexamethasone perfusion plus intravenous dexamethasone has been very good, with very little risk of further hearing loss, and it holds great promise for the future.

Administration, Topical↗
PubMed1997

An ATP-dependent inwardly rectifying potassium channel, KAB-2 (Kir4. 1), in cochlear stria vascularis of inner ear: its specific subcellular localization and correlation with the formation of endocochlear potential.

Cochlear endolymph has a highly positive potential of approximately +80 mV. This so-called endocochlear potential (EP) is essential for hearing. Although pivotal roles of K+ channels in the formation of EP have been suggested, the types and distribution of K+ channels in cochlea have not been characterized. Because EP was depressed by vascular perfusion of Ba2+, an inhibitor of inwardly rectifying K+ (Kir) channels, but not by either 4-aminopyridine or tetraethylammonium, we examined the expression of Kir channel subunits in cochlear stria vascularis, the tissue that is supposed to play the central role in the generation of positive EP. Of 11 members of the Kir channel family examined with reverse transcription-PCR, we could detect only expression of KAB-2 (Kir4.1) mRNA in stria vascularis. KAB-2 immunoreactivity was specifically localized at the basolateral membrane of marginal cells but not in either basal or intermediate cells. Developmental expression of KAB-2 in marginal cells paralleled formation of EP. Furthermore, deaf mutant mice (viable dominant spotting; WV/WV) expressed no KAB-2 in their marginal cells. These results suggest that KAB-2 in marginal cells may be critically involved in the generation of positive EP.

4-Aminopyridine↗
PubMed1976

An experimental study on the onset of endolymphatic secretion in chick embryos.

Extirpation of the endolymphatic anlage of the ear vesicle or that part of the ear placode which develops into the endolymphatic anlage in chick embryos, resulted in the absence of the endolymphatic system. In specimens of which the endolymphatic anlage was removed on the fourth day, healing of the wound was completed soon after the fifth day of incubation. Most of these experimental animals developed endolymphatic hydrops at a later stage. However, where healing was delayed after the fifth day, the open wound acted as an escape route for the endolymph (thus preventing further closure) which at that stage (or soon after) reached an appreciable volume.

Animals↗
PubMed2001

Superior canal dehiscence: mechanisms of pressure sensitivity in a chinchilla model.

BACKGROUND: Patients with superior canal dehiscence syndrome may experience vertigo and nystagmus when pressure changes occur in the external auditory canal, the middle ear, or the intracranial space. The cause is a defect in the bone of the superior canal. OBJECTIVE: To study the mechanisms of pressure sensitivity of the labyrinth in superior canal dehiscence syndrome and its surgical repair in a chinchilla model. METHODS: We investigated the changes in firing rates of vestibular nerve afferents in the chinchilla in response to changes in external auditory canal pressure before and after fenestration of the superior canal, and after repair of the fenestra. RESULTS: Before superior canal fenestration, external auditory canal pressure changes caused no responses in horizontal canal or otolith afferents, and only 1 of 9 superior canal afferents responded to pressure. After fenestration, all superior canal afferents were excited by positive pressure and inhibited by negative pressure. Half of 18 otolith and most (21 of 33) horizontal canal afferents were unaffected by pressure. The superior canal afferents had higher pressure gain than the horizontal canal afferents (P =.03). Pressure responses could be abolished only by applying a rigid seal to the fenestra. CONCLUSIONS: Fenestration of the superior canal rendered all superior canal afferents sensitive to pressure, whereas less than half of the other afferents became pressure sensitive. The direction of the superior canal afferent responses agreed with the predictions of our model of endolymph flow within the superior canal. A rigid seal applied to the fenestra abolished pressure sensitivity while maintaining physiologic rotational sensitivity.

Animals↗
PubMed1979

Intracellular potential changes of Corti's organ with anoxia.

Intracellular measurements of the resting cell membrane potentials of guinea pig Corti's organ were made in order to determine the sensitivity of this cell potential to anoxic hypoxia (a lowered oxygen state due to lack of respiratory oxygen) and to establish differences according to cell types or morphologic regions of the sensory epithelium. The negative cell potentials measured from successful electrode penetrations were found to be relatively more stable and resistant to change during a 120-s period of anoxia than was the positive endocochlear potential. The intracellular resting potentials were also much slower to recover after resumption of respiration. Data obtained from various cells in two different regions of Corti's organ is receiving oxygen from both the perilymph and the endolymph. An iontophoretic dye-marking technique was used to label some experimental cells for later histologic identification.

Action Potentials↗
PubMed1984

Human endolymphatic duct. An ultrastructural study.

The fine structure of the human endolymphatic duct was observed by transmission electron microscopy. Well-preserved specimens were obtained after fixation of inner ear tissue by perilymphatic perfusion. The morphologic findings seemed to be in accordance with earlier propositions that the human endolymphatic duct may be involved in endolymph resorption. The duct was found to contain otoconialike bodies, suggesting that the endolymphatic duct and sac in man may also play a role in the turnover of macular otoconia.

Adult↗