[Immunological studies on inner ear fluids under the influence of acute middle ear inflammation. Part 2. (author's transl)].
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Lactic dehydrogenase of fetal ear fluids under ambient and high-intensity sound.
Lactic dehydrogenase (LDH) was determined in the fluids of the inner ear scalae and the middle ear cavity of fetal guinea pigs near term. Scalar dissimilarities in prenatal perilymph and distinctions between fetal and maternal perilymph suggest functional differentiation between the antenatal scalae vestibuli and tympani, elevated glycolytic activity in the prenatal vestibular channel and primarily aerobic processes in fetal perilymph although anaerobic metabolism is also evident. Disparities between fetal middle ear fluid and prenatal perilymph as well as maternal serum indicate that the former medium is probably not directly derived from either of the latter sources. After experimental treatment consisting of the presentation of high-intensity sound to gravid animals, the total LDH activity of the fetal middle ear fluid decreased.
Acoustic Stimulation↗
Pathology of Ménière's disease as it relates to the sac and tack procedures.
The rationale for endolymphatic sac and tack operations is to prevent the further accumulation of endolymph, the former by draining endolymph into extralabyrinthine tissues and the latter by shunting endolymph into the perilymphatic space. While the basic concepts are reasonable enough, the probability of achieving these objectives seems remote. There appears to be adequate clinical evidence, however, to show that these procedures are of therapeutic value in selected cases. It is tempting to speculate that these surgical insults to the labyrinth, with the associated inflammatory and biochemical changes, alter the function of cells which control fluid physiology and thus improve the symptoms of Ménière's disease.
Adult↗
Symposium: Congenital anomalies of the middle ear. IV. Management of profuse perilymph leak.
Profuse perilymph leak during an otological operation can be controlled by inserting an epidural teflon cannula into the lumbar subarachnoid space and draining away the excess spinal fluid. After about 100 cc is removed the perilymph leak stops, and the oval window can be sealed with a living seal, such as vein, and the operation completed. The catheter is left in the subarachnoid space for about four days, with a bottle on the distal end positioned to remove no more than 150 cc of spinal fluid per day. Results with two patients in which this maneuver was used to control profuse perilymph leak are reported.
Catheterization↗
The effect of intracisternally injected ouabain on perilymph electrolyte concentrations.
A means for altering the ionic composition of perilymph utilizing the cochlear aqueduct and cerebrospinal fluid in chinchillas is introduced. A decrease in sodium and an increase in potassium concentration in perilymph was observed after ouabain was injected into cerebrospinal fluid. The time course of changes in the perilymph paralleled the CSF change but with a time lag which had not reached equilibrium within 60 minutes.
Animals↗
ABO(H) group substances in human inner ear fluid.
Tests were carried out on 89 specimens of human inner ear fluid and the results compared with those of blood and salivary gland tests. It was found that ABO(H) group substances are present in the perilymph of secretors.
ABO Blood-Group System↗
[The effects of methodical factors on the microphonic potential in the guinea pig cochlea with perfusion of perilymph].
The decreas in microphonic potentials detected from the round window (RMP) is negligible only if the bores are located very close to the round window, whereas it will increase with increasing distance from it. Only at pressures of more than +/- 30 cm water column, in rare cases even below that, will a sharp decrease in the RMP occur, possibly because of a lesion of either the oval or the round windown membrane. At a perfusion pressure above +5.6 cm water column, the perfusion liquid will enter the cerebrospinal fluid space. At a lower pressure the perfusion liquid is diluted by cerebrospinal fluid via the cochlear aqueduct. The perfusion speed of 1 to 50 mul/min has no effect on the function of the organ of Corti.
Action Potentials↗
Enzymatic activity of inner and middle ear fluids in fetal guinea pigs under ambient and high-intensity sound presentation.
The enzymes in perilymph of the inner ear scala and within fluid filling the middle ear cavity were investigated in the fetal guinea pig near term. Perilymph lactic dehydrogenase (LDH) exhibited differential activity between fetal scalae vestibuli and tympani, and LDH, aldolase, phosphohexose isomerase and creatine phosphokinase in perilymph of particular fetal scalae were elevated in activity in activity in comparison to corresponding maternal values. Moreover, LDH displayed different isozyme patterns for antenatal and gravid perilymph. In the middle ear fluid, all of the above enzymes were encountered but varied somewhat from the quantities determined for either prenatal perilymph or maternal serum. After gravid guinea pigs were exposed to a tone of 4 kHz, 100 dB SPL for 2 hours, LDH of the fetal middle ear fluid was reduced in activity 24 hours later. The metabolic significance of the fetal distinctions in the ear fluids and the clinical implications of the current work are discussed.
Acoustic Stimulation↗
[A biochemical and cytological explanation of cochlear otospongiosis].
In a study of 250 otosclerotic perilymphatic fluids, it was found statistically that in the presence of developing inner ear deafness, 90% of cases will demonstrate increased trypsin activity. Conversely, elevated antitrypsin levels are found in the absence of developing inner ear deafness.
Histocytochemistry↗
Diode pump cochlear audition theory.
A model of the cochlea is developed whereby the motion of the basilar membrane due to sound pressure in the scala media creates, through the pivotal motion of the pillars of Corti, modulated pressure on the fluid in the inner sulcus. This modulated pressure causes fluid to flow through the tectorial gap at selected longitudinal positions along the basilar membrane causing excitation or inhibition of the hair cell activity depending upon the direction of fluid flow. Specific functional relationships are developed for a two component model composed of a resonant and a nonresonant region. Relevant experimental data show good agreement with the predictions of the model.
Adaptation, Physiological↗
Perilymph penetration of methotrexate in cats.
The perilymph of the inner ear has recently been suggested as a site of frequent leukemic or lymphomatous infiltrates. Experimental evidence supports the existence of barrier mechanisms and explains the attenuated entry of several substances, including chemotherapeutic agents, from either the cerebrospinal fluid or blood into theperilymph. The present study describes the attenuated entry of methotrexate into the perilymph compartment of experimental animals following intrathecal or iv administration.
Animals↗
Hereditary deafness in the cat. Free amino acid and sugar content in the perilymph.
The free amino acid and sugar content of cat perilymph was studied from 11 normal and 17 deaf ears, and compared with simultaneous estimations from cerebrospinal fluid and serum. Each fluid has a distinctive amino acid composition, whilst glucose was the only saccharide demonstrable. The functional status of the cochlea did not influence the biochemical parameters studied.
Amino Acids↗
Gm(1) factor in human inner ear fluid.
The authors carried out investigations on the possibility of determining the Gm(1) factor in endolymph taken from human cadavers, as compared with tests of the blood. No difficulties or anomalies were found in the determination of Gm(1) factor either in the endolymph or the blood taken from cadavers.
Blood Group Antigens↗
Experimental pathogenesis of hydrops.
1. The best method for inducing hydrops in guinea pigs is obliteration of the endolymphatic duct. 2. The location of hydrops produced in the guinea pig is comparable to that of Menière's disease. 3. The major histopathological finding in the guinea pig is atrophy of sensorineural elements in the apical turns of the cochlea. 4. The vestibular sensory cell population is rarely decreased, though ultrastructural changes are noted. 5. Attempts to prevent or minimize development of hydrops by surgical fistulization of the vestibular endolymphatic walls or by administration of a diuretic drug, ethacrynic acid, failed in the guinea pig. Treatment of Menière's disease by these means is questionable. 6. Electron microscopy of the organ of Corti in cochleas taken from a patient with bilateral Menière's disease revealed that only a small percentage of te sensorineural elements was abnormal at the apical turns. Thus, it is questionable whether these small ultrastructural changes in the organ of Corti are a major cause of severe hearing loss. 7. In Menière's disease biochemical changes in cochlear fluid and/or changes in motion mechanics of the cochlear duct are probably important factors producing the hearing loss. 8. The present ultrastructural study did not resolve the question of the etiology of Menière's disease.
Animals↗
Fluid dynamics in sudden sensorineural hearing loss.
A change in fluid pressure in one intracochlear compartment also causes a pressure gradient in the other. Thus, one membrane break is likely to cause a secondary break. We have presented indirect evidence for such double membrane breaks in sudden hearing loss, and argue that one of the two breaks can heal spontaneously while the other remains active.
Adult↗
Experimental alteration of physiological state of inner ear fluids.
Mechanisms of endolymphatic hydrops formation in the inner ear are not yet fully understood. The available knowledge of the composition and the function of inner ear fluids, of mechanisms for maintenance of microhomeostasis, and the possible factors responsible for hydrops formation were reviewed. The nature of the functional barrier systems of the inner ear was investigated by measuring the amount of intravenously or intracisternally injected test substances which entered the perilymph. Based on studies of the osmotic relationship between the blood and the perilymph, an hypothesis of hydrops formation is proposed. The hypothesis predicts an osmotic imbalance, resulting from an upset of the homeostasis between the fluid compartments and the tissues of the inner ear, as a factor responsible for endolymphatic hydrops formation. An osmotic imbalance can be induced by various experimental conditions including metabolic disorders. The results of animal experiments strongly suggest the necessity of further survey of metabolic imbalance in Ménière's patients.
Adenosine Triphosphatases↗
The effect of changes in endolymphatic ion concentrations on the tectorial membrane.
The development of a new preparation technique has allowed the effects of fluid-substitution experiments on the tectorial membrane (t.m.) to be studied morphologically and not only, as previously, electrophysiologically. The organ of Corti and t.m. were examined in situ, unfixed and with in vivo-like ionic conditions under light-microscopical control (differential-interference-contrast, magnification 400--800X). An irreversible shrinkage of the marginal and middle zones of the t.m. was observed under the influence of Na+ ions (substitution of endolymph with artificial perilymph). This shrinkage is also seen in specimens prepared for scanning electron microscopy after perfusion of scale media with perilymph. If endolymph is replaced by an isotonic solution of EDTA (ethylenediaminetetraacetate) the t.m. can swell in its vestibulo-tympanal extent, e.g. from 39 to 72 microns. This swelling is reversible on addition of CaCl2. Although the size of the t.m. is not influenced to any great extent by changes in fluid osmolarity, reduction of H+ ion concentration leads to a minimal state of hydration of the protobril system at pH 4.3 (i.e. region of isoelectric point). The mechanism of Na+ and Ca2+ effects are discussed. These results indicate that the subtectorial space is morphologically separated from the scala media proper by the marginal zone.
Animals↗
[Pathophysiological aspects of therapeutic procedures in Menière's disease (author's transl)].
Meniére's disease is a nosologic entity. Its underlying pathophysiological mechanism is based on a disturbance of the quantitative correlation between peri- and endolymph volume on the one side and on a qualitative disorder of sodium and potassium concentration in the inner ear fluids on the other, resulting in a disregulation of osmotic pressure within the labyrinth. However, a critical review of the current literature as well as personal observations confirm that at the present time the scientific basis of a causal therapy is still lacking. Hence, both conservative and surgical treatment of Menière's disease does not allow to cure the cause but only some of the symptoms.
Humans↗