Ear Fluid Pressure Research Articles

Effects of body tilt on multifrequency admittance tympanometry.

Hydrops and abnormalities of inner fluid pressure are involved in some otologic diseases such as Ménière's disease (MD). However, demonstrating abnormal perilymphatic or endolymphatic pressure is challenging. Multifrequency tympanometry studies in MD patients demonstrated an increase of the width of conductance tympanograms (outside an attack) compared with controls. To confirm that the increase in conductance width is caused by hyperpressure and not hypopressure in these patients tested outside an attack, we assessed the effect of changes in inner ear fluid pressure caused by body tilt on the results of multifrequency admittancemetry tympanograms. A multifrequency tympanometry including conductance (G) tympanogram at 2 kHz and resonance frequency measurements were performed in 20 volunteers (40 ears) free of otologic or neurologic disease. The measures were collected in three different positions: vertical, supine, and Trendelenburg positions. Changes in inner ear fluid pressure caused by body tilt induced an increase in the width of G tympanograms. In the vertical position, the mean value was 141.7 ± 56.5 daPa; in the supine position, it increased to 158 ± 58.3 daPa; and increased even more in the Trendelenburg position (20 degrees), with a mean of 184 ± 69.6 daPa (p < 0.01). Resonance frequency also increased in the Trendelenburg position.We conclude that the increased width of G tympanograms in MD patients outside an attack may be caused by an increase in inner ear fluid pressure.

Eustachian tube function in patients with inner ear disorders

The influence of Eustachian tube (ET) dysfunction on the inner ear fluid pressure and thus on the inner ear function in Meniere's disease has been discussed controversially. So far, most of the studies examining ET function in inner ear disorders indirectly analyzed ET function by tympanometric methods. The present study directly studied ET function in inner ear disorders by sonotubometry. Healthy subjects and patients with Meniere's disease, sudden sensorineural hearing loss, cholesteatoma and chronic suppurative otitis media were examined by sonotubometry. Mean increase of sound pressure intensity (dB) and mean duration of sound pressure increase (s) were analyzed. Highest mean increase of sound pressure intensity was seen in healthy subjects when using >5 dB peaks (11.6 ± 0.7 dB) and >0 dB peaks (9.6 ± 0.6 dB). Comparative analysis including bilateral ears showed decreased ET function in patients with cholesteatoma (p = 0.002) and in patients with Meniere's disease (p = 0.003) when using >0 dB peaks. Examination of each specific ET opening maneuver showed impaired ET function in pathological ears of patients with cholesteatoma and with Meniere's disease, during yawning (p = 0.001; p < 0.001), dry swallowing (p = 0.010; p = 0.049), Toynbee maneuver (p = 0.033; p = 0.032) and drinking (p = 0.044; p = 0.027). Mild ET dysfunction is detected in patients with Meniere's disease by direct sonotubometric assessment of ET function.

Effect of inner ear blood flow changes on the endolymphatic sac

Conclusions. That the endolymphatic sac (ES) reacts to changes in inner ear blood flow may be important for homeostasis of the inner ear fluid volume and pressure. Objectives. To elucidate the effect of changes in inner ear blood flow on the ES and to learn more about the volume and pressure regulatory function of the ES. Materials and methods. Epinephrine or sodium nitroprusside (SNP) was injected into the middle ear cavity of adult CBA/J mice. The ES were analyzed morphologically by light microscopy. Results. Epinephrine reduced the luminal size of the ES leading to an accumulation of intraluminal homogeneous substance. Injection of SNP increased the size of the ES lumen, accompanied by a collapse of the lateral intercellular space (LIS) and dense perisaccular tissue. These changes were almost reversed 4 h after injection.

Changes in CMDP and DPOAE during acute increased inner ear pressure in the guinea pig

During and after an increase of inner ear pressure, induced by injection of artificial perilymph, the 2f1 − f2 and f2 − f1 distortion products (DPs) in cochlear microphonics (CM) and otoacoustic emissions (OAE) were recorded in the guinea pig. An inner pressure increase of ∼600 Pa gave only small changes in CMDP and DPOAE. Along with a decrease in f1 amplitude, a small decrease in amplitude of the 2f1 − f2 and a small increase in the f2 − f1 were measured in CM. This matches a shift from a symmetrical position of the operating point for hair cell transduction, leading to an increase in even-order distortion and a decrease in odd-order distortion. Similar, a decrease in 2f1 − f2 DPOAE was expected. This might be the case at the generation sites but this effect was then more than compensated for by a better middle ear transfer, accounting for the increase of 0.4 dB of the 2f1 − f2 DPOAE amplitude. In conclusion, changes of overall inner ear fluid pressure have minor effects on cochlear function. This is a relevant finding for further understanding of diseases with changed inner ear fluid volumes, as Ménière’s.

An Interstitial Network of Podoplanin-Expressing Cells in the Human Endolymphatic Duct

The human endolymphatic duct (ED) with encompassing interstitial connective tissue (CT) is believed to be important for endolymph resorption and fluid pressure regulation of the inner ear. The periductal CT cells are interconnected via numerous cellular extensions, but do not form vessel structures. Here we report that the periductal CT is populated by two distinct cell phenotypes; one expressing podoplanin, a protein otherwise found on lymph endothelia and on epithelia involved in fluid fluxes, and a second expressing a fibroblast marker. A majority of the interstitial cells expressed podoplanin but not the lymphatic endothelial cell markers hyaluronan receptor (LYVE-1) or vascular endothelial growth factor receptor-3 (VEGFR-3). The fibroblast marker positive cells were found close to the ED epithelium. In the mid- and distal parts of the ED, these cells were enriched under folded epithelia. Furthermore, subepithelial CT cells were found to express activated platelet derived growth factor (PDGF)-beta receptors. Cultured CT cells from human inner ear periductal and perisaccular explant tissues were identified as fibroblasts. These cells compacted a three-dimensional collagen lattice by a process that could be promoted by PDGF-BB, a factor involved in interstitial fluid pressure regulation. Our results are compatible with the notion that the periductal CT cells are involved in the regulation of inner ear fluid pressure. By active compaction of the periductal CT and by the formation of villous structures, the CT cells could modulate fluid fluxes over the ED epithelium as well as the longitudinal flow of endolymph in the ED.

Network organization of interstitial connective tissue cells in the human endolymphatic duct.

The human endolymphatic duct (ED) and sac of the inner ear have been suggested to control endolymph volume and pressure. However, the physiological mechanisms for these processes remain obscure. We investigated the organization of the periductal interstitial connective tissue cells and extracellular matrix (ECM) in four freshly fixed human EDs by transmission electron microscopy and by immunohistochemistry. The unique surgical material allowed a greatly improved structural and epitopic preservation of tissue. Periductal connective tissue cells formed frequent intercellular contacts and focally occurring electron-dense contacts to ECM structures, creating a complex tissue network. The connective tissue cells also formed contacts with the basal lamina of the ED epithelium and the bone matrix, connecting the ED with the surrounding bone of the vestibular aqueduct. The interstitial connective tissue cells were non-endothelial and non-smooth muscle fibroblastoid cells. We suggest that the ED tissue network forms a functional mechanical entity that takes part in the control of inner ear fluid pressure and endolymph resorption.

Cochlear aqueduct flow resistance is not constant during evoked inner ear pressure change in the guinea pig

Inner ear fluid pressure was measured during 6.25 mHz square wave middle ear pressure manipulation, with a perforated tympanic membrane. After a negative-going middle ear pressure change the calculated flow resistance of the inner ear pressure release routes (mainly the cochlear aqueduct) was approximately constant, with a value of 12 Pa s/nl (averaged over two ears), when values for the inner ear window compliance are taken from the literature. After a positive-going middle ear pressure change the calculated flow resistance changed with round window position and with the pressure difference across the cochlear aqueduct. It reached an average maximum value of 114 Pa s/nl. The change of flow resistance during inner ear pressure variation can be explained by a permeability change of the cochlear aqueduct, caused by a change of structures filling the aqueduct and its entrance in scala tympani.

Change of Guinea Pig Inner Ear Pressure by Square Wave Middle Ear Cavity Pressure Variation

The inner ear fluid pressure of guinea pigs was measured during square wave middle ear cavity pressure variation. Time constants were derived for the slopes of the inner ear pressure recovery curves after middle ear pressure change. A "single exponential" function did not fit well and therefore more complicated functions were used for this purpose. For middle ear pressure increasing from zero to a few centimetres of water, returning to zero again, decreasing from zero to minus a few centimetres of water and then returning to zero again, time constants for the inner ear pressure recovery curves were on average 15.0, 8.6, 2.5 and 2.5 s, respectively. The results could not be described using a linear model with constant window membrane compliance and cochlear aqueduct flow resistance. A possible explanation for the large difference in time constants for positive or negative middle ear pressure changes is a dependence on aqueduct flow resistance or round window membrane position.

Inner ear pressure changes in normal guinea pigs induced by the Meniett 20

Introduction. The objective was measurement of inner ear fluid pressure changes of normal guinea pigs induced by the Meniett 20 (Pascal Medical, Sweden), a possible therapeutic pressure generator to be used by patients with Meniere's disease. Methods. In seven guinea pigs, the tip of a micropipette was inserted into the inner ear via the round window membrane, reached by a retroauricular approach. A small hole was cut in the tympanic membrane and the bulla was closed again. Middle ear pressure was altered via the external meatus using a pressure generator (Meniett 20) which produced complex oscillatory pressure pulses. Inner ear pressure was simultaneously measured with a WPI micropressure system. Results. Middle ear pressure changes were transferred instantly to the inner ear of guinea pigs. Inner ear pressure declined while middle ear pressure kept relatively stable. An average undershoot of −1.0 cm water with respect to the steady state pressure was seen after application of a pressure pulse, which was released in a few seconds. There was no change in steady state inner ear pressure after a complete session. Conclusion. Complex oscillatory pressure pulses produced by the Meniett 20 applied to the middle ear of guinea pigs causes a transient reduction of inner ear fluid volume.

Tympanic Membrane Displacement Analyser Tracing Modifications Induced by Glycerol in Menièrés Disease: El Analizador de Desplazamiento de la Membrana Timpánica: Seguimiento de las Modificaciones inducidas por el Glicerol en la Enfermedad de Ménière

The aim of the study was to detect inner ear fluid pressure changes induced by glycerol in Meniere's disease (MD) by means of a tympanic membrane displacement analyser (TDA). The study group consisted of 25 MD patients. The Vi (maximum inward displacement of the tympanic membrane) and the Vm (mean displacement of the tympanic membrane) were measured at 10, 20 and 25 dB above the stapedial reflex threshold. Each patient received therapy based on glycerol. The control group consisted of 20 patients with non-hydropic sudden hearing loss. At 20 and 25 dB above stapedial threshold MD patients had lower Vi values before therapy. After glycerol, we observed a Vi increasing in the hydropic ears in 68–96 per cent of patients. Since a Vi improvement implies a reduction of perilymph pressure, our results confirm the effectiveness of Vi in detecting specific action of glycerol in MD.El objetivo de este estudio fue detectar los cambios de presion inducidos en el liquido del oido interno por el glicerol, en la enfermed...

Monitoring Inner Ear Pressure Changes in Normal Guinea Pigs Induced by the Meniett®20

The inner ear fluid pressure of guinea pigs was measured during a series of complex oscillating middle ear pressure changes induced by the Meniett®20 (Pascal Medical, Sweden), a possible therapeutic pressure generator to be used by patients with Ménière's disease. Middle ear pressure changes were transferred instantly to the inner ear, although inner ear pressure declined while middle ear pressure stayed relatively stable. An average undershoot of -1.0 cm H2O with respect to the steady-state pressure was seen after application of a pressure pulse, which was released in a few seconds. The results did not fully comply with a simple linear model in which a constant flow resistance between the inner ear and cerebrospinal space was assumed.

Dynamics of inner ear pressure release, measured with a double-barreled micropipette in the guinea pig

The inner ear fluid pressure was measured in scala media of the guinea pig through one barrel of a double-barreled micropipette after a sudden volume increase or decrease, caused by injection or withdrawal of artificial endolymph through the other barrel. During injection or withdrawal, the inner ear pressure changed in the order of 1–10 cm water, but it returned to its initial value within a few seconds. The time constant for the pressure recovery depended on the flow direction. It was on average 1.1 s after a short overpressure and 2.8 s after underpressure. The obtained results could be fitted with a simple physical model, when it was assumed that inner ear pressure recovery is a non-linear process, governed by a pressure-dependent flow resistance and/or membrane compliance.

The pharmacological treatment of Menière's disease.

The management of Menière's disease often provides a formidable clinical challenge largely because its precise aetiology is unknown. There is no known 'cure' once the condition is established, but drugs may be helpful in treating both the acute attacks of vertigo, and in more long-term management, particularly in the earlier fluctuant stage. These remedies are largely symptomatic and there are few if any properly controlled studies of their efficacy. Suppressant drugs may act centrally at neurotransmitter sites, or peripherally on the labyrinth. Conventional diuretics and osmotically acting agents have been given to reduce the endolymph fluid volume. Histamine analogues directly reduce inner ear fluid pressure mainly by increasing the cochlear blood flow, and are probably the treatment of choice. Otovestibulotoxic drugs given systemically to cause chemical labyrinthine ablation are frequently effective in abolishing attacks of vertigo but often resulted in disabling oscillopsia and ataxia. There is now evidence that local administration by intratympanic injection may well be more efficacious resulting in selective partial end organ ablation. To date innovative immune modifying regimes have not proved helpful.

Effect of glycerol on the guinea pig inner ear after removal of the endolymphatic sac.

The effects of glycerol were investigated in guinea pigs in which the endolymphatic sac (ES) and duct (ED) had been obliterated unilaterally. Twenty-four hours after obliteration of the right ES and ED, glycerol was injected intraperitoneally. One to two hours after administration of glycerol, collapse or folding of Reissner's membrane was observed in the operated cochlea. No remarkable change was found in the nonoperated ear. The lumen of the ES of the nonoperated ear collapsed with intraluminal stainable substance within 1 h. The volume of the stainable substance increased with time and could still be seen 4 h after the injection of glycerol. Twenty-four hours after the injection of glycerol, the configuration of the ES was normal again. In addition, the animals showed marked unilateral (operated side) vestibular dysfunction after injection of glycerol. These findings suggest that the ES also has a secretory capacity and plays an important role in inner ear fluid volume and pressure regulation.

On the pathomechanism of cochlear dysfunction in experimental perilymph fistulas

The mechanism leading to hearing impairment in perilymph fistulas was investigated in guinea pigs with perforated round window membranes (RWM) by analyzing alterations of inner ear fluid pressure, changes of auditory function following manipulations to get presumed air bubbles out of the cochlea ("positional audiometry"), and temporal bone sections. The instantaneous loss of normal positive inner ear fluid pressure after RWM perforation had no immediate effect on auditory function. Inner ear pressure was restored 4 days following RWM perforation. "Positional audiometry" was negative in guinea pigs with perforated RWM. All ears in which auditory thresholds had increased had additional iatrogenic lesions at the spiral lamina. Fistulas in the RWM per se do not affect auditory thresholds. The question of the surgical repair of fistulas was not directly addressed; it only can be concluded that there are no direct sequelae of an isolated fistula which induce auditory impairment and which could be prevented by surgical repair of the fistula.

Transmission of cerebrospinal fluid pressure changes to the inner ear and its effect on cochlear microphonics

Alterations in inner ear fluid pressure and cochlear microphonics (CM) associated with increased cerebrospinal fluid (CSF) pressure were studied in the guinea pig. Hydrostatic pressure in the endolymph and perilymph of the cochlea were measured by use of a servo-controlled micropipet system. Endolymphatic and perilymphatic pressure increased in a linear manner with little or no time lag following pressure increases of 0-50 mm Hg. There was no pressure gradient between the endolymph and perilymph. CM in response to 500 Hz and 4000 Hz tone bursts was recorded before, during and after CSF pressurization. The input-output function of CM showed suppression of 2-8 dB in both maximum output and sensitivity unless the increase in CSF pressure exceeded a level which reduced the cochlear blood flow.

内リンパ嚢の内リンパ調節機能について

The endolymphatic sac has been considered to absorb endolymph. Recent studies have revealed that the endolymphatic sac also has a secretory capacity and is closely involved in the regulation of inner ear fluid volume and pressure.This study was designed to investigate this regulatory function of the andolymphatic sac in an animal model in which the andolymphatic sac and duct had been obliterated unilaterally. Fifteen guinea pigs were used in this study. Twenty four hours after obliteration of the right endolymphatic sac and duct, glycerol was injected intraperitoneally. The animals were sacrificed under general anesthesia, 15, 30 minutes, 1, 2, 4 and 24 hours after the injection of glycerol. The temporal bones were dissected out and fixed with 10% formalin and decalcified with 0.1 M buffered Na-EDTA for 1 month. The specimens were embedded in Agar 100 resin. The sections were stained with toluidine blue and examined with a light microscope.One to 2 hours after injection, collapse or folding of Reissner's membrane was observed in the operated cochlea with obliterated endolymphatic sac and duct. No remarkable change of Reissner's membrane was found in the non-operated ear with normal endolymphatic sac and duct. In the lumen of the endolymphatic sac of the non-operated ears, material stained with toluidine blue appeared 15 minutes after the injection of glycerol. The volume of this material increased with time and could still be seen 4 hours after the glycerol injection. Twenty four hours after the glycerol injection, no toluidine blue stained material could be seen.These findings suggested that the endolymphatic sac has a secretory capacity and plays an important role in the regulation of inner ear fluid volume and pressure.

The effects of glycerol on vestibular function and the endolymphatic sac after pre-treatment with colchicine.

The endolymphatic sac (ES) is believed to absorb endolymph. Recent studies have suggested that the ES also has a secretory capacity, a function that may be related to the regulation of inner ear fluid volume and pressure. Other studies indicate that hyperosmolar substances, such as glycerol and urea, may initiate a secretion of glycoprotein into the ES. This function was suggested to be related to a regulatory function of the ES by which it can compensate for a decrease in endolymph pressure. In order to investigate this regulatory potential of the ES, the effect of glycerol on the ES was investigated with or without the presence of pharmacological inhibition of glycoprotein secretion through colchicine treatment. Animals treated in such a way showed marked signs of impaired inner ear function, including loss of postural control and loss of Preyer's reflex. Significant ultrastructural changes were noted in the endolymphatic sac suggesting a disturbed secretory activity. The results may indicate that the endolymphatic sac may actively respond to changes in endolymph homeostasis through secretion of macromolecular substances and that alterations in this secretion may lead to functional disturbances of the inner ear.