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Wichova H, Alvi S, Boatright C, Ledbetter L, Staecker H, Lin J. High-Resolution Computed Tomography of the Inner Ear: Effect of Otosclerosis on Cochlear Aqueduct Dimensions. Ann Otol Rhinol Laryngol 2019; 128:749-754. [PMID: 30971097 DOI: 10.1177/0003489419842579] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
OBJECTIVES The cochlear aqueduct is a bony duct connecting the scala tympani with the subarachnoid space. Given the pathophysiology of otosclerosis, including bone resorption and new bone deposition, we hypothesize that the cochlear aqueduct in otosclerotic ears is narrowed. METHODS A retrospective review of patients with otosclerosis who have undergone high-resolution computed tomography (HRCT) of the temporal bone was completed. The control cohort included 20 patients with the diagnosis of noise-induced hearing loss, without the diagnosis of otosclerosis. Uniform measurements of cochlear aqueduct dimensions were performed using the axial plane. RESULTS The otosclerosis cohort included 25 males and 52 females with mean age of 52.2 ± 17.6 years. The control group included 10 males and 10 females with mean age of 64.0 ± 18.5 years. The mean cochlear aqueduct length, width mid canal, aperture base, aperture widest diameter, and funnel diameter in millimeters were 12.19 ± 1.66, 0.68 ± 0.28, 4.21 ± 1.67, 3.23 ± 1.47, and 2.70 ± 1.05 in the ears with otosclerotic foci and 11.57 ± 1.66, 0.69 ± 0.29, 2.56 ± 1.59, 2.77 ± 1.67, and 2.58 ± 1.03 in control group, respectively. Statistical difference was seen in length of cochlear aqueduct, aperture base, and aperture widest diameters (P = .017, <.001, .007). CONCLUSIONS The length of the cochlear aqueduct and the funnel width are statistically longer in the otosclerotic population compared to control. The width of the cochlear aqueduct is not statistically different.
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Affiliation(s)
- Helena Wichova
- 1 Department of Otolaryngology, Head & Neck Surgery, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Sameer Alvi
- 1 Department of Otolaryngology, Head & Neck Surgery, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Christine Boatright
- 2 Department of Radiology, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Luke Ledbetter
- 2 Department of Radiology, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Hinrich Staecker
- 1 Department of Otolaryngology, Head & Neck Surgery, The University of Kansas Medical Center, Kansas City, Kansas, USA
| | - James Lin
- 1 Department of Otolaryngology, Head & Neck Surgery, The University of Kansas Medical Center, Kansas City, Kansas, USA
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Plontke SK, Hartsock JJ, Gill RM, Salt AN. Intracochlear Drug Injections through the Round Window Membrane: Measures to Improve Drug Retention. Audiol Neurootol 2016; 21:72-9. [PMID: 26905306 DOI: 10.1159/000442514] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 11/17/2015] [Indexed: 11/19/2022] Open
Abstract
The goal of this study was to develop an appropriate methodology to apply drugs quantitatively to the perilymph of the ear. Intratympanic applications of drugs to the inner ear often result in variable drug levels in the perilymph and can only be used for molecules that readily permeate the round window (RW) membrane. Direct intracochlear and intralabyrinthine application procedures for drugs, genes or cell-based therapies bypass the tight boundaries at the RW, oval window, otic capsule and the blood-labyrinth barrier. However, perforations can release inner ear pressure, allowing cerebrospinal fluid (CSF) to enter through the cochlear aqueduct, displacing the injected drug solution into the middle ear. Two markers, fluorescein or fluorescein isothiocyanate-labeled dextran, were used to quantify how much of an injected substance was retained in the cochlear perilymph following an intracochlear injection. We evaluated whether procedures to mitigate fluid leaks improved marker retention in perilymph. Almost all procedures to reduce volume efflux, including the use of gel for internal sealing and glue for external sealing of the injection site, resulted in improved retention of the marker in perilymph. Adhesive on the RW membrane effectively prevented leaks but also influenced fluid exchange between CSF and perilymph. We conclude that drugs can be delivered to the ear in a consistent, quantitative manner using intracochlear injections if care is taken to control the fluid leaks that result from cochlear perforation.
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Affiliation(s)
- Stefan K Plontke
- Department of Otorhinolaryngology, Head and Neck Surgery, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
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Perilymph Kinetics of FITC-Dextran Reveals Homeostasis Dominated by the Cochlear Aqueduct and Cerebrospinal Fluid. J Assoc Res Otolaryngol 2015; 16:357-71. [PMID: 25801074 DOI: 10.1007/s10162-015-0512-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 02/13/2015] [Indexed: 02/07/2023] Open
Abstract
Understanding how drugs are distributed in perilymph following local applications is important as local drug therapies are increasingly used to treat disorders of the inner ear. The potential contribution of cerebrospinal fluid (CSF) entry to perilymph homeostasis has been controversial for over half a century, largely due to artifactual contamination of collected perilymph samples with CSF. Measures of perilymph flow and of drug distribution following round window niche applications have both suggested a slow, apically directed flow occurs along scala tympani (ST) in the normal, sealed cochlea. In the present study, we have used fluorescein isothiocyanate-dextran as a marker to study perilymph kinetics in guinea pigs. Dextran is lost from perilymph more slowly than other substances so far quantified. Dextran solutions were injected from pipettes sealed into the lateral semicircular canal (SCC), the cochlear apex, or the basal turn of ST. After varying delays, sequential perilymph samples were taken from the cochlear apex or lateral SCC, allowing dextran distribution along the perilymphatic spaces to be quantified. Variability was low and findings were consistent with the injection procedure driving volume flow towards the cochlear aqueduct, and with volume flow during perilymph sampling driven by CSF entry at the aqueduct. The decline of dextran with time in the period between injection and sampling was consistent with both a slow volume influx of CSF (~30 nL/min) entering the basal turn of ST at the cochlear aqueduct and a CSF-perilymph exchange driven by pressure-driven fluid oscillation across the cochlear aqueduct. Sample data also allowed contributions of other processes, such as communications with adjacent compartments, to be quantified. The study demonstrates that drug kinetics in the basal turn of ST is complex and is influenced by a considerable number of interacting processes.
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Park JJH, Shen A, Keil S, Kraemer N, Westhofen M. Radiological findings of the cochlear aqueduct in patients with Meniere’s disease using high-resolution CT and high-resolution MRI. Eur Arch Otorhinolaryngol 2014; 271:3325-31. [DOI: 10.1007/s00405-014-3199-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Accepted: 07/04/2014] [Indexed: 10/25/2022]
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Park JJH, Boeven JJ, Vogel S, Leonhardt S, Wit HP, Westhofen M. Hydrostatic fluid pressure in the vestibular organ of the guinea pig. Eur Arch Otorhinolaryngol 2011; 269:1755-8. [PMID: 22045302 DOI: 10.1007/s00405-011-1813-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2011] [Accepted: 10/06/2011] [Indexed: 11/25/2022]
Abstract
Since inner ear hair cells are mechano-electric transducers the control of hydrostatic pressure in the inner ear is crucial. Most studies analyzing dynamics and regulation of inner ear hydrostatic pressure performed pressure measurements in the cochlea. The present study is the first one reporting about absolute hydrostatic pressure values in the labyrinth. Hydrostatic pressure of the endolymphatic system was recorded in all three semicircular canals. Mean pressure values were 4.06 cmH(2)O ± 0.61 in the posterior, 3.36 cmH(2)O ± 0.94 in the anterior and 3.85 cmH(2)O ± 1.38 in the lateral semicircular canal. Overall hydrostatic pressure in the vestibular organ was 3.76 cmH(2)O ± 0.36. Endolymphatic hydrostatic pressure in all three semicircular canals is the same (p = 0.310). With regard to known endolymphatic pressure values in the cochlea from past studies vestibular pressure values are comparable to cochlear values. Until now it is not known whether the reuniens duct and the Bast's valve which are the narrowest passages in the endolymphatic system are open or closed. Present data show that most likely the endolymphatic system is a functionally open entity.
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Affiliation(s)
- Jonas J-H Park
- Department of Otorhinolaryngology and Head and Neck Surgery, RWTH Aachen University, Pauwelsstrasse 30, 52074 Aachen, Germany.
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Kingma CM, Wit HP. The effect of changes in perilymphatic K+ on the vestibular evoked potential in the guinea pig. Eur Arch Otorhinolaryngol 2010; 267:1679-84. [PMID: 20532902 PMCID: PMC2945631 DOI: 10.1007/s00405-010-1298-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Accepted: 05/25/2010] [Indexed: 12/04/2022]
Abstract
To investigate the effect on the functioning of the vestibular system of a rupture of Reissner's membrane, artificial endolymph was injected in scala media of ten guinea pigs and vestibular evoked potentials (VsEPs), evoked by vertical acceleration pulses, were measured. Directly after injection of a sufficient volume to cause rupture, all ears showed a complete disappearance of VsEP, followed by partial recovery. To investigate the effect of perilymphatic potassium concentration on the vestibular sensory and neural structures, different concentrations of KCl were injected directly into the vestibule. The KCl injections resulted in a dose-dependent decrease of VsEP, followed by a dose-dependent slow recovery. This animal model clearly shows a disturbing effect of a higher than normal K(+) concentration in perilymph on the vestibular and neural structures in the inner ear. Potassium intoxication is the most probable explanation for the observed effects. It is one of the explanations for Menière attacks.
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Affiliation(s)
- C. M. Kingma
- Department of Otorhinolaryngology, University Medical Center Groningen, P.O. Box 30.0001, 9700 RB Groningen, The Netherlands
| | - H. P. Wit
- Department of Otorhinolaryngology, University Medical Center Groningen, P.O. Box 30.0001, 9700 RB Groningen, The Netherlands
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Yu VM, Strykowski PJ, Odland RM. A Preliminary Theoretical Model of Hydrodynamics in the Inner Ear. EAR, NOSE & THROAT JOURNAL 2010. [DOI: 10.1177/014556131008900407] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Head movement should create a transient pressure imbalance across the membranous inner ear. We used basic concepts of fluid dynamics to develop a theoretical model of the inner ear. According to this model, two contiguous fluidic systems—the perilymphatic system and the endolymphatic system—are in hydrostatic equilibrium across a compliant membrane. Our model demonstrates that changes in resistance or compliance in one system results in a transient distortion of the membranous inner ear until equilibrium between the two systems is restored. The concept of hydrodynamic pressure changes in the inner ear has received little attention, but it may represent a new approach to understanding the inner ear and treating inner ear diseases.
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Affiliation(s)
- Vivian M. Yu
- Department of Otolaryngology-Head and Neck Surgery,
Lahey Clinic, Burlington, Mass
| | - Paul J. Strykowski
- Department of Mechanical Engineering, University of
Minnesota Institute of Technology, Minneapolis
| | - Rick M. Odland
- Department of Otolaryngology, University of Minnesota
Medical School, Minneapolis
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Inamoto R, Miyashita T, Akiyama K, Mori T, Mori N. Endolymphatic sac is involved in the regulation of hydrostatic pressure of cochlear endolymph. Am J Physiol Regul Integr Comp Physiol 2009; 297:R1610-4. [PMID: 19793958 DOI: 10.1152/ajpregu.00073.2009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To clarify the role of the endolymphatic sac (ES) in the regulation of endolymphatic pressure, the effects of isoproterenol, a beta-adrenergic receptor agonist, and acetazolamide, a potent carbonic anhydrase inhibitor, both of which decrease ES direct current potential on cochlear hydrostatic pressure, were examined in guinea pigs. When isoproterenol was applied intravenously, hydrostatic pressures of cochlear endolymph and perilymph were significantly increased with no change in endocochlear potential or the hydrostatic pressure of cerebrospinal fluid. Acetazolamide produced no marked change in the hydrostatic pressure of cochlear endolymph. In ears with an obstructed ES, the action of isoproterenol on the hydrostatic pressure of cochlear endolymph and perilymph was suppressed. These results suggest that the ES may regulate the hydrostatic pressure of the endolymphatic system via the action of the agents such as catecholamines on the ES.
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Affiliation(s)
- Ryuhei Inamoto
- Department of Otolaryngology, Faculty of Medicine, Kagawa University, Kagawa, Japan.
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Traboulsi R, Avan P. Transmission of infrasonic pressure waves from cerebrospinal to intralabyrinthine fluids through the human cochlear aqueduct: Non-invasive measurements with otoacoustic emissions. Hear Res 2007; 233:30-9. [PMID: 17716844 DOI: 10.1016/j.heares.2007.06.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 06/28/2007] [Accepted: 06/29/2007] [Indexed: 10/23/2022]
Abstract
The cochlear aqueduct connecting intralabyrinthine and cerebrospinal fluids (CSF) acts as a low-pass filter that should be able to transmit infrasonic pressure waves from CSF to cochlea. Recent experiments have shown that otoacoustic emissions generated at 1kHz respond to pressure-related stapes impedance changes with a change in phase relative to the generator tones, and provide a non-invasive means of assessing intracochlear pressure changes. In order to characterize the transmission to the cochlea of CSF pressure waves due to respiration, the distortion-product otoacoustic emissions (DPOAE) of 12 subjects were continuously monitored around 1kHz at a rate of 6.25epochs/s, and their phase relative to the stimulus tones was extracted. The subjects breathed normally, in different postures, while thoracic movements were recorded so as to monitor respiration. A correlate of respiration was found in the time variation of DPOAE phase, with an estimated mean amplitude of 10 degrees , i.e. 60mm water, suggesting little attenuation across the aqueduct. Its phase lag relative to thoracic movements varied between 0 degrees and -270 degrees . When fed into a two-compartment model of CSF and labyrinthine spaces, these results suggest that respiration rate at rest is just above the resonance frequency of the CSF compartment, and just below the corner frequency of the cochlear-aqueduct low-pass filter, in line with previous estimates from temporal bone and intracranial measurements. The fact that infrasonic CSF waves can be monitored through the cochlea opens diagnostic possibilities in neurology.
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Affiliation(s)
- Raghida Traboulsi
- Laboratory of Sensory Biophysics, School of Medicine, University of Auvergne, 28 Place Henri Dunant, 63000 Clermont-Ferrand, France.
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Hofman R, Segenhout JM, Albers FWJ, Wit HP. The relationship of the round window membrane to the cochlear aqueduct shown in three-dimensional imaging. Hear Res 2005; 209:19-23. [PMID: 16039079 DOI: 10.1016/j.heares.2005.06.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2005] [Indexed: 10/25/2022]
Abstract
The round window membrane and cochlear aqueduct complex in the guinea pig are reconstructed with 3D-imaging, using orthogonal plane fluorescence optical sectioning (OPFOS). The 3D-images show that the periotic duct and the aqueduct are connected to a pouch-like extension of the round window. The function of this may be regulation of aqueduct flow resistance under the influence of a pressure difference between inner ear fluid and middle ear.
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Affiliation(s)
- R Hofman
- Department of Otorhinolaryngology, University Hospital Groningen, The Netherlands.
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Feijen RA, Segenhout JM, Albers FWJ, Wit HP. Cochlear aqueduct flow resistance depends on round window membrane position in guinea pigs. J Assoc Res Otolaryngol 2005; 5:404-10. [PMID: 15682510 PMCID: PMC2504568 DOI: 10.1007/s10162-004-5001-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The resistance for fluid flow of the cochlear aqueduct was measured in guinea pigs for different positions of the round window membrane. These different positions were obtained by applying different constant pressures to the middle ear cavity. Fluid flow through the aqueduct was induced by small pressure steps superimposed on these constant pressures. It was found that the resistance for fluid flow through the aqueduct depended on the round window position but not on flow direction. The results can be explained by special fibrous structures that connect the round window with the entrance of the aqueduct. It was also found that the equilibrium inner ear pressure depends on middle ear pressure, indicating that the aqueduct does not connect the inner ear with a cavity with constant pressure.
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Affiliation(s)
- R A Feijen
- Department of Otorhinolaryngology, University Hospital Groningen, Groningen, The Netherlands.
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Chi FL, Liang Q, Wang ZM. Effects of hyperbaric therapy on function and morphology of Guinea pig cochlea with endolymphatic hydrops. Otol Neurotol 2005; 25:553-8. [PMID: 15241235 DOI: 10.1097/00129492-200407000-00024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objective of this study was to investigate the effect on experimental endolymphatic hydrops in guinea pigs after hyperbaric therapy. BACKGROUND The histopathologic character of Ménière's disease is the presence of endolymphatic hydrops. Endolymphatic hypertension could be one of the factors resulting from endolymphatic hydrops. Some treatments of Ménière's disease are aimed toward preventing the endolymphatic hypertension. Exposure to pressure change has risen in recent years. METHODS Thirty-two guinea pigs were operated on the right ears to induce endolymphatic hydrops by obliterating the endolymphatic sac through an extradural posterior cranial fossa approach. After 5 weeks' survival, 12 guinea pigs were put into a chamber with an absolute atmospheric pressure of 2.2 for 3 weeks (90 minutes once a day 5 times a week). We observed the morphologic and functional changes in guinea pig cochleae of the pressure group, 4-week hydrops group (n = 10), 8-week hydrops group (n = 10), and the normal group (n = 10). We measured the hearing threshold of the auditory brainstem response, the 70-dB SPL action potential (AP) latency, the ratio of 70-dB SPL summating potential magnitude to action potential magnitude (-SP/AP) of the electrocochleogram, and the maximum scala media area (SMA) ratio, respectively. RESULTS The average 70-dB SPL-SP/AP magnitude of right ears (0.29 +/- 0.09) and the average maximum SMA ratio (2.23 +/- 0.20) in the pressure group were significantly less than that in the 8-week hydrops group (0.69 +/- 0.15 and 4.04 +/- 0.52, respectively) with the same survival time (p < 0.05). The results in the pressure group were almost as similar as that in the 4-week hydrops group (0.29 +/- 0.13 and 2.22 +/- 0.20, respectively) (p > 0.05). The average hearing threshold of ABR of right ears in the pressure group (36.67 +/- 14.30-dB SPL) was lower than that of the 8-week hydrops group (44 +/-1 4.30-dB SPL), but the difference was insignificant (p > 0.05). The average 70-dB SPL AP latency of right ears in the pressure group was not significantly different from those of the 8-week hydrops group, the 4-week hydrops group, or the normal group (p > 0.05). CONCLUSIONS Our findings suggest hyperbaric therapy can significantly suppress the development of endolymphatic hydrops and improve cochlear function in guinea pigs. This study provided strong evidence for the development of pressure treatment of Ménière's disease without destroying the inner ear.
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Affiliation(s)
- Fang-Lu Chi
- Department of Otolaryngology, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai, PR China.
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Salt AN, Rask-Andersen H. Responses of the endolymphatic sac to perilymphatic injections and withdrawals: evidence for the presence of a one-way valve. Hear Res 2004; 191:90-100. [PMID: 15109708 DOI: 10.1016/j.heares.2003.12.018] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2003] [Accepted: 12/30/2003] [Indexed: 11/23/2022]
Abstract
Although the endolymphatic sac (ES) is thought to be a primary site for endolymph volume regulation, we have limited knowledge of how it responds to volume and pressure changes. In a prior publication, we demonstrated changes of K(+), Na(+) and endolymphatic sac potential (ESP) resulting from volume injections into, and withdrawals from, scala media of the cochlea. In the present study, we compared the influence of injections into and withdrawals from scala tympani of the cochlea on the endolymphatic sac. It is assumed that similar pressure changes are induced in endolymph and perilymph of both the cochlear and vestibular compartments of the ear. Pressure changes induced by the perilymphatic injections and withdrawals did not induce similar K(+) changes in the ES. The majority of perilymph withdrawals caused K(+) and ESP reductions in the sac, but few injections caused any measurable changes in the sac. Pressure measurements from the ES demonstrated that transmission of labyrinthine pressures to the lumen was directionally sensitive, with negative pressure transmitted more effectively than positive. In other experiments, application of infrasonic stimulation to the ear canal resulted in K(+) increase in the ES. These physiological measurements suggest that the endolymphatic duct may be closed by sustained positive pressure in the vestibule but open during pressure fluctuations. Study of the anatomy where the endolymphatic duct enters the vestibule suggests that the membranous sinus of the endolymphatic duct could act as a mechanical valve, limiting the flow of endolymph from the saccule to the endolymphatic sac when pressure is applied. This structure could therefore play an important role in endolymph volume regulation.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Box 8115, Washington University School of Medicine, 660 South Euclid Avenue, St. Louis, MO 63110, USA.
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