Inner ear is composed of cochlea, vestibule, and endolymphatic sac which are enclosed by thin layer of epithelial cells. The enclosed space is filled with fluid named as endolymph where the [K⁺] is high and [Na⁺] is low. This unique ion composition is very important in maintaining normal hearing and balance function by providing K⁺ ions into sensory hair cells, which finally depolarize hair cells to facilitate the transport of sound and acceleration stimulation to central nervous system. The ion composition of inner ear is maintained by various ion transport through ion channels, transporters, and exchangers in the inner ear sensory and extra-sensory epithelium. The disruption of normal endolymphatic ion composition by the deterioration of the function of those ion channels can cause dysfunction of sensory epithelium, which consequently results in hearing and balance disorders. One of the possible pathology from the disruption of inner ear ion homeostasis is endolymphatic hydrops which is a phenomenon of excessive fluid accumulation of inner ear. The dysfunction of ion channels in inner ear epithelium can be an etiology of Ménière's disease since endolymphatic hydrops is a main pathological finding of the disease. In this review, we discussed about the possible pathological mechanism of Ménière's disease as a perspective of channelopathy as well as the role of various ion channels in the regulation of inner ear fluid volume based on the findings revealed by electrophysiological studies.
Acceleration ; Central Nervous System ; Channelopathies ; Cochlea ; Ear, Inner ; Electrophysiology ; Endolymph ; Endolymphatic Hydrops ; Endolymphatic Sac ; Epithelial Cells ; Epithelium ; Hair ; Hearing ; Homeostasis ; Ion Channels ; Ion Transport ; Ions ; Meniere Disease ; Pathology

Benign paroxysmal positional vertigo (BPPV) is a common inner ear cause of vertigo, most of which can be treated by particle repositioning maneuver (PRM). However, in rare cases, positional vertigo could persist or frequently recur after several PRM. In these intractable cases, surgical treatments including singular neurectomy and semicircular canal occlusion have been used. Posterior semicircular canal occlusion has some advantages over singular neurectomy in hearing preservation and feasible surgical technique. Also free-floating endolymph particles causing intractable BPPV are known to occur in about 20% of the cases during canal occlusion surgery. Nevertheless, to the best of our knowledge, there has not been any report on the identification of those particles in the Korean literature. In this paper, we report a case of free-floating endolymph particle found during transmastoid posterior semicircular canal occlusion for intractable posterior canal BPPV.
Benign Paroxysmal Positional Vertigo* ; Ear, Inner ; Endolymph* ; Hearing ; Semicircular Canals* ; Vertigo

Because inner ear organs are interconnected through the endolymph and surrounding endolymphatic membrane, the patients with sudden sensorineural hearing loss (SSNHL) often complain of vertigo. In this study, we report a patient with SSNHL accompanied by persistent positional vertigo, and serial findings of head-roll tests are described. At acute stage, head-roll test showed persistent geotropic direction-changing positional nystagmus (DCPN), which led to a diagnosis of SSNHL and ipsilateral light cupula. Although vertigo symptom gradually improved, positional vertigo lasted for more than 3 weeks. At this chronic stage, persistent apogeotropic DCPN was observed in a head roll test, which led to a diagnosis of the heavy cupula. Although the mechanism for the conversion of nystagmus direction from geotropic to apogeotropic persistent DCPN is unclear, the change of specific gravity of the endolymph might be one of the plausible hypothetical explanations.
Diagnosis ; Ear, Inner ; Endolymph ; Head ; Hearing Loss, Sensorineural* ; Humans ; Membranes ; Nystagmus, Physiologic ; Specific Gravity ; Vertigo*

BACKGROUND AND OBJECTIVES: The plasma stress-related hormonal [cortisol, growth hormone, prolactin, antidiuretic hormone (ADH), adrenocorticotropic hormone (ACTH)] levels have been reported to be elevated in sudden sensorineural hearing loss (SSNHL) patients. However, little is known regarding the mechanisms related with the elevation of stress-related hormonal levels in SSNHL. Therefore, we measured the level of plasma stress-related hormones in SSNHL patients and in normal persons to demonstrate the association between the stress-related hormones and SSNHL. SUBJECTS AND METHOD: Stress-related hormonal levels were measured from 68 patients who were diagnosed with SSNHL. These values were compared with the stress-related hormonal levels of 24 healthy control subjects. RESULTS: The plasma ADH levels was significantly higher in SSNHL group compared with that in their normal control group, as shown by their respective values, 4.46 [95% confidence interval (CI): 3.80-5.24 pg/mL] and 3.05 (95% CI: 2.34-3.98 pg/mL). The values for plasma cortisol, growth hormone, and ACTH levels whose values were 2.07 (95% CI: 1.65-2.61 microg/L), 0.20 (95% CI: 0.14-0.29 microg/L), and 12.79 (95% CI: 11.16-14.66 pg/mL), respectively, were significantly lower in the SSNHL group than those in the normal control group whose values were 7.86 (95% CI: 5.33-5.24 microg/L), 0.61 (95% CI: 0.36-1.04 microg/L), 18.48 (95% CI: 14.99-22.78 pg/mL), respectively. But there was no significant difference in prolactin between the two groups. CONCLUSION: This study demonstrates a possible role of stress-related hormones in the pathogenesis of SSNHL. However, only ADH level was higher than the control group. Furthermore, ACTH, growth hormone and cortisol levels were lower than the control groups. This means ADH, growth hormone, cortisol, ACTH levels are related with SSNHL. However, the impact of this hormone on the inner ear and endolymph homeostasis is still unknown. Further investigation is necessary to identify the action mechanism of these hormones in the inner ear.
Adrenocorticotropic Hormone ; Ear, Inner ; Endolymph ; Growth Hormone ; Hearing Loss, Sensorineural* ; Homeostasis ; Humans ; Hydrocortisone ; Plasma ; Prolactin

OBJECTIVE: Comparison of the sensitivity of Sp/Ap amplitude and area ratio in the aid of diagnosis of Meniere's disease. Meniere's disease was defined by the 1995 American Academy of Otolaryngology-Head and Neck Surgery Committee on Hearing and Equilibrium. METHOD: The study sample consisted of 35 patients in our hospital, who were undergone tympanic electrocochleography (EcochG). A control group of 10 patients (20 ears) with normal Sp/Ap ratio and EcochG data were identified. Sp/Ap amplitude and area curve ratios for both group were measured. RESULT: The traditional upper limit and the upper limit of normal for Sp/Ap amplitude and area curve were respectively 0.4, 46 and 1.94. Of 35 patients with Meniere's disease, had an abnormal Sp/Ap amplitude ratio,and had an abnormal Sp/Ap area curve ratio; the difference between groups was statistically significant. CONCLUSION Sp/Ap curve area curve ratio is more sensitive than conventional Sp/Ap amplitude ratios in diagnosis of Meniere's disease.
Adult ; Aged ; Aged, 80 and over ; Audiometry, Evoked Response ; Case-Control Studies ; Endolymph ; Female ; Humans ; Male ; Meniere Disease ; diagnosis ; Middle Aged ; Sensitivity and Specificity ; Young Adult

Hydrops of the endolymphatic space in the inner ear deteriorates hearing and balance function. This idiopathic syndrome of endolymphatic hydrops is Meniere's disease and is characterized by episodic vertigo, fluctuating hearing loss, tinnitus and ear fullness. For the pathophysiologic mechanisms of the episode, the progression of the hydrops leads to ruptures in the membranes separating endolymph from perilymph, producing a sudden increase in potassium concentration in the perilymph. Recurrent episodes may interfere with routine daily activities and sometimes accompany sudden drop attacks, so called Tumarkin's otolithic crisis, which may lead to serious injuries. Life style modification, low salt diet and prescription of diuretics have been traditionally tried in order to relieve endolymphatic hydrops. Surgical and destructive treatment options are necessary in selected intractable patients depending on the frequency of vertigo, severity of hearing loss and the possibility of bilateral involvement. However, a large proportion of these patients shows a spontaneous cure of vertigo with the aggravation of hearing loss (burnt out stage) over time. The goal of treatment is trying not to make the patient worse than this natural course of disease.
Diet ; Diuretics ; Dizziness ; Ear ; Ear, Inner ; Edema ; Endolymph ; Endolymphatic Hydrops ; Hearing ; Hearing Loss ; Humans ; Life Style ; Membranes ; Meniere Disease ; Otolithic Membrane ; Perilymph ; Potassium ; Prescriptions ; Rupture ; Syncope ; Tinnitus ; Vertigo

This review deals with the characteristics of various inflammatory mediators identified in the middle ear during otitis media and in cholesteatoma. The role of each inflammatory mediator in the pathogenesis of otitis media and cholesteatoma has been discussed. Further, the relation of each inflammatory mediator to the pathophysiology of the middle and inner ear along with its mechanisms of pathological change has been described. The mechanisms of hearing loss including sensorineural hearing loss (SNHL) as a sequela of otitis media are also discussed. The passage of inflammatory mediators through the round window membrane into the scala tympani is indicated. In an experimental animal model, an application of cytokines and lipopolysaccharide (LPS), a bacterial toxin, on the round window membrane induced sensorineural hearing loss as identified through auditory brainstem response threshold shifts. An increase in permeability of the blood-labyrinth barrier (BLB) was observed following application of these inflammatory mediators and LPS. The leakage of the blood components into the lateral wall of the cochlea through an increase in BLB permeability appears to be related to the sensorineural hearing loss by hindering K+ recycling through the lateral wall disrupting the ion homeostasis of the endolymph. Further studies on the roles of various inflammatory mediators and bacterial toxins in inducing the sensorineumral hearing loss in otitis media should be pursued.
Bacterial Toxins ; Chemokines ; Cholesteatoma ; Cochlea ; Cytokines ; Ear, Inner ; Ear, Middle ; Endolymph ; Evoked Potentials, Auditory, Brain Stem ; Hearing Loss ; Hearing Loss, Sensorineural ; Homeostasis ; Membranes ; Models, Animal ; Otitis ; Otitis Media ; Permeability ; Recycling ; Scala Tympani

OBJECTIVETo attempt to visualize the endolymph in patients with Meniere's disease by applying non-invasive intratympanic gadolinium through eustachian tube and three-dimensional fluid-attenuated inversion recovery magnetic resonance imaging (3D-FLAIR MRI).

METHODSWith a 3 Tesla magnetic resonance imaging (MRI) unit, 3D-FLAIR imaging was performed 24 hours after intratympanic gadolinium through eustachian tube in two patients with medically active and intractable Meniere's disease. Pure tone test and tympanometry were performed 24 hours before and after the administration of gadolinium.

RESULTSThe gadolinium appeared in almost all parts of the perilymph inside the inner ear; moreover, the border between the perilymph and the endolymph was visible so endolymphatic space was clearly shown on 3D-FLAIR. No change in pure tone test and tympanometry was noted.

CONCLUSIONS3D-FLAIR MRI with intratympanic gadolinium through eustachian tube can clearly reveal the visualization of endolymph in patients with Meniere's disease. Intratympanic gadolinium therapy through eustachian tube is a safe and effective.

Adult ; Endolymph ; diagnostic imaging ; Female ; Humans ; Imaging, Three-Dimensional ; Magnetic Resonance Imaging ; Male ; Meniere Disease ; diagnostic imaging ; Middle Aged ; Radiography

BACKGROUND AND OBJECTIVES: It is well known that noise exposure leads to the sensory hair cell loss and other neuronal damage in the cochlea. But recently it has been reported that noise exposure could also damage lateral wall of cochlea such as stria vascularis and spiral ligament. K+ is the major cation in endolymph and important to maintain homeostasis within the cochlea. We have investigated the expression patterns of KCNJ10 K+ channel in noise induced cochlear damage. MATERIALS AND METHOD: Twenty adult male guinea pigs (300-350 g) were included in this study. In experimental group (n=16), acoustic trauma was induced by continuous broad band noise for 2 hr to 115 dB SPL and broad band noise for 6 hr to 120 dB SPL with 3 consecutive days. After noise exposure, auditory brainstem response threshold shift and hair cell loss were evaluated. A study for KCNJ10 K+ channel expression was examined by immunohistochemical staining. RESULTS: After noise exposure, auditory brainstem response showed transient threshold shift (TTS) and permanent threshold shift (PTS) in accordance with noise exposure. The expression patterns of CKNJ10 K+ channel were changeable in TTS group. But there were no change of expression patterns in PTS group. CONCLUSION: In the cochlear lateral wall, KCNJ10 K+ channel expressions were affected with noise exposure and these changes might be associated with the regulation of homeostasis in the cochlea lateral wall.
Acoustics ; Adult ; Animals ; Cochlea ; Endolymph ; Evoked Potentials, Auditory, Brain Stem ; Guinea Pigs ; Hair ; Hearing Loss, Noise-Induced ; Homeostasis ; Humans ; Male ; Neurons ; Noise ; ortho-Aminobenzoates ; Spiral Ligament of Cochlea ; Stria Vascularis

Pendred syndrome is an autosomal recessive condition classically characterized by congenital deafness and goiter, and is the most common cause of hereditary deafness in Korea. It is caused by mutations in the PDS gene (SLC26A4) located in 7q31. The PDS gene encodes a chloride-iodide transport protein called pendrin, which plays a role in the reabsorption of endolymph and the maintenance of the endolymph homeostasis in the inner ear and in the uptake and organification of iodide in the thyroid gland. A mutation in PDS also causes non-syndromic recessive deafness (DFNB4) and therefore securing the diagnosis is important for genetic counseling purposes. The perchlorate discharge test and radiological conformation of the inner ear anomaly are useful diagnostic aids but have limited diagnostic value. However, because PDS mutations are widely distributed along the gene, it consumes too much time and money to perform molecular studies in clinics. We present a case of congenital sensorineural hearing loss with multinodular goiter, which shows definite findings of Pendred syndrome.
Deafness ; Diagnosis ; Ear, Inner ; Endolymph ; Genetic Counseling ; Goiter* ; Hearing Loss, Sensorineural* ; Homeostasis ; Korea ; Thyroid Gland ; Vestibular Aqueduct