Na+ homeostasis in the inner ear is important to maintain normal hearing and balance. Na+ transport in the inner ear is reported to be occurred in non-sensory epithelium of inner ear which forms a barrier between endolymphatic space and perilymphatic space. Functionally identified and constitutively active Na+ absorption sites in the inner ear are Reissner's membrane, outer sulcus cells, vestibular transitional cells, saccular nonsensory epithelial cells, and endolymphatic sac epithelial cells. Na+ transport in these epithelial cells is mediated by apically located epithelial Na+ channels (ENaC), nonselective cation channels and basolaterally located Na+, K+-ATPase. Na+ absorption is increased by glucocorticoid through glucocorticoid receptor or ATP through purinergic receptors depending on cell types.
Absorption ; Adenosine Triphosphate ; Ear, Inner ; Endolymphatic Sac ; Epithelial Cells ; Epithelium ; Hearing ; Homeostasis ; Membranes ; Receptors, Glucocorticoid ; Receptors, Purinergic ; Sodium

Benign paroxysmal positional vertigo (BPPV) is a most common cause of vertigo. Although endolymphatic flow which is caused by movement of detached-otoconia from otolithic organs has been suggested as a cause of positional vertigo, none has proved it in the human inner ear. Therefore, there were many trials to explain the anatomical characteristics of cupula, physiology of cupula deviation, pathologic mechanisms of BPPV, and clinical characteristics of BPPV using animal membranous labyrinth. In this review, results of basic animal experimental studies to understand anatomical structures and pathological mechanisms related to BPPV are introduced. In addition, future directions for experimental studies to elucidate the mechanism of BPPV will be suggested.
Animal Experimentation ; Animals ; Ear, Inner ; Humans ; Otolithic Membrane ; Vertigo

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

Background and Objectives: Microtia is a congenital deformity where the pinna and middle ear structures are underdeveloped. Auricular reconstruction in microtia is one of the most difficult surgeries in otolaryngology due to the complex three-dimensional structure of the auricle. This study investigated the post-operative results in total auricular reconstruction performed by otologic surgeons in a single institution.Subjects and Method We analyzed data from 27 microtia patients who underwent auricular reconstruction in our institution from 2011 to 2019. The post-operative results were evaluated in terms of the shape of the auricle, the symmetry of the ear, and the degree of auriculocephalic sulcus stricture. The type and frequency of post-operative complications associated with the reconstruction were also evaluated. Results: Of the 24 patients, the shape of the auricle was good in 11 (40.7%), moderate in 11 (40.7%), and poor in 5 (18.6%) patients. The symmetry of the ear size was symmetric in 24 (88.9%) and asymmetric in 3 (11.1%) patients. The degree of auriculocephalic sulcus stricture was good in 11 (40.7%), partial stricture in 12 (44.4%), and severe stricture in 4 (14.8%) patients. Postoperative complications included skin necrosis, suture material exposure, and wound infection with cartilage deformation. Conclusion Total auricular reconstruction is a complex and sophisticated operation utilizing either autologous rib cartilage or artificial implant material. Considering that microtia is often accompanied by ear canal stenosis and hearing impairment, otolaryngologists should be more interested in the field of auricular reconstruction.

Objectives: . The aim of this study was to investigate whether preserved vestibular function in the high-frequency range influences the prognosis of patients with bilateral vestibulopathy (BVP) after vestibular rehabilitation. Methods: . Twenty-four patients followed up with vestibular rehabilitation were recruited. The enrolled patients were divided into two groups according to the preservation of the high-frequency vestibulo-ocular reflex (VOR) based on the video head impulse test (vHIT). The results of computerized dynamic posturography and the Dizziness Handicap Inventory (DHI) survey collected at baseline and at the 6-month follow-up after vestibular rehabilitation therapy were analyzed. Results: . Both groups showed significantly increased composite and DHI scores after follow-up with vestibular rehabilitation. The group with preserved high-frequency VOR showed a better composite score (p=0.064) and vestibular score (p= 0.008) than the group with lost high-frequency VOR at the 6-month follow up. The DHI score significantly decreased only in the group with lost high-frequency VOR (p=0.047). Among the three vestibular function tests (caloric test, rotary chair test, and vHIT) used to diagnose BVP, only vHIT showed a significant correlation (p=0.015) with a favorable prognosis (composite score ≥70). Conclusion . Better treatment outcomes are likely in patients with BVP with preserved vestibular function in response to high-frequency stimulation, as measured by the vHIT.

Objectives: . The aim of this study was to investigate whether preserved vestibular function in the high-frequency range influences the prognosis of patients with bilateral vestibulopathy (BVP) after vestibular rehabilitation. Methods: . Twenty-four patients followed up with vestibular rehabilitation were recruited. The enrolled patients were divided into two groups according to the preservation of the high-frequency vestibulo-ocular reflex (VOR) based on the video head impulse test (vHIT). The results of computerized dynamic posturography and the Dizziness Handicap Inventory (DHI) survey collected at baseline and at the 6-month follow-up after vestibular rehabilitation therapy were analyzed. Results: . Both groups showed significantly increased composite and DHI scores after follow-up with vestibular rehabilitation. The group with preserved high-frequency VOR showed a better composite score (p=0.064) and vestibular score (p= 0.008) than the group with lost high-frequency VOR at the 6-month follow up. The DHI score significantly decreased only in the group with lost high-frequency VOR (p=0.047). Among the three vestibular function tests (caloric test, rotary chair test, and vHIT) used to diagnose BVP, only vHIT showed a significant correlation (p=0.015) with a favorable prognosis (composite score ≥70). Conclusion . Better treatment outcomes are likely in patients with BVP with preserved vestibular function in response to high-frequency stimulation, as measured by the vHIT.

Objectives: . The aim of the present study was to evaluate audiologic and vestibular functions in patients with lateral semicircular canal (LSCC) dysplasia/aplasia. Methods: . We conducted a retrospective study of a patients with LSCC dysplasia and aplasia at tertiary referral center. The subjects included 15 patients with LSCC dysplasia or aplasia, with or without combined inner ear anomalies. Medical history, temporal bone computed tomography scans, pure-tone audiograms, and vestibular function test results were analyzed. Results: . LSCC anomaly was identified in 15 patients (20 ears). Nine patients had unilateral LSCC dysplasia only and showed a mean pure-tone average of 45.5±28.7 dB, while three patients (33.3%) among them had normal hearing. Six patients had bilateral LSCC dysplasia/aplasia combined with other inner ear anomalies and profound bilateral hearing loss. Notably, only four out of 15 patients (26.7%) had dizziness symptoms. On caloric test, patients with isolated LSCC dysplasia showed a 51.8%±29.3% level of canal paresis (eight out of nine patients showed anomalies), whereas patients with bilateral LSCC dysplasia/aplasia presented bilateral vestibular loss. One patient with isolated LSCC underwent video-head impulse test; horizontal canal gain decreased to 0.62 (17% asymmetry) and anterior canal gain was 0.45 (52.6% asymmetry), whereas posterior canal gain was normal. Conclusion . Bilateral LSCC dysplasia/aplasia is comorbid with other inner ear anomalies and presents as profound bilateral hearing loss and vestibulopathy. In contrast, isolated unilateral LSCC dysplasia presents as ipsilateral horizontal canal paresis. Hearing function in isolated LSCC dysplasia is usually, but not always, impaired with varying severity.

BACKGROUND AND OBJECTIVES: Video head impulse tests (vHITs) and caloric tests are widely used to assess the loss of vestibular function in acute vestibular neuritis. Although previous studies have reported on the results of each test, longitudinal comparison of these tests is rare. In the present study, vHITs and caloric tests were performed in patients with unilateral vestibular neuritis during the acute phase and after a long follow-up period (>6 months). The goal of this study was to evaluate the changes in vHIT and caloric test results and to analyze the relationships between them. SUBJECTS AND METHOD: Between September 2013 and December 2015, charts from 13 patients with unilateral vestibular neuritis were retrospectively reviewed. Among the 13 patients, caloric tests and vHITs were performed in 9 and 10 patients, respectively. Results of the vHITs and caloric tests were analyzed and the changes were compared. RESULTS: During the acute phase of vestibular neuritis, the results of the caloric test showed an increase in canal paresis (CP), and the results of the vHIT showed a decrease in horizontal gain. Although subjective symptoms improved in all patients after a long follow-up period (mean: 13.9 months), the occurrence of CP determined from the caloric test was not significantly changed (p=0.889). On the other hand, the mean horizontal gain of the vHIT had improved significantly (p < 0.05). CONCLUSION: While CP determined from the caloric test did not change after a long follow-up period, the decreased horizontal gain in the vHIT was significantly recovered in patients with unilateral vestibular neuritis.
Caloric Tests* ; Follow-Up Studies ; Hand ; Head Impulse Test ; Head* ; Humans ; Methods ; Paresis ; Retrospective Studies ; Vestibular Neuronitis*

The dizziness associated with paraneoplastic neurologic syndrome is hard to diagnose clinically because the prevalence of disease is rare, and radiologic and serologic examination result may come out normal. Opsoclonus-myoclonus symdrome is a representative of classical paraneoplastic neurologic syndromes. In this paper, we report 2 cases of paraneoplastic neurologic syndromes with negative serologic auto-antibody test and no brain lesion on MRI. Both cases were eventually diagnosed through PET. Patients with opsoclonus-myoclonus type nystagmus should be evaluated for paraneoplastic neurologic syndrome even if their radiologic and serologic findings are normal.
Brain ; Dizziness ; Humans ; Magnetic Resonance Imaging ; Myoclonus ; Ocular Motility Disorders ; Opsoclonus-Myoclonus Syndrome ; Paraneoplastic Syndromes, Nervous System ; Prevalence