Myung Hoon Yoo

Quantitative analysis of gains and catch-up saccades of video-head-impulse testing by age in normal subjects.

To evaluate video‐head‐impulse test (vHIT) results in normal subjects, to determine the normative values of vHIT for the vestibulo‐ocular reflex (VOR) and to characterise the catch‐up saccades (CSs).

Results of video head impulse and caloric tests in 36 patients with vestibular migraine and 23 patients with vestibular neuritis: a preliminary report.

Abstract Caloric test has been used to probe the low-frequency range of lateral canal function and video head impulse test (vHIT) provides an objective measurement of the high-frequency range of canal function in vestibular disorders. Abnormal lateral canal function for high-frequency stimuli tested by vHIT was rare (8%) in vestibular migraine (VM), suggesting that there is a substantial remaining high-frequency canal function in VM. In vestibular neuritis (VN), caloric and vHIT responses are more frequently affected than VM, with a significant positive correlation between both tests. Caloric and vHIT probe different frequencies of head movement and provide complementary information regarding the lateral canal function. This article is protected by copyright. All rights reserved.

Prognostic significance of vestibulospinal abnormalities in patients with vestibular migraine.

Objectives We evaluated vestibular function test results in vestibular migraine (VM) patients, including caloric, vestibular evoked myogenic potential (VEMP), and dynamic posturography measurements and assessed their relationship with treatment responses. Study Design Retrospective case series review. Setting Tertiary referral center. Methods We investigated a cohort of 80 VM patients who had suffered recurrent vertigo attacks for more than 6 months. A combination of lifestyle modifications and prophylactic medications were used to treat these subjects. The patients were asked to score the treatment success by ranking symptom score from 0% to 100% for the improvement in overall severity of headache and vertigo. Patients were then classified as complete remission, symptomatic improvement 50% or more, or less than 50% improvement after 6 months of treatment. The periods needed for symptomatic improvement in the 50% or more patient group were recorded, and the responsiveness to medications and the vestibular test result metrics were analyzed to identify clinical outcome predictors. Results A symptomatic improvement of 50% or more in vertigo and headache was observed in 71% and 75% of the study subjects across mean periods of 2.3 and 2.2 months, respectively. Improvements in vertigo and headache did not coincide in all. Abnormal caloric, VEMP, and vestibular ratio measurements were found in 25%, 29%, and 58%, respectively. Abnormal vestibular ratios on posturography showed a significant correlation with a poor treatment response of vertigo, and a normal VEMP was significantly related to complete remission from headache, although abnormal caloric results showed no significant correlation with treatment responses. A poor response of vertigo symptoms was observed in 6% of patients with a normal vestibular ratio and 48% of patients with abnormal vestibular ratio. Complete remission from headache was observed in 61% of patients with a normal VEMP and 30% in patients with an abnormal VEMP. Conclusion More than 70% of the patients with VM experienced improvements in both headache and vertigo through a combination of lifestyle changes and prophylactic medications. Abnormal vestibular ratios on posturography and abnormal VEMP responses were frequent findings in VM patients with recurrent attacks for more than 6 months and were indicators of a poor prognosis. The pathophysiology of VM appears to be closely related to vestibular abnormalities, especially in vestibulospinal pathways. Further study with a large population is needed to establish the relationship exactly. Level of Evidence 2b Individual retrospective cohort study.

Short-term changes in tinnitus pitch related to audiometric shape in sudden sensorineural hearing loss

OBJECTIVE Sudden sensorineural hearing loss (SSNHL) is frequently accompanied by tinnitus. This study investigated the relationships between new-onset tinnitus and audiometric parameters in SSNHL patients. METHODS Sixty-one patients with SSNHL with new-onset tinnitus were enrolled. Changes of tinnitus pitch, and their correlations with the maximum hearing loss frequency (Fmax) and the edge frequency (Fedge) at initial and 1-month follow-up (FU) were analyzed. RESULTS At 1-month FU, tinnitus disappeared in 16 (26%) patients and they also showed hearing normalization. In 36 patients who still showed tonal tinnitus, the mean tinnitus pitch (2.9 kHz) at initial examination, which was close to Fedge (2.7 kHz), increased to a significantly higher frequency (4.6 kHz) at 1-month examination, which was close to Fmax (5.6 kHz). The tinnitus pitch had a more significant correlation with Fedge (r=0.46) than with Fmax (r=0.33) at initial examination and the tinnitus pitch showed a significant correlation only with Fmax (r=0.52) at 1-month examination. CONCLUSIONS Hearing normalization was crucial for the disappearance of tinnitus at 1-month FU. Patients who still had tonal tinnitus at 1-month FU showed the tinnitus pitch closer to the edge frequency (Fedge) at initial examination, and this tinnitus pitch increased to the maximum hearing loss frequency (Fmax) at 1-month FU. This change in tinnitus pitch may give insight about tinnitus generation.

Prognostic Value of Labyrinthine 3D-FLAIR Abnormalities in Idiopathic Sudden Sensorineural Hearing Loss

BACKGROUND AND PURPOSE: According to recent research, modern MR imaging can detect the presense of abnormalities on labyrinthine. Our aim was to report the patterns and prognostic role of abnormal findings on labyrinthine imaging in patients with sudden sensorineural hearing loss. MATERIALS AND METHODS: This study comprised 113 patients who were diagnosed with unilateral sudden sensorineural hearing loss and underwent 3T MR imaging, including pre-/postcontrast 3D fluid-attenuated inversion recovery and T1-weighted imaging. We analyzed abnormalities on MR imaging and correlated them with audiometric results. RESULTS: Thirty-one (27%) patients showed abnormal findings on labyrinthine MR imaging in the affected ear. The initial/final hearing levels of the MRI+ group (91 ± 25/73 ± 27 dB hearing loss) were significantly worse than those of the MRI− group (69 ± 30/48 ± 24 dB hearing loss). The incidence of abnormalities on labyrinthine MR imaging was significantly lower (3 of 40, 8%) in 40 patients with initial mild-to-moderate hearing loss than in those with profound hearing loss (16 of 34, 47%). Considering hearing improvement by the Siegel criteria, the rate of complete or partial recovery was significantly higher in the MRI− group (34%) than in the MRI+ group (10%). In patients with initial severe or profound hearing loss, the MRI− group showed greater hearing improvement (38 ± 21 dB) than the MRI+ group (23 ± 22 dB). CONCLUSIONS: Abnormalities on labyrinthine MR imaging were found in 27% of patients with sudden sensorineural hearing loss. The initial hearing loss was worse in the MRI+ group than in the MRI− group. In patients with initial severe and profound hearing loss, the presence of abnormalities on labyrinthine MR imaging indicated a poor prognosis.

Diagnostic Value of Gains and Corrective Saccades in Video Head Impulse Test in Vestibular Neuritis

Objectives We investigated changes in video head impulse test (vHIT) gains and corrective saccades (CSs) at the acute and follow-up stages of vestibular neuritis to assess the diagnostic value of vHIT. Study Design Case series with chart review. Setting Tertiary medical center. Subjects and Methods Sixty-three patients with vestibular neuritis who underwent vHIT at an initial presentation and an approximately 1-month follow-up were included. vHIT gains, gain asymmetry (GA), peak velocities of CS, and interaural difference of CS (CSD) were analyzed. Results Mean vHIT gains increased significantly from the acute stage to the follow-up exam. The mean GA, peak velocities of CS, and CSD had decreased significantly at the follow-up. The incidence of CSs was also significantly decreased at the follow-up. The abnormal rate (87%) considering both gain and CS value was significantly higher than that (62%) considering vHIT gain only at the follow-up, although the abnormal rates did not differ at the acute stage (97% vs 87%). Conclusion The abnormal rates based on both vHIT gains and CS measurements are similar at the acute stage of VN but are considerably higher at the follow-up stage compared with the abnormal rates based on vHIT gains alone. It is thus advisable to check both CS and vHIT gain while performing vHIT to detect vestibular hypofunction.

Prevalence of hearing loss and associated factors in subjects with normal otoscopy: a national cross-sectional study

Abstract Objective: To report the prevalence of hearing loss (HL) and associated factors in a nationwide study. Design: Cross-sectional study. Study sample: We investigated the prevalence of HL in 10,845 participants ≥12 years of age and analysed the associated factors with HL from 7434 participants ≥40 years of age. Results: The prevalence of worse ear HL was 21.9% (1.2% in youngest and 81.9% in oldest) and that of better ear was 12.5% (none in youngest and 65.3% in oldest). Based on the worse ear HL, the prevalence of HL was more common in men, and related with low education and income. In univariable analysis, hypertension, smoking, diabetes, depressive mood, stroke or cardiac disease, anaemia, hypercholesterolaemia and underweight showed positive associations with HL, and alcohol consumption and regular walking showed negative associations with HL. There were five associated factors in multivariable analysis, including smoking (OR =1.36 for smokers with <20 pack years; OR =1.55 for smokers with ≥20 pack years), noise exposure at workplace (OR = 1.28), stroke (OR = 1.72), anaemia (OR = 1.36) and depressive mood (OR = 1.29). Conclusion: Prevention of smoking and reduction of noise, as well as awareness of the association with stroke, anaemia and depression would help to reduce the burden of HL.

Embryotoxicity and hair cell toxicity of silver nanoparticles in zebrafish embryos

OBJECTIVES The purpose of the present study was to evaluate silver nanoparticles (AgNP)-induced embryotoxicity and hair cell toxicity during zebrafish development. METHODS We exposed zebrafish embryos to various AgNP concentrations (30, 60, 120, and 240nM) and evaluated embryotoxicity at 72h and ototoxicity at 120h. Embryotoxicity parameters including abnormal morphology, mortality, hatching rate, and heart rate were investigated. Hair cells within four neuromasts were evaluated. In the present study, the average number of hair cells of zebrafish exposed to AgNP was compared with that of an unexposed control group. RESULTS The hatching rate was not significantly different between groups (control: 90%; AgNP 240nM: 89%). The control group showed 2% mortality and 0% teratogenicity, while the AgNP 240nM group showed increased mortality (11%) and teratogenicity (15%) at 72h (n=100). The heart rate of AgNP-exposed embryos tended to be lower than that of the control group (n=38). Furthermore, AgNP induced apoptotic hair cell damage in the neuromasts (control: 50.7±7.4 cells; 240nM AgNP: 41.1±6.3 cells, n=23). TUNEL positive cell counts increased significantly as AgNP concentration increases (p<0.001, n=20 in each group). CONCLUSIONS The results of this study indicate that AgNP exposure causes embryotoxicity and hair cell toxicity in zebrafish embryos.

Sodium Selenite Acts as an Otoprotectant against Neomycin-Induced Hair Cell Damage in a Zebrafish Model

Sodium selenite is a trace element essential for many physiological functions in the body. It is involved in various biological processes; it acts as a cofactor for antioxidant enzymes that protect against free radicals and is reported to limit metal-mediated oxidative DNA damage. In the present study, we investigated the effect of sodium selenite on neomycin ototoxicity in wild-type and transgenic zebrafish (Brn3C: EGFP). Five or six days post-fertilization, zebrafish larvae were co-exposed to 125 μM neomycin and various concentrations (10 μM, 100 μM, 250 μM, and 500 μM) of sodium selenite for 1 h. Hair cells within neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed by fluorescence microscopy (n = 10 fish per treatment). Hair cell survival was estimated as the ratio of the hair cell numbers in each group compared to those of the control group that were not exposed to neomycin. Apoptosis and hair cell damage of neuromasts were evaluated using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay and 2-[4-(dimethylamino) styryl]-N-ethylpyridinium iodide (DASPEI) assay, respectively. Ultrastructural changes were evaluated using scanning electron microscopy and transmission electron microscopy. Neuromast hair cells were preserved in zebrafish exposed to 125 μM neomycin and 500 μM sodium selenite for 1 h. Sodium selenite protected against neomycin-induced hair cell loss of neuromasts, reduced apoptosis, and prevented zebrafish ultrastructural changes. We propose that sodium selenite protects against neomycin-induced hair cell damage by inhibiting apoptosis, decreasing the disarray of stereocilia, and preventing ultrastructural changes in the neuromast hair cells of the zebrafish.

Ecabet sodium alleviates neomycin-induced hair cell damage.

Ecabet sodium (ES) is currently applied to some clinical gastrointestinal disease primarily by the inhibition of the ROS production. In this study, the protective role of ES was evaluated against the neomycin-induced hair cell loss using zebrafish experimental animal model. Zebrafish larvae (5-7 dpf), were treated with each of the following concentrations of ES: 5, 10, 20, 40, and 80 μg/mL for 1 h, followed by 125 μM neomycin for 1h. The positive control group was established by 125 μM neomycin-only treatment (1h) and the negative control group with no additional chemicals was also established. Hair cells inside four neuromasts ( SO1, SO2, O1, OC1) were assessed using fluorescence microscopy (n = 10). Hair cell survival was calculated as the mean number of viable hair cells for each group. Apoptosis and mitochondrial damage were investigated using special staining (TUNEL and DASPEI assay, respectively), and compared among groups. Ultrastructural changes were evaluated using scanning electron microscopy. Pre-treatment group with ES increased the mean number of viable hair cells as a dose-dependent manner achieving almost same number of viable hair cells with 40 μM/ml ES treatment (12.98 ± 2.59 cells) comparing to that of the negative control group (14.15 ± 1.39 cells, p = 0.72) and significantly more number of viable hair cells than that of the positive control group (7.45 ± 0.91 cells, p < 0.01). The production of reactive oxygen species significantly increased by 183% with 125 μM neomycin treatment than the negative control group and significantly decreased down to 105% with the pre-treatment with 40 μM/ml ES (n = 40, p = 0.04). A significantly less number of TUNEL-positive cells (reflecting apoptosis, p < 0.01) and a significantly increased DASPEI reactivity (reflecting viable mitochondria, p < 0.01) were observed in 40 μM/ml ES pre-treatment group. Our data suggest that ES could protect against neomycin-induced hair cell loss possibly by reducing apoptosis, mitochondrial damages, and the ROS generation.