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This study was aimed at investigating the effects of placenta-derived mesenchymal stem cells (PL-MSCs) on particulate matter- (PM-) exposed human middle ear epithelial cells (HMEECs). HMEECs were treated with 300 μg/ml PM for 24 hours. The PL-MSCs were cocultured with PM-treated HMEECs. Cells were harvested on days 0, 1, and 4, and the expression of the inflammatory genes TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs and anti-inflammatory genes PTGES, TGFβ, and VEGF in PL-MSCs was examined by qRT-PCR. The culture media were collected to measure the secreted PGE2 level using an enzyme-linked immunosorbent assay. The mRNA expression of TNFα, COX2, IL1β, IL6, and MUC5B in HMEECs increased following PM treatment. PM-treated HMEECs cocultured with PL-MSCs showed alleviated inflammatory reactions represented by lower mRNA expression levels of MUC5B, TNFα, IL1β, and IL6 compared to monocultured PM-treated HMEECs. The mRNA expression levels of PGE2, TGFβ, and VEGF were elevated in cocultured PL-MSCs compared to those of control PL-MSCs. The medium of PM-treated HMEECs cocultured with PL-MSCs exhibited increased PGE2 levels. The increased inflammatory response in PM-treated HMEECs was reversed using PL-MSCs. The PGE2, TGFβ, and VEGF were the mediators of the anti-inflammatory effects of PL-MSCs.

Supplemental material, Supplemental_material for Phantom Perception of Sound and the Abnormal Cortical Inhibition System: An Electroencephalography (EEG) Study by Jeong-Sug Kyong, Tae-Soo Noh, Moo Kyun Park, Seung-Ha Oh, Jun Ho Lee and Myung-Whan Suh in Annals of Otology, Rhinology & Laryngology

To study the vestibular system or the vestibular compensation process, a number of methods have been developed to cause vestibular damage, including surgical or chemical labyrinthectomy and vestibular neurectomy. Surgical labyrinthectomy is a relatively simple, reliable, and rapid method. Here, we describe the surgical technique for rat labyrinthectomy. A postauricular incision is made under general anesthesia to expose the external auditory canal and the tympanic membrane, after which the tympanic membrane and the ossicles are removed without the stapes. The stapes artery, which is located between the stapes and the oval window, is a vulnerable structure and must be preserved to obtain a clear surgical field. A hole to fenestrate the vestibule is made with a 2.1-mm drill bur superior to the stapes. Then, 100% ethanol is injected through this hole and aspirated several times. Meticulous dissection under a microscope and careful bleeding control are essential to obtain reliable results. Symptoms of vestibular loss, such as nystagmus, head tilting, and a rolling motion, are seen immediately after surgery. The rotarod or rotation chair test can be used to objectively and quantitatively evaluate the vestibular function.

Background Otitis media (OM) is a major reason for children’s visits to physicians and a major cause of their being treated with antibiotics. It not only causes economic burdens but also influences hearing, speech, and education. To our knowledge, no nationwide population-based study has assessed the association between air pollution and OM. Therefore, this study evaluated the association between air pollution levels and the incidence of OM. Methods We identified cases of OM that occurred in South Korea between January 2011 and December 2012 from the Korea National Health Insurance Service-National Sample Cohort database, and evaluated its relationship with five air pollutants: particulate matter (PM10, particulates ≤10 μm in diameter), nitrogen dioxide (NO2), ozone (O3), sulfur dioxide, and carbon monoxide. Associations between the weekly incidence of OM and the five air pollutants were analyzed using generalized estimating equations. Conditional logistic regression analysis was used to obtain odds ratios (ORs) and their 99.9% Bonferroni-corrected confidence intervals after adjusting for gender, age, season, and region. Results We based our analysis on 160,875 hospital visits for OM by children aged

Background and objectives Determination of the lesion side based on the direction of the nystagmus could result in confusions to the clinicians due to mismatch between the vestibular function tests and also between vestibular and audiologic features. To minimize these mistakes, we elucidated the clinical manifestation and vestibular function test results in cases with recovery spontaneous nystagmus (rSN). Subjects and. Methods Patients who visited ENT clinic of tertiary referral hospital for acute onset continuous vertigo from January 2008 to December 2011 were enrolled. In these patients, we assessed onset time of vertigo, time point of paralytic spontaneous nystagmus (SN) and time point of rSN. At each time point of SN, vestibular function tests and hearing function tests were performed. Results We confirmed the rSN among patients with unilateral vestibulopathy and demonstrated that high gain of the rotatory chair test (slow harmonic acceleration) and/or mismatch of the SN direction and contralateral caloric weakness could indicate the recovery state of patients and nystagmus observed in this stage is recovery phase nystagmus. Conclusions In acute vestibulopathy patients, recovery phase nystagmus was observed and on this stage of disease vestibular function tests shows several features that could predict recovery state.

The increasing use of personal listening devices (PLDs) has been accompanied by a rise in the prevalence of hearing loss (HL) in younger age groups. However, there have been few reports on the relationship between HL and leisure noise exposure (LNE) in adolescents. The purpose of our study was to investigate the prevalence of HL in students attending general middle and high schools and to identify factors affecting HL prevalence. A total of 2,879 nationally representative adolescents in the first years of middle and high school underwent audiometric testing and otological examinations, and completed questionnaires, from June to December 2016. A speech-frequency hearing loss (SFHL) was considered present when the pure tone averages (PTAs) at 0.5, 1, and 2 kHz were ≥ 15 dB and a high-frequency hearing loss (HFHL) was considered present when the PTAs at 3, 4, 6, and 8 kHz were ≥ 15 dB. About 17% of Korean adolescents exhibited at least slight HL. The prevalence rates of SFHL and HFHL in the poorer ear were 11.6% and 10.3%, respectively, among Korean adolescents. The use of local area network (LAN) gaming centers and an experience of being asked by others to lower earphone volume were associated with both SFHL and HFHL. It is important to avoid excessive LNE to prevent adolescent HL. Additionally, SFHL or HFHL in the poorer ear was associated with lower academic performance.

We evaluated functional and morphological changes after trans-tympanic laser application using several different powers of photobiomodulation (PBM). The left (L) ears of 17 rats were irradiated for 30 min daily over 14 days using a power density of 909.1 (group A, 5040 J), 1136.4 (group B, 6300 J), and 1363.6 (group C, 7560 J) mW/cm(2). The right (N) ears served as controls. The safety of PBM was determined by endoscopic findings, auditory brainstem response (ABR) thresholds, and histological images of hair cells using confocal microscopy, and light microscopic images of the external auditory canal (EAC) and tympanic membrane (TM). Endoscopic findings revealed severe inflammation in the TM of C group; no other group showed damage in the TM. No significant difference in ABR threshold was found in the PBM-treated groups (excluding the group with TM damage). Confocal microscopy showed no histological difference between the AL and AN, or BL and BN groups. However, light microscopy showed more prominent edema, inflammation, and vascular congestion in the TM of BL ears. This study found a dose-response relationship between laser power parameters and TM changes. These results will be useful for defining future allowance criteria for trans-tympanic laser therapies.

AIMS: The purpose of this study is to compare the test-retest reliability of cervical vestibular evoked myogenic potential (cVEMP) parameters between monaural sequential (mSEQ) cVEMP and binaural simultaneous (bSIM) cVEMP recordings. MATERIALS AND METHODS: Twenty two volunteers aged 22 from 38 years were enrolled. Two different methods of cVEMP measurement were performed in the subjects. The two methods were (1) monaural sequential (mSEQ) measurement and (2) binaural simultaneous (bSIM) measurement. After a mean test-retest interval of 7.1 ± 2.8 days, the second run of the cVEMP measurement was performed in a random order. To compare the test-retest reliability of mSEQ and bSIM cVEMP responses, Intraclass correlation coefficient (ICC) and Spearman correlation were applied. RESULTS: Both p13 and n23 latencies did not show a statistically significant difference between the two cVEMP recording methods. Also, there were no significant differences in the inter-peak amplitude (IPA) and interaural amplitude difference (IAD) ratio between the two methods. The test-retest reliability of inter-peak amplitude (IPA) demonstrated a positive correlation for both mSEQ and bSIM cVEMP methods. The IAD ratio of bSIM cVEMP response demonstrated a statistically significant testretest reliability (ICC = 0.691, p = 0.015). However, the IAD ratio of mSEQ cVEMP response did not demonstrate a statistically significant test-retest correlation. CONCLUSION: Results implicate that bSIM cVEMP not only saves time, but it also has an advantage of a more reliable test-retest outcome.

OBJECTIVE The purpose was to evaluate brain plasticity that contributes to speech performance after cochlear implantation (CI) in postlingual elderly (>60 years) patients. MATERIALS AND METHODS Fifteen elderly postlingual deaf patients who underwent preoperative brain fluorodeoxyglucose positron emission tomography (FDG-PET) and were followed-up for more than 1 year after CI were included. The mean age of these patients was 64.6 years (range, 60-80 years). Based on their sentence score at 1 year after CI surgery, the patients were classified into two groups: poor performers (CID score of

Objectives/Hypothesis To evaluate the correlation between a narrow bony cochlear nerve canal (BCNC) and facial nerve stimulation (FNS) after cochlear implantation (CI) and their underlying mechanisms and to predict the risk of FNS preoperatively. Study Design Retrospective cohort study. Methods A total of 64 pediatric cases that underwent CI were included. Among them, 32 cases experienced FNS after CI, and another 32 cases were selected from 817 pediatric implantees by stratified random sampling. The width of the BCNC, the status of the cochlear nerve (CN) and the internal auditory canal (IAC), T level, and C level were compared and analyzed. Strategies for eliminating FNS were also analyzed. Results The FNS group showed a narrower BCNC (1.09 ± 0.52 mm) than the control group (1.99 ± 0.61 mm; P < .01), a lower CN/facial nerve ratio (0.32 ± 0.36) than the control group (1.34 ± 0.76; P < .01), and narrower IAC diameter (4.06 ± 1.71 mm) than the control group (5.66 ± 1.36 mm; P < .01). The FNS group also showed higher T level (165.7 ± 28.3 μA) than the control group (142.2 ± 21.2 μA; P < .01). Adjustment of the C levels and/or pulse width and switching off offending electrodes were attempted to eliminate FNS, with a 75.0% success rate. The FNS group still showed low Categories of Auditory Performance scores (3.00 ± 1.90) compared with the control group (5.94 ± 1.41, P < .01) after adjustment. Conclusions A narrow BCNC could be a cause of FNS after CI. Therefore, careful selection of the side for CI and programming strategies are required to reduce FNS. Level of Evidence 4. Laryngoscope, 2015

The gap-startle paradigm has been used as a behavioral method for tinnitus screening in animal studies. This study aimed to investigate gap prepulse inhibition (GPI) of the auditory late response (ALR) as the objective response of the gap-intense sound paradigm in humans. ALRs were recorded in response to gap-intense and no-gap-intense sound stimuli in 27 healthy subjects. The amplitudes of the baseline-to-peak (N1, P2, and N2) and the peak-to-peak (N1P2 and P2N2) were compared between two averaged ALRs. The variations in the inhibition ratios of N1P2 and P2N2 during the experiment were analyzed by increasing stimuli repetitions. The effect of stimulus parameter adjustments on GPI ratios was evaluated. No-gap-intense sound stimuli elicited greater peak amplitudes than gap-intense sound stimuli, and significant differences were found across all peaks. The overall mean inhibition ratios were significantly lower than 1.0, where the value 1.0 indicates that there were no differences between gap-intense and no-gap-intense sound responses. The initial decline in GPI ratios was shown in N1P2 and P2N2 complexes, and this reduction was nearly complete after 100 stimulus repetitions. Significant effects of gap length and interstimulus interval on GPI ratios were observed. We found significant inhibition of ALR peak amplitudes in performing the gap-intense sound paradigm in healthy subjects. The N1P2 complex represented GPI well in terms of suppression degree and test-retest reliability. Our findings offer practical information for the comparative study of healthy subjects and tinnitus patients using the gap-intense sound paradigm with the ALR.

To evaluate the efficacy of tinnitus retraining therapy (TRT), especially in patients who did not revisit the clinic after starting the program, and to determine the current status of patients who were lost to follow-up.Telephone survey.Tertiary referral center.Forty-seven patients enrolled in a TRT program at Seoul National University Hospital. Twenty-four patients who regularly visited the clinic were deemed the good follow-up (GF) group, and 23 patients who did not return after the initial counseling were deemed the follow-up loss (FL) group.Post-TRT questionnaires with the Tinnitus Handicap Inventory (THI) and a tinnitus visual analog scale (VAS), performed with a telephone survey.TRT efficacy, evaluated via the THI, and tinnitus VAS scores. A questionnaire on reasons for non-attendance after TRT was used.Pre-TRT VAS and THI scores showed no significant difference between groups. After TRT, both groups showed significant decreases in tinnitus VAS and THI scores. Post-TRT VAS scores for awareness, effects on daily life, and post-TRT THI scores were significantly lower in the FL group.Treatment outcomes were better in the FL group than in the GF group in several parameters. The FL group was greatly influenced by the first TRT counseling and obtained sufficient relief that they no longer felt the need for additional treatment. Treatment outcomes in patients lost to follow-up may not be as bad as presumed.

Congenital cytomegalovirus (cCMV) infection is a common congenital infection that causes sensorineural hearing loss (SNHL). Despite its substantial impact on public health and cost burden, epidemiology and clinical features of CMV-related SNHL have never been reported in the Korean populations. This study investigated the detailed audiologic phenotypes of cCMV infection to see if a specific SNHL pattern is associated with a particular clinical setting. A total of 38 patients with cCMV infection were studied retrospectively. Patients were classified into three groups with distinct demographics: clinically driven diagnosis (n=17), routine newborn CMV screening according to the NICU protocols (n=10), or referral to ENT for cochlear implant (CI) (n=11). The incidence of cCMV infection was 3.6%, showing 33.3% of SNHL among cCMV patients, 38% of asymmetric hearing loss, 29% of late-onset hearing loss, and diverse severity spectrum in patients with CMV-related SNHL. CI recipients with CMV-related SNHL showed a significantly improved speech perception. Surprisingly, in 36.4 % of CI implantees, initial audiological manifestation was significant asymmetry of hearing thresholds between both ears, with better ear retaining significant residual hearing up to 50dB. CMV turns out to be a significant etiology of SNHL, first to date reported in the Korean pediatric population. Analysis of audiologic phenotypes showed a very wide spectrum of SNHL and favorable CI outcomes in case of profound deafness. Especially for the patients with asymmetric hearing loss, close surveillance of hearing should be warranted and CI could be considered on the worse side first, based on the observation of rapid progression to profound deafness of better side.

Formaldehyde (FA) is a familiar indoor air pollutant found in everything from cosmetics to clothing, but its impact on the middle ear is unknown. This study investigated whether FA causes cytotoxicity, inflammation, or induction of apoptosis in human middle ear epithelial cells (HMEECs). Cell viability was investigated using the trypan blue assay and a cell counting kit (CCK-8) in HMEECs treated with FA for 4 or 24 h. The expression of genes encoding the inflammatory cytokine tumor necrosis factor alpha (TNF-α) and mucin (MUC5AC) was analyzed using RT-PCR. Activation of the apoptosis pathway was determined by measuring mitochondrial membrane potential (MMP), cytochrome oxidase, caspase-9/Mch6/Apaf 3, and Caspase-Glo® 3/7 activities. The CCK-8 assay and trypan blue assay results showed a reduction in cell viability in FA-treated HMEECs. FA also increased the cellular expression of TNF-α and MUC5AC and reduced the activities of MMP and cytochrome oxidase. Caspase-9 activity increased in cells stimulated for 4 h, as well as caspase-3/7 activity in cells stimulated for 24 h. The decreased cell viability, the induction of inflammation and mucin gene expression, and the activation of the apoptosis pathway together indicate a link between environmental FA exposure and the development of otitis media.

Objectives The central auditory pathway matures through sensory experiences and it is known that sensory experiences during periods called critical periods exert an important influence on brain development. The present study aimed to investigate whether temporary auditory deprivation during critical periods (CPs) could have a detrimental effect on the development of auditory temporal processing. Materials and methods Twelve neonatal rats were randomly assigned to control and study groups; Study group experienced temporary (18–20 days) auditory deprivation during CPs (Early deprivation study group). Outcome measures included changes in auditory brainstem response (ABR), gap prepulse inhibition of the acoustic startle reflex (GPIAS), and gap detection threshold (GDT). To further delineate the specific role of CPs in the outcome measures above, the same paradigm was applied in adult rats (Late deprivation group) and the findings were compared with those of the neonatal rats. Results Soon after the restoration of hearing, early deprivation study animals showed a significantly lower GPIAS at intermediate gap durations and a larger GDT than early deprivation controls, but these differences became insignificant after subsequent auditory inputs. Additionally, the ABR results showed significantly delayed latencies of waves IV, V, and interpeak latencies of wave I-III and wave I-V in study group. Late deprivation group didn't exhibit any deterioration in temporal processing following sensory deprivation. Conclusion Taken together, the present results suggest that transient auditory deprivation during CPs might cause reversible disruptions in the development of temporal processing.

Gentamicin, which is still used in modern medicine, is a known vestibular toxic agent, and various degrees of balance problems have been observed after exposure to this pharmacologic agent. Photobiomodulation is a candidate therapy for vertigo due to its ability to reach deep inner ear organs such as the cochlea. Previous reports have suggested that photobiomodulation can improve hearing and cochlea function. However, few studies have examined the effect of photobiomodulation on balance dysfunction. We used a rat model to mimic human vestibulopathy resulting from gentamicin treatment and evaluated the effect of photobiomodulation on vestibular toxicity. Slow harmonic acceleration (SHA) rotating platform testing was used for functional evaluation and both qualitative and quantitative epifluorescence analyses of cupula histopathology were performed. Animals were divided into gentamicin only and gentamicin plus laser treatment groups. Laser treatment was applied to one ear, and function and histopathology were evaluated in both ears. Decreased function was observed in both ears after gentamicin treatment, demonstrated by low gain and no SHA asymmetry. Laser treatment minimized the damage resulting from gentamicin treatment as shown by SHA asymmetry and recovered gain in the treated ear. Histology results reflected the functional results, showing increased hair cell density and epifluorescence intensity in laser-treated cupulae.

Conclusion: Any test for visual fixation suppression by itself is insufficient for screening central pathology and should be interpreted in conjunction with other neurotologic findings.We evaluated the correlation of visual fixation suppression (VFS) under three different test conditions (spontaneous nystagmus, caloric stimulation, and slow harmonic acceleration, SHA), as well as the diagnostic accuracy of each test for predicting central pathology, in dizzy patients.We retrospectively reviewed cases in a tertiary referral center; 504 consecutive dizzy patients who visited the ENT clinic were enrolled. The fixation index (FI, slow component velocity during fixation/slow component velocity before fixation × 100%) for the caloric test and spontaneous nystagmus was calculated and failure was indicated when the FI was greater than 60%. VFS during the SHA test at a frequency of 0.04 Hz was also performed and gain more than 0.2 was considered as failure of VFS.The incidence of VFS failure was 5.4% in the caloric test, 3.4% in spontaneous nystagmus, and 2.3% in the SHA test, respectively. Significant correlation was found only between the caloric test and the SHA test (r = 0.341, p0.001). The sensitivity of VFS in different tests did not exceed 35%. The specificity of VFS was highest (96.4%) in the 0.04 Hz SHA test, and exceeded 80% in the other tests.

Background and Objectives According to previous reports, patients with vestibular migraine (VM) display variable results from vestibular function tests (VFT): central, peripheral, or normal. The aim of this study was to classify the VM patients into the three groups according to interictal VFT findings (central, peripheral or normal) and to clarify the relationship between VFT results and the clinical manifestations and prognosis in each group. Subjects and Methods We reviewed the medical records of 81 patients diagnosed as VM using the criteria of Neuhauser, et al. between December 2004 and June 2009. Patients were divided into three groups according to the results of VFT. We compared the clinical manifestations and prognosis between groups. Characteristics including dizziness, the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time were analyzed. Results The number of patients with central, peripheral vestibular dysfunction and normal finding in VFT were 15, 28, and 38 respectively. There were no significant differences in the nature of headache, associated otologic symptoms, hearing threshold, duration of illness, and recovery time. A small difference was observed in the mean age and characteristics of dizziness, but these were not significant. Conclusions In patients with VM, classification according to the type of vestibular dysfunction was not helpful in the prediction of prognosis and clinical manifestations.

We evaluated treatment outcomes following single-site repetitive transcranial magnetic stimulation (rTMS) in the dorsolateral prefrontal cortex (DLPFC) and dual-site rTMS in the auditory cortex (AC) and DLPFC (AC + FC).This prospective randomized double-blind trial initially included 19 patients with chronic tinnitus and 17 of these patients received rTMS on the left AC and left DLPFC or only the left DLPFC. The subjects were randomly allocated to either the dual-site rTMS (AC + FC) protocol (Group 1, n = 9) or the singlesite rTMS (DLPFC) protocol (Group 2, n = 8). Group 1 received daily treatments with 2,000 pulses applied to the AC and 1,000 pulses applied to the DLPFC for 4 days (total of 12,000 pulses) and Group 2 received daily treatments with 3,000 pulses applied the DLPFC for 4 days (total of 12,000 pulses).The severity of tinnitus was assessed before rTMS treatment using the Tinnitus Handicap Inventory (THI) and the self-rated Visual Analog Scale. These measures were used to determine the awareness, loudness, annoyance, and effects of tinnitus on daily life at 1, 2, 4, and 12 weeks after treatment.The improvement in THI score was significantly better in Group 1 than in Group 2, even after controlling for the between-group differences in pretreatment THI score. In terms of psychological factors, Group 1 exhibited significant improvements in scores on the State-Trait Anxiety Inventory (STAI) for both state anxiety (STAI-X1) and trait anxiety (STAI-X2) at 12 weeks posttreatment and scores on the Pittsburgh Sleep Quality Index at 4 weeks posttreatment. Group 2 showed an improvement in only the STAI-X2 score at 12 weeks posttreatment.The rTMS protocol effectively suppressed tinnitus in the dual-site rTMS (AC+FC) group but not in the single-site rTMS (DLPFC) group. Although recent evidence has shown that non-auditory cortices in the tinnitus network play an important role in the generation of tinnitus, our findings indicate that rTMS on non-auditory cortical sites alone may not be sufficient for treatment. Thus, dual-site rTMS in the AC and DLPFC may be preferable for controlling this condition.

Objectives Children differ from adults in the expression of dizziness symptoms and the causes of dizziness. In several studies, benign paroxysmal vertigo of childhood (BPVC) and vestibular migraine (VM) were seen exclusively in children with vertigo, but the age threshold used to define ‘children’ varies, and there are few reported studies about adolescents with dizziness. In this study, we investigated the prevalence of vestibular and balance disorders according to age category in a multi-center study (otolaryngology departments of 11 hospitals) of children and adolescents. Methods Children and adolescents aged under 18 who visited the otolaryngology departments of 11 hospitals for dizziness were included. We classified the patients into three categories: preschool (up to and including 6-year-olds), school age (7- to 12-year-olds), and adolescents (13- to 18-year-olds). These patients were reviewed retrospectively based on their clinical charts. Results In the preschool age group, BPVC was most common, followed by VM. In the school-age group, BPVC and VMs were most common, followed by psychogenic vertigo and benign paroxysmal positional vertigo (BPPV). In adolescents, VM was the most common, and Meniere's disease, cardiogenic vertigo, and BPVC, which are seen primarily in adults, were also seen in some adolescents. Conclusion In children and adolescents with dizziness, VM and BPVC were the most common diseases, and prevalence of disease by age showed differing distributions. These findings will help in diagnosing and managing children and adolescents with vertigo.

Objective: To determine the optimal surgical approach for cochlear implantation (CI) preoperatively based on the spatial relation of a displaced facial nerve (FN) and middle ear structures and to analyze clinical outcomes of CHARGE syndrome. Methods: Facial nerve displacement and associated deviation of inner ear structures were analyzed in 13 patients (17 ears) with CHARGE syndrome who underwent CI. Surgical accessibility through the facial recess was assessed based on anatomical landmarks. Postoperative speech performance and associated clinical characteristics were analyzed. Results: The most consistently identified ear anomalies were semicircular canal aplasia (100%), ossicular anomaly (100%), and vestibular hypoplasia (88%). Facial nerve displacement was found in 77% of cases (anteroinferior: 47%, anterior: 24%, inferior: 6%). The width of available surgical space around facial recess was significantly greater in cases of facial recess approach (2.85 ± 0.9 mm) than those of alternative approach (0.12 ± 0.29 mm, P = .02). Postoperatively, 53% achieved better than category 4 on the categories of auditory perception (CAP) scale. The CAP category was significantly correlated with internal auditory canal diameter ( P = .025) and did not differ according to the applied surgical approach. Conclusion: Preoperative determination of surgical accessibility through facial recess would be useful for safe surgical approach, and successful hearing rehabilitation was achievable by applying appropriate surgical approaches.

A 45-year-old female patient visited the clinic due to ear fullness. A 8 mm sized mass was found in the external auditory canal. It was surgically removed and the pathology exam confirmed epithelial-myoepithelial carcinoma (EMC). EMC is glandular epithelial neoplasm of the salivary gland. EMC originating from the external auditory canal is very rare, and only 1 case has been reported so far in the literature. The difference between our case and the one previously published was that the tumor was previously proven as a benign tumor (i.e. pleomorphic adenoma) 5 years ago. Therefore, this is the first case in the literature showing the evolvement of pleomorphic adenoma of the external auditory canal into EMC.

OBJECTIVES From our previous study about the weak expressions of potassium-chloride (KCC2) and sodium-potassium-2 chloride (NKCC1) co-transporters in the lateral superior olive (LSO) in circling mice, we hypothesized that partially damaged cochlea of circling mice might be a cause of the weak expressions of KCC2 or NKCC1. To test this possibility, we reproduced the altered expressions of KCC2 and NKCC1 in the LSO of rats, whose cochleae were partially destroyed with kanamycin. METHODS Rat pups were treated with kanamycin from postnatal (P)3 to P8 (700 mg/kg, subcutaneous injection, twice a day) and sacrificed for immunohistochemical analysis, scanning electron microscope (SEM) and auditory brain stem response. RESULTS The SEM study revealed partially missing hair cells in P9 rats treated with kanamycin, and the hearing threshold was elevated to 63.8±2.5 dB SPL (4 ears) at P16. Both KCC2 and NKCC1 immunoreactivities were more prominent in control rats on P16. On 9 paired slices, the mean densities of NKCC1 immunoreactivities were 118.0±1.0 (control) and 112.2±1.2 (kanamycin treated), whereas those of KCC2 were 115.7±1.5 (control) and 112.0±0.8 (kanamycin treated). CONCLUSION We concluded that weak expressions of KCC2 and NKCC1 in circling mice were due to partial destruction of cochleae.

Mucopolysaccharidosis (MPS) II is an X-linked metabolic disorder caused by dysfunction of iduronate-2-sulfatase (I2S). This abnormality causes the progressive accumulation of incompletely degraded glycosaminoglycans (GAGs) in the lysosomes. The auditory characteristics of MPS II in mouse models have not been reported. In this study, we evaluated the auditory characteristics of the MPS II in IDS knock-out (IDS-KO) mice. In addition, the effect of enzyme replacement therapy (ERT) on hearing was studied. The IDS-KO mice had normal histology of the cochlea and retained good hearing at 7 weeks of age. However, at 17 weeks of age, the hearing thresholds of the IDS-KO mice were elevated and exudates were found in the middle ear. The hearing thresholds of the enzyme-treated IDS-KO (IDS-ERT) mice were similar to the wild-type (WT) mice at 17 weeks. Moreover, the microstructure of the inner ear was similar to the IDS-KO by transmission electron microscopy. The histology findings indicated that the microstructure of the inner ear was similar in comparisons between IDS-KO and IDS-ERT mice, even after 10 weeks of treatment. However, the hearing deficits in the MPS II mouse model can be prevented if ERT is started before the onset of hearing impairment. © 2012 Wiley Periodicals, Inc.

An abrupt change in the venous caliber, producing turbulent flow, may be a cause of pulsatile tinnitus (PT). The largest area/smallest area (L/S) ratio4.75 may be a criterion indicating abrupt caliber change and causing PT.Contrast-enhanced CT is recommended as an initial work-up modality in PT. But, in the majority of cases, no definite pathology can be found, even after extensive work-up. In these cases, the unilateral dominant venous system may be the cause of PT. The aim of this study was to compare, through 3D-reformatted images of the intracranial venous system, the volume, cross-sectional area, and caliber changes in patients with PT and normal controls.This was a cross-sectional study set in a tertiary referral center. Eleven patients (11 unilateral PT ears) and 12 normal control ears were enrolled. All the subjects were confirmed with normal CT angiography findings. The intracranial venous structure was three-dimensionally reconstructed. Three areas with the largest and the smallest dimension were selected for further analysis: the transverse sinus (T), isthmus (I), and the jugular bulb (B). The total volume, cross-sectional area, and cross-sectional area ratios of the three areas were compared in the PT group and the normal control group.The L/S ratio was significantly increased in the PT group (5.01), compared with the control group (3.42). When the threshold value of the L/S ratio was assessed by the ROC method, 4.75 seemed to be the significant dissecting point. The sensitivity of this method was 0.64 and the specificity was 0.83.

Cochlear hair cells are the sensory receptors of the auditory system. It is well established that antibiotic drugs such as gentamicin can damage hair cells and cause hearing loss. Rescuing hair cells after ototoxic injury is an important issue in hearing recovery. Although many studies have indicated a positive effect of low-level laser therapy (LLLT) on neural cell survival, there has been no study on the effects of LLLT on cochlear hair cells. Therefore, the aim of this study was to elucidate the effects of LLLT on hair cell survival following gentamicin exposure in organotypic cultures of the cochlea of rats. The cochlea cultures were then divided into a control group (n = 8), a laser-only group (n = 8), a gentamicin-only group (n = 8) and a gentamicin plus laser group (n = 7). The control cultures were allowed to grow continuously for 11 days. The laser-only cultures were irradiated with a laser with a wavelength of 810 nm at 8 mW/cm(2) for 60 min per day (0.48 J/cm(2)) for 6 days. The gentamicin groups were exposed to 1 mM gentamicin for 48 h and allowed to recover (gentamicin-only group) or allowed to recover with daily irradiation (gentamicin plus laser group). The hair cells in all groups were stained with FM1-43 and counted every 3 days. The number of hair cells was significantly larger in the gentamicin plus laser group than in the gentamicin-only group. The number of hair cells was larger in the laser-only group than in the control group, but the difference did not reach statistical significance. These results suggest that LLLT may promote hair cell survival following gentamicin damage in the cochlea. This is the first study in the literature that has demonstrated the beneficial effect of LLLT on the recovery of cochlear hair cells.

It has been demonstrated that kanamycin treatment during early developmental period induces partial cochlear destruction and enhanced glutamatergic transmission at the medial nucleus of the trapezoid body (MNTB) – the lateral superior olive (LSO) synapses in the superior olivary complex (SOC). As c-fos was expected to be expressed in the SOC by kanamycin-induced cochlear damage, the expression of c-fos protein (Fos) was investigated using immunohistochemistry in kanamycin-treated rat pups. In the control rat pups less than postnatal (P) day 9 in age, Fos-like immunoreactivity (Fos-IR) was transiently observed in the MNTB and LSO on P6, but disappeared on P9, which reflects a physiologic process. In contrast, in kanamycin-treated rats, Fos-IR was consistently observed through P9. Because a significant increase in terminal uridine deoxynucleotidyl transferase-mediated 2′-deoxyuridine 5′-triphosphate-biotin nick-end labeling (TUNEL) and glial fibrillary acidic protein (GFAP) IR was not demonstrated in the MNTB and LSO of kanamycin-treated rats, the increased Fos-IR does not appear to indicate an ongoing pathologic process, but may be related to the increased activity caused by the disturbance in excitatory and inhibitory balance between brainstem auditory circuits.

Cochlear dependency of glutamate co-transmission at the medial nucleus of the trapezoid body (MNTB)--the lateral superior olive (LSO) synapses was investigated using developing rats treated with high dose kanamycin. Rats were treated with kanamycin from postnatal day (P) 3 to P8. A scanning electron microscopic study on P9 demonstrated partial cochlear hair cell damage. A whole cell voltage clamp experiment demonstrated the increased glutamatergic portion of postsynaptic currents (PSCs) elicited by MNTB stimulation in P9-P11 kanamycin-treated rats. The enhanced VGLUT3 immunoreactivities (IRs) in kanamycin-treated rats and asymmetric VGLUT3 IRs in the LSO of unilaterally cochlear ablated rats supported the electrophysiologic data. Taken together, it is concluded that glutamate co-transmission is cochlear-dependent and enhanced glutamate co-transmission in kanamycin-treated rats is induced by partial cochlear damage.

Coffee is the one of the most common beverages worldwide and has received considerable attention for its beneficial health effects. However, the association of coffee with hearing and tinnitus has not been well studied. The aim of this study was to investigate the association of coffee with hearing and tinnitus based on a national population-based survey. We evaluated hearing and tinnitus data from the 2009&ndash, 2012 Korean National Health and Nutrition Examination Survey and their relationship with a coffee consumption survey. All patients underwent a medical interview, physical examination, hearing test, tinnitus questionnaire and nutrition examination. Multivariable logistic regression models were used to examine the associations between coffee and hearing loss or tinnitus. We evaluated 13,448 participants (&ge, 19 years) participants. The frequency of coffee consumption had a statistically significant inverse correlation with bilateral hearing loss in the 40&ndash, 64 years age group. Daily coffee consumers had 50&ndash, 70% less hearing loss than rare coffee consumers, which tended to be a dose-dependent relationship. In addition, the frequency of coffee consumption had an inverse correlation with tinnitus in the 19&ndash, 64 years age group but its association was related with hearing. Brewed coffee had more of an association than instant or canned coffee in the 40&ndash, 64 years age group. These results suggest a protective effect of coffee on hearing loss and tinnitus.

Background Sinonasal inverted papilloma (IP) is a neoplasm in the nasal cavity, characterized by its local aggressiveness and tendency to cause malignancy. Despite the frequent recurrence of IP, few studies have reported the effects of situational parameters including smoking on the recurrence rate of IP. This study was performed to evaluate clinical and environmental factors including smoking that can predict neoplasm recurrence after surgery in patients with IP. Methods This study was conducted retrospectively on 132 patients who were diagnosed with IP between November 1985 and September 2007. The study focused on the risk factors of recurrence, such as smoking behaviors, diabetes mellitus (DM), hypertension (HTN), allergic rhinitis (AR), the sites of tumor origin and involvement, neoplasm staging, and the surgical method. The age of the patients ranged from 22 to 85 years, and among the 132 patients, 39 patients were smokers (29.5%), 17 (13.3%) with DM, 31 (24.4%) with HTN, and 11 (9.3%) with AR. Results The recurrence rate showed great disparity between the groups of smokers and nonsmokers: 28.2% of smokers suffered recurrence compared with 10.7% recurrence from the nonsmoker group. The Krouse stage IV group experienced more frequent recurrence than the stage I, II, and III groups. Some patients in Krouse stage III (5/72, 6.9%) and IV (3/3, 100%) groups underwent malignant transformation of IP. Histories of DM, HTN, and AR did not exert a statistically meaningful influence on the recurrence and malignant transformation. Conclusion The smoking behavior and tumor with extranasal/sinus extension appear to be associated with recurrence of IP after surgical resection.

OBJECTIVES: This study was undertaken to confirm the clinical characteristics of recurrent pleomorphic adenoma (RPA), and to identify those factors that affect the development of malignant transformation (MT) from RPA. METHODS: The medical records of 270 patients, who were operated upon for parotid PA, were retrospectively reviewed. The pathologic specimens of a selected series of 23 patients were reviewed for histologic subtype and microscopic multi-nodularity. RESULTS: Mean age of initial operation in RPA without MT (RPA(-MT)) group was significantly lower than that of primary PA group. Mean age of the revision operation in RPA with MT (RPA(+MT)) group was significantly greater than that of RPA(-MT) group. Mean interval from operation to recurrence shortened after each revision operation. The risk of MT and additional recurrence increased significantly with recurrence. In RPA(-MT) group tumor recurrence occurred in 21.4% of patients despite a clear resection margin. CONCLUSION: The risk factors for MT may be an age of over 45 yr and multiple recurrences. However, younger patients are more at risk of recurrence. A clear resection margin cannot guarantee a cure in RPA, and it seems that parotid pleomorphic adenomas slowly gain malignant characteristics after repeated recurrences.

Objectives. The objective of this study was to compare the long-term auditory performance and language skill depending on the age of cochlear implantation in the Korean population. We especially tried to separate the effect of maturation/ development from that of the age at implantation. Methods. Eighty-six pre-lingual children with profound hearing loss who underwent a cochlear implantation before the age of six and had been followed for more than 3 yr were included in this study prospectively. Categories of Auditory Performance (CAP) and Korean Picture Vocabulary Test (K-PVT) were serially followed up. In order to separate the age at implantation effect, K-PVT results were readjusted to the child’s chronological age in the normal hearing population. Results. When the CAP and K-PVT scores were directly compared without chronological readjustment, we failed to show a significant difference for improvements according to the age at implantation. Early cochlear implantation was associated with better language development, only when the K-PVT scores were readjusted to percentile scores of their chronological age. Conclusion. Early cochlear implantation was associated with better language development even within the critical period. This advantage may be recognized only when the effect of the age at implantation is separated from the effect of maturation/development.

Objectives/Hypothesis: The aim of this study was to evaluate the antibacterial effects of photodynamic therapy (PDT) on common bacteria causing otitis media with effusion (OME). Methods: An in vitro study was carried out using a hematoporphyrin derivative sensitizer (Photogem; Lemonosov Institute of Fine Chemical, Moscow, Russia) and a 632-nm diode laser on Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae. The presence of colony-forming units of the bacteria was examined, the microscopic structures of the bacteria were examined by transmission electron microscopy (TEM), and flow cytometry of the bacteria was performed. An in vivo PDT study was performed using gerbils. S. pneumoniae or H. influenzae were injected into bullae. The Photogem was injected into the bullae 2 days later when OME developed, and transcanal irradiation with the 632-nm diode laser (90 J) was performed. Middle ear and bulla were washed with Dulbecco's phosphate buffered saline (DPBS) and the washed DPBS was cultured. The presence of bacterial colonies was examined. Results: The PDT was effective in killing all three kinds of bacteria. TEM showed damaged bacterial cell membranes and cytoplasmic structures, and the flow cytometry showed a lower number of viable bacteria in the PDT group compared to the control group. PDT was effective in killing S. pneumoniae in 87% of the infected bullae with OME, whereas it was effective in eradicating H. influenzae in 50% of the infected bullae with OME. Conclusions: The results of these studies demonstrated that PDT may be effective to treat otitis media. PDT may have clinical implications in the treatment of otitis media that is resistant to antibiotic therapy. Laryngoscope, 2009

Dizziness and vertigo frequently occur after cochlear implantation (CI) surgery, particularly during the early stages. It could recover over time but some of the patients suffered from delayed or sustained vestibular symptoms after CI. This study used rat animal models to investigate the effect of unilateral cochleostomy on the vestibular organs over time. Twenty-seven Sprague Dawley rats underwent cochleostomy to evaluate the postoperative changes in hearing threshold, gain and symmetry of the vestibular ocular response, overall balance function, number of hair cells in the crista, and the c-Fos activity in the brainstem vestibular nucleus. Loss of vestibular function was observed during the early stages, but function recovered partially over time. Histopathological findings demonstrated a mild decrease in vestibular hair cells numbers. Increased c-Fos immunoreactivity in the vestibular nucleus, observed in the early stages after cochleostomy, decreased over time. Cochleostomy is a risk factor for peripheral vestibular organ damage that can cause functional impairment in the peripheral vestibular organs. Altered vestibular nucleus activity may be associated with vestibular compensation and plasticity after unilateral cochleostomy.

Background The aim of this study was to evaluate the incidence of and possible risk factors for residual diplopia after surgical repair of pure blowout fracture (BOF) of the orbit. Methods Sixty-three patients with pure orbital BOFs who had preoperative symptomatic diplopia were investigated. In each patient, the relationship of residual diplopia and the following factors were analyzed: (1) timing of surgery, (2) presence of enophthalmos, (3) site of fracture, (4) type of fracture, (5) extraocular muscle swelling, and (6) surgical method. Results Fifty-five (87.3%) of 63 patients experienced improvement in diplopia and 8 (12.7%) patients had residual symptomatic diplopia after surgery. Of the six factors, only swelling of extraocular muscle on computed tomography (CT) scan was significant for the development of residual diplopia after surgery (p < 0.01). Conclusion In pure BOF of the orbit, patients who have swelling of the extraocular muscles on CT scan are more likely to have residual postoperative diplopia.

To evaluate the correlation between a narrow bony cochlear nerve canal (BCNC) and facial nerve stimulation (FNS) after cochlear implantation (CI) and their underlying mechanisms and to predict the risk of FNS preoperatively.Retrospective cohort study.A total of 64 pediatric cases that underwent CI were included. Among them, 32 cases experienced FNS after CI, and another 32 cases were selected from 817 pediatric implantees by stratified random sampling. The width of the BCNC, the status of the cochlear nerve (CN) and the internal auditory canal (IAC), T level, and C level were compared and analyzed. Strategies for eliminating FNS were also analyzed.The FNS group showed a narrower BCNC (1.09 ± 0.52 mm) than the control group (1.99 ± 0.61 mm; P.01), a lower CN/facial nerve ratio (0.32 ± 0.36) than the control group (1.34 ± 0.76; P.01), and narrower IAC diameter (4.06 ± 1.71 mm) than the control group (5.66 ± 1.36 mm; P.01). The FNS group also showed higher T level (165.7 ± 28.3 μA) than the control group (142.2 ± 21.2 μA; P.01). Adjustment of the C levels and/or pulse width and switching off offending electrodes were attempted to eliminate FNS, with a 75.0% success rate. The FNS group still showed low Categories of Auditory Performance scores (3.00 ± 1.90) compared with the control group (5.94 ± 1.41, P.01) after adjustment.A narrow BCNC could be a cause of FNS after CI. Therefore, careful selection of the side for CI and programming strategies are required to reduce FNS.4. Laryngoscope, 126:1433-1439, 2016.

Objective We evaluated conventional ASSR (Bio-logic MASTER II) and NB CE-Chirp ASSR thresholds as objective hearing measures in both normal and hearing loss subjects. Methods Patients with sensorineural hearing loss and volunteer normal hearing subjects were enrolled. Pure tone thresholds at 0.5, 1, 2 and 4 kHz were compared with the corresponding thresholds measured using Bio-logic MASTER II and the Eclipse ASSR systems. The threshold differences and correlation with pure tone were measured and reliability was evaluated with Cronbach's α . In part I of the study, all subjects were included, in part II of the study, only mild hearing loss and normal hearing subjects were included. Results In part I , NB CE-Chirp ASSR revealed a significantly smaller difference in threshold than conventional ASSR, a better correlation and better reliability. However, lower frequencies of NB CE-Chirp tended to be less reliable than higher frequencies. In part II , NB CE-Chirp revealed smaller threshold differences than conventional ASSR. Both correlation scores and reliability values were generally lower in the part II results. Conclusion NB CE-Chirp ASSR generally revealed more favorable outcomes. However, its reliability was reduced at lower frequencies and in patients with milder hearing loss.

We aimed to compare the treatment result between 6,000 and 12,000 pulses of low-frequency repetitive transcranial magnetic stimulation (rTMS) and to evaluate the correct location of rTMS in Korean brains compared with that of Caucasians.Controlled trial.Tertiary referral center.Fourteen patients with chronic essential tinnitus were treated with rTMS on the left auditory cortex (AC) and prefrontal cortex (FC). AC targets were determined using the 10-20 electroencephalographic (EEG) method proposed by Langguth in 2006. Six patients received a total of 6,000 pulses rTMS (AC, 1,000; FC, 1,000; 3-d course; Group 1), and eight patients were given 12,000 pulses (AC, 2,000; FC, 1,000; 4-d course; Group 2).Treatment results were assessed with pretreatment and posttreatment Tinnitus Handicap Inventory (THI) and self-rating Visual Analog Scale (VAS) of awareness, loudness, annoyance, and effect on daily life of tinnitus at 1, 2, 4, 8, and 12 weeks after treatment. Using the individual subject's magnetic resonance image and Neuronavigation System, the location of primary AC was determined and compared with that of the 10-20 method in four patients.There was no improvement of THI and VAS in Group 1. On the contrary, a substantial decrease of THI scores and VAS scores for awareness, loudness, and effect on daily life was observed in Group 2.Despite the small number of patients, a beneficial effect of rTMS on tinnitus suppression was found in the 12,000-pulse treatment group, whereas no effect was found in the 6,000-pulse treatment group. rTMS localization based on the 10-20 EEG method seems to be valid even in Koreans with a shorter anteroposterior skull diameter.

Aim: The LLLT was found to recover NIHL and ototoxicity induced hearing loss in rats but the optimal LLLT laser dosage to treat NIHL needs to be determined. The aim of this study was to find the optimal laser dosage to recover a NIHL with transmeatal-LLLT. Methods: Bilateral ears of rats were exposed to noise (narrow band noise, 120 dB, 16 kHz, 6 h). Left ears of the rats were irradiated with transmeatal-LLLT (830 nm) of 50, 100, 150, 200, 250, 300 mW for 60 minutes per day for 12 days, starting 1 day post induction of NIHL. Right ears were not irradiated and used as control ears. The hearing levels were measured at each frequency of 8, 12, and 32 kHz before the noise exposure, 1, 3, 8, and 12 days post noise exposure. The differences of hearing levels between left treated ear and right controlled ear at each frequency of different laser dosages (50 – 300 mW) were compared to see the most effective laser dosages to treat NIHL. Results: Hearing levels were most improved by 150 mW, slightly improved by 200 mW, not improved by 50 and 250 mW, and became worse by 300 mW. Conclusion: The results of this study suggest that most effective therapeutic laser dosage window to treat NIHL with transmeatal-LLLT was 150 mW for 12 days and it was not effective by 50, 250, and 300 mW.

This paper presents the development of a single platform that records auditory evoked potential synchronized to specific acoustic stimuli of the gap prepulse inhibition method for objective tinnitus diagnosis research. The developed system enables to program various parameters of the generated acoustic stimuli. Moreover, only by simple filter modification, the developed system provides high flexibility to record not only short latency auditory brainstem response but also late latency auditory cortical response. The adaptive weighted averaging algorithm to minimize the time required for the experiment is also introduced. The results show that the proposed algorithm can reduce the number of the averaging repetitions to 70% compared with conventional ensemble averaging method.

OBJECTIVE The aims of the study are to investigate the effect of hearing loss, age, and gender on the outcome of the cochlear hydrops analysis masking procedure (CHAMP) and to assess the clinical utility of CHAMP for the diagnosis of Meniere's disease (MD). STUDY DESIGN Prospective observational study. SETTING Otolaryngology department of a tertiary referral hospital. PATIENTS We recruited MD patients (MD, 12 subjects) and hearing loss patients (HL, 10 subjects). Control subjects (NC, 43 subjects) were matched for gender and age. INTERVENTION CHAMP was performed in the patients and control subjects. MAIN OUTCOME MEASURE The mean difference in latency between the wave V for the click alone response and wave V for the 0.5-kHz high-pass masking noise condition was compared among groups, and the effects of gender and age on the results were analyzed in the NC group. RESULTS Both the MD group and the HL group had a smaller difference in latency compared to the NC group. The MD group and HL group showed no significant difference in latency. In the NC group, there were no significant differences in latency depending on gender and age. CONCLUSIONS Hearing level seems to significantly affect the CHAMP results, making it unreliable to differentiate between MD patients and non-MD hearing loss patients. Therefore, the diagnostic value of CHAMP might be limited in MD.

Objective: To compare the quality of perilymphatic enhancement in the rat inner ear after intratympanic injection of two types of gadolinium with a 9.4-tesla micro-MRI. Materials and Methods: Gadolinium was injected into the middle ear in 6 Sprague-Dawley rats via the transtympanic route. The left ear was injected with Gd-DO3A-butrol first, and then the right ear was injected with Gd-DOTA. MR images of the inner ear were acquired 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4 h after intratympanic (IT) injection using an Agilent MRI system 9.4T/160/AS. The normalized signal intensity was quantitatively analyzed at the scala vestibuli (SV), scala media, and scala tympani (ST) using a Marosis M-view system. Then the normalized signal intensities (SIs) were compared between the two contrast agents. Results: For Gd-DO3A-butrol, the SI was as low as 1.0-1.5 throughout 1-4 h at the SV and ST of the basal turn. The maximum SI was 1.5 ± 0.5 at the SV (2 h) and 1.3 ± 0.5 at the ST (2 h). For Gd-DOTA, the 1-hour postinjection SI at the basal turn was 2.5 ± 0.5 at the SV, 1.6 ± 0.3 at the ST, and 1.2 ± 0.3 at the scala media. In the apical turn, the maximum SI was reached after 2.5 h. The maximum SI in the apical turn was 1.8 ± 0.4 at the SV (3.5 h), 1.8 ± 0.4 at the ST (4 h), and 1.4 ± 0.3 at the scala media (4 h). Conclusions: We were able to clearly visualize and separate the ST and SV using IT Gd and 9.4-tesla micro-MRI. We recommend using Gd-DO3A-butrol over Gd-DOTA and to perform the MRI 2.5 h after using IT Gd in the rat inner ear.

Prolonged deprivation of auditory input can change brain networks in pre- and postlingual deaf adults by brain-wide reorganization. To investigate morphological changes in these brains voxel-based morphometry, voxel-wise correlation with the primary auditory cortex, and whole brain network analyses using morphological covariance were performed in eight prelingual deaf, eleven postlingual deaf, and eleven hearing adults. Network characteristics based on graph theory and network filtration based on persistent homology were examined. Gray matter density in the primary auditor cortex was preserved in prelingual deafness, while it tended to decrease in postlingual deafness. Unlike postlingual, prelingual deafness showed increased bilateral temporal connectivity of the primary auditory cortex compared to the hearing adults. Of the graph theory-based characteristics, clustering coefficient, betweenness centrality, and nodal efficiency all increased in prelingual deafness, while all the parameters of postlingual deafness were similar to the hearing adults. Patterns of connected components changing during network filtration were different between prelingual deafness and hearing adults according to the barcode, dendrogram, and single linkage matrix representations, while these were the same in postlingual deafness. Nodes in fronto-limbic and left temporal components were closely coupled, and nodes in the temporo-parietal component were loosely coupled, in prelingual deafness. Patterns of connected components changing in postlingual deafness were the same as hearing adults. We propose that the preserved density of auditory cortex associated with increased connectivity in prelingual deafness, and closer coupling between certain brain areas, represent distinctive reorganization of auditory and related cortices compared with hearing or postlingual deaf adults. The differential network reorganization in the prelingual deaf adults could be related to the absence of auditory speech experience.

It is well established that ototoxic antibiotics and acoustic trauma can damage cochlear hair cells and cause hearing loss. Previous studies using transcanal LLLT (Low level laser therapy) showed that LLLT can promote recovery of hearing thresholds and cochlear hair cells. However, its mechanism has not been studied. Aim: The aim of this study is to investigate the mechanism of hearing recovery from gentamicin induced ototoxic hearing loss by LLLT. Methods: HEI- OC1 (House ear institute organ of Corti) cells were cultured for 18 hours and ototoxicity was induced by gentamicin (GM) treatment to the cells. Cultured cells were divided into 6 groups, No treatment control, LLLT only, GM 6.6 mM and GM 13.1 mM, GM 6.6 mM+LLLT and GM 13.1 mM+LLLT cells. LD laser 808 nm, 15 mW, was irradiated to the cultured cells for 15 min, at 4 hours after GM treatment to the cells. ATP was assayed using the ATP assay Kit. ROS was measured using confocal microscope after application of H2DCFDA dye. Results: ATP was decreased in GM 13.1 mM cells and increased in LLLT only cells and GM 13.1 mM+LLLT cells compared to control and 13.1 mM cells. ROS was increased in GM 6.6 mM and GM 13.1 mM cells, and decreased in GM 6.6 mM+LLLT and GM 13.1 mM+LLLT cells compared to GM 6.6 and 13.1 mM cells immediately after laser irradiation. Conclusion: This study demonstrated that LLLT on GM treated HEI-OC1 cells increased ATP and decreased ROS that may contribute to the recovery of hearing.

BACKGROUND AND OBJECTIVES Turner and colleagues introduced a new method that can detect tinnitus in animals. The stimulus is composed of a small background noise that is identical to the pitch of the tinnitus and a large pulse noise that can evoke a startle response. In normal rats, the gap decreases the startle reflex. However, in tinnitus rats, the gap does not decrease the startle reflex. The goal of this study was to optimize the stimulation paradigm so that the prepulse inhibition of N1-P2 amplitude would be maximized in the normal human subjects. SUBJECTS AND METHODS Seven normal control subjects without tinnitus were recruited. The stimulus was composed of two different sounds: the softer background noise and the louder pulse noise. A 50 msec silent gap was inserted before the pulse noise as the gap condition (G condition) but not in the no-gap condition (N condition). The averaged amplitude of the N1-P2 cortical response was recorded for the G and N conditions. RESULTS The G/N ratio was the smallest when the gap was 20 msec prior to the pulse noise. The G/N ratio was 84.8±16.8% with the Hanning window and 78.5±5.9% without the window. The G/N ratio was 91.1±24.9%, 78.0±5.4%, and 79.0±18.1% when the intensity of the background noise was 10, 20, and 32 dB SL, respectively. When the intensity of the background noise was 20 and 32 dB SL, the N1-P2 amplitude of the G condition was significantly smaller than that of the N condition. CONCLUSIONS The optimal stimulus should be composed of the 1 kHz pulse noise without Hanning window. The intensity of the background noise should be 20 dB HL and the location of the gap should be 20 msec prior to the pulse noise. It seems that with these optimized parameters we could expect a 78.0% inhibition of N1-P2 amplitude in normal subjects without tinnitus.

Aim: To develop a bilateral vestibulopathy animal model induced by gentamicin using RS rat and to see the effect of LLLT on this bilateral vestibulopathy model. Method: RS rats were divided into 3 groups, control group (C), laser group (L), and histology group (H). All animals in the 3 groups received gentamicin (GM) 110 mg/kg, intravenously once daily for 3 days. The animals underwent sinusoidal oscillation about a vertical axis before the GM injection, 1, 3, and 7 days post injections. Transcanal low level laser therapy (LLLT) was irradiated to left ear canal for 7 days, starting 1 day post the GM injection. The H group animals were irradiated into the left ear of L group for 3 days, starting 1 day post GM injections for 3 days. C and L groups were sacrifice on 9 th day and H group was sacrificed on 7 th day. Results: The gain of the C group was significantly decreased in 3 and 7 days. The gain of the right ear of L group was decreased significantly in 3 and 7 days. The gain of left ear of L group was decreased in 3 days post LLLT but the decreased gain was improved significantly comparing to the level of 7 days gain of right ear and it was much closer to the pre-GM level. The average number of cells in cupula of H group after laser treatment for 3 days was significantly lower in non laser treated right ear comparing to the laser treated left ear and ears of the normal rats. Conclusion: The present study demonstrated that LLLT restores vestibular function and vestibular hair cells in rats post gentamicin induced ototoxic damage. LLLT may have clinical implications in the treatment of various vestibular dysfunction. Further studies are essential to verify the exact mechanisms and the most effective application of LLLT to rescue vestibular dysfunction.

The aim of this study was to find out the effect of low-level laser therapy (LLLT) on salicylate-induced tinnitus in the rat model. Fourteen Sprague-Dawley rats (8 weeks; 240–280 gm) were divided into 2 groups (study group, control group). Rats of both groups were treated with 400 mg/kg/day of sodium salicylate for 8 consecutive days. Tinnitus was monitored using GPIAS (Gap Prepulse Inhibition of Acoustic Startle) 2 h after first salicylate treatment, and every 24 h during 9 days of treatment. Rats in laser group were irradiated to each ear with wavelength of 830 nm diode laser (165 mW/cm2) for 30 min daily for 8 days. During salicylate treatment, rats of study group irradiated with low level laser showed significantly higher GPIAS values throughout the experiment. Therapeutic effect of LLLT is demonstrated in animal tinnitus model by means of GPIAS. Further experimental studies are needed to find possible mechanisms and better methods to improve LLLT efficacy.