Hearing loss in beta-thalassaemia: An Italian multicentre case-control study.

BACKGROUND: Despite numerous studies, the true scenario of hearing loss in beta-thalassaemia remains rather nebulous. MATERIALS AND METHODS: Pure tone audiometry, chelation therapy, demographics and laboratory data of 376 patients (mean age 38.5 ± 16.6 years, 204 females, 66 non-transfusion-dependent) and 139 healthy controls (mean age 37.6 ± 17.7 years, 81 females) were collected. RESULTS: Patient and control groups did not differ for age (p = 0.59) or sex (p = 0.44). Hypoacusis rate was higher in patients (26.6% vs. 7.2%; p < 0.00001), correlated with male sex (32.6% in males vs. 21.8% in females; p = 0.01) and it was sensorineural in 79/100. Hypoacusis rate correlated with increasing age (p = 0.0006) but not with phenotype (13/66 non-transfusion-dependent vs. 87/310 transfusion-dependent patients; p = 0.16). Sensorineural-notch prevalence rate did not differ between patients (11.4%) and controls (12.2%); it correlated with age (p = 0.01) but not with patients' sex or phenotype. Among adult patients without chelation therapy, the sensorineural hypoacusis rate was non-significantly lower compared to chelation-treated patients while it was significantly higher compared to controls (p = 0.003). CONCLUSIONS: Sensorineural hypoacusis rate is high in beta-thalassaemia (about 21%) and it increases with age and in males while disease severity or chelation treatment seems to be less relevant. The meaning of sensorineural-notch in beta-thalassaemia appears questionable.

Binaural sound therapy for tinnitus treatment: A psychometric and neurophysiological evaluation.

INTRODUCTION: Tinnitus is an annoying buzz that manifests itself in many ways. In addition, it can provoke anxiety, stress, depression, and fatigue. The acoustic therapies have become the most commonly applied treatment for tinnitus, either self-administered or clinically prescribed. Binaural Sound Therapy (BST) and Music Therapy (MT) aim to reverse the neuroplasticity phenomenon related to tinnitus by adequately stimulating the auditory path-way. The goal of this research is to evaluate the feasibility of applying BST for tinnitus treatment by comparing its effect with MT effect. MATERIALS AND METHODS: 34 patients with tinnitus from 29 to 60 years were informed about the experimental procedure and consented their participation. Patients were divided into two groups: 1) MT and 2) BST. They applied their sound-based treatment for one hour every day along eight weeks. Each treatment was adjusted to Hearing Loss (HL) and tinnitus characteristics of each participant. To record EEG data, a bio-signal amplifier with sixteen EEG channels was used. The system recorded data at a sampling frequency of 256 Hz within a bandwidth between 0.1 and 100 Hz. RESULTS: The questionnaire-monitoring reported that MT increased tinnitus perception in 30% of the patients, and increased anxiety and stress in 8% of them. Regarding EEG-monitoring, major neural synchronicity over the frontal lobe was found after the treatment. In the case of BST reduced stress in 23% of patients. Additionally, BST reduced tinnitus perception similar to MT (15% of patients). With respect to EEG-monitoring, slightly major neural synchronicity over the right frontal lobe was found after the treatment. CONCLUSIONS: MT should be applied with caution since it could be worsening the tinnitus sufferer condition. On the other hand, BST is recommended for tinnitus sufferers who have side effects concerning stress but no anxiety.

Dietary fat intake and risk of disabling hearing impairment: a prospective population-based cohort study.

PURPOSE: To examine the associations of specific dietary fats with the risk of disabling hearing impairment in the UK Biobank study. METHODS: This cohort study investigated 105,592 participants (47,308 men and 58,284 women) aged ≥ 40 years. Participants completed a minimum of one valid 24-h recall (Oxford Web-Q). Dietary intake of total fatty acids, polyunsaturated fatty acids (PUFA), saturated fatty acids (SFA), and monounsaturated fatty acids (MUFA) was assessed at baseline. Functional auditory capacity was measured with a digit triplet test (DTT), and disabling hearing impairment was defined as a speech reception threshold in noise > - 3.5 dB in any physical exam performed during the follow-up. RESULTS: Over a median follow-up of 3.2 (SD: 2.1) years, 832 men and 872 women developed disabling hearing impairment. After adjustment for potential confounders, including lifestyles, exposure to high-intensity sounds, ototoxic medication and comorbidity, the hazard ratios (HRs), and 95% confidence interval (CI) of disabling hearing function, comparing extreme quintiles of intakes were 0.91 (0.71-1.17) for total fat, 1.09 (0.83-1.44) for PUFA, 0.85 (0.64-1.13) for SFA and 1.01 (0.74-1.36) for MUFA among men. Among women, HRs comparing extreme intakes were 0.98 (0.78-1.24) for total fat, 0.69 (0.53-0.91) for PUFA, 1.26 (0.96-1.65) for SFA, and 0.91 (0.68-1.23) for MUFA. Replacing 5% of energy intake from SFA with an equivalent energy from PUFA was associated with 25% risk reduction (HR: 0.75; 95% CI: 0.74-0.77) among women. CONCLUSIONS: PUFA intake was associated with decreased risk of disabling hearing function in women, but not in men.

Umbilical Cord Mesenchymal Stromal Cell-Derived Exosomes Rescue the Loss of Outer Hair Cells and Repair Cochlear Damage in Cisplatin-Injected Mice.

Umbilical cord-derived mesenchymal stromal cells (UCMSCs) have potential applications in regenerative medicine. UCMSCs have been demonstrated to repair tissue damage in many inflammatory and degenerative diseases. We have previously shown that UCMSC exosomes reduce nerve injury-induced pain in rats. In this study, we characterized UCMSC exosomes using RNA sequencing and proteomic analyses and investigated their protective effects on cisplatin-induced hearing loss in mice. Two independent experiments were designed to investigate the protective effects on cisplatin-induced hearing loss in mice: (i) chronic intraperitoneal cisplatin administration (4 mg/kg) once per day for 5 consecutive days and intraperitoneal UCMSC exosome (1.2 µg/µL) injection at the same time point; and (ii) UCMSC exosome (1.2 µg/µL) injection through a round window niche 3 days after chronic cisplatin administration. Our data suggest that UCMSC exosomes exert protective effects in vivo. The post-traumatic administration of UCMSC exosomes significantly improved hearing loss and rescued the loss of cochlear hair cells in mice receiving chronic cisplatin injection. Neuropathological gene panel analyses further revealed the UCMSC exosomes treatment led to beneficial changes in the expression levels of many genes in the cochlear tissues of cisplatin-injected mice. In conclusion, UCMSC exosomes exerted protective effects in treating ototoxicity-induced hearing loss by promoting tissue remodeling and repair.

Inferior collicular cells that project to the auditory thalamus are increasingly surrounded by perineuronal nets with age.

The age-related loss of GABA in the inferior colliculus (IC) likely plays a role in the development of age-related hearing loss. Perineuronal nets (PNs), specialized aggregates of extracellular matrix, increase with age in the IC. PNs, associated with GABAergic neurotransmission, can stabilize synapses and inhibit structural plasticity. We sought to determine whether PN expression increased on GABAergic and non-GABAergic IC cells that project to the medial geniculate body (MG). We used retrograde tract-tracing in combination with immunohistochemistry for glutamic acid decarboxylase and Wisteria floribunda agglutinin across three age groups of Fischer Brown Norway rats. Results demonstrate that PNs increase with age on lemniscal and non-lemniscal IC-MG cells, however two key differences exist. First, PNs increased on non-lemniscal IC-MG cells during middle-age, but not until old age on lemniscal IC-MG cells. Second, increases of PNs on lemniscal IC-MG cells occurred on non-GABAergic cells rather than on GABAergic cells. These results suggest that synaptic stabilization and reduced plasticity likely occur at different ages on a subset of the IC-MG pathway.

Resolved External Ophthalmoplegia and Hearing Loss in Wernicke's Encephalopathy With Thiamine Replacement.

BACKGROUND: Wernicke encephalopathy (WE) is classically described by a clinical triad consisting of confusion, ataxia, and ophthalmoplegia, but recent reports emphasize a history of malnutrition along with 2 elements of the WE triad (Caine's criteria) to enhance diagnostic sensitivity. The ophthalmoplegia, vestibular, and auditory expeditious improvement with intravenous thiamine usually confirms the diagnosis; serum levels generally provide additional diagnostic certainty. METHODS: Here, we discuss the case of a woman with a distant history of gastric sleeve, poor nutrition and protracted vomiting, who developed acute confusion, imbalance, near-total external ophthalmoplegia (EO), and hearing loss. The baseline thiamine level was 28 πmol/L (Normal: 70-180 πmol/L). We performed serial neurological, vestibular, and audiological examination to document over 5 days, the effect of intravenous (IV) thiamine, and again at 3 months with continued oral supplementation. We provide serial documentation with photographs and video recording of oculomotor abnormalities, audiometric testing, and a video of horizontal head impulse testing, and imaging findings. RESULTS: Over the course of 5 days of IV thiamine supplementation, we demonstrate our patient's resolution of near complete EO. We assessed vestibular paresis with horizontal head impulse testing, after complete resolution of the EO. The initially positive bilateral h-HIT showed decreased gain and overt corrective saccades, it clinically resolved by day 5, but video h-HIT testing demonstrated persistent decreased horizontal vestibulo-ocular reflex (VOR) gain and covert horizontal saccades, which persisted at the 3-month examination. By contrast, the vertical VOR gain was normal without corrective saccades. Bedside audiometry completed during the acute phase demonstrated severely restricted auditory speech comprehension, which normalized 3 months later. Severe truncal ataxia improved as well. CONCLUSIONS: This case is an example of how awareness of the variations in the clinical presentation of WE can be crucial in achieving an early diagnosis and obtaining better outcomes. A history of the poor nutritional status can be an important clue to aid in this early diagnosis.

Wernicke's encephalopathy-induced hearing loss complicating sleeve gastrectomy.

A 25-year-old woman brought to the hospital with symptoms of acute confusion, disorientation, diplopia, hearing loss and unsteady gait which started 4 days prior to her presentation with rapid worsening in its course until the day of admission. She had a surgical history of laparoscopic sleeve gastrectomy 2 months earlier which was complicated by persistent vomiting around one to three times per day. She lost 30 kg of her weight over 2 months and was not compliant to vitamin supplementation. CT of the brain was unremarkable. Brain MRI was done which showed high signal intensity lesions involving the bilateral thalamic regions symmetrically with restricted diffusion on fluid-attenuated inversion recovery imaging. Other radiological investigations, such as magnetic resonance venography and magnetic resonance angiography of the brain were unremarkable. An official audiogram confirmed the sensorineural hearing loss. A diagnosis of Wernicke's encephalopathy due to thiamin deficiency post-sleeve gastrectomy was made based on the constellation of her medical background, clinical presentation and further supported by the distinct MRI findings. Consequently, serum thiamin level was requested and intravenous thiamin 500 mg three times per day for six doses was started empirically, then thiamin 250 mg intravenously once daily given for 5 more days. Marked improvement in cognition, eye movements, strength and ambulation were noticed soon after therapy. She was maintained on a high caloric diet with calcium, magnesium oxide, vitamin D supplements and oral thiamin with successful recovery of the majority of her neurological function with normal cognition, strength, reflexes, ocular movements, but had minimal resolution of her hearing deficit. Serum thiamin level later was 36 nmol/L (67-200).

Broadband Sound Equalized by The Hearing Loss Curves as an Improved Stimulus for Tinnitus Retraining Therapy-A Pilot, Non-Controlled Observational Study.

OBJECTIVES: This study aimed to assess if a short tinnitus treatment, combining counseling with broadband noise filtered by the hearing loss curves, provided significant relief in tinnitus patients. MATERIALS AND METHODS: 25 tinnitus subjects of heterogeneous etiology were subjected to sound therapy, 1 hour per day, for 4 months. All of them underwent a unique initial counseling session aimed at undoing previous negative perceptions of tinnitus and highlighting the real expectations from tinnitus therapies. Customized stereo sound stimuli were designed by filtering broadband noise using the hearing loss curves of each ear. A monthly follow-up was carried out by assessing the severity of tinnitus through a validated Spanish version of the Tinnitus Handicap Inventory (THI). RESULTS: 88% (22 of 25) of the patients completing the treatment obtained significant relief after 4 months. After 4 months of treatment, the average decrease in THI from its initial value for the 22 successful participants was 29. CONCLUSION: The average THI score reduction after 4 months of treatment can be considered to be an excellent improvement when compared with other similar studies. The proposed customized sound therapy was effective in reducing tinnitus in patients of heterogeneous etiology.

Long-term residual hearing in cochlear implanted adult patients who were candidates for electro-acoustic stimulation.

PURPOSE: To evaluate the long-term hearing outcomes in cochlear implanted adults with residual hearing at low frequencies, and the proportion of patients using electro-acoustic stimulation (EAS). METHODS: A monocentric retrospective cohort study was performed in a tertiary referral center. Population demographics, surgical approach, pre- and postoperative hearing at low frequencies, in the implanted and contralateral ear, were recorded as well as duration of EAS use. The percentage hearing preservation was calculated according to the formula S (HEARRING group). RESULTS: In total, 63 adults (81 ears) with residual hearing underwent cochlear implantation with intent to use EAS processors. Six different types of electrode array were implanted. The mean pure tone audiometry (PTA) shift after cochlear implantation was 16 ± 15 dB HL (range 0-59 dB HL). Half of the implanted ears had minimal hearing preservation or total hearing loss (HL) at 5.5 years and the cumulative risk of total HL was 50% at 7 years. During the follow-up, total HL occurred in 22 ears. The decrease in hearing levels was similar in both implanted and contralateral ear during follow-up (ns, F = 2.46 ± 3, Linear Mixed Model (LMM)). Only 44 patients found a benefit from EAS at the first fitting. At the last visit, EAS processors were fitted in 30% of the cases. The pre- and postoperative mean PTA thresholds were not predictive of EAS use (Cox's proportional hazards analysis). CONCLUSIONS: Postoperative residual hearing was observed in 93% of implanted ears, but only half of them had an initial benefit from EAS. No predictive factors were found to influence the use of EAS processors.

Análise das emissões otoacústicas transitórias por banda de frequência em adolescentes com diabetes mellitus tipo 1 / Transient otoacoustic emissions analysis by frequency bands in adolescents with type 1 diabetes mellitus

Introdução: A associação entre perda auditiva e Diabetes Mellitus tipo 1 (DM1) é ainda pouco estudada. A perda auditiva é uma das complicações crônicas relacionadas ao grau de controle glicêmico, que os pacientes podem apresentar com a progressão da doença. Objetivo: Investigar o comprometimento auditivo por meio das emissões otoacústicas transitórias (EOAT) por banda de frequência em adolescentes com DM1 e relação com o controle glicêmico. Métodos: Foram incluídos 80 adolescentes, 50% do gênero masculino, entre 10 e 19 anos de idade: 40 com DM1 e 40 controles saudáveis, pareados por gênero e idade. Os dados clínicos e laboratoriais foram pesquisados nos prontuários médicos. O controle glicêmico foi avaliado por meio dos exames de hemoglobina glicada e os pacientes com DM1 analisados de acordo com o controle glicêmico. A avaliação auditiva foi realizada por meio da imitanciometria, audiometria, e posteriormente EOAT, em sala tratada acusticamente, pelo protocolo "TE Test" de clique não-linear (1 KHz a 4 kHz) a 80 dB NPS de intensidade (AuDX - Biologic). Resultados: As respostas às EOAT foram ausentes em 5,12% em pacientes com DM1, com diferença significativa em relação aos controles (p=0,04). A análise das EOAT por bandas de frequência mostrou maior proporção de alteração nos adolescentes com DM1 mal controlados quando comparados aos bem controlados, nas frequências de 1000Hz, 2000Hz e 3000Hz (p<0,05). Conclusão: As EOAT por bandas de frequência permitiram a identificação precoce de comprometimento auditivo em adolescentes com DM1 e mostraram associação entre DM1 mal controlado e perda auditiva. (AU)

Introduction: The association between hearing loss and type 1 diabetes mellitus (DM1) is still poorly studied. Hearing loss is one of the chronic complications related to the degree of glycemic control that patients may present with the progression of the disease. Objective: To investigate auditory impairment through transient otoacoustic emissions (TEOAE) by frequency band in adolescents with DM1 and in relation to glycemic control. Methods: Were included 80 adolescents, 50% males, between 10 and 19 years of age: 40 with DM1 and 40 healthy controls, matched by gender and age. Clinical and laboratory data were taken from the medical records. Glycemic control was evalueted by glycated hemoglobin and the patients with DM1 were analyzed according to glycemic control. To the auditory evaluation were used the immittance and audiometry, and the TEOAE. The test was performed in the acoustically treated room, the non-linear TE test protocol (1 KHz to 4 kHz) at 80 dB SPL (AuDX - Biologic ). Results: TEOAE responses were absent in 5.12% of patients with DM1, with a significant difference in relation to controls (p = 0.04). The analysis of TEOAE by frequency bands showed a higher proportion of alteration in adolescents with DM1 poorly controlled when compared to well controlled ones, in the frequencies of 1000Hz, 2000Hz and 3000Hz (p <0.05). Conclusion: TEOAE by frequency bands allowed the early identification of auditory impairment in adolescents with DM1 and showed an association between poorly controlled DM1 and hearing loss. (AU)

Cultivating resiliency in patients with neurofibromatosis 2 who are deafened or have severe hearing loss: a live­video randomized control trial.

INTRODUCTION: Patients with NF2 who are deaf or have significant hearing loss face numerous and unique challenges which lead to poor quality of life, and thus may benefit from resiliency programs. METHODS: We performed secondary data analyses on a single blind, randomized controlled trial of an 8 week mind-body resiliency program (the Relaxation Response and Resiliency program for Deaf NF2; d3RP-NF2) versus a health education control (Health Enhancement Program for Deaf NF2;dHEP-NF2) which showed improvement in quality of life (Funes in JAMA 2019, https://doi.org/10.1007/s11060-019-03182-3). Here we report on improvements in resiliency factors (i.e. optimism, gratitude, perceived social support, mindfulness, and perceived coping abilities) assessed at baseline, post-test and 6-month follow-up. Both programs were delivered via Skype using Communication Access Real-Time Translation. RESULTS: Patients who were randomized to the d3RP-NF2 program exhibited significant improvements from baseline to post-program in gratitude (Mdifference = 4.04, 95% CI 1.58-6.50; p = 0.002), perceived social support (Mdifference = 16.36, 95% CI 9.20-23.51; p < 0.001), mindfulness (Mdifference = 4.02, 95% CI 1.10-6.94; p = 0.008), perceived coping (Mdifference = 15.25, 95% CI 10.21-20.28; p < 0.001), and a non-significant trend of improvement in optimism (Mdifference = 1.15, 95% CI -0.14-12.44; p = 0.079). These improvements were all maintained through the 6-month follow up. Improvements in perceived coping (Mdifference = 12.34, 95% CI 4.75-19.93; p = 0.002), social support (Mdifference = 13.11, 95% CI 2.19-24.03; p = 0.02), and gratitude (Mdifference = 4.59, 95% CI 0.83-8.36; p = 0.018) were over and above the changes observed in those randomized to dHEP-NF2. CONCLUSION: The d3RP-NF2 sustainably improves multiple dimensions of resiliency. Promoting resiliency may be of utmost importance for this uderserved population.

Acupuncture for hearing loss after traumatic brain injury: A protocol for systematic review of randomized controlled trial.

BACKGROUND: This study aims to systematically assess the effectiveness and safety of acupuncture on hearing loss (HL) after traumatic brain injury (TBI). METHODS: In this study, the following databases will be retrieved from inception up to the May 1, 2019: PUBMED, EMBASE, Cochrane Library, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database. All databases will be retrieved without any language restrictions. Two reviewers will independently carry out article selection, data collection, and risk of bias evaluation. Any disagreements will be solved by a third reviewer through discussion. RESULTS: This study will systematically investigate the effectiveness and safety of acupuncture for treating HL after TBI through evaluating HL assessment, hearing threshold, quality of life, and adverse events. CONCLUSION: The expected findings of this study will provide latest evidence for assessing the effectiveness and safety of acupuncture for HL after TBI. ETHICS AND DISSEMINATION: This study is supposed to be published in a peer-reviewed journal. No ethical approval is needed because this study will based on the literature analysis, but not the individual patient. PROSPERO REGISTRATION NUMBER: PROSPERO CRD42019133417.

Associations of Dietary Riboflavin, Niacin, and Retinol with Age-related Hearing Loss: An Analysis of Korean National Health and Nutrition Examination Survey Data.

Because age-related hearing loss (ARHL) is irreversible, prevention is very important. Thus, investigating modifying factors that help prevent ARHL is critical for the elderly. Nutritional status or nutritional factors for the elderly are known to be associated with many problems related to aging. Emerging studies suggest that there was the interaction between nutrition and ARHL. We aimed to investigate the possible impact of dietary nutrients on ARHL using data from the fifth Korean National Health and Nutrition Examination Survey (KNHANES) which included 4742 subjects aged ≥ 65 years from 2010 to 2012. All participants underwent an otologic examination, audiologic evaluation, and nutritional survey. The associations between ARHL and nutrient intake were analyzed using simple and multiple regression models with complex sampling adjusted for confounding factors, such as BMI, smoking status, alcohol consumption, and history of hypertension and diabetes. Higher intake groups of riboflavin, niacin and retinol was inversely associated with ARHL prevalence (riboflavin aOR, 0.71; 95% CI, 0.54-0.94; p = 0.016, niacin aOR, 0.72; 95% CI, 0.54-0.96; p = 0.025, retinol aOR 0.66; 95% CI, 0.51-0.86; p = 0.002, respectively). Our findings suggest the recommended intake levels of riboflavin, niacin, and retinol may help reduce ARHL in the elderly.

Neuromuscular electrical stimulation on hearing loss caused by skull base fracture: A protocol for systematic review of randomized controlled trial.

BACKGROUND: This systematic review aims to investigate the effectiveness and safety of neuromuscular electrical stimulation (NMES) on hearing loss (HL) caused by skull base fracture (SBF). METHODS: We will retrieve the following electronic databases of Cochrane Library, PUBMED, EMBASE, Cumulative Index to Nursing and Allied Health Literature, Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database from the inception to January 1, 2019 for relevant RCTs of NMES for HL caused by SBF. Two experienced authors will independently perform the study selection, data extraction, and methodology quality assessment. A 3rd author will solve any disagreements between 2 authors through discussion. RESULTS: This study will provide a high-quality synthesis of latest evidence of NMES for HL caused by SBF from comprehensive assessments, including hearing loss evaluation, hearing threshold, quality of life, and any relevant adverse events. CONCLUSION: The expected results of this systematic review will provide the up-to-date evidence to assess the effectiveness and safety of NEMS for patients with HL caused by SBF. ETHICS AND DISSEMINATION: The results of this study will be disseminated through publication in a peer-reviewed journal or will be presented at an associated conference meeting. This study will not use individual patient data, thus, the ethical approval is not needed. PROSPERO REGISTRATION NUMBER: PROSPERO CRD42019120195.

Oral administration of an herbal medicine to prevent progressive hearing loss in a mouse model of diabetes.

OBJECTIVE: Tsumura Suzuki Obese Diabetes (TSOD) mice exhibit early age-associated hearing loss. Histopathological analysis of these mice shows narrowing of capillaries in the stria vascularis and chronic reduction of blood flow in the cochlea. In this study, we investigated the effect of oral administration of a herbal medicine or calorie restriction on hearing in TSOD mice. METHODS: TSOD mice were divided into 4 groups: CR (calorie restriction), BF and DS (treated with the herbal medicines, Bofutsushosan and Daisaikoto, respectively), and the control group. Body weight, blood glucose levels, and auditory brainstem responses (ABRs) were measured. The cochleae were excised and evaluated histopathologically. RESULTS: Blood glucose levels were suppressed in the CR, BF, and DS groups. In addition, the elevation of ABR thresholds was inhibited in the CR, BF, and DS groups. Cochlear blood vessels remained wide in the three treatment groups compared with the control group. These results suggested that the administration of these herbal medicines improved glucose tolerance and yielded results similar to those on calorie restriction. CONCLUSION: Oral administration of 2 herbal medicines can prevent hearing function disorder in a model mouse of diabetes. The results may clarify the possibility of clinical application.

Is There a Safe Level for Recording Vestibular Evoked Myogenic Potential? Evidence From Cochlear and Hearing Function Tests.

OBJECTIVE: There is a growing concern among the scientific community about the possible detrimental effects of signal levels used for eliciting vestibular evoked myogenic potentials (VEMPs) on hearing. A few recent studies showed temporary reduction in amplitude of otoacoustic emissions (OAE) after VEMP administration. Nonetheless, these studies used higher stimulus levels (133 and 130 dB peak equivalent sound pressure level [pe SPL]) than the ones often used (120 to 125 dB pe SPL) for clinical recording of VEMP. Therefore, it is not known whether these lower levels also have similar detrimental impact on hearing function. Hence, the present study aimed at investigating the effect of 500 Hz tone burst presented at 125 dB pe SPL on hearing functions. DESIGN: True experimental design, with an experimental and a control group, was used in this study. The study included 60 individuals with normal auditory and vestibular system. Of them, 30 underwent unilateral VEMP recording (group I) while the remaining 30 did not undergo VEMP testing (group II). Selection of participants to the groups was random. Pre- and post-VEMP assessments included pure-tone audiometry (250 to 16,000 Hz), distortion product OAE, and subjective symptoms. To simulate the time taken for VEMP testing in group I, participants in group II underwent these tests twice with a gap of 15 minutes. RESULTS: No participant experienced any subjective symptom after VEMP testing. There was no significant interear and intergroup difference in pure-tone thresholds and distortion product OAE amplitude before and after VEMP recording (p > 0.05). Furthermore, the response rate of cervical VEMP was 100% at stimulus intensity of 125 dB pe SPL. CONCLUSIONS: Use of 500 Hz tone burst at 125 dB pe SPL does not cause any temporary or permanent changes in cochlear function and hearing, yet produces 100% response rate of cervical VEMP in normal-hearing young adults. Therefore, 125 dB pe SPL of 500 Hz tone burst is recommended as safe level for obtaining cervical VEMP without significantly losing out on its response rate, at least in normal-hearing young adults.

Hidden hearing loss in patients with Charcot-Marie-Tooth disease type 1A.

The aim of this study was to investigate hidden hearing loss in patients with Charcot-Marie-Tooth disease type 1 A (CMT1A), a common inherited demyelinating neuropathy. By using pure-tone audiometry, 43 patients with CMT1A and 60 healthy controls with normal sound detection abilities were enrolled. Speech perception in quiet and noisy backgrounds, spectral ripple discrimination (SRD), and temporal modulation detection (TMD) were measured. Although CMT1A patients and healthy controls had similar pure-tone thresholds and speech perception scores in a quiet background, CMT1A patients had significantly (p < 0.05) decreased speech perception ability in a noisy background compared to controls. CMT1A patients showed significantly decreased temporal and spectral resolution (both p < 0.05). Also, auditory temporal processing of CMT1A patients was correlated with speech perception in a noisy background (r = 0.447, p < 0.01) and median motor conduction velocity (r = 0.335, p < 0.05). Therefore, we assumed that demyelination of auditory nerve in CMT1A causes defective cochlear neurotransmission, which reduces temporal resolution and speech perception in a noisy background. Because the temporal resolution test was well correlated with the degree of demyelination in auditory and peripheral motor nerves, temporal resolution testing could be performed as an additional marker for CMT1A.

Tinnitus and temporary hearing loss result in differential noise-induced spatial reorganization of brain activity.

Loud noise frequently results in hyperacusis or hearing loss (i.e., increased or decreased sensitivity to sound). These conditions are often accompanied by tinnitus (ringing in the ears) and changes in spontaneous neuronal activity (SNA). The ability to differentiate the contributions of hyperacusis and hearing loss to neural correlates of tinnitus has yet to be achieved. Towards this purpose, we used a combination of behavior, electrophysiology, and imaging tools to investigate two models of noise-induced tinnitus (either with temporary hearing loss or with permanent hearing loss). Manganese (Mn2+) uptake was used as a measure of calcium channel function and as an index of SNA. Manganese uptake was examined in vivo with manganese-enhanced magnetic resonance imaging (MEMRI) in key auditory brain regions implicated in tinnitus. Following acoustic trauma, MEMRI, the SNA index, showed evidence of spatially dependent rearrangement of Mn2+ uptake within specific brain nuclei (i.e., reorganization). Reorganization of Mn2+ uptake in the superior olivary complex and cochlear nucleus was dependent upon tinnitus status. However, reorganization of Mn2+ uptake in the inferior colliculus was dependent upon hearing sensitivity. Furthermore, following permanent hearing loss, reduced Mn2+ uptake was observed. Overall, by combining testing for hearing sensitivity, tinnitus, and SNA, our data move forward the possibility of discriminating the contributions of hyperacusis and hearing loss to tinnitus.

Cannula-based drug delivery to the guinea pig round window causes a lasting hearing loss that may be temporarily mitigated by BDNF.

Sustained local delivery of drugs to the inner ear may be required for future regenerative and protective strategies. The round window is surgically accessible and a promising delivery route. To be viable, a delivery system should not cause hearing loss. This study determined the effect on hearing of placing a drug-delivery microcatheter on to the round window, and delivering either artificial perilymph (AP) or brain-derived neurotrophic factor (BDNF) via this catheter with a mini-osmotic pump. Auditory brainstem responses (ABRs) were monitored for 4 months after surgery, while the AP or BDNF was administered for the first month. The presence of the microcatheter - whether dry or when delivering AP or BDNF for 4 weeks - was associated with an increase in ABR thresholds of up to 15 dB, 16 weeks after implantation. This threshold shift was, in part, delayed by the delivery of BDNF. We conclude that the chronic presence of a microcatheter in the round window niche causes hearing loss, and that this is exacerbated by delivery of AP, and ameliorated temporarily by delivery of BDNF.