Types Of Sensorineural Hearing Loss Research Articles

Внезапная односторонняя сенсоневральная тугоухость. Анализ заболевания

Sudden sensorineural hearing loss is still a difficult task for many specialists, not only due to the fact that in most cases the cause of the disease cannot be identified but also due to the lack of effective methods of treatment and rehabilitation. Objective. To assess the etiology, prevalence, structure, and gender aspects of sudden single-sided sensorineural hearing loss. Material and methods. A retrospective review of outpatient records to identify patients with single-sided sudden sensorineural hearing loss for subsequent detailed analysis of the data obtained. The main inclusion criteria were age over 18 years, single-sided hearing loss with perception thresholds corresponding to the IV degree of hearing loss/deafness (according to the unified WHO classification, 1997), sensorineural type of hearing loss, and sudden onset of the disease. Results. A study group was formed consisting of 82 patients with sudden single-sided sensorineural hearing loss. An analysis was made of the main etiological factors, prevalence, structure, and gender aspects of this pathological condition. Conclusions. It was found that sudden unilateral SNT is diagnosed on average in 3.2% of cases, is predominantly idiopathic in nature, manifests itself in the 4th–5th decade of life, has no gender differences, but is characterized by a more frequent lesion of the left ear.

Hubungan tingkat intensitas bunyi dengan penurunan daya dengar pekerja

Abstract
 Noise is unwanted sound that can cause health problems and environmental comfort at a certain level and time. Noise Induced Hearing Loss (NHL) is a type of sensorineural hearing loss caused by exposure to sufficient/loud noise over a long period of time. This study was conducted to determine the effect of noise on the hearing of workers working in the Ground Handling area of ​​Samarinda airport, to determine the noise level received by workers in the Airport Ground Handling Area, and to know the importance of using PPE on the hearing of workers while doing work. The noise measurement method is measuring at predetermined points using a Sound Level Meter. Then, it was continued by measuring the hearing level of workers in a soundproof room alternately using audiometry, then a correlation test was carried out to determine the relationship between the two variables, namely noise and the hearing level of workers. Based on the results of the study, it is known from the results of the average hearing that has been correlated with total noise exposure in the work area, it can be seen that the hearing level of workers is decreasing over time, this is due to the amount of noise exposure received by workers during work activities.

Characteristics of Hearing Impairment in Children Aged Six Months to Two Years with Global Developmental Delay

Introduction: Children with global developmental delay (GDD) are at greater risk to have hearing impairments. These impairments interfere with developmental progress or rehabilitation effects. Hearing impairments may be correctable and if so, may improve developmental outcomes. We aimed to study the incidence, characteristics and probable risk factors of hearing impairment in children aged six months to two years with GDD. Methods: In this prospective study, an auditory evaluation was carried out by a trained audiologist in children with GDD. Transient evoked otoacoustic emissions (TEOAE) and brainstem auditory evoked response (BERA) were assessed in these children. Hearing loss was classified based on Goodmann's classification. Results: Of 113 children with GDD assessed, hearing impairment was identified in 35 (30.9%) children. Of 35 children, 22 (62.8%) had isolated sensorineural hearing loss (SNHL). Conductive hearing loss was identified in four (11.5%) and combined hearing loss in nine (25.7%). Of 31 children with SNHL, hearing loss was bilateral in 25 (80.6%). In SNHL, hearing loss was profound in one (3.2%), severe in 14 (45%), moderately severe in three (9.6%), and moderate in five (16.2%). Hearing impairment was associated with 31.7% (20/63) children with cerebral palsy. Kernicterus was another predominant risk factor associated with SNHL. Metabolic disorders, otitis media, tuberous sclerosis, and metachromatic leukodystrophy were other conditions associated with hearing impairment. Conclusions: Hearing impairment is accompanied by about a third of children with GDD. The hearing impairment in children with GDD tends to severe SNHL type in about 45% and bilateral in about 80%.

Inner Ear Symptoms Are Prevalent in Patients with High Head Abbreviated Injury Scale Scores after Blunt Head Trauma

Introduction: The purpose of this article was to determine the prevalence of inner ear symptoms in patients with blunt head trauma and to explore whether the severity of head trauma was associated with the incidence of such symptoms. Methods: We performed a retrospective review of 56 patients admitted with blunt head trauma who underwent audiovestibular evaluation within 1 month after injury. Two scales were used to measure the severity of trauma; these were the Glasgow Coma Scale (GCS) and the Head Abbreviated Injury Scale (H-AIS). Patients with sensorineural-type hearing loss, or dizziness with nystagmus, were considered to have inner ear symptoms. Results: About half of all patients (45%) with blunt head trauma showed trauma-related inner ear symptoms. Patients with inner ear symptoms were significantly more likely to have H-AIS scores ≥4 than those without inner ear symptoms (p = 0.004), even without concomitant temporal bone fracture (p > 0.05). Also, patients with inner ear symptoms required a statistically significantly longer time (measured from admission) before undergoing their ontological evaluations than did those without such symptoms (p = 0.002), possibly due to prolonged bed rest and use of sedatives. Conclusion: Thus, detailed history-taking and early evaluation using trauma scales are essential for all patients suffering from severe head trauma. It may be necessary to initiate early treatment of traumatic inner ear diseases.

Sensorineural Hearing Loss as the Prominent Symptom in Meningeal Carcinomatosis.

Sensorineural hearing loss (SNHL) has been reported rarely in patients with meningeal carcinomatosis (MC). We summarized the clinical data of eight MC patients with SNHL and 35 patients reported from publications. In the eight patients with SNHL, the medium onset age was 48 (range from 37 to 66) years and six (75%) were male. Seven (87.5%) suffered from headaches as the initial symptom, and they experienced SNHL during the first two months after the occurrence of headaches (0.5 to 2 months, average 1.5 months). The audiogram configuration was flat in three patients (37.5%) and showed total deafness in five patients (62.5%). The damage of cranial nerves VI (abducens) was observed in six patients (75%), and four patients (50%) had cranial nerves VII (facial) injury during the disease course. The percentage of damage of cranial nerves was higher than the patients without SNHL (VIth, 75.0% vs. 13.3%, p = 0.002 and VIIth 50.0% vs. 6.7%, p = 0.012). Four (50%) patients suffered from lung adenocarcinoma as primary tumor, two (25%) experienced stomach adenocarcinoma, one had colon cancer, and one patient was unknown. The symptom of SNHL improved after individualized therapy in four patients (focal radiotherapy and chemotherapy for three patients and whole brain radiotherapy for one patient), but all passed away from 2 to 11 months after diagnosis. Total deafness and flat hearing loss in audiogram were the common types of SNHL resulting from MC. MC patients with SNHL were more likely to suffer from the damage of other cranial nerves, especially to cranial nerves VI and VII. Treatment might improve SNHL, but not improve the case fatality rate.

Sudden Sensorineural Hearing Loss: A Guide to Causes, Treatment, Problems, and Coping Strategies

Sudden Sensorineural Hearing Loss: A Guide to Causes, Treatment, Problems, and Coping Strategies Christine Isley-Farmer (bio) CARE OF THE PROFESSIONAL VOICE Acomprehensive description of the various types of hearing loss singers can experience, authored by Drs. Amanda Hu and Robert Sataloff, appears in an earlier issue of the Journal of Singing. In it, the following types of hearing loss are discussed: Conductive (CHL), Sensorineural (SNHL), Mixed (MHL), and Occupational (OHL).1 Sudden Sensorineural Hearing Loss (SSNHL) is a designated type of Sensorineural Hearing Loss (SNHL). This article discusses the definition of SSNHL, causes, treatment, problems resulting from SSNHL onset, and coping strategies during treatment and after treatment. Portions of the article are written from a personal perspective, since I was diagnosed with SSNHL in January 2015 and treated until March 2015. DEFINITION OF SSNHL Unlike many cases of hearing loss that progress over a span of time, SSNHL can manifest within a matter of seconds or progress over several days. Incidence of SSNHL is estimated to be 1 in 5,000 Americans each year.2 Any age group can be affected, but incidence seems to be higher in the fifth and sixth decades of life.3 Onset manifests unilaterally in most cases; bilateral or simultaneous bilateral onset is infrequent.4 Associated symptoms with SSNHL onset are tinnitus (ringing in the ear), aural fullness (plugged ear), and vertigo (dizziness). Loss can be frequency range and pantonal.5 Considered an ear emergency, SSNHL requires early intervention. Patients with this condition have a short window to begin treatment. Delaying treatment for longer than two to four weeks after onset results in irreversible hearing loss.6 In my case, SSNHL onset occurred while practicing singing. Sound in the left ear suddenly became muffled. Inserting a wax solvent into the ear several times did not resolve the plugged feeling by the following morning. Believing there might be embedded wax or water in the ear, I went to a walk-in clinic. Blood pressure had spiked to 150, which was abnormal for me. The nurse said she saw a bit of fluid in the ear but no wax. She prescribed a nasal spray and a course of prednisone in case of infection. I was scheduled to judge a competition for the next two days. During the competition, which was over a weekend, [End Page 75] there was no improvement in hearing. Stressing that hearing had suddenly changed and not returned despite treatment, I was able to get an appointment with an ENT on the fifth day after SSNHL onset. The audiometry results (Figure 1) show speech discrimination as 100% in the right ear. Left ear speech discrimination is 12%. Loss of hearing in the left ear is diagnosed as severe to moderately severe at 90+dB. CAUSES OF SSNHL In a research study of SSNHL published in 2010, researchers divided into two research groups. The first group examined 23 articles in which multiple etiologies (causes) were identified; the majority were idiopathic (unknown cause). The second group evaluated SSNHL patients with specific diagnostic tests. The results revealed 71% of the cases to be idiopathic. Other diagnoses ranged from 2.2% to 12.8%, with infectious disease having the highest percentage after idiopathic. Attempts to pinpoint a specific cause or causes for SSNHL in this study remained unconfirmed.7 Since most causes of SSNHL onset are generally idiopathic, patients may undergo screenings and/or treatment for several possible disorders. They are as follows: viral ear infection, vascular impairment, autoimmune disease, inner ear problems, and central nervous system abnormalities. In the latter, an MRI is the most useful method for identifying temporal bone or intracranial pathology when SSNHL is the primary symptom.8 I was referred to a rheumatologist for testing for autoimmune disease and underwent an MRI after SSNHL diagnosis. SSNHL studies at Radebeul Hospital in Germany from January 2004 to December 2009 led to an interesting discovery. Of 489 SSNHL patients with a male to female ratio of 1:1.24, a slight predominance of left side hearing loss in female as opposed to male patients was discovered. Although the cause was unclear, researchers proposed the slight predominance of sudden deafness in the left ear...

COVID-19 caused hearing loss.

PurposeThe objective of this cross-sectional study was to determine if there is a potential link between COVID-19 infection and hearing loss.MethodsThe prospective study was conducted in the COVID Hospital Clinical Centre Niš, Serbia. We performed tonal audiometry and used a custom questionnaire and medical histories to determine the incidence of hearing loss in COVID-19 positive patients.ResultsThere were 74 patients with COVID-19 that met the inclusion criteria of this study and they composed our experimental group. Fifty-four (73%) were men and 20 (27%) women. There were 30 (40.5%) patients with hearing loss. Seventeen patients had unilateral and 13 had bilateral hearing loss. Significant differences between hearing loss groups and control group were found across all age groups, but not at all frequencies. No important differences were found when unilateral hearing loss and bilateral hearing loss groups were compared. There were no significant differences in distributions of comorbidities between the patients with hearing loss and normal hearing patients.ConclusionsWe found that 30 (40.5%) of the COVID-19 positive patients had sensorineural type of hearing loss. Across all age groups, there were statistically significant differences in frequencies between the COVID-19 positive patients and the control group. There were no significant differences in distributions of comorbidities between the patients with hearing loss and normal hearing patients. Distribution of unilateral and bilateral hearing loss and audiogram types was also not significantly different between the age groups.

Hearing Impairment with Hypertention and Diabetes Melitus Type2 on Cronic Kidney Disease with Hemodialysis

Background: Sensorineural-type hearing loss can occur in people who have chronic kidney disease (CKD) and with hemodialysis treatment. Sensorineural-type hearing loss is a hearing loss that occurs due to damage to the cochlear and the 8th cranial nerve. Hearing loss in CKD undergoing HD can occur at both high and low frequencies. Purposed: The aimed of this study was find out incidence of hearing loss and correlation of Hearing Impairment between Risk Factors Hypertention and Diabetes Melitus Type 2 in CKD patients with hemodialysis treatment. Methods: This study was observational analytics. The sample examined in this study were all CKD patient with hemodialysis treatment based criteria study. The hearing impairment were examined using audiometry. For statistic test using Spearman correlation test with significance level p = 0.05. Results: Fifteen patients (28.8%) with normal hearing. Patients who experience hearing loss as many as 37 patients (71.1%). Most of them were mild degree hearing loss, 29 patients (55.8%). Six patients (11.5%) were moderate hearing loss, and two patients (3.8%) were moderate hearing loss. Based on the results of the Spearman rho test showed that p=0.602 for hypertention and DM type 2 was p= 0.102 Conclusion: There was no correlation of hearing impairment between risk factors Hypertention and DM type 2 in CKD patients with hemodialysis treatment.

Nox3-Derived Superoxide in Cochleae Induces Sensorineural Hearing Loss.

Reactive oxygen species (ROS) produced by NADPH oxidases (Nox) contribute to the development of different types of sensorineural hearing loss (SNHL), a common impairment in humans with no established treatment. Although the essential role of Nox3 in otoconia biosynthesis and its possible involvement in hearing have been reported in rodents, immunohistological methods targeted at detecting Nox3 expression in inner ear cells reveal ambiguous results. Therefore, the mechanism underlying Nox3-dependent SNHL remains unclear and warrants further investigation. We generated Nox3-Cre knock-in mice, in which Nox3 was replaced with Cre recombinase (Cre). Using Nox3-Cre;tdTomato mice of either sex, in which tdTomato is expressed under the control of the Nox3 promoter, we determined Nox3-expressing regions and cell types in the inner ear. Nox3-expressing cells in the cochlea included various types of supporting cells, outer hair cells, inner hair cells, and spiral ganglion neurons. Nox3 expression increased with cisplatin, age, and noise insults. Moreover, increased Nox3 expression in supporting cells and outer hair cells, especially at the basal turn of the cochlea, played essential roles in ROS-related SNHL. The extent of Nox3 involvement in SNHL follows the following order: cisplatin-induced hearing loss > age-related hearing loss > noise-induced hearing loss. Here, on the basis of Nox3-Cre;tdTomato, which can be used as a reporter system (Nox3-Cre+/−;tdTomato+/+ and Nox3-Cre+/+;tdTomato+/+), and Nox3-KO (Nox3-Cre+/+;tdTomato+/+) mice, we demonstrate that Nox3 inhibition in the cochlea is a promising strategy for ROS-related SNHL, such as cisplatin-induced HL, age-related HL, and noise-induced HL.SIGNIFICANCE STATEMENT We found Nox3-expressing regions and cell types in the inner ear, especially in the cochlea, using Nox3-Cre;tdTomato mice, a reporter system generated in this study. Nox3 expression increased with cisplatin, age, and noise insults in specific cell types in the cochlea and resulted in the loss (apoptosis) of outer hair cells. Thus, Nox3 might serve as a molecular target for the development of therapeutics for sensorineural hearing loss, particularly cisplatin-induced, age-related, and noise-induced hearing loss.

An Observational Study to Compare Prevalence and Demography of Sensorineural Hearing Loss Among Military Personnel and Civilian Population.

To evaluate the pattern of sensorineural hearing loss (SNHL) in patients attending ENT OPD in a military setup as well as to compare the incidence of hearing loss in Military Personnel with civilian population. This observational cross sectional comparative study was conducted over a period of April 2018 to July 2019. A total of 300 patients with hearing loss (HL) were included. Demographic characteristics along with laterality of sensorineural hearing impairment were compared between military personnel and civilians. Data was statistically compared between civilians and military personnel. A P-value of < 0.05 was considered statistically significant. We report an overall prevalence of 3.78% SNHL in the ENT OPD. Specifically the prevalence of SNHL among military personnel was 2.17% and in civilian population was 4.83% (P < 0.0001). The mean age of the military personnel was significantly less than civilians (62.53 ± 10.03 vs 65.98 ± 12.46, P = 0.003). There were 68% Males and 32% females. Significantly higher number of males were present in military group as all participants were males (100% vs 58.62%, P < 0.0001). There was no significant difference in the laterality of SNHL between Military personnel and the civilian population with bilateral involvement being common in both populations. It can be concluded that bilateral SNHL type is the most common type of hearing impairment among military personnel as well as civilians complaining of HL. Males of 51-70years are most affected with SNHL.

Causes and Types of Sensorineural Hearing Loss. Clinical Manifestations and Basic Principles of Treatment

Sensorineural hearing loss is a disorder associated with the damage to the inner ear structures: the cochlea (cortical organ), dysfunctioning of the vestibule-cochlear nerve or the central part of the auditory analyser (brain stem and cortical representation of the cortical temporal lobe). In recent years, there has been a steady increase in ensorineural hearing loss patients; they account for ca. 70% among the total patients with impaired hearing. The disease has numerous causes and a complex pathogenesis. Among the main factors contributing to hearing loss are genetic predisposition, perinatal pathology, including hypoxia at childbirth, exposure to infectious and toxic agents and metabolic disorders, injuries (mechanical, acoustic and altitude trauma). Vascular-rheological disorders in the vertebro-basilar system play an important part because blood is supplied to the inner ear from the anterior inferior cerebellar artery. There are sudden, acute and chronic sensorineural hearing loss. The ensorineural hearing loss isdiagnosed by examinations that allow to verify the diagnosis and to determine the sound analyser damage level. This complex includes audiometric examinations, including the tuning fork examination, speech audiometry, and acoustic impedancemetry. If necessary, ultrasound Doppler imaging of the main blood vessels of the brain, computed tomography of the temporal bones, and MRI of the brain are prescribed. The pattern of comprehensive treatment should include, first of all, the elimination of the disease cause and anti-hypoxic drugs, anti-oxidants and a number of physiotherapy procedures.

Score of Hearing Handicap Inventory for the Elderly (HHIE) Compared to Whisper Test on Presbycusis.

Presbycusis is a sensorineural type of hearing loss caused by a degenerative process of the hearing organ. Examination was done to detect hearing loss, with Audiometry as the diagnostic gold standard and screening with whisper test and using Hearing Handicap Inventory for the Elderly-Screening (HHIE-S) questionnaire. This study was aimed to compare the sensitivity and specificity between Hearing Handicap Inventory for the Elderly Screening questionnaire score and Whisper test in hearing loss of presbycusis patients in Dr. Soetomo Hospital. Subjects were elderly patients in outpatient clinic of Geriatry and Audiology of Dr. Soetomo General Hospital in Surabaya. Data samples were collected by consecutive sampling. All collected samples were analyzed statistically by Pearson correlation test to identify the correlation between variables. Results: Statistic analysis with Pearson correlation test obtained p-value = 0.001 and correlation coefficient (r) = 0.691 for HHIE-S questionnaire and p = 0.001 and (r) = 0.298 for Whisper test. The sensitivity of the Whisper test was 72.73% while the HHIE-S questionnaire was 61.82%. Both tests had the same specificity of 80%. Conclusions: The Whisper test is more sensitive than HHIE-S questionnaires in detecting hearing loss in presbycusis patients in outpatient clinic of Geriatry and Audiology of Dr. Soetomo General Hospital in Surabaya.

Hearing impairment in patients of hypothyroidism in sub Himalayan region

&lt;p class="abstract"&gt;&lt;strong&gt;Background:&lt;/strong&gt; The objective of the study was to assess the hearing impairment in patients of hypothyroidism.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Methods:&lt;/strong&gt; A prospective clinical study has done at a referral centre included 33 diagnosed patients of hypothyroidism in the age group of 15 to 65 years, fulfilling the inclusion and exclusion criteria who attended the outpatient department. The diagnosis of hypothyroidism was confirmed by thyroid function tests i.e., serum T3, T4 and TSH levels while hearing assessment was done using tuning fork tests, pure tone audiometry, impedance audiometry and otoacoustic emissions. Hearing impairment was measured in decibels of hearing loss, or dB HL and graded as mild, moderate, moderately severe, severe, or profound. &lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Results:&lt;/strong&gt; Percutaneous transluminal angioplasty showed 42.7% of the patients had high frequency sensorineural type of hearing loss. The air bone gap was not significant. On tympanometry, all the patients had type A graph and distortion product otoacoustic emissionss in all patients were pass.&lt;/p&gt;&lt;p class="abstract"&gt;&lt;strong&gt;Conclusions:&lt;/strong&gt; Acquired hypothyroidism affects primarily high frequency hearing thresholds causing high frequency sensorineural hearing loss, with little or no effect on lower frequencies.&lt;/p&gt;

Intracochlear Perfusion of Tumor Necrosis Factor-Alpha Induces Sensorineural Hearing Loss and Synaptic Degeneration in Guinea Pigs.

Tumor necrosis factor-alpha (TNF-α) is a proinflammatory cytokine that plays a prominent role in the nervous system, mediating a range of physiologic and pathologic functions. In the auditory system, elevated levels of TNF-α have been implicated in several types of sensorineural hearing loss, including sensorineural hearing loss induced by vestibular schwannoma, a potentially fatal intracranial tumor that originates from the eighth cranial nerve; however, the mechanisms underlying the tumor's deleterious effects on hearing are not well-understood. Here, we investigated the effect of acute elevations of TNF-α in the inner ear on cochlear function and morphology by perfusing the cochlea with TNF-α in vivo in guinea pigs. TNF-α perfusion did not significantly change thresholds for compound action potential (CAP) responses, which reflect cochlear nerve activity, or distortion product otoacoustic emissions, which reflect outer hair cell integrity. However, intracochlear TNF-α perfusion reduced CAP amplitudes and increased the number of inner hair cell synapses without paired post-synaptic terminals, suggesting a pattern of synaptic degeneration that resembles that observed in primary cochlear neuropathy. Additionally, etanercept, a TNF-α blocker, protected against TNF-α-induced synaptopathy when administered systemically prior to intracochlear TNF-α perfusion. Findings motivate further investigation into the harmful effects of chronically elevated intracochlear levels of TNF-α, and the potential for etanercept to counter these effects.

Aetiology and Hearing Status of Children under 12 years in a School for Hearing Impaired

Objective: To assess degree, type and cause of hearing loss in children under 12 years of age in preschool for hearing impaired children.&#x0D; Methods: This cross sectional study was carried out in children of integrated preschool for hearing impaired children (IPSHIC) of SAHIC, Mohakhali, Dhaka, from September 2010 to March 2011. 50 deaf children were included with age 3-12 years and clinically detected hearing impairment. Data were collected by detailed history, clinical examination and audiometric findings and result were expressed in table form.&#x0D; Results: Most of the children presented with bilateral profound hearing loss and majority of patients presented with sensorineural type of hearing loss. Family history positive in 36% cases and consanguineous marriage were found in 34%.Commonest causes of deafness was infection.&#x0D; Conclusion: Early detection with universal neonatal screening should be practiced in our country and early rehabilitation reveals better out come.&#x0D; Bangladesh J Otorhinolaryngol; April 2016; 22(1): 36-39

Age‑associated variation in the expression and function of TMEM16A calcium‑activated chloride channels in the cochlear stria vascularis of guinea pigs.

The present study was designed to investigate the expression and function of transmembrane protein 16 (TMEM16A), a calcium-activated chloride channel (CaCC), in the stria vascularis (SV) of the cochlea of guinea pigs at different ages, and to understand the role of CaCCs in the pathogenesis of presbycusis (age-related hearing loss), the most common type of sensorineural hearing loss that occurs with natural aging. Guinea pigs were divided into the following groups: 2 weeks (young group), 3 months (youth group), 1 year (adult group), D-galactose intervention (D-gal group; aging model induced by subcutaneous injection of D-galactose) and T16Ainh-A01 (intraperitoneal injection of 50 µg/kg/day TMEM16A inhibitor T16Ainh-A01 for 2 weeks). Differences in the hearing of guinea pigs between the various age groups were analyzed using auditory brainstem response (ABR), and immunofluorescence staining was performed to detect TMEM16A expression in the SV and determine the distribution. Reverse transcription-quantitative PCR and western blot analyses were conducted to detect the mRNA and protein levels of TMEM16A in SV in the different age groups. Morris water maze behavior analysis demonstrated that spatial learning ability and memory were damaged in the D-gal group. Superoxide dismutase activity and malondialdehyde content assays indicated that there was oxidative stress damage in the D-gal group. The ABR thresholds gradually increased with age, and the increase in the T16Ainh-A01 group was pronounced. Immunofluorescence analysis in the cochlear SV of guinea pigs in different groups revealed that expression of TMEM16A increased with increasing age (2 weeks to 1 year); fluorescence intensity was reduced in the D-gal model of aging. As the guinea pigs continued to mature, the protein and mRNA contents of TMEM16A in the cochlea SV increased gradually, but were decreased in the D-gal group. The findings indicated that CaCCs in the cochlear SV of guinea pigs were associated with the development of hearing in guinea pigs, and that downregulation of TMEM16A may be associated with age-associated hearing loss.

Gene therapy for hearing loss.

Sensorineural hearing loss (SNHL) is the most common sensory disorder. Its underlying etiologies include a broad spectrum of genetic and environmental factors that can lead to hearing loss that is congenital or late onset, stable or progressive, drug related, noise induced, age related, traumatic or post-infectious. Habilitation options typically focus on amplification using wearable or implantable devices; however exciting new gene-therapy-based strategies to restore and prevent SNHL are actively under investigation. Recent proof-of-principle studies demonstrate the potential therapeutic potential of molecular agents delivered to the inner ear to ameliorate different types of SNHL. Correcting or preventing underlying genetic forms of hearing loss is poised to become a reality. Herein, we review molecular therapies for hearing loss such as gene replacement, antisense oligonucleotides, RNA interference and CRISPR-based gene editing. We discuss delivery methods, techniques and viral vectors employed for inner ear gene therapy and the advancements in this field that are paving the way for basic science research discoveries to transition to clinical trials.

Auditory and speech performance in cochlear implanted ANSD children

Background: Auditory neuropathy spectrum disorder (ANSD) is a distinct type of SNHL that is characterized by the presence of otoacoustic emissions and/or cochlear microphonics. Cochlear implantation was initially not recommended for ANSD children, later studies showed variable outcomes among those subjects.Objective: To assess the auditory and speech performance of cochlear implanted children with auditory neuropathy spectrum disorder (ANSD) and to compare these results to those obtained from cochlear implanted children with sensorineural hearing loss (SNHL)Material and methods: 18 cochlear implanted children with ANSD and 40 cochlear implanted children with SNHL were included in this study. Auditory and speech performance results were compared across both subject groups using the Category of Auditory Performance (CAP) and Speech Intelligibility Rate (SIR) tests, with measurements recorded one year post implantation.Results: Cochlear implanted children with ANSD showed clinically significant improvements that were comparable to those observed from cochlear implanted subjects without ANSD.Conclusions: Children with ANSD benefit from early cochlear implantation and can reach similar auditory and speech performance results as that achieved by children without ANSD.

Association of Glutathione s-transferase M1 and T1 gene polymorphisms with the susceptibility to acquired sensorineural hearing loss: a systematic review and meta-analysis

Acquired sensorineural hearing loss (SNHL), including age-related hearing loss (ARHL), noise-induced hearing loss (NIHL), drug-induced hearing loss (DIHL) and sudden sensorineural hearing loss (SSHL), is one of the most common sensory deficits in humans. Several studies have reported that antioxidant gene glutathione s-transferase M1 and T1 (GST M1 and T1) polymorphisms have a close relationship with the susceptibility to acquired SNHL, but other articles have reported opposite results. This meta-analysis aims to identify whether an association exists between GST M1 and T1 polymorphisms and the susceptibility to acquired SNHL. Seventeen independent studies containing 1749 cases and 2018 controls were included. According to the I2 value of the heterogeneity test, random-effects model was selected to calculate the pooled odds ratios (ORs) with their 95% confidence intervals (95% CIs) and p values. The pooled ORs (95% CI, p-value) of GST M1 and T1 were 1.186(0.955–1.473, p = 0.122) and 1.107(0.841–1.458, p = 1.467), respectively. In addition, subgroup analyses according to the type of SNHL and ethnicity showed no relationship between GST M1 and T1 polymorphisms and the susceptibility to acquired SNHL. Our results suggest that no significant relationship was found between GST M1 and T1 polymorphisms and the susceptibility to acquired SNHL.

Transmission Disrupted: Modeling Auditory Synaptopathy in Zebrafish.

Sensorineural hearing loss is the most common form of hearing loss in humans, and results from either dysfunction in hair cells, the sensory receptors of sound, or the neurons that innervate hair cells. A specific type of sensorineural hearing loss, referred to as auditory synaptopathy, occurs when hair cells are able to detect sound but fail to transmit sound stimuli at the hair-cell synapse. Auditory synaptopathy can originate from genetic alterations that specifically disrupt hair-cell synapse function. Additionally, environmental factors such as noise exposure can leave hair cells intact but result in loss of hair-cell synapses, and represent an acquired form of auditory synaptopathy. The zebrafish model has emerged as a valuable system for studies of hair-cell function, and specifically hair-cell synaptopathy. In this review, we describe the experimental tools that have been developed to study hair-cell synapses in zebrafish. We discuss how zebrafish genetics has helped identify and define the roles of hair-cell synaptic proteins crucial for hearing in humans, and highlight how studies in zebrafish have contributed to our understanding of hair-cell synapse formation and function. In addition, we also discuss work that has used noise exposure or pharmacological mimic of noise-induced excitotoxicity in zebrafish to define cellular mechanisms underlying noise-induced hair-cell damage and synapse loss. Lastly, we highlight how future studies in zebrafish could enhance our understanding of the pathological processes underlying synapse loss in both genetic and acquired auditory synaptopathy. This knowledge is critical in order to develop therapies that protect or repair auditory synaptic contacts.