Cochlear Dysfunction Research Articles

Investigation of hearing and outer hair cell function of the cochlea in patients with vitiligo.

Vitiligo is a systemic disease that affects not only the skin but also other areas that contain melanocytes, such as the inner ear. Studies of the effect of vitiligo on hearing loss have shown inconsistent results, and it is not clear which parameters related to the disease affect hearing. The aim of this study was to determine which disease-related parameters trigger damage to cochlear melanocytes in vitiligo patients and the effect of vitiligo on the outer hair cells and hearing. Thirty-one vitiligo patients and 40 sex- and age-matched healthy volunteers were evaluated. The conventional pure tone audiometry (C-PTA) test and the distortion product otoacoustic emission (DPOAE) test were performed. There was no significant difference between vitiligo patients and controls in C-PTA test results, but the DPOAE test results were abnormal in vitiligo patients. The duration of the disease was significantly related to hypoacusis. As the duration of the disease increases, cochlear dysfunction may increase. Especially in patients with longer disease duration, otoacoustic emission tests should be performed in addition to conventional audiometry tests for early detection of damage to the outer hair cells.

Effect of Vitiligo on Auditory Functions: Is There Any Association?

Introduction Vitiligo is an acquired pigmentary disorder of unknown etiology, clinically characterized by whitish macules caused by selective loss of melanocytes. There are many melanocytes in the human cochlea. Recent studies have suggested a direct relation between cochlear dysfunction and decreased amounts of melanin. Objective To determine the effect of vitiligo on auditory function. Methods The present prospective, case control study was performed over a period of 1 year in patients between 15 and 40 years old with nonsegmental disease and the same number of controls. Pure tone audiometry (PTA) and Otoacoustic emission (OAE) were performed to analyze the correlation between vitiligo and auditory function. Results The mean pure tone audiometric threshold in the right ear at 0.5, 8 kHz, and in the left ear at the frequency of 8 kHz in the case group were significantly higher as compared with controls. The average band reproducibility (%) in the right and left ear of controls was significantly higher at the frequency of 4 kHz as compared with cases. It has been observed that signal to noise ratio was statistically higher at the frequency of 5kHz in the right ear and at 2, 3, and 5kHz in the left ear in controls as compared with cases. On the basis of disease type and duration of disease; mean pure tone audiometric threshold, average band reproducibility and signal to noise ratio, no significant effect was observed in the present study. Conclusion Vitiligo has an effect on cochlear function irrespective of the duration or distribution of the disease.

Successful Surgical Treatment of Arnold-Chiari Malformation Combined with a Pontocerebellar Cyst and Unilateral Hearing Loss

Arnold Chiari malformation (ACM) is a group of congenital malformations of the hindbrain development that affect structural...

Determinants of the Audiometric Notch at 4000 and 6000 Hz in Young Adults.

Noise-induced hearing loss (NIHL) is often characterized by the presence of an audiometric notch at 3000-6000 Hz in a behavioral audiogram. The audiometric notch is widely used to investigate NIHL in children and young adults. However, the determinants of the audiometric notch in young adults largely remain unknown. The study aimed to investigate the determinants of the audiometric notch in young adults. A cross-sectional design was adopted for the study. A sample of 124 adults (38 males and 86 females) aged 18-35 years with normal otoscopic and tympanometric findings was recruited. Hearing thresholds and real-ear sound pressure levels (RESPLs) were obtained with calibrated ER-3A (Etymotic Research, Elk Grove Village, IL) andTDH-50P receivers (Telephonics, Farmingdale, NY). Distortion-product otoacoustic emissions (DPOAEs) were used to evaluate the cochlear function. The external auditory canal (EAC) length was measured using the acoustical method. Noise exposure background (NEB) was estimated using the Noise Exposure Questionnaire. The notched audiograms were identified using: Phillips, Coles, and Niskar criteria. The prevalence of notched audiograms was substantially higher for TDH-50P supra-aural receivers than for ER-3A insert receivers. RESPLs at 6000 and 8000 Hz were the major predictors of notched audiograms for TDH-50P receivers. These predictors explained around 45% of the variance in the notched audiograms. The notched audiograms obtained with TDH-50P receivers showed no association with NEB. Individuals with notched audiograms measured using TDH-50P did not show convincing evidence of cochlear dysfunction as assessed by DPOAEs. Individuals with notched audiograms obtained with TDH-50P receivers revealed an average of shorter EAC and a poorer hearing threshold at 6000 Hz. The calibration error in the RESPLs at 6000 and 8000 Hz that are likely to be influenced by the shorter EAC was the major determinant of the notched audiograms when the supra-aural transducers were used to measure hearing thresholds. Therefore, the supra-aural receivers should not be used to estimate the prevalence of NIHL in children and young adults when the less restrictive notch identification criteria are used to identify NIHL. Real-ear calibration techniques that are least influenced by the standing waves in the EAC should be preferred when investigating the prevalence of and risk factors for NIHL in young adults.

Insula and Amygdala Atrophy Are Associated With Functional Impairment in Subjects With Presbycusis.

Hearing loss is an important risk factor for dementia. However, the mechanisms that relate these disorders are still unknown. As a proxy of this relationship, we studied the structural brain changes associated with functional impairment in activities of daily living in subjects with age related hearing loss, or presbycusis. One hundred eleven independent, non-demented subjects older than 65 years recruited in the ANDES cohort were evaluated using a combined approach including (i) audiological tests: hearing thresholds and cochlear function measured by pure tone averages and the distortion product otoacoustic emissions respectively; (ii) behavioral variables: cognitive, neuropsychiatric, and functional impairment in activities of daily living measured by validated questionnaires; and (iii) structural brain imaging—assessed by magnetic resonance imaging at 3 Tesla. The mean age of the recruited subjects (69 females) was 73.95 ± 5.47 years (mean ± SD) with an average educational level of 9.44 ± 4.2 years of schooling. According to the audiometric hearing thresholds and presence of otoacoustic emissions, we studied three groups: controls with normal hearing (n = 36), presbycusis with preserved cochlear function (n = 33), and presbycusis with cochlear dysfunction (n = 38). We found a significant association (R2D = 0.17) between the number of detected otoacoustic emissions and apathy symptoms. The presbycusis with cochlear dysfunction group had worse performance than controls in global cognition, language and executive functions, and severe apathy symptoms than the other groups. The neuropsychiatric symptoms and language deficits were the main determinants of functional impairment in both groups of subjects with presbycusis. Atrophy of insula, amygdala, and other temporal areas were related with functional impairment, apathy, and language deficits in the presbycusis with cochlear dysfunction group. We conclude that (i) the neuropsychiatric symptoms had a major effect on functional loss in subjects with presbycusis, (ii) cochlear dysfunction is relevant for the association between hearing loss and behavioral impairment, and (iii) atrophy of the insula and amygdala among other temporal areas are related with hearing loss and behavioral impairment.

Nightly Hypoxia Does Not Seem to Lead to Otolith Dysfunction in Patients With Obstructive Sleep Apnea.

Obstructive sleep apnea (OSA) is a common sleep disorder, which is associated with recurrent oxygen desaturation during sleep. It has already been shown that nocturnal hypoxia may lead to cochlear dysfunction in patients with OSA. Less is known whether hypoxia during sleep also impacts vestibular function in those patients. Thus, the aim of the presented study was to assess a potential vestibulotoxic effect of nightly desaturations with hypoxia in patients with OSA by investigating a possible correlation between respiratory parameters and vestibular function tests. A total of 56 patients were included in the study and underwent a fully attended cardiorespiratory polysomnography (PSG). Vestibular function was assessed using video head impulse test to evaluate horizontal semicircular canal function and cervical vestibular evoked myogenic potentials (cVEMPs) and ocular vestibular evoked myogenic potentials (oVEMPs) to measure otolith function. Descriptive data analysis was conducted and correlation analysis between selected PSG parameters and the results of vestibular testing was performed using Kendall τ coefficient. A significant correlation between vestibular function and respiratory polysomnographic parameters could not be demonstrated in the study (P > .05) but cVEMP and oVEMP results showed a trend toward a correlation with oxygen desaturation indices and apnea-hypopnea index. Additionally, otolith hypofunction was more prevalent in patients with hypertension as well as OSA. The results of our study show that there is no significant correlation between vestibular function and sleep apnea parameters, although otolith dysfunction might be more prevalent in patients with OSA and hypertension.

Cochlear Dysfunction in Chronic Otitis Media and Its Determinants.

Introduction:Long-standing chronic otitis media (COM) may lead to sensorineural hearing loss (SNHL). The present study aimed to evaluate the factors affecting the sensorineural component to counsel patients regarding the risk of SNHL at the event of untreated COM.Material and Methods:A time-bound cross-sectional study was conducted in the Department of Otorhinolaryngology at a tertiary care hospital. The study population included the study group comprising 137 patients with chronic suppurative otitis media (CSOM) and the control group which consisted of 137 individuals with the same age range and gender as the case study group. Moreover, the hearing was assessed using a pure tone audiogram and special tests of hearing.Results:Based on the findings of the present study, the SNHL was found in 71.4% of CSOM cases with an ear discharge duration of more than 5 years. The SNHL occurred in 55.2% and 44.7% of the cases with pars flaccida and of pars tensa perforations, respectively. In the case of pars tensa perforation, greater perforation size resulted in a steady increase in the odds of developing SNHL. Patients with subtotal and total perforations were at higher risk of developing SNHL. Conclusion:Patients with longer duration of disease, squamous type of disease, and larger size of pars tensa perforation had greater susceptibility to develop SNHL. Therefore, eradication of the disease from the middle ear and early reconstruction of the hearing mechanism during the course of the disease result in reducing the burden of SNHL.

Auditory function and prevalence of specific ear and hearing related pathologies in the general population at age 70

Objective: To describe the auditory function in early old age in detail based on both psychoacoustic and physiological measures, and to investigate the prevalence of specific audiological and otological pathologies.Design: An unscreened subsample from a population-based geriatric investigation was examined with otoscopy; tympanometry; pure-tone audiometry; word-recognition-in-noise test; distortion-product otoacoustic emissions; and auditory-evoked brainstem responses. Audiometric subtypes and diagnoses were established based on set criteria. The association between word scores and ABR was examined with linear regression analysis.Study Sample: 251 persons aged 70 (113 men, 138 women, born in 1944) that were representative of the inhabitants of the city of Gothenburg.Results: The prevalence of conductive pathology was 2% versus 49% for cochlear and 2% for auditory-neural pathology. Four percent had indeterminate type. Cochlear dysfunction was present in the majority of ears and around 20% performed worse-than-expected on speech testing. Poor performance on the speech in noise test was associated with prolonged interpeak latency interval of ABR waves I-V.Conclusion: Specific otological and audiological pathologies, other than cochlear hearing loss, are rare in the general population at age 70. Additionally, there is subtle evidence of age-related decline of the auditory nerve. Longitudinal follow-up would be of great interest.

Towards optogenetic approaches for hearing restoration

Hearing impairment (HI) is the most frequent sensory deficit in humans. As yet there is no causal therapy for sensorineural HI - the most common form – that results from cochlear dysfunction. Hearing aids and electrical cochlear implants (eCIs) remain the key options for hearing rehabilitation. The eCI, used by more than 0.7 Mio people with profound HI or deafness, is considered the most successful neuroprosthesis as it typically enables open speech comprehension in quiet. By electrically stimulating the auditory nerve, eCIs constitute a brain-machine interface re-connecting the patient with the auditory scene. Nonetheless, there are short-comings resulting from the wide spread of electric current inside the cochlea which limit the quality of artificial hearing. Since light can be better confined in space than electric current, optogenetic stimulation of the auditory nerve has been suggested as an alternative approach for hearing restoration, enabling higher resolution of artificial sound encoding. Future optical CIs (oCIS) promise increased spectral selectivity of artificial sound encoding, and hence might improve speech recognition in background noise as well as processing of music.

Cochlear dysfunction is associated with styrene exposure in humans.

AimOccupational exposure to styrene has been shown to be associated with an increased probability of developing hearing loss. However, the sites of lesions in the auditory system in humans remain unknown. The aim of this study was to investigate the possible adverse effects of styrene exposure on the cochlea of human subjects.DesignThe hearing function of 98 styrene-exposed male workers from the glass fibre-reinforced plastics industry (mean concentration of 55 mg/m3) was evaluated bilaterally using pure-tone audiometry (1000–16000 Hz), distortion product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR). The results were compared to a group of 111 male workers exposed to noise (above 85 dBA) and 70 male white-collar workers exposed to neither noise nor solvents. Age and noise exposure levels were accounted for as confounding variables in all statistical models.ResultsStyrene exposure was significantly associated with poorer pure-tone thresholds (1–8 kHz), lower DPOAE amplitudes (5–6 kHz), and shorter wave V latencies in both ears compared to control-group subjects. Similar results were found among noise-exposed subjects. A further analysis with wave V latency showed that styrene-exposed subjects showed significantly shorter latencies than expected according to normative data. These results suggest that occupational exposure to styrene at moderate concentrations is associated with cochlear dysfunction, at least at high frequencies. DPOAEs may be considered a valuable diagnostic tool in hearing conservation programs in workers exposed to styrene.

Early detection of hearing impairment in type 2 diabetic patients

Background: Hearing impairment is an under-recognized complication of type 2 diabetic patients. Exploring an appropriate technique and method to detect early hearing impairment in diabetic patients is the key to good hearing care.Objectives: The objectives of this study are to evaluate the application effects of extended high-frequency audiometry and distortion product otoacoustic emissions in early detection of hearing impairment in diabetic patients.Materials and methods: The study recruited 65 type 2 diabetic patients with normal hearing thresholds detected by conventional PTA, and 60 control subjects. All subjects completed detailed medical history questionnaires and underwent ENT (Ear, Nose and Throat) physical examinations and laboratory tests. Then they underwent the conventional pure tone audiometry (PTA) tests, extended high frequency audiometry (HFA) and distortion product of otoacoustic emissions (DPOAEs). Audiologic data and the related risk factors of audiology were analyzed.Results: Of 65 diabetic patients, 41 patients (63.1%) suffered from high frequency hearing loss detected by HFA and 58 patients (89.2%) suffered from cochlear dysfunction detected by DPOAEs. The incidence of high frequency hearing loss was 38%, 83.3% and 42.3% at the age of 30–39, 40–49 and 50–59 years, respectively. The factors of age (p = .00) and disease duration (p = .00) were related with the high frequency hearing threshold, while the factor of glycosylated hemoglobin (HbA1c) (p = .716) had no relationship with it.Conclusions and significance: There can be cochlear dysfunction and high frequency hearing loss in diabetic patients with normal hearing thresholds of conventional frequencies. The examinations of HFA and DPOAEs are of great importance for early diagnosis of hearing loss in type 2 diabetic patients.

Influence of cardiovascular risk factors on cochlear dysfunction

Background: Cochlear dysfunction can arise not only from various factors such as ear diseases but also from systemic disorders of the body. The occurrence of otologic symptoms such as hearing loss, dizziness, and tinnitus can be due to cardiovascular disorders. Therefore, current understandings in the field of the diagnosis and therapy of cardiovascular diseases (CVDs) should include, among others, evidence of otologic disorders. Objective: The aim of this study is to determine the association between risk factors for CVD and cochlear dysfunction. Methods: The cross-sectional study included 128 participants with major CVD risk factors who underwent auditory function examination (pure tone audiometry). Results: There were 52 women (40.6%) and 76 men (59.4%) in total. The mean age of the participants was 58 years (a range of 28–83 years). The mean age among participants with hearing loss was 60 (±10.88), whereas the mean age among participants that had normal hearing thresholds was 54 (±12.18). Sensorineural hearing loss (SNHL) was measured in 59% of participants, of most frequent mild degree hearing loss. The prevalence of SNHL was higher in participants with arterial hypertension (P

Vestibular evaluation in patients with congenital profound hearing loss using ice cold water caloric test and rotational chair test

Introduction: With the introduction of newborn hearing screening, hearing problems are often detected at the neonatal stage and in early infancy, and holistic approach including not only auditory but also vestibular function is needed. This study hopes to establish some corelation between cochlear and vestibular system dysfunction in a patient born with congenital profound hearing loss (CPHL). Materials and Methods: In this observational and descriptive study conducted at a tertiary care hospital, we evaluated eighty patients with bilateral CPHL from 2016 to 2018. After taking a detailed history and thorough ear, nose, and throat examination, the patients underwent vestibular function evaluation by ice cold water caloric test (ICCT) and rotational chair test (RCT) in the outpatient department, and the duration of nystagmus was calculated based on which hypoactive or absent vestibular function was found out. Results: In the present study, out of eighty patients with CPHL, vestibular function of 62 (77.50%) was normal, 9 (11.25%) hypoactive, and 9 (11.25%) with absent vestibular function. Conclusion: In the outpatient department where sophisticated equipment and laboratory facilities are not available, ICCT can be used to determine the vestibular function and also RCT can be used. From the present study, it can be concluded that vestibular dysfunction is present in 22.50% of patients with CPHL with the use of ICCT and RCT. There is a strong possibility of genetic origin etiology for vestibular dysfunction. The present study also concludes that consanguinity may be major etiological factor for vestibular dysfunction.

Auditory Evaluation with Pure Tone Audiometry and DPOAE in Kanamycin Treatment of Multidrug-Resistant Tuberculosis

Background: Kanamycin treatment is mainly used in multidrug-resistant tuberculosis (MDR-TB) patients. Hearing impairment associated along with the treatment leads to be permanently. Audiology assessments and monitoring may benefits to detect early on hearing loss. This study aimed to determine the evaluation of hearing alteration after kanamycin injection in the first month treatment. Method: We conducted a prospective study, observational longitudinal analytic with pre and post design in patients treated with kanamycin-based regimens in MDR-TB Outpatients Pulmonology Department Dr. Soetomo general hospital Surabaya. Assessment of hearing result using Pure Tone Audiometry and DPOAE, compared between baseline data and after 4 weeks treatments. Statistical analysis for hearing threshold and cochlear dysfunction based on overall frequency and specific frequency DPOAE examination, using Wilcoxon ranks test and Mc Nemar test. Results: A total of 15 patients (8 males and 7 females) with confirmed diagnosis of MDR-TB were included in this study conducted within 3 months in 2018. There were 15 ears represented with based line and compared to 4 weeks after treatment, showed on Audiometry and DPOAE on overall frequencies, found no significant difference (p > 0.05), but in DPOAE at frequency of 10,000 Hertz (Hz) was found a significant difference (p = 0.002). Conclusion: DPOAE at high frequency (10,000 Hz) may benefits for early detection on hearing impairment. A baseline data with DPOAE is recommended, besides Audiometry for ototoxicity monitoring in Kanamycin treatment in MDRTB patients.

Elmod3 knockout leads to progressive hearing loss and abnormalities in cochlear hair cell stereocilia.

ELMOD3, an ARL2 GTPase-activating protein, is implicated in causing hearing impairment in humans. However, the specific role of ELMOD3 in auditory function is still far from being elucidated. In the present study, we used the CRISPR/Cas9 technology to establish an Elmod3 knockout mice line in the C57BL/6 background (hereinafter referred to as Elmod3-/- mice) and investigated the role of Elmod3 in the cochlea and auditory function. Elmod3-/- mice started to exhibit hearing loss from 2months of age, and the deafness progressed with aging, while the vestibular function of Elmod3-/- mice was normal. We also observed that Elmod3-/- mice showed thinning and receding hair cells in the organ of Corti and much lower expression of F-actin cytoskeleton in the cochlea compared with wild-type mice. The deafness associated with the mutation may be caused by cochlear hair cells dysfunction, which manifests with shortening and fusion of inner hair cells stereocilia and progressive degeneration of outer hair cells stereocilia. Our finding associates Elmod3 deficiencies with stereocilia dysmorphologies and reveals that they might play roles in the actin cytoskeleton dynamics in cochlear hair cells, and thus relate to hearing impairment.

Characteristic of Stimulus Frequency Otoacoustic Emissions: Detection Rate, Musical Training Influence, and Gain Function.

Stimulus frequency otoacoustic emission (SFOAE) is an active acoustic signal emitted by the inner ear providing salient information about cochlear function and dysfunction. To provide a basis for laboratory investigation and clinical use, we investigated the characteristics of SFOAEs, including detection rate, musical training influence, and gain function. Sixty-five normal hearing subjects (15 musicians and 50 non-musicians, aged 16–45 years) were tested and analyzed at the probe level of 30 and 50 dB sound pressure levels (SPL) in the center frequency of 1 and 4 kHz in the study. The results indicate that (1) the detection rates of SFOAE are sensitive to the gender, (2) musicians reveal enhanced hearing capacity and SFOAE amplitudes compared with non-musicians, and (3) probe frequency has a significant effect on the compression threshold of SFOAE. Our findings highlight the importance of SFOAE in the clinical hearing screening and diagnosis and emphasize the use of musical training for the rehabilitation enhancement of the auditory periphery and hearing threshold.

Relationship between cochlear mechanics and speech-in-noise reception performance

Some normal-hearing listeners report difficulties in speech perception in noisy environments, and the cause is not well understood. The present study explores the correlation between speech-in-noise reception performance and cochlear mechanical characteristics, which were evaluated using a principal component analysis of the otoacoustic emission (OAE) spectra. A principal component, specifically a characteristic dip at around 2-2.5 kHz in OAE spectra, correlated with speech reception thresholds in noise but not in quiet. The results suggest that subclinical cochlear dysfunction specifically contributes to difficulties in speech perception in noisy environments, which is possibly a new form of "hidden hearing deficits."

Clinical characteristics and etiological analysis of sudden deafness patients with vertigo

Objective: To explore the possible causes and mechanisms of sudden deafness with vertigo. Methods: Between August 2016 and December 2017, 74 patients with sudden deafness and vertigo were hospitalized in the Department of Otolaryngology, First Affiliated Hospital of Sun Yat-sen University. Among them, 36 were male and 38 were female, aged 18-75 (40.5±6.5) years. According to the results of magnetic resonance imaging (MRI), the patients were divided into two groups: internal ear hemorrhage (IEH) and non-IEH (NIEH). The characteristics of deafness, vertigo, laboratory examination and follow-up results were compared between the two groups. Results: In IEH group, deafness and vertigo occurred simultaneously in 22 cases (84.6%), abnormalities of semicircular canal function, cervical vestibular evoked myogenic potential (C-VEMP), ocular vestibular evoked myogenic potential (O-VEMP) in 26 cases (100%) and benign paroxysmal positional vertigo (BPPV) in 10 cases (38.5%). The total effective rate was 19.2% (5/26) after 14 days of treatment, and 11 cases (42.3%) appeared disturbance after 180 days of treatment. The abnormal rate of lateral vestibular function, C-VEMP and O-VEMP was 69.2% (18/26), 53.8% (14/26) and 57.7% (15/26) respectively. The improvement of hearing threshold was (28.6±9.7) dB. In NIEH group, deafness and vertigo occurred simultaneously in 25 cases (52.1%). The abnormalities of semicircular canal function, C-VEMP and O-VEMP happened in 37 cases (77.1%), 34 cases (70.8%), 26 cases (54.2%), respectively, and 6 cases (12.5%) were of BPPV. The total effective rate was 52.1% (25/48) after 14 days of treatment. After 180 days of treatment, 8 cases (16.7%) were out of balance, and the abnormal rate of lateral vestibular function, C-VEMP and O-VEMP were 31.2% (15/48), 25.0% (12/48) and 20.8% (10/48) respectively. The improvement of hearing threshold was (42.5±10.3) dB. The incidence of stimulantous deafness and vertigo, vestibular dysfunction rate, BPPV incidence rate and the total effective rate after 14 days of treatment were significantly different between the two groups (all P<0.05). The vestibular and cochlear dysfunction in IEH group was more serious than that in NIEH group. After 180 days of treatment, the vestibular dysfunction rate, imbalance rate and improvement of hearing threshold in NIEH group were significantly higher than that in IEH group (all P<0.05). The recovery of vestibular and cochlear function in NIEH group was better than that in IEH group. Conclusions: Sudden deafness with vertigo can cause vestibular and cochlear dysfunction. Different etiologies may lead to different clinical features and prognosis. The vestibular and cochlear function damage caused by inner ear hemorrhage was more serious and the recovery effect was poor.

Early Indices of Reduced Cochlear Function in Young Adults with Type-1 Diabetes Revealed by DPOAE Fine Structure

The relationship between type-1 diabetes mellitus (DM) and cochlear dysfunction remains inconclusive. The purpose of this study was to examine otoacoustic emissions (OAEs) in normal-hearing young adults with type-1 DM as compared with matched controls and identify potential covariates influencing OAE findings. Cross-sectional study. N = 40 young adults aged 18-28 years including individuals with type-1 DM (n = 20) and age-gender matched controls (n = 20) with normal hearing sensitivity. Measures of pure-tone threshold sensitivity and OAEs, including distortion product otoacoustic emissions (DPOAEs), transient evoked OAEs, and DPOAE fine structure, were compared between groups. Covariates such as noise exposure and DM-related factors (e.g., duration of disease, glycated hemoglobin levels) were considered. Statistical analysis included analysis of variance and linear regression. Measures of hearing sensitivity and auditory function in both groups were comparable for all assays, except DPOAE fine structure. A reduced number of fine structure peaks and component amplitudes were found in the type-1 diabetes DM group with the primary difference in the reflection component. The results indicate that reduced cochlear function in young adults with type-1 DM can be revealed using DPOAE fine structure, suggesting potential clinical applications of DPOAE fine structure in early identification of cochlear pathology. Potential factors underlying these findings are discussed.

Subclinical cochlear dysfunction in newly diagnosed relapsing-remitting multiple sclerosis

BackgroundHearing impairment in multiple sclerosis has long been considered a process mainly related to the central auditory system. However, increasing evidence also suggests a peripheral involvement of the inner ear. The objective of this study was to investigate subclinical cochlear dysfunction and possible correlation with disease severity in untreated newly diagnosed multiple sclerosis patients using transient-evoked and distortion-product otoacoustic emissions. MethodsForty patients with newly diagnosed relapsing-remitting multiple sclerosis, clinically normal hearing and no brainstem lesions (study group) and forty matched controls (control group) were included in the study. All subjects had a routine audiological evaluation including history and clinical examination, pure tone audiometry, acoustic immittance test, auditory brainstem response and otoacoustic emissions recording. Self-administered questionnaires were used to evaluate self-perception of hearing disability. ResultsAuditory brainstem response and pure tone audiometry thresholds resulted within normal range in all patients. The amplitudes of transient-evoked and distortion-product otoacoustic emissions responses were significantly reduced at 1000, 1500, 2000 and 3000 Hz in the study group compared to the control group. ConclusionsThis study shows decreased otoacoustic emission amplitudes in untreated multiple sclerosis patients with clinically normal hearing and no brainstem demyelinating plaques, suggesting a subclinical cochlear impairment. This alteration may represent an early sign of peripheral hearing damage, suggesting a role for otoacoustic emissions in the early diagnosis of cochlear dysfunction in multiple sclerosis patients. However, given that otoacoustic emissions primarily reflects cochlear function, and that the wave I of the auditory brainstem responses was spared, the evidence supporting a peripheral involvement of acoustic pathways due to multiple sclerosis can only be hypothetically attributed to an early subclinical involvement of outer hair cells.