Vitamin D deficiency--a new cause of cochlear deafness

SOX2, JAGGED1, β-Catenin, and Vitamin D Receptor Expression Patterns during Early Development and Innervation of the Human Inner Ear

Sensorineural hearing loss can be caused by lesions to the inner ear during development. Understanding the events and signaling pathways that drive inner ear formation is crucial for determining the possible causes of congenital hearing loss. We have analyzed the innervation and expression of SOX2, JAGGED1, β-catenin (CTNNB1), and vitamin D receptor (VDR) in the inner ears of human conceptuses aged 5 to 10 weeks after fertilization (W) using immunohistochemistry. The prosensory domains of the human inner ear displayed SOX2 and JAGGED1 expression throughout the analyzed period, with SOX2 expression being more extensive in all the analyzed timepoints. Innervation of vestibular prosensory domains was present at 6 W and extensive at 10 W, while nerve fibers reached the base of the cochlear prosensory domain at 7-8 W. CTNNB1 and VDR expression was mostly membranous and present during all analyzed timepoints in the inner ear, being the strongest in the non-sensory epithelium. Their expression was stronger in the vestibular region compared to the cochlear duct. CTNNB1 and VDR expression displayed opposite expression trends during the analyzed period, but additional studies are needed to elucidate whether they interact during inner ear development.

Association of serum 25-hydroxyvitamins D2 and D3 with hearing loss in US adults: analysis from National Health and Nutrition Examination Survey, 2015-2016

Background

Hearing loss (HL) is increasingly recognized as a significant global public health issue, and research on its relationship with vitamin D levels has gained wider attention. However, the association between serum biomarkers 25-hydroxyvitamin D2 (25(OH)D2) and D3 (25(OH)D3) with different types of HL remains unclear. This study aimed to investigate the potential association of serum 25(OH)D2 and 25(OH)D3 with HL in US adults.

Methods

A sample of 3,684 individuals aged 20-69 years from the 2015-2016 National Health and Nutrition Examination (NHANES) was analyzed in this study. HL was defined as a pure tone average > 25 dB in either ear at low frequencies (500, 1,000, 2000 Hz), speech frequencies (500, 1,000, 2000, 4,000 Hz), and high frequencies (3,000, 4,000, 6,000, 8,000 Hz). Logistic regression was employed to examine the association between serum 25(OH)D2 and 25(OH)D3 and HL. The study population was then stratified by age, gender, race, and education level to analyze potential differences between adults in different subgroups.

Results

In the multivariate analysis, it was found that serum 25(OH)D2 was independently associated with low-frequency hearing loss (LFHL) (OR: 1.012 [95% CI, 1.005-1.020]) and speech-frequency hearing loss (SFHL) (OR: 1.011 [95% CI, 1.003-1.018]). Restrictive cubic spline analysis demonstrated a linear dose-response relationship between serum 25(OH)D2 levels and LFHL (p for linearity <0.001), as well as SFHL (p for linearity = 0.001). Conversely, an L-shaped association was observed between serum 25(OH)D3 levels and both LFHL (p for nonlinearity = 0.014) and SFHL (p for nonlinearity = 0.025), with threshold values identified at 35.3 and 36.5 nmol/L, respectively. Higher levels of serum 25(OH)D3 were associated with a lower probability of high-frequency hearing loss (HFHL) (OR: 0.994 [95% CI, 0.989-0.999]), with a threshold value identified at 53.9 nmol/L. Furthermore, a significant interaction between diabetes and serum 25(OH)D2 in LFHL was revealed through subgroup analysis (p = 0.041). In the non-diabetic population, serum 25(OH)D2 maintained its association with LFHL.

Conclusion

Our findings suggested a positive association between serum 25(OH)D2 concentrations and both LFHL and SFHL in the studied cohort. Additionally, an L-shaped relationship was found between serum 25(OH)D3 and LFHL and SFHL, and higher levels of serum 25(OH)D3 were identified to be associated with a lower risk of HFHL.

Vitamin D Deficiency as a Risk Factor of Tinnitus: An Epidemiological Study

OBJECTIVES

Vitamin D deficiency as a risk factor of tinnitus has not been well known. We tried to evaluate the association between the serum 25-(OH) vitamin D levels and tinnitus among the Korean population to propose the possible role of serum vitamin D in patients with tinnitus.

METHODS

This cross-sectional study investigated the potential risk factors of tinnitus in relation to serum 25(OH)D levels within the Korean population. It encompassed a health interview, nutrition assessment, and a health examination. Data was sourced from the KNHANES V (2010-2012), conducted by the Division of Health and Nutritional Survey under the Korean Centers for Disease Control and Prevention (KCDCP). Participants were chosen from various sampling units categorized by geography, gender, and age group. The selection was facilitated through household registries using a stratified, multistage, clustered probability sampling approach.

RESULTS

Data of 16 408 subjects were collected in this study. There were significant differences in gender, economic status, educational level, and sun exposure duration between the tinnitus and non-tinnitus groups. Serum 25(OH) vitamin D level between hearing loss and normal hearing was also significantly different. The logistic regression models with serum 25(OH) vitamin D quartile and tinnitus as the dependent variable, which were controlled for age, sex, smoking status, BMI, diabetes, hypertension, sun exposure, regular exercise, income, and education, eventually demonstrated that serum vitamin D deficiency and low sun exposure duration significantly increased the risk of tinnitus development.

CONCLUSION

This study demonstrated a significant association between serum vitamin D levels and tinnitus, driven by large epidemiological data. The results of our study provide baseline data for further research to investigate the role of vitamin D in the pathogenesis and management of tinnitus.

Association between Serum Vitamin D Levels and Risk of Sudden Sensorineural Hearing Loss: A cross-sectional Study

Background

Sudden sensorineural hearing loss (SSNHL) is an autoimmune diseases of the inner ear which is usually defined by acute onset of hearing loss in one or both ears, of 30 dB or more on at least three contiguous audiometric frequencies within 3 days or less. This study aimed to compare the serum levels of 25-hydroxyvitamin D (VitD) between patients with SSNHL and healthy controls.

Methods

A total of 50 patients with SSNHL and 50 healthy individuals without hearing loss as control group were enrolled in this study. Serum levels of VitD and other related laboratory tests such as calcium (Ca), phosphorus (P), and parathyroid hormone (PTH) were measured and compared between two study groups.

Results

Serum level of VitD was significantly lower in patients suffering from SSNHL compared to the healthy controls (26.55 ± 14.44 vs. 33.51 ± 14.21, P = 0.017, respectively). VitD insufficiency was observed in 70% (n = 35) of the patients with SSNHL as compared to 44% (n = 22) of healthy individuals, demonstrating a significant difference between two study groups. However, no statistically difference was observed for serum levels of Ca, P, and PTH.

Conclusion

This study indicated an increased prevalence of VitD insufficiency in subjects with SSNHL, suggesting a possible association between serum VitD levels and the development of SSNHL. VitD may protect the hearing loss through its antioxidant role.

Clinical role of vitamin D, vitamin B12, folate levels and hematological parameters in patients with sudden sensorineural hearing loss

BACKGROUND

Sudden sensorineural hearing loss (SSNHL), which is frequently observed in otolaryngology clinics, is characterized by sudden onset hearing loss that can develop within hours or days. Its etiology is still not fully understood.

AIMS/OBJECTIVES

This research aims to identify prognostic biomarkers that can be utilized to assess the progress of SSNHL as well as circumstances that may predispose individuals to the disease.

MATERIALS AND METHODS

Between 1 January 2019 and 1 October 2020, patients diagnosed with SSNHL in our clinic and a control group consisting of healthy people were examined retrospectively. The files of the groups were examined and the levels of hemoglobin, Neutrophil-Lymphocyte Ratio (NLR), ferritin, iron, iron binding capacity (UIBC), vitamin D, vitamin B12, folate were statistically compared with the control group. In addition, the effect of the parameters studied in the patient group on the degree of recovery was examined.

RESULTS

There was no statistically significant difference between the groups in terms of mean age and gender distribution (p > .05). NLR level of the patient group was higher than the control group (p < .05). Vitamin D level of the patient group was lower than the control group (p < .05). NLR and vitamin D levels had no effect on the degree of recovery (p > .05). There was no significant difference between the groups in terms of other parameters (p > .05).

CONCLUSIONS AND SIGNIFICANCE

We think that our study can be a guide for adding vitamin D as a routine laboratory test in patients with SSNHL. In addition, we think that NLR value can be used as a marker in patients with SSNHL. It is recommended to investigate the role of vitamin D supplementation in better and faster response in these patients.

Serum fat-soluble vitamin levels may be related to sudden sensorineural hearing loss

BACKGROUND

Few related studies reported yet the association between vitamins and the onset of sudden sensorineural hearing loss (SSNHL).

OBJECTIVE

To explore the relationship between the serum levels of fat-soluble vitamins A, D, and E and the risk of SSNHL.

METHODS

This retrospective analysis included 310 SSNHL patients and 154 people without risk of hearing loss. The demographic information of all participants like age, gender, body mass index, occupation, cigarette smoking or drinking status, etc. were recorded. The serum levels of vitamins A, D, and E were determined using the electrochemical method.

RESULTS

The results indicated that serum vitamin D levels in SSNHL patients were significantly lower. Vitamin D deficiency was only observed in SSNHL group. Similarly, serum vitamin A levels in female SSNHL patients were significantly lower than the control group. Meanwhile, serum vitamin E levels in male SSNHL patients were significantly lower than the control group.

CONCLUSION AND SIGNIFICANCE

Our results revealed that the serum levels of fat-soluble vitamins A, D, and E in SSNHL patients were lower than those in the control group with normal hearing, indicating that the decrease of serum fat-soluble vitamins may be related to SSNHL pathogenesis.

Serum Vitamin D Concentration Is Lower in Patients with Tinnitus: A Meta-Analysis of Observational Studies

Background: Tinnitus is a highly prevalent and frequently disabling condition, such that the identification of possible causal mechanisms would yield significant clinical and social benefits. Since vitamin D (Vit D) is involved in the pathogenesis of several ear disturbances, we review here the current scientific literature addressing the relationship between Vit D status and tinnitus. Methods: An electronic search was conducted in PubMed, Scopus and Web of Science with the keywords “tinnitus” and “Vitamin D” or “Vit D” or “25OH-D” or “cholecalciferol” or “ergocalciferol” or “hydroxycholecalciferol”, without date (i.e., up to 8 February 2023) or language restrictions, in accordance with a protocol based on the transparent reporting of systematic reviews and meta-analysis (PRISMA) 2020 checklist, for identifying studies which assayed serum Vit D concentration in patients with or without tinnitus. Results: Three observational, case-control studies encompassing four cohorts and totaling 468 patients with (n = 268) or without tinnitus (n = 200) were included in this meta-analysis. Pooled analysis with quality effects models evidenced significantly reduced serum Vit D levels in patients with tinnitus compared to those without (weighted mean difference [WMD], −6.2 ng/mL; 95% CI, −10.3 to −2.1 ng/mL; I2, 56%). Serum Vit D was found to be 22% lower in patients with tinnitus compared to those without. Conclusions: Lower serum Vit D levels may be associated with tinnitus, thus paving the way to plan future trials aimed at exploring whether Vit D supplementation may aid in preventing and/or improving tinnitus.

Deafness in an auditory specialist, the big brown bat (Eptesicus fuscus)

Bats are long-lived animals that show presumed resistance to noise-induced and age-related hearing loss, which has been attributed to their dependence on sound processing for survival. Echolocation and basic auditory functions have been studied extensively in the big brown bat (Eptesicus fuscus), an insectivorous microchiropteran species. We conducted hearing tests and analysis of cochlear sensory cells in a group of big brown bats that exhibited anomalies in behavioral sonar tracking experiments and/or lacked neural responses to acoustic stimulation in subcortical auditory nuclei. We show for the first time the presence of profound deafness and extensive cochlear damage in an echolocating bat species. Auditory brainstem responses were abnormal or absent in these bats, and histological analyses of their cochleae revealed extensive loss of hair cells, supporting cells, and spiral ganglion neurons. The underlying cause of deafness is unknown.

The role of vitamin D in subjective tinnitus-A case-control study

Regarding the high prevalence of vitamin D (25(OH)D) deficiency in the population and its possible association with ear diseases, we aimed to investigate the 25(OH)Dserum level in patients with subjective, nonpulsating tinnitus and its effect on tinnitus severity. The study included 201 tinnitus patients and 99 controls. Patient clinical information, including tinnitus characteristics and severity according to Tinnitus Handicap Inventory (THI), loudness assessed by Visual Analogue Scale (VAS), audiometry, and the blood level of vitamin D, was recorded. The level of 25(OH)D in tinnitus patients was significantly decreased compared with the controls (19.86 ± 7.53 and 27.43 ± 8.85 ng/ml, respectively; P value < 0.0001). More patients in the tinnitus group were deficient in vitamin D, compared with the controls (50.7% vs. 22.2% respectively, p < 0.0001). Tinnitus patients with a lower serum level of 25(OH)D (≤15 ng/dl) were significantly younger, had a higher degree of tinnitus severity measured with THI and VAS scales, had higher triglyceride and TSH levels, and a lower HDL level compared with individuals who had higher 25(OH)D level (>15 ng/dl). There was a strong correlation between the 25(OH)D level and THI. Our findings suggest that a large proportion of tinnitus patients suffers from vitamin D deficiency and that the vitamin D level correlates with tinnitus impact. We recommend a vitamin D assessment for all tinnitus patients.

Relationship Between Diet, Tinnitus, and Hearing Difficulties

OBJECTIVES

Diet may affect susceptibility of the inner ear to noise and age-related effects that lead to tinnitus and hearing loss. This study used complementary single nutrient and dietary pattern analysis based on statistical grouping of usual dietary intake in a cross-sectional analysis of tinnitus and hearing difficulties in a large population study sample.

DESIGN

The research was conducted using the UK Biobank resource. Tinnitus was based on report of ringing or buzzing in one or both ears that lasts more than five minutes at a time and is currently experienced at least some of the time. Identification of a hearing problem was based on self-reported difficulties with hearing. Usual dietary intake and dietary patterns (involving statistical grouping of intake to account for how foods are combined in real-life diets) were estimated based on between two and five administrations of the Oxford Web-Q 24-hour dietary recall questionnaire over the course of a year for 34,576 UK adult participants aged 40 to 69.

RESULTS

In a multivariate model, higher intake of vitamin B12 was associated with reduced odds of tinnitus, while higher intakes of calcium, iron, and fat were associated with increased odds (B12, odds ratio [OR] 0.85, 95% confidence interval [CI] 0.75 to 0.97; Calcium, OR 1.20, 95% CI 1.08 to 1.34; Iron, OR 1.20, 95% CI 1.05 to 1.37; Fat, OR 1.33, 95% CI 1.09 to 1.62, respectively, for quintile 5 versus quintile 1). A dietary pattern characterised by high protein intake was associated with reduced odds of tinnitus (OR 0.90, 95% CI 0.82 to 0.99 for quintile 5 versus quintile 1). Higher vitamin D intake was associated with reduced odds of hearing difficulties (OR 0.90, 95% CI 0.81 to 1.00 for quintile 5 versus quintile 1), as were dietary patterns high in fruit and vegetables and meat and low in fat (Prudent diet: OR 0.89, 95% CI 0.83 to 0.96; High protein: OR 0.88, 95% CI 0.82 to 0.95; High fat: OR 1.16, 95% CI 1.08 to 1.24, respectively, for quintile 5 versus quintile 1).

CONCLUSIONS

There were associations between both single nutrients and dietary patterns with tinnitus and hearing difficulties. Although the size of the associations was small, universal exposure for dietary factors indicates that there may be a substantial impact of diet on levels of tinnitus and hearing difficulties in the population. This study showed that dietary factors might be important for hearing health.

Low vitamin D status is associated with hearing loss in the elderly: a cross-sectional study

BACKGROUND

The elderly are at increased risk of both hearing loss (HL) and osteoporosis. Bone mineral density (BMD) has been putatively linked to HL. However, the roles of serum calcium concentrations and vitamin D status have yet to be elucidated.

OBJECTIVES

The purpose of this study was to examine the relation between vitamin D status, parathyroid hormone (PTH), total calcium, BMD, and HL in a nationally representative sample of elderly adults.

METHODS

Using the NHANES (2005-2010), audiometry and BMD data of 1123 participants aged ≥70 y were analyzed in a cross-sectional manner. HL was defined as pure tone averages >25 dB HL at 500, 1000, and 2000 Hz (low frequency); 500, 1000, 2000, and 4000 Hz (speech frequency); and 3000, 4000, 6000, and 8000 Hz (high frequency) in either ear. Multivariable logistic regression was used to examine the relation between HL and total 25-hydroxyvitamin D [25(OH)D], PTH, total calcium, and BMD, adjusting for covariates.

RESULTS

In multivariable analyses, total 25(OH)D < 20 ng/mL was found to be associated with greater odds of low-frequency HL (OR: 2.02; 95% CI: 1.28, 3.19) and speech-frequency HL (OR: 1.96; 95% CI: 1.12, 3.44). A 1-unit decrease in femoral neck BMD (OR: 4.55; 95% CI: 1.28, 16.67) and a 1-unit decrease in total spine BMD (OR: 6.25; 95% CI: 1.33, 33.33) were found to be associated with greater odds of low-frequency HL. Serum PTH and total calcium were not found to be associated with HL.

CONCLUSIONS

In the elderly, low vitamin D status was associated with low-frequency and speech-frequency HL. Low vitamin D status may be a potential risk factor for age-related HL.

Vitamin D Deficiency, Hypocalcemia, and Hearing Loss in Children

OBJECTIVE

Characterize relations between vitamin D deficiency (VDD), hypocalcemia, and hearing loss (HL) in children.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral hospital.

PATIENTS

Children in the Audiological and Genetic Database with a diagnosis of VDD, rickets, or osteomalacia.

INTERVENTION

None.

MAIN OUTCOME MEASURES

Prevalence, type, severity (4-tone pure-tone average, PTA), and progression of HL. HL was defined as greater than 15 dB HL at any threshold by pure tone, greater than 20 dB HL by sound field audiometry, or greater than 25 dB in infants less than 1 year of age.

RESULTS

Of 888 children with VDD, 474 (53.4%) had HL, with 17% having moderate-profound HL. Compared with an age-matched cohort of 13,320 children drawn from the same database, children with VDD were significantly more likely to have sensorineural HL (SNHL) (adjusted odds ratios [aOR] 1.26 [95% confidence interval [CI] 1.01-1.58]). Among children with VDD, children with femur fracture had a significantly higher rate of HL (81% versus 53%, p = 0.008) and children with hypocalcemia had a significantly higher rate of moderate-profound HL (36% versus 18%, p = 0.016). Additionally, hypocalcemia with and without VDD was associated with SNHL (aOR 2.30 [1.07-4.56]).

CONCLUSIONS

Both vitamin D deficiency and hypocalcemia were found to be independently associated with SNHL, a type of HL that is less likely to improve over time. Recognition of VDD and hypocalcemia as independent risk factors for the development of SNHL could allow for better evaluation and treatment of this patient population. Routine audiological evaluation should be considered in this population.

The Price of Immune Responses and the Role of Vitamin D in the Inner Ear

OBJECTIVE

In this review the authors discuss evidence from the literature concerning vitamin D and temporal bone diseases (benign paroxysmal positional vertigo [BPPV], Menière's disease [MD], vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss). Common features shared by Menière's disease, glaucoma, and the possible influence by vitamin D are briefly discussed.

DATA SOURCES, STUDY SELECTION

Publications from 1970 until recent times have been reviewed according to a keyword search (see above) in PubMed.

CONCLUSIONS

MD, BPPV, vestibular neuritis, idiopathic facial paralysis, idiopathic acute hearing loss may all have several etiological factors, but a common feature of the current theories is that an initial viral infection and a subsequent autoimmune/autoinflammatory reaction might be involved. Additionally, in some of these entities varying degrees of demyelination have been documented. Given the immunomodulatory effect of vitamin D, we postulate that it may play a role in suppressing an eventual postviral autoimmune reaction. This beneficial effect may be enhanced by the antioxidative activity of vitamin D and its potential in stabilizing endothelial cells. The association of vitamin D deficiency with demyelination has already been established in other entities such as multiple sclerosis and experimental autoimmune encephalitis. Mice without vitamin D receptor show degenerative features in inner ear ganglia, hair cells, as well as otoconia. The authors suggest further studies concerning the role of vitamin D deficiency in diseases of the temporal bone. Additionally, the possible presence and degree of demyelination in these entities will have to be elucidated more systematically in the future.

Investigation of vitamin D levels in patients with Sudden Sensory-Neural Hearing Loss and its effect on treatment

BACKGROUND

Due to high prevalence of vitamin D deficiency and the possible association with Sudden Sensory-Neural Hearing Loss (SSNHL) finding the main causes and appropriate treatments are highly essential. This study aimed to investigate vitamin D levels in patients suffering SSNHL and its effect on response to treatment.

MATERIALS AND METHODS

This cross-sectional study was performed on two groups of case (34 SSNHL patients) and control (34 healthy subjects without risk of hearing loss). All patient information such as age, sex, audiogram illustration of hearing frequency and the level of vitamin D were recorded at baseline. Patients with SSNHL received routine treatments such as 10 days of 1 mg/kg/day steroid and the response or lack of complete response to treatment was recorded and analyzed according to the audiometry.

RESULTS

Vitamin D level in SSNHL group with a mean of 19.28 ± 9.56 ng/ml was significantly less than the control group (25.71 ± 11.21 ng/ml; P value < 0.001). After treatment, 76.5% were completely recovered and 23.5% did not recover completely. Factors such as age, sex and level of initial hearing loss did not have a significant effect on the response to treatment, but the level of vitamin D in these patients had a significant relationship with the response to treatment (P value = 0.004); so that all patients with sufficient vitamin D level had completely recovered, versus 87.5% of patients with vitamin D deficiency and 12.5% of insufficient vitamin D had no response to treatment.

CONCLUSION

According to the results of the present study, the prevalence of vitamin D deficiency in patients with SSNHL was more than healthy people. SSNHL patients with deficient vitamin D had the highest percentage of no response to treatment.

Effect of Malnutrition on Hearing Loss in Children

OBJECTIVE

To characterize the relation between protein-calorie malnutrition (PCM) and hearing loss (HL) in children.

STUDY DESIGN

Retrospective review.

SETTING

Tertiary referral hospital.

PATIENTS

Children in the Audiological and Genetic Database with a diagnosis of protein-calorie malnutrition, marasmus, and/or kwashiorkor.

INTERVENTIONS

None.

MAIN OUTCOME MEASURES

Prevalence, type, severity (4-tone pure-tone average, PTA), and progression of HL.

RESULTS

Of 770 children with PCM, 57.8% had HL, compared to 45.5% of children without PCM (p < 0.001). Severely malnourished children had significantly higher odds of moderate-profound HL (aOR 2.27, 95% CI 1.47-3.43), high-frequency HL (aOR 1.82, 95% CI 1.21-2.75), and sensorineural or mixed HL (aOR 1.60, 95% CI 1.05-2.41) compared to children without PCM. Severely malnourished children had significantly worse initial (35.0 dB vs 25.0 dB, p < 0.001), and final median PTA (31.3 dB vs 20.0 dB, p < 0.001) compared to children without PCM. Additionally, HL in children who were moderately and severely malnourished was significantly less likely to improve (aOR 0.47, 95% CI 0.25-0.82 and aOR 0.4, 95% CI 0.2-0.9) when compared to those without PCM.

CONCLUSIONS

Given the greater prevalence and severity of hearing loss, children with PCM should be considered an at-risk group for poor audiological outcomes, and clinical practice should focus on early treatment and intervention for malnourished children. Routine audiological evaluation should be considered in this population.

Evaluation of Saccule Function in Patients with Vitamin D Deficiency

BACKGROUND AND OBJECTIVES

Considering important role of vitamin D in many physiological processes including vestibular system in the ear, aim of present study is to evaluate saccule function via cervical vestibular evoked myogenic potential (cVEMP), in patients with vitamin D deficiency. Subjects and.

METHODS

After routine audiological tests, cVEMP were recorded in 15 patients with vitamin D deficiency and 16 normal subjects. The short tone burst (95 dB nHL, 500 Hz) was presented to ears. cVEMP was recorded with surface electromyography over the contracted ipsilateral sternocleidomastoid muscle.

RESULTS

Mean of p13, n13, interpeak latencies and amplitude ratios were measured in both groups. Statistical analysis did not show differences between two groups.

CONCLUSIONS

Maybe serum 25-hydroxyvitamin D concentration was not low enough to have effect on saccule in the patients in present study or saccule have had low susceptibility to effects of vitamin D deficiency. For better judgment about effect of vitamin D deficiency on saccular function planning studies with high sample size is recommended.

Biochemical alteration in children with idiopathic nephrotic syndrome associated with an increased risk of sensorineural hearing loss; additional insights in cochlear renal relationship

OBJECTIVES

Children with Idiopathic Nephrotic Syndrome (INS) are at risk of hearing loss due to the adverse impact of medications and related immunological and genetic factors on both cochlea and kidney. So this work was planned to evaluate hearing status in children with INS and to clarify the possible associated risk factors by interpreting the clinical and laboratory profiles of those children.

METHODS

Ninety children with INS aged 5-14 years [30 patients with steroid-sensitive nephrotic syndrome (SSNS), 30 patients with steroid dependent/frequently relapsing nephrotic syndrome (SDNS/FRNS), and 30 patients with steroid-resistant nephrotic syndrome (SRNS)], and 90 age and sex matched normal controls were enrolled into this study. Laboratory measurements of serum calcium, creatinine, cholesterol, blood urea and other relevant investigations were done. Pure tone audiometry was done with the sensory-neural hearing loss (SNHL) diagnosed when the level bone conduction was >20 dB and the difference in air to the bone gap was <15 dB.

RESULTS

40% children with INS had SNHL, mostly of mild degree HL and primarily occurred at the lower frequencies. A highly significant statistical difference between controls and various types of nephrotic syndrome regarding pure tone audiometry measurements at frequencies 250, 500, 1000 Hz, whereas insignificant difference interpreting pure tone audiometry measurements in 2000, 4000 and 8000 Hz.

CONCLUSIONS

Children with different phenotypes of nephrotic syndrome are at risk of sensorineural hearing impairment. The hazards associated with this impairment were higher blood pressure, hypercholesterolemia, hypoalbuminemia, and hypocalcemia.

Vestibular-evoked myogenic potentials and subjective visual vertical testing in patients with vitamin D deficiency/insufficiency

Otolith function in subjects with vitamin D deficiency/insufficiency is investigated through vestibular-evoked myogenic potentials (VEMP) and subjective visual vertical (SVV) testing. The study group included 62 patients with vitamin D deficiency/insufficiency (30 females, 32 males), with age range 24-56 years (40.6 ± 9.1). The control group included 44 healthy volunteers of similar age and gender distribution. The entire study group had: (1) serum level of 25-hydroxyvitamin D <30 ng/ml; (2) normal bone mineral density as indicated by dual-energy X-ray absorptiometry with T-score >-1; (3) normal middle ear function; (4) Age is ≤60 years. All subjects enrolled in the current study underwent audiovestibular evaluation consisting of pure-tone audiometry, immittancemetry, cervical VEMP (cVEMP), ocular VEMP (oVEMP), and SSV. The entire control group had normal cVEMP, two subjects had abnormal oVEMP. Thirty-three subjects (53%) in the study group had abnormal oVEMP and 31 subjects (50%) had abnormal cVEMP. Forty-one (66%) had abnormal VEMP when abnormal VEMP was considered as either abnormal oVEMP or cVEMP. The entire control and study groups had normal SSV test results. Vitamin D deficiency may be associated with development of otolith dysfunction affecting both the utricle and saccule. This was suggested by the high prevalence of abnormal ocular vestibular-evoked myogenic potentials (oVEMP) and cervical vestibular-evoked myogenic potentials (cVEMP) in the study group.

Hearing status in children with frequently relapsing and steroid resistant nephrotic syndrome

BACKGROUND

Children with idiopathic nephrotic syndrome (INS) are at risk of hearing impairment due to nephrotoxic drugs and biochemical impairments.

METHODS

Forty children with INS aged 5-16 years [20 patients with frequently relapsing nephrotic syndrome (FRNS)/steroid dependent nephrotic syndrome (SDNS) and 20 with steroid resistant nephrotic syndrome (SRNS)] and 20 normal healthy controls were enrolled in this study. Pure tone audiometry was done using the ALPS AD 2000 audiometer. Sensorineural hearing loss was diagnosed when the bone conduction level was >20 dB and the difference in air to bone gap was ≤15 dB. Based on the air conduction (AC) threshold, deafness was graded into the following categories: mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-91 dB) and profound (>91 dB).

RESULTS

Children with FRNS/SDNS had a higher threshold for hearing at frequencies of 250 and 500 Hz, respectively, than the controls. Of the children in the FRNS/SDNS category, three (15 %) had mild sensorineural hearing impairment. These children had a low serum calcium level (P < 0.03) and received higher cumulative doses of furosemide (P < 0.04). Children with SRNS had a higher threshold for hearing at frequencies of 250, 500, 1,000, and 2,000 Hz, respectively, than the controls. Of the 20 children with SRNS, ten (50 %) had sensoineural hearing impairment (8 mild, 2 moderate). Children with SRNS with a hearing defect had received a higher cumulative dose of furosemide (P < 0.03).

CONCLUSIONS

Children with FRNS/SDNS and SRNS are at risk of sensorineural hearing impairment. The risk factors associated with this impairment were higher cumulative doses of furosemide and hypocalcemia. Larger prospective cohort studies are required to evaluate this association.

Perspectives of pharmacological treatment in otosclerosis

To review our current knowledge of the pathologic bone metabolism in otosclerosis and to discuss the possibilities of non-surgical, pharmacological intervention. Otosclerosis has been suspected to be associated with defective measles virus infection, local inflammation and consecutive bone deterioration in the human otic capsule. In the early stages of otosclerosis, different pharmacological agents may delay the progression or prevent further deterioration of the disease and consecutive hearing loss. Although effective anti-osteoporotic drugs have become available, the use of sodium fluoride and bisphosphonates in otosclerosis has not yet been successful. Bioflavonoids may relieve tinnitus due to otosclerosis, but there is no data available on long-term application and effects on sensorineural hearing loss. In the initial inflammatory phase, corticosteroids or non-steroidal anti-inflammatory drugs may be effective; however, extended systemic application may lead to serious side effects. Vitamin D administration may have effects on the pathological bone loss, as well as on inflammation. No information has been reported on the use of immunosuppressive drugs. Anti-cytokine targeted biological therapy, however, may be feasible. Indeed, one study on the local administration of infliximab has been reported. Potential targets of future therapy may include osteoprotegerin, RANK ligand, cathepsins and also the Wnt-β-catenin pathway. Finally, anti-measles vaccination may delay the progression of the disease and potentially decrease the number of new cases. In conclusion, stapes surgery remains to be widely accepted treatment of conductive hearing loss due to otosclerosis. Due to lack of solid evidence, the place of pharmacological treatment targeting inflammation and bone metabolism needs to be determined by future studies.

Expression of epithelial calcium transport system in rat cochlea and vestibular labyrinth

BACKGROUND

The low luminal Ca2+ concentration of mammalian endolymph in the inner ear is required for normal hearing and balance. We recently reported the expression of mRNA for a Ca2+-absorptive transport system in primary cultures of semicircular canal duct (SCCD) epithelium.

RESULTS

We now identify this system in native vestibular and cochlear tissues by qRT-PCR, immunoblots and confocal immunolocalization. Transcripts were found and quantified for several isoforms of epithelial calcium channels (TRPV5, TRPV6), calcium buffer proteins (calbindin-D9K, calbindin-D28K), sodium-calcium exchangers (NCX1, NCX2, NCX3) and plasma membrane Ca2+-ATPase (PMCA1, PMCA2, PMCA3, and PMCA4) in native SCCD, cochlear lateral wall (LW) and stria vascularis (SV) of adult rat as well as Ca2+ channels in neonatal SCCD. All components were expressed except TRPV6 in SV and PMCA2 in SCCD. 1,25-(OH)2vitamin D3 (VitD) significantly up-regulated transcripts of TRPV5 in SCCD, calbindin-D9K in SCCD and LW, NCX2 in LW, while PMCA4 in SCCD and PMCA3 in LW were down-regulated. The expression of TRPV5 relative to TRPV6 was in the sequence SV > Neonatal SCCD > Adult SCCD > LW > primary culture SCCD. Expression of TRPV5 protein from primary culture of SCCD did not increase significantly when cells were incubated with VitD (1.2 times control; P > 0.05). Immunolocalization showed the distribution of TRPV5 and TRPV6. TRPV5 was found near the apical membrane of strial marginal cells and both TRPV5 and TRPV6 in outer and inner sulcus cells of the cochlea and in the SCCD of the vestibular system.

CONCLUSIONS

These findings demonstrate for the first time the expression of a complete Ca2+ absorptive system in native cochlear and vestibular tissues. Regulation by vitamin D remains equivocal since the results support the regulation of this system at the transcript level but evidence for control of the TRPV5 channel protein was lacking.

Stria vascularis and vestibular dark cells: characterisation of main structures responsible for inner-ear homeostasis, and their pathophysiological relations

The regulation of inner-ear fluid homeostasis, with its parameters volume, concentration, osmolarity and pressure, is the basis for adequate response to stimulation. Many structures are involved in the complex process of inner-ear homeostasis. The stria vascularis and vestibular dark cells are the two main structures responsible for endolymph secretion, and possess many similarities. The characteristics of these structures are the basis for regulation of inner-ear homeostasis, while impaired function is related to various diseases. Their distinct morphology and function are described, and related to current knowledge of associated inner-ear diseases. Further research on the distinct function and regulation of these structures is necessary in order to develop future clinical interventions.

Progressive hearing loss in mice with a mutated vitamin D receptor gene

BACKGROUND

Both hypo- and hypervitaminosis D can cause sensorineural hearing loss, and aural symptoms due to vitamin D insufficiency are especially common during gravidity. Hormonal forms of vitamin D regulate transcription by binding with the high-affinity vitamin D receptor (VDR).

OBJECTIVE

To assess the effects of impaired vitamin D action in VDR knockout (KO) mice on hearing, cochlear morphology, and cochlear gene expression.

MATERIALS AND METHODS

Eighteen young male and female mice (10 VDR KO and 8 wild type, WT, < or =6 months old), 33 adult male and female mice (16 VDR KO and 17 WT, between 7 and 14 months old), and 11 aged male and female mice (5 VDR KO and 6 WT, > or =15 months old) on 129S1 genetic background were studied. Auditory thresholds were evaluated by auditory brain stem response. Morphological changes were analyzed using plastic embedding and light microscopy. The expression of key genes (known to play a role in the regulation of cochlear function), and caspase 3 activity, were assessed using immunofluorescent confocal microscopy.

RESULTS

There was a statistically significant difference between the young and the adult groups, and between the adult and aged groups of WT mice. There was also a statistically significant difference between the adult and aged groups in VDR KO mice, and between the young WT group and the young VDR KO group. Spiral ganglion cell loss was observed in the basal turn of adult VDR KO mice, a phenomenon infrequently found in WT mice. Expression of connexin 26, KCNJ10, and transient receptor potential channel vanilloid subfamily 4/6 was not affected by VDR KO-mediated hearing loss. Caspase 3 activation was detected in the spiral ganglion cell and its satellite cells, stria vascularis, spiral ligament fibrocytes, and the organ of Corti in both genotypes. However, the percentage of positive cells and the staining intensity were lower in the VDR KO (compared to the WT) mice.

CONCLUSION

These data suggest that sensorineural hearing loss progressively developed at an earlier age in VDR KO mice. While the fundamental gene expressions in the cochlea were not influenced by VDR mutation, it resulted in decrease of caspase 3 activation, which may be one of the factors underlying accelerating age-related hearing loss observed in VDR KO mice.

Estrogen and the inner ear: megalin knockout mice suffer progressive hearing loss

Megalin, the largest member of the low-density lipoprotein receptor-related protein family, functions as an endocytic receptor for a variety of essential lipophilic metabolites, including the steroid hormone estrogen. In the cochlea, megalin is strongly expressed within the marginal cells of the stria vascularis, and previous studies demonstrated that beta-estrogen receptors are also expressed in megalin-expressing marginal cells. In the present study, we demonstrate that homozygous megalin mutant mice exhibit profound hearing loss at 3 months of age associated with features of presbycusis, enrichment of lipofuscin granules, and a reduced number of microvilli in marginal cells of the stria vascularis. FITC-labeled beta-estrogen is taken up into the strial marginal cells; however, in megalin-deficient mice the uptake of FITC-labeled beta-estrogen is reduced. This highlights beta-estrogen as a possible carrier-bound candidate ligand for megalin and supports the concept that estrogen may function via megalin within the inner ear. A crucial role of megalin in hearing should be considered and the megalin/estrogen interaction needs to be discussed in the context of early presbycusis in estrogen-deficient humans and mice.

Neophobia, sensory and cognitive functions, and hedonic responses in vitamin D receptor mutant mice

Vitamin D is a seco-steroid hormone with multiple actions in the brain, mediated through the nuclear vitamin D receptor (VDR). We have recently shown that mutant mice lacking functional VDR demonstrate altered emotional behavior and specific motor deficits. Here we further examine phenotype of these mice, testing their novelty responses, as well as cognitive and sensory (olfactory and gustatory) functions in the novel food, two-trial Y-maze and tastant consumption tests. In addition, we study depression-like behavior in these mice, using anhedonia-based sucrose preference test. Overall, VDR mutant mice showed neophobic response in several different tests, but displayed unimpaired olfactory and gustatory functions, spatial memory and baseline hedonic responses. Collectively, these data confirm that mutation of VDR in mice leads to altering emotional/anxiety states, but does not play a major role in depression, as well as in the regulation of some sensory and cognitive processes. These results support the role of the vitamin D/VDR neuroendocrine system in the regulation of behavior, and may have clinical relevance, enabling a better focus on psychiatric and behavioral disorders associated with dysfunctions in this neuroendocrine system.

Supporting sensory transduction: cochlear fluid homeostasis and the endocochlear potential

The exquisite sensitivity of the cochlea, which mediates the transduction of sound waves into nerve impulses, depends on the endocochlear potential and requires a highly specialized environment that enables and sustains sensory function. Disturbance of cochlear homeostasis is the cause of many forms of hearing loss including the most frequently occurring syndromic and non-syndromic forms of hereditary hearing loss, Pendred syndrome and Cx26-related deafness. The occurrence of these and other monogenetic disorders illustrates that cochlear fluid homeostasis and the generation of the endocochlear potential are poorly secured by functional redundancy. This review summarizes the most prominent aspects of cochlear fluid homeostasis. It covers cochlear fluid composition, the generation of the endocochlear potential, K(+) secretion and cycling and its regulation, the role of gap junctions, mechanisms of acid-base homeostasis, and Ca(2+) transport.

Observation of the morphology and calcium content of vestibular otoconia in rats after simulated weightlessness

Reduction in bone formation may have been the main reason for the lower calcium content of the otoconia after simulated weightlessness in rats. The head-ward distribution of blood volume may explain the morphological changes observed in the middle and inner ears. To observe morphological changes in the vestibular organs and measure the calcium content of otoconia in rats after simulated weightlessness. We used a tail suspension model of simulated weightlessness and then investigated changes in the vestibular organs using scanning electron microscopy and X-ray microanalysis. In comparison to untreated rats, the vestibular otoconia of the rats subjected to simulated weightlessness were small, irregularly shaped or fissured, and were arranged loosely and out of order. In addition, the calcium content of the otoconia was markedly decreased.

Age-related hearing loss, vitamin B-12, and folate in elderly women

BACKGROUND

Hearing impairment is 1 of the 4 most prevalent chronic conditions in the elderly. However, the biological basis of age-related hearing loss is unknown.

OBJECTIVE

The objective was to test the hypothesis that age-related hearing loss may be associated with poor vitamin B-12 and folate status.

DESIGN

A thorough audiometric assessment was conducted in 55 healthy women aged 60-71 y. Hearing function was determined by the average of pure-tone air conduction thresholds at 0.5, 1, 2, and 4 kHz and was categorized into 2 groups for logistic regression analyses: normal hearing (<20 dB hearing level; n = 44) and impaired hearing (> or = 20 dB hearing level; n = 11).

RESULTS

Mean age was the same (65 y) for the normal hearing and impaired hearing groups. Pure-tone averages were inversely correlated with serum vitamin B-12 (r = -0.58, P = 0.0001) and red cell folate (r = -0.37, P = 0.01). Women with impaired hearing had 38% lower serum vitamin B-12 (236 compared with 380 pmol/L, respectively, P = 0.008) and 31% lower red cell folate (425 compared with 619 nmol/L, respectively, P = 0.02) than women with normal hearing. Among participants who did not take supplements containing vitamin B-12 or folate, women with impaired hearing had 48% lower serum vitamin B-12 (156 compared with 302 pmol/L, respectively, P = 0.0007) and 43% lower red cell folate (288 compared with 502 nmol/L, respectively, P = 0.001) than women with normal hearing.

CONCLUSION

Poor vitamin B-12 and folate status may be associated with age-related auditory dysfunction.

Sensorineural hearing loss associated with Byler disease

Progressive familial intrahepatic cholestasis, sometimes described as Byler disease, is a lethal liver disease and its inheritance is autosomal recessive. There is a previous report on the occasional association between this disease and sensorineural hearing loss without any audiological findings. We report here two siblings, an 18-year-old female and a 16-year-old male, suffering from Byler disease and hearing loss. Pure tone, Bekesy and speech audiometries and auditory brain stem response examination were performed. Audiometric data showed hearing characteristics of cochlear origin, high-frequency loss and progressiveness. This sensorineural hearing loss possibly results from a genetic mutation. The mechanism of cochlear disorder in patients with Byler disease is unknown, however, a novel gene responsible for deafness might be found to be related to Byler disease.

CT screening for temporal bone abnormalities in idiopathic bilateral sensorineural hearing loss

Bilateral sensorineural hearing loss can be caused by a variety of temporal bone abnormalities including primary cochlear otosclerosis, local and systemic bony diseases and some metabolic conditions. These may be identified using computerized tomography (CT), with attenuation recordings taken across the cochlear capsule (CT densitometry). Eighty patients with bilateral sensorineural hearing loss were screened over a period of six and a half years using this technique, and only three cases (3.8 per cent) of treatable disease were detected. Positive yields may be increased by screening selected cases with other clinical or biochemical stigmata of temporal bone disease.

Hearing loss in former prisoners of war of the Japanese

OBJECTIVE

To describe the prevalence, degree, and types of hearing loss present in a group of older American veterans who had been prisoners of war of the Japanese.

DESIGN

A descriptive study.

SETTING

A Veterans Affairs university hospital.

PARTICIPANTS

Seventy-five male veterans, mean age 68 (+/- 3.6) years.

INTERVENTIONS

Hearing aids were prescribed for eight veterans.

MEASUREMENTS

Subjects were examined, and pure tone air and bone conduction, speech reception threshold, and speech discrimination were determined. Results were compared with age- and sex-matched controls from the largest recent American population study of hearing loss.

RESULTS

95% of subjects had been imprisoned longer than 33 months. Starvation conditions (100%), head trauma (85%), and trauma-related loss of consciousness (23%) were commonly reported. A total of 73% complained of hearing loss, and 29% (22/75) dated its onset to captivity. Most of those with the worst losses in hearing and speech discrimination were found in this subgroup. When the entire group was compared with published age- and sex-matched controls from the Framingham Study, no significant differences were found.

CONCLUSIONS

We advocate screening examinations and long-term follow-up of populations with similar histories of starvation, head trauma, and torture.

Age-related hearing loss and bone mass in a population of rural women aged 60 to 85 years

Demineralization of the cochlear capsule in conjunction with age-related bone mass loss may be one biologic factor contributing to hearing loss in the elderly. In other metabolic bone diseases, including Paget's disease of the bone and cochlear otosclerosis, demineralization of the cochlea has been associated with sensorineural hearing loss. In 1988/1989, the relation between hearing loss and bone mass of the radius and femoral neck was studied cross-sectionally in 369 women aged 60 to 85 years from three rural communities. Hearing sensitivity was measured using audiometry, and bone mineral density of the radius and femoral neck was measured using single- and dual-photon densitometry, respectively. Three variables, ascertained by interview, were associated with an increased odds for hearing loss: age, family history of hearing loss before the age of 50 years, and current use of more than two nonestrogen, nonthiazide prescription medications. After consideration of the effect of these three variables, women with femoral neck bone mass values below the mean value of 0.696 g/cm2 for this population had a 1.9 greater odds of having a hearing loss (confidence interval: 1.30, 2.50). This study demonstrated a consistent adjusted association between femoral neck bone mass and age-related hearing loss in a population of rural women aged 60 to 85 years. No consistent association was observed between radial bone mass and hearing loss.

Auditory abnormalities, including 'precocious presbyacusis', in myotonic dystrophy

Auditory function tests were performed on 13 patients with myotonic dystrophy (MD). Seven patients had a sensorineural high-frequency hearing loss (HFL) of 30-85 dB at 8 kHz in their pure-tone audiogram, which was in excess of that expected for their age and could be attributed to MD. Their hearing loss resembled 'precocious presbyacusis', i.e. if the patients had been considerably older (or 'functionally' older) than they really were, their HFL could (to some extent) have been attributed to presbyacusis alone. The HFL showed the phenomenon of (genetic) anticipation. Tympanograms and acoustic reflexes were normal. Brainstem auditory evoked potentials (BAEPs) showed a significant increase in the I-V interpeak interval (by 0.35-0.7 ms) and in the III-V interpeak interval (by 0.21-0.67 ms). There was no correlation between the BAEP and the audiometric findings. It should be noted that precocious presbyacusis may be linked to specific gene defects.

Xeroderma pigmentosum: recent clinical and photobiological aspects

In Japan, more than 400 patients with xeroderma pigmentosum (XP) have been registered. The major groups are XP-A and variant, while clinically mild types of XP with intermediate levels of unscheduled DNA synthesis (UDS) have recently been increasing. The classical type of XP-A and some of the XP-D patients exhibit neurologic abnormalities. XP individuals display a marked increase in the frequency of skin malignancy. Development of skin malignancies appears to be related to the level of DNA repair capacity; the lower the capacity, the earlier and more frequently the skin tumors develop. Furthermore, the incidence of internal malignancy in XP patients is at least ten times higher than that for the Japanese general population over the age of 40 years. Cultured fibroblasts from XP patients exhibit higher sensitivity not only to UVC but also to UVB. The cellular sensitivity to UVB may correlate to photosensitivity in vivo from a study on a group E patient who showed age-related changes in photosensitivity and cellular sensitivity to UVB. We have also reviewed current status of molecular genetics in XP.

Hearing-loss and calciferol deficiency

Vitamin D (calciferol) deficiency has recently been claimed to cause cochlear hearing-loss (Brookes and Morrison, 1981; Brookes, 1983, 1984). In view of the therapeutic and pathophysiological implications of this finding, a confirmatory study was undertaken in the Department of Neuro-otology at The Royal National Throat, Nose and Ear Hospital. Screening of 112 consecutive new referrals revealed 32 patients with biochemical abnormalities compatible with vitamin D deficiency. Of these, 26 agreed to serum vitamin D assay and normal values were obtained in all of these cases. This study does not support the claim that vitamin D deficiency is a cause of hearing-loss.

Audiologic findings in young patients with hypophosphatemic bone disease

Audiometric tests were conducted on 19 subjects with hypophosphatemic bone disease to investigate whether auditory impairment like that reported in affected adults occurs in young patients. No hearing loss or significant auditory findings were noted among the children or young adult patients. However, sensorineural hearing loss of cochlear origin was identified in the three oldest subjects (40 to 58 years), although a history of noise exposure in two of them could explain the observations. The results indicate that if an association exists between hypophosphatemic bone disease and hearing impairment, the auditory signs will not develop until adulthood in treated patients. Additional studies of large populations of affected adults are needed to identify the incidence and mechanism(s) of the auditory system abnormalities and to assess any effect of medical therapy for the metabolic bone disease.

Vitamin D deficiency and otosclerosis

A prospective study of 47 patients with otosclerosis was undertaken to investigate the possible etiologic role of vitamin D undernutrition. The population comprised 27 women and 20 men, with a mean age of 46.4 years (range 21 to 79). The disease was bilateral in 43 patients, and cochlear involvement was present in 84.4%. The mean duration of symptoms was 17.1 years. Vitamin D status was evaluated by measuring the plasma 25-hydroxy vitamin D3 (25-OHD), which is the main storage metabolite. Abnormally low 25-OHD levels were found in 10 patients (21.7%) and borderline low levels in another two. Raised serum alkaline phosphatase levels were present in 32.6%, calcium in 6.5%, and inorganic phosphate in 4.3%. Calcium and vitamin D replacement therapy resulted in significant hearing improvement in 3 of 16 patients; these data support a causal correlation. Vitamin D deficiency is probably a factor in the etiology of some cases of otosclerosis and is important, since the deafness resulting from cochlear involvement may be reversible.