High risk of sensorineural hearing loss in men born small for gestational age with and without obesity or height catch-up growth: a prospective longitudinal register study on birth size in 245,000 Swedish conscripts

Associations Between Body Composition and Sensorineural Hearing Loss Among Adults Based on the UK Biobank

OBJECTIVE

To explore the association between body composition and sensorineural hearing loss (SNHL).

STUDY DESIGN

Cross-sectional study, prospective study and Mendelian randomization (MR) analyses.

SETTING

UK Biobank.

METHODS

This cross-sectional study included 147,296 adult participants with complete data on body composition and the speech-reception-threshold (SRT) test. We further conducted a prospective study with 129,905 participants without SNHL at baseline and followed up to 15 years to explore the association between body composition and new-onset SNHL. Multivariable logistic regression and Cox regression models were used. Subgroup analyses stratified by age and sex were performed. We further assessed the causal association between body composition and SNHL using two-sample MR analyses.

RESULTS

Our cross-sectional study revealed that fat percentage, especially leg (odds ratio [OR] 1.46, p = .029) and arm (OR 1.43, p = .004), were significant risk factors for SNHL. However, fat-free mass, especially in the arm (OR 0.27, p < .001) and leg (OR 0.58, p < .001) showed significant protective effects against SNHL, which was substantially consistent with the results of the prospective study. In addition, we found that young women with SNHL were more susceptible to body composition indicators. However, MR analyses revealed no evidence of significant causal association.

CONCLUSION

Fat percentage, especially in the leg and arm, was a significant risk factor for SNHL, whereas fat-free mass, especially in the leg and arm, had significant protective effects against SNHL, however, these associations may not be causal.

A Narrative Review of Lifestyle Risk Factors and the Role of Oxidative Stress in Age-Related Hearing Loss

Age-related hearing loss affects a significant proportion of adults aged 60 years and above, with a prevalence of 65%. This condition has a negative impact on both physical and mental well-being, and while hearing interventions can help alleviate the effects of hearing loss, they cannot completely restore normal hearing or halt the progression of age-related hearing loss. Oxidative stress and inflammation have been identified as potential contributors to this condition. By addressing modifiable lifestyle risk factors that exacerbate oxidative stress, there may be an opportunity to prevent hearing loss. Therefore, this narrative review provides an overview of the major modifiable lifestyle risk factors associated with age-related hearing loss, that is, exposure to noise and ototoxic chemicals, smoking, diet, physical activity, and the presence of chronic lifestyle diseases, and offers an overview of the role of oxidative stress in the pathophysiology of this condition.

Association of Body Mass Index with Hearing Loss in Korean Adult Population

This study aimed to explore the relationship between body mass index (BMI) and hearing loss. We analyzed data from the Korean National Health Insurance Service Health Screening Cohort 2009−2019 (291,471 patients with hearing loss and 6,088,979 control participants). Both patient groups were subsequently divided into four groups according to BMI: <18.5 (underweight), 18.5−24.9 (normal), 25−29.9 (obese I), and ≥30 (obese II). To evaluate the relationship between BMI and hearing loss, multivariate logistic regression analysis was used, adjusting for age, sex, smoking, alcohol consumption, blood pressure, triglycerides, total cholesterol, low-density lipoprotein, proteinuria, serum creatinine, aspartate aminotransferase, alanine aminotransferase, and fasting glucose levels. The adjusted odds ratio (OR) of the underweight group for hearing loss was 1.21 (95% CI = 1.19−1.24) compared to the normal BMI group, whereas the adjusted ORs of obese I and obese II groups for hearing loss were 0.95 and 0.87, respectively. Being underweight was generally associated with an increased prevalence of hearing loss in the Korean adult population.

Early Life Influences on Hearing in Adulthood: a Systematic Review and Two-Step Individual Patient Data Meta-Analysis

Objectives:

Adverse prenatal and early childhood development may increase susceptibility of hearing loss in adulthood. The objective was to assess whether indices of early development are associated with adult-onset hearing loss in adults ≥18 years.

Design:

In a systematic review and meta-analysis, four electronic databases were searched for studies reporting associations between indices of early development (birth weight and adult height) and adult-onset hearing loss in adults ≥18 years. We screened studies, extracted data, and assessed risk of bias. Authors were contacted to provide adjusted odds ratios from a logistic regression model for relationships between birth weight/adult height and normal/impaired hearing enabling a two-step individual patient data random-effects meta-analysis to be carried out. The study is registered with PROSPERO, CRD42020152214.

Results:

Four studies of birth weight and seven of adult height were identified. Three studies reported smaller birth weight associated with poorer adult hearing. Six studies reported shorter height associated with poorer hearing. Risk of bias was low to moderate. Four studies provided data for two-step individual patient data random-effects meta-analysis. Odds of hearing impairment were 13.5% lower for every 1 kg increase in birth weight [OR: 0.865 (95% confidence interval: 0.824 to 0.909)] in adulthood over two studies (N=81,289). Every 1 cm increase in height was associated with a 3% reduction in the odds of hearing impairment [OR: 0.970 (95% confidence interval: 0.968 to 0.971)] over four studies (N=156,740).

Conclusions:

Emerging evidence suggests that adverse early development increases the likelihood of hearing impairment in adulthood. Research and public health attention should focus on the potential for prevention of hearing impairment by optimizing development in early life.

Birth Weight and Adult-Onset Hearing Loss

OBJECTIVES

Among low-birth-weight infants, exposure to stress or undernutrition in utero may adversely affect cochlear development. As cochlear reserve declines, the risk of hearing loss may increase with age. While low birth weight is associated with a higher risk of neonatal hearing loss, our objective was to examine whether birth weight was associated with adult-onset, self-reported hearing loss in the Nurses' Health Studies (NHS) I and II (n = 113,130).

DESIGN

We used Cox proportional hazards regression to prospectively examine whether birth weight, as well as gestational age at birth, is associated with adult-onset hearing loss. Participants reported their birth weight in 1992 in NHS I and 1991 in NHS II. Mothers of NHS II participants reported gestational age at birth in a substudy (n = 28,590). The primary outcome was adult-onset, self-reported moderate or greater hearing loss, based on questionnaires administered in 2012/2016 in NHS I and 2009/2013 in NHS II.

RESULTS

Our results suggested a higher risk of hearing loss among those with birth weight <5.5 lbs compared with birth weight 7 to <8.5 lbs (pooled multivariable-adjusted hazard ratio 1.14, 95% confidence interval = 1.04-1.23; p trend = 0.01). Additionally, participants with gestational age at birth ≥42 weeks had a higher risk of hearing loss, compared with gestational age 38 to <42 weeks (multivariable-adjusted hazard ratio 1.33, 95% confidence interval = 1.06-1.65).

CONCLUSIONS

Birth weight <5.5 lbs was independently associated with higher risk of self-reported, adult-onset hearing loss. In addition, gestational age at birth ≥42 weeks was also associated with higher risk.

The genetic architecture of age-related hearing impairment revealed by genome-wide association analysis

Age-related hearing impairment (ARHI) is the most common sensory disorder in older adults. We conducted a genome-wide association meta-analysis of 121,934 ARHI cases and 591,699 controls from Iceland and the UK. We identified 21 novel sequence variants, of which 13 are rare, under either additive or recessive models. Of special interest are a missense variant in LOXHD1 (MAF = 1.96%) and a tandem duplication in FBF1 covering 4 exons (MAF = 0.22%) associating with ARHI (OR = 3.7 for homozygotes, P = 1.7 × 10-22 and OR = 4.2 for heterozygotes, P = 5.7 × 10-27, respectively). We constructed an ARHI genetic risk score (GRS) using common variants and showed that a common variant GRS can identify individuals at risk comparable to carriers of rare high penetrance variants. Furthermore, we found that ARHI and tinnitus share genetic causes. This study sheds a new light on the genetic architecture of ARHI, through several rare variants in both Mendelian deafness genes and genes not previously linked to hearing.

Associations of Retinal Vessel Caliber With Hearing Status in Childhood and Midlife: A Cross-Generational Population-Based Study

Importance

Microvascular phenotypes, which can be assessed using retinal imaging, may be informative about the life course pathogenesis of hearing loss.

Objective

To investigate whether differences in retinal vessel caliber (specifically wider venules and narrower arterioles) are associated with hearing threshold and hearing loss in mid-childhood and midlife.

Design, Setting, and Participants

A population-based cross-sectional study (Child Health CheckPoint) was nested within the Longitudinal Study of Australian Children. A total of 1281 children and 1255 attending parents were assessed using retinal microvasculature and air conduction audiometry data at a main assessment center in 7 large cities in Australia.

Main Outcomes and Measures

Air conduction audiometry was used to calculate the high Fletcher index (mean threshold of 1, 2, and 4 kHz), and bilateral hearing loss was defined as a high Fletcher index greater than 15 dB hearing level in the better-hearing ear. Retinal arteriolar and venular caliber were measured from fundus photographs using validated computer-based software. Linear and logistic regression quantified the associations of retinal vessel caliber with hearing threshold and hearing loss, respectively.

Results

Of the 1281 included children (mean age, 11.4 years; 49.1% boys), the mean (SD) high Fletcher index was 7.9 (5.8) dB hearing level. Of the 1255 included adults (mean age, 43.8 years; 86.6% women), the mean (SD) high Fletcher index was 13.0 (6.8) dB hearing level; 109 of 1281 children (8.5%) and 328 of 1255 adults (26.1%) had hearing loss. In adults, each 1-SD (18.6-μm) wider retinal venular caliber (worse) was associated with higher (worse) hearing threshold at lower individual frequencies (eg, 2 kHz: β = 0.63; 95% CI, 0.10-1.17) and overall high Fletcher index (eg, 2 kHz: β = 0.52; 95% CI, 0.07-0.96), as well as a 1.20-fold (95% CI, 1.03-1.40) higher odds of hearing loss. In children, patterns of venular associations were similar but smaller and less certain. Narrower retinal arteriolar caliber (worse) was associated with a 1.16-fold (95% CI, 1.00-1.37) higher odds of hearing loss in adults (per 1-SD [14.0-μm] narrower arteriolar caliber) but not in children.

Conclusions and Relevance

Adverse retinal microvascular characteristics are associated with hearing loss by midlife, with venular associations possibly emerging by age 11 to 12 years. Microvascular health may contribute to the pathogenesis of hearing loss across the life course, warranting replication and mechanistic studies to inform causal inference and prevention efforts.

Synergistic effect of smoking on age-related hearing loss in patients with diabetes

This study investigated the synergistic effects of risk factors on age-related hearing loss (ARHL) using nationwide cross-sectional data of 33,552 individuals from the 2010‒2013 Korea National Health and Nutrition Examination Survey. Patients with ARHL were selected based on their pure-tone audiometry results. Previously reported risk factors for ARHL were analyzed using logistic regression and propensity score-matching, and synergistic effects between risk factors were analyzed using propensity score-matching. Of the 12,570 individuals aged 40–79 years, 2002 (15.9%) met the criteria for ARHL. Male sex, exposure to occupational noise, and diabetes showed a significant relationship with ARHL (p < 0.05) in both the logistic regression and propensity score-matching analyses. Smoking and diabetes showed the strongest significant synergistic effect on ARHL (odds ratio [OR] 1.963, 95% confidence interval [CI] 1.285‒2.998; p = 0.002). In the subgroup analysis based on smoking status, current smokers with diabetes had a significant relationship with ARHL (OR 1.883, CI 1.191‒2.975; p = 0.009), whereas ex-smokers with diabetes did not (OR 1.250; CI 0.880‒1.775; p = 0.246). This implies that current smokers with diabetes may benefit from the cessation of smoking. In conclusion, patients with diabetes should strictly avoid or cease smoking to prevent the progression of ARHL.

Body mass index, waist circumference, and risk of hearing loss: a meta-analysis and systematic review of observational study

BACKGROUND

Emerging evidence implicates excess weight as a potential risk factor for hearing loss. However, this association remained inconclusive. Therefore, we aimed to systematically and quantitatively review the published observational study on the association between body mass index (BMI) or waist circumference (WC) and hearing loss.

METHODS

The odds ratios (ORs) or relative risks (RRs) with their 95% confidence intervals (CIs) were pooled under a random-effects model. Fourteen observational studies were eligible for the inclusion in the final analysis.

RESULTS

In the meta-analysis of cross-sectional studies, the ORs for prevalent hearing loss were 1.10 (95% CI 0.88, 1.38) underweight, 1.14 (95% CI 0.99, 1.32) for overweight, OR 1.40 (95% CI 1.14, 1.72) for obesity, 1.14 (95% CI 1.04, 1.24) for each 5 kg/m2 increase in BMI, and 1.22 (95% CO 0.88. 1.68) for higher WC. In the meta-analysis of longitudinal studies, the RRs were 0.96 (95% CI 0.52, 1.79) for underweight, 1.15 (95% CI 1.04, 1.27) for overweight, 1.38 (95% CI 1.07, 1.79) for obesity, 1.15 (95% CI 1.01, 1.30) for each 5 kg/m2 increase in BMI, and 1.11 (95% CI 1.01, 1.22) for higher WC.

CONCLUSIONS

In summary, our findings add weight to the evidence that elevated BMI and higher WC may be positively associated with the risk of hearing loss.

An Investigation of Hearing (250-20,000 Hz) in Children with Endocrine Diseases and Evaluation of Tinnitus and Vertigo Symptoms

Introduction  Despite much advancement in medicine, endocrine and metabolic diseases remain an important cause of morbidity and even mortality in children.

Objective  The present study was planned to investigate the evaluation of hearing that also includes high frequencies, and the presence and degree of vertigo and tinnitus symptoms in pediatric patients diagnosed with endocrine diseases such as type 1 diabetes mellitus (DM), growth hormone deficiency (GHD), obesity, idiopathic short stature, and precocious puberty

Methods  The present study included a patient group of 207 children patients diagnosed with endocrine disease (95 males, 112 females; mean age 9.71 years old [range 6–16 years old]) and a control group including 55 healthy children who do not have any kind of chronic disease (26 males, 29 females; mean age 9.33 years old [range 6–16 years old]). The subjects underwent a hearing test with frequencies between 250 and 20,000 Hz. The vestibular and tinnitus symptoms were evaluated with the Pediatric Vestibular Symptom Questionnaire.

Results  Out of 207 patients in the patient group, 5 (2.4%) had hearing loss in pure tones, 10 (4.8%) had it in high frequencies, 40 (19.3%) had tinnitus symptoms, and 18 (8.7%) had vertigo symptoms. A total of 4 out of 207 patients in the study group (1.9%), 2 out of 59 with type 1 DM patients (3.4%), 1 out of 46 with GHD (2.2%), and 1 out of 43 obesity patients (2.3%) had hearing loss, vertigo, and tinnitus symptoms.

Conclusions  Our results suggest that some childhood endocrine diseases can cause some changes in the inner ear, although the exact cause is unknown. Perhaps, a detailed hearing and balance examination should be a routine in a child diagnosed with an endocrine disease. We think it is necessary to work on more comprehensive patient groups and tests in the future.

Metabolic Syndrome as a Risk Factor for Sensorineural Hearing Loss in Adult Patients with Turner Syndrome

Background and purpose

Metabolic syndrome (MetS) is a disorder associated with an increased risk of cardiovascular disease. The frequency of each component of MetS in Turner syndrome (TS) subjects is high. An elevated incidence of hearing loss has also been reported in TS. Sensorineural hearing loss (SNHL) affects at least half of young women with TS. The association between MetS and SNHL has not been previously considered in TS. The aim of this study is to evaluate the association between these two conditions.

Patients and Methods

Cross-sectional anthropometric, cardio-metabolic and audiological data were obtained from a cohort consisting of unrelated TS subjects (>20 years of age; n = 93). Metabolic syndrome was defined according to the International Diabetes Federation criteria. Types and severity of hearing loss were based on the American Speech Hearing Association guidelines.

Results

Hearing loss was detected in 74% of ears from adult TS subjects and SNHL was observed in half of our TS subjects. The prevalence of MetS in TS subjects with or without SNHL was 64% and 11%, respectively (P < 0.05). After adjusting for age, MetS was related to a ninefold increase in the odds of SNHL. This odds increased in a stepwise manner as the number of MetS components increased.

Conclusion

MetS and its individual components were associated factors for SNHL in TS subjects. A reduction in the number and severity of the components of MetS might potentially contribute to decreasing the progression of SNHL at younger ages, but further studies will be needed to explain the underlying pathological mechanism connecting MetS and SNHL.

Academic, behavioural and quality of life outcomes of slight to mild hearing loss in late childhood: a population-based study

OBJECTIVE

To investigate the associations of hearing thresholds and slight to mild hearing loss with academic, behavioural and quality of life outcomes in children at a population level.

METHODS

Design and participants:children aged 11-12 years in the population-based cross-sectional Child Health CheckPoint study within the Longitudinal Study of Australian Children. Audiometry:mean hearing threshold across 1, 2 and 4 kHz (better and worse ear); slight/mild hearing loss (threshold of 16-40 decibels hearing loss (dB HL)). Outcomes: National Assessment Program - Literacy and Numeracy, language, teacher-reported learning, parent and teacher reported behaviour and self-reported quality of life. Analysis:linear regression quantified associations of hearing threshold/loss with outcomes.

RESULTS

Of 1483 children (mean age 11.5 years), 9.2% and 13.1% had slight/mild bilateral and unilateral hearing loss, respectively. Per SD increment in better ear threshold (5.7 dB HL), scores were worse on several academic outcomes (eg, reading 0.11 SD, 95% CI 0.05 to 0.16), parent-reported behaviour (0.06 SD, 95% CI 0.01 to 0.11) and physical (0.09 SD, 95% CI 0.04 to 0.14) and psychosocial (0.06 SD, 95% CI 0.01 to 0.11) Pediatric Quality of Life Inventory (PedsQL). Compared with normally hearing children, children with bilateral slight/mild losses scored 0.2-0.3 SDs lower in sentence repetition, teacher-reported learning and physical PedsQL but not other outcomes. Similar but attenuated patterns were seen in unilateral slight/mild losses.

CONCLUSIONS

Hearing thresholds and slight/mild hearing loss showed small but important associations with some child outcomes at 11-12 years. Justifying hearing screening or intervention at this age would require better understanding of its longitudinal and indirect effects, alongside effective management and appropriate early identification programmes.

Role of Obesity in Otorhinolaryngologic Diseases

PURPOSE OF REVIEW

Obesity is a major public health problem associated with various diseases. Improving obesity control and achieving greater patient satisfaction are critical unmet needs. Various otorhinolaryngologic diseases can have negative effects on quality of life or actual health status depending on their type. Over the past decade, the relationship between obesity and otorhinolaryngologic conditions has been investigated. The purpose of this review was to discuss the relationship between obesity and otorhinolaryngological diseases.

RECENT FINDINGS

This is a narrative review on the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. In various otologic diseases, otitis media (OM) and hearing loss (HL) are associated with obesity. In rhinologic parts, chronic rhinosinusitis (CRS) and obstructive sleep apnea (OSA) were significantly associated with obesity. Most of these diseases are reported to have higher susceptibility and severity as body mass index (BMI) increases. However, the incidence of head and neck cancer (HNC) was inversely associated with obesity, especially central adiposity. The relevance of obesity in laryngopharyngeal reflux disease (LPR) and allergic rhinitis (AR) has yet to be clarified, and this remains controversial. This review provides a comprehensive overview of the current state of incidence, effects, and associated mechanisms between obesity and otorhinolaryngologic diseases. Various otorhinolaryngological diseases are related to obesity. As obesity can be a negative risk factor in these otorhinolaryngologic diseases, early diagnosis and treatment of these diseases in obese patients will be critical.

The Association Between ENT Diseases and Obesity in Pediatric Population: A Systemic Review of Current Knowledge

Obesity in pediatric population is an important global problem. The prevalence of obesity in children is dramatically rising. According to World Health Organization, about 41 million children under the age of 5 years are obese or overweight worldwide. Overweight and obesity are well-known risk factors for a number of health disorders. Diseases commonly observed in this group of patients are metabolic disorders, type 2 diabetes mellitus, cardiovascular diseases, fatty liver disease, musculoskeletal problems, and many others. The main aim of this study was to present the current knowledge of the association between childhood obesity and common otorhinolaryngological disorders. It is suggested that obese children are more prone to suffer from otorhinolaryngological illnesses than the lean ones. Obesity may predispose to otorhinolaryngological diseases in various ways. It strongly interferes with the immune system (increases serum levels of interleukin 6, tumor necrosis factor, C-reactive protein, and leptin and reduces adiponectin concentration) affecting organs of the upper respiratory tract. Additionally, obesity induces mechanical disorders in the upper airways. According to our review, obesity predisposes to otitis media with effusion, acute otitis media, recurrent otitis media, obstructive sleep apnea, sensorineural hearing loss, adenotonsillar hypertrophy, and post-/perioperative complications after adenotonsillectomy. Obesity in children significantly correlates with both obstructive sleep apnea (OSA) and asthma and constitutes a significant component of "OSA, obesity, asthma" triad.

Association of Nutritional Factors with Hearing Loss

Hearing loss (HL) is a major public health problem. Nutritional factors can affect a variety of diseases, such as HL, in humans. Thus far, several studies have evaluated the association between nutrition and hearing. These studies found that the incidence of HL was increased with the lack of single micro-nutrients such as vitamins A, B, C, D and E, and zinc, magnesium, selenium, iron and iodine. Higher carbohydrate, fat, and cholesterol intake, or lower protein intake, by individuals corresponded to poorer hearing status. However, higher consumption of polyunsaturated fatty acids corresponded to better hearing status of studied subjects. In addition to malnutrition, obesity was reported as a risk factor for HL. In studies of the relationship between middle ear infection and nutrition in children, it was reported that lack of vitamins A, C and E, and zinc and iron, resulted in poorer healing status due to vulnerability to infection. These studies indicate that various nutritional factors can affect hearing. Therefore, considering that multifactorial nutritional causes are responsible, in part, for HL, provision of proper guidelines for maintaining a proper nutritional status is expected to prevent some of the causes and burden of HL.

The Role of Insulin-Like Growth Factor 1 in the Progression of Age-Related Hearing Loss

Aging is associated with impairment of sensorial functions and with the onset of neurodegenerative diseases. As pari passu circulating insulin-like growth factor 1 (IGF-1) bioavailability progressively decreases, we see a direct correlation with sensory impairment and cognitive performance in older humans. Age-related sensory loss is typically caused by the irreversible death of highly differentiated neurons and sensory receptor cells. Among sensory deficits, age-related hearing loss (ARHL), also named presbycusis, affects one third of the population over 65 years of age and is a major factor in the progression of cognitive problems in the elderly. The genetic and molecular bases of ARHL are largely unknown and only a few genes related to susceptibility to oxidative stress, excitotoxicity, and cell death have been identified. IGF-1 is known to be a neuroprotective agent that maintains cellular metabolism, activates growth, proliferation and differentiation, and limits cell death. Inborn IGF-1 deficiency leads to profound sensorineural hearing loss both in humans and mice. IGF-1 haploinsufficiency has also been shown to correlate with ARHL. There is not much information available on the effect of IGF-1 deficiency on other human sensory systems, but experimental models show a long-term impact on the retina. A secondary action of IGF-1 is the control of oxidative stress and inflammation, thus helping to resolve damage situations, acute or made chronic by aging. Here we will review the primary actions of IGF-1 in the auditory system and the underlying molecular mechanisms.

The Association Between Age-Related Hearing Impairment and Metabolic Syndrome in Korean Women: 5-Year Follow-Up Observational Study

BACKGROUND

Although several observational studies showed a relationship between various conditions of metabolic syndrome (MetS) and hearing threshold, there are no studies about longitudinal audiometric results related MetS. The aim of this study was to investigate the association between MetS and age-related hearing impairment (ARHI) through a large, average 5-year longitudinal follow-up, clinical comparative analysis.

MATERIALS AND METHODS

We recruited 1381 women older than 50 years who were enrolled in 2007 and reevaluated in 2012. They had normal or symmetrical sensorineural hearing loss. For the evaluation of the independent impact of MetS on hearing, multivariate analysis was used.

RESULTS

The average follow-up period was 5.0 ± 0.2 years. Subjects with MetS had higher hearing thresholds than subjects without MetS. The loss in high-frequency hearing (≥2000 Hz) progressed more rapidly in women with MetS over a 5-year period.

CONCLUSION

Our analysis using longitudinal and large data revealed that MetS is associated with ARHI in women 50 years and older. High-frequency hearing loss tended to be greater in women with MetS than in those without MetS at the 5-year follow-up. Therefore, older women with MetS should be followed up closely for hearing evaluation.

A narrative review of obesity and hearing loss

The comorbidities related to obesity are already extensive, but as the prevalence of obesity increases globally, so do the number of its associated conditions. The relationship between hearing impairment and obesity is a relatively recent research interest, but is significant as both conditions have the ability to substantially reduce an individual's quality of life both physically and psychologically. Obesity has a significant effect on vascular function, and this may have an impact on highly vascular organs such as the auditory system. This review aims to provide an overview of the existing literature surrounding the association between hearing loss and obesity, in order to emphasise these two highly prevalent conditions, and to identify areas of further investigation. Our literature search identified a total of 298 articles with 11 articles of relevance to the review. The existing literature in this area is sparse, with interest ranging from obesity and its links to age-related hearing impairment (ARHI) and sudden sensorineural hearing loss (SSNHL), to animal models and genetic syndromes that incorporate both disorders. A key hypothesis for the underlying mechanism for the relationship between obesity and hearing loss is that of vasoconstriction in the inner ear, whereby strain on the capillary walls due to excess adipose tissue causes damage to the delicate inner ear system. The identified articles in this review have not established a causal relationship between obesity and hearing impairment. Further research is required to examine the emerging association between obesity and hearing impairment, and identify its potential underlying mechanisms.

Is Body Mass Index Associated With the Development of Age-Related Hearing Impairment in Koreans? The Korean National Health and Nutrition Examination Survey 2009-2012

Objectives

The aim of this study was to evaluate whether body mass index (BMI) is associated with age-related hearing loss (ARHL) in the Asian elderly population.

Methods

Data from the Korean National Health and Nutrition Examination Survey 2009–2012 were used for the analyses. The pure tones at 0.5 and 1 kHz of both ears of each subject were averaged to obtain the low-frequency, those at 2 and 3 kHz were averaged to obtain the mid-frequency, and those at 4 and 6 kHz were averaged to obtain the high-frequency. The average hearing threshold (AHT) was calculated as pure tone average at 4 frequencies in the better ear. ARHL was defined as the AHT >25 dB.

Results

Univariate analyses revealed an increase in the BMI tertile in men was associated with a decreased low-frequency threshold, while an increase in the BMI tertile in women was associated with decreased mid- and high-frequency thresholds. Multivariate analyses adjusted for confounders show no significant differences in low-, mid-, or high-frequency. There was no significant difference in the prevalence of ARHL by BMI tertiles. Linear regression analyses show no association between BMI and low-, mid-, and high-frequency or AHTs. The area under the receiver operating characteristic curve values for AHT was 0.515 in men and 0.522 in women. The logistic regression analyses showed no association between BMI and ARHL in either sex.

Conclusion

BMI is not advantageous for the prediction of ARHL. In future epidemiological studies, BMI as a covariate of obesity may be replaced by other active metabolic parameters that have better predictive ability of ARHL than BMI.

Newborn hearing screening programme in Belgium: a consensus recommendation on risk factors

Background

Understanding the risk factors for hearing loss is essential for designing the Belgian newborn hearing screening programme. Accordingly, they needed to be updated in accordance with current scientific knowledge. This study aimed to update the recommendations for the clinical management and follow-up of newborns with neonatal risk factors of hearing loss for the newborn screening programme in Belgium.

Methods

A literature review was performed, and the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system assessment method was used to determine the level of evidence quality and strength of the recommendation for each risk factor. The state of scientific knowledge, levels of evidence quality, and graded recommendations were subsequently assessed using a three-round Delphi consensus process (two online questionnaires and one face-to-face meeting).

Results

Congenital infections (i.e., cytomegalovirus, toxoplasmosis, and syphilis), a family history of hearing loss, consanguinity in (grand)parents, malformation syndromes, and foetal alcohol syndrome presented a ‘high’ level of evidence quality as neonatal risk factors for hearing loss. Because of the sensitivity of auditory function to bilirubin toxicity, hyperbilirubinaemia was assessed at a ‘moderate’ level of evidence quality. In contrast, a very low birth weight, low Apgar score, and hospitalisation in the neonatal intensive care unit ranged from ‘very low’ to ‘low’ levels, and ototoxic drugs were evidenced as ‘very low’. Possible explanations for these ‘very low’ and ‘low’ levels include the improved management of these health conditions or treatments, and methodological weaknesses such as confounding effects, which make it difficult to conclude on individual risk factors. In the recommendation statements, the experts emphasised avoiding unidentified neonatal hearing loss and opted to include risk factors for hearing loss even in cases with weak evidence. The panel also highlighted the cumulative effect of risk factors for hearing loss.

Conclusions

We revised the recommendations for the clinical management and follow-up of newborns exhibiting neonatal risk factors for hearing loss on the basis of the aforementioned evidence-based approach and clinical experience from experts. The next step is the implementation of these findings in the Belgian screening programme.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-015-0479-4) contains supplementary material, which is available to authorized users.

Hyperinsulinemia/diabetes, hearing, and aging in the University of Wisconsin calorie restriction monkeys

The purpose of this study was to determine the effects of hyperinsulinemia/Type 2 diabetes mellitus (HI-T2DM) on hearing impairment using rhesus monkeys to obtain control over diet and lifestyle factors that confound human studies. The study is a retrospective evaluation of rhesus monkeys from the Wisconsin National Primate Research Center (WNPRC) study on caloric restriction and aging. The research questions were the following: 1. Is HI-T2DM related to hearing impairment? 2. If so, what is the site of lesion in the auditory system? and 3. What physiological factors affect the risk of hearing loss in HI-T2DM? Three groups of eight monkeys each were matched by sex and age; the caloric restricted (CR) monkeys had a reduced risk of diabetes, the normal control (NL) group had a normal risk, and the hyperinsulinemia/diabetes (HI-D) group had already developed HI-T2DM. Auditory testing included distortion product otoacoustic emissions (DPOAEs) with f2 frequencies from 2211 to 8837 Hz and auditory brainstem responses (ABRs) obtained with clicks and tone bursts (8, 16, and 32 kHz). DPOAEs had signal-to-noise ratios 8-17 dB larger in the NL group than in the HI-D and CR groups, signifying that cochlear function was best in the NL group. ABR thresholds were 5-8 dB better in the NL group than in the HI-D group, although no significant differences across the groups were evident for the thresholds, latencies, interwave intervals, or amplitudes. Correlations were significant for quadratic relations between body mass index (BMI) and DPOAE, with largest DPOAEs for animals in the middle of the BMI range. ABR thresholds elicited with 16 and 32 kHz signals were significantly correlated, positively with BMI and HbA1c, and negatively with KG (glucose tolerance), SI (insulin sensitivity index) and DI (disposition index). These findings suggest that the hearing loss associated with HI-T2DM is predominantly cochlear, and auditory structures underlying the higher frequencies are at risk with HI-T2DM. Loss of auditory function begins in the hyperinsulinemia, pre-diabetic state.

Components of Metabolic Syndrome as Risk Factors for Hearing Threshold Shifts

Background

Hearing loss was a common, chronically disabling condition in the general population and had been associated with several inflammatory diseases. Metabolic syndrome, which was associated with insulin resistance and visceral obesity, was considered a chronic inflammatory disease. To date, few attempts had been made to establish a direct relationship between hearing loss and metabolic syndrome. The aim of the present study was to investigate the relationship between metabolic syndrome and hearing loss by analyzing the data in the reports of the National Health and Nutrition Examination Survey 1999–2004.

Methods

This study included 2100 participants aged ≤ 65 years who enrolled in the National Health and Nutrition Examination Survey (1999–2004). We examined the relationship between the presence of different features of metabolic syndrome in the participants and their pure-tone air-conduction hearing thresholds, including low-frequency and high-frequency thresholds.

Results

After adjusting for potential confounders, such as age, medical conditions, and smoking status, the participants with more components of metabolic syndrome were found to have higher hearing thresholds than those with fewer components of metabolic syndrome (p < 0.05 for a trend). The low-frequency hearing threshold was associated with individual components of metabolic syndrome, such as abdominal obesity, high blood pressure, elevated triglycerides, and a low level of high-density lipoprotein cholesterol (HDL-C) (p < 0.05 for all parameters).

Conclusions

The results indicated that the presence of a greater number of components of metabolic syndrome was significantly associated with the hearing threshold in the US adult population. Among the components of metabolic syndrome, the most apparent association was observed between low HDL and hearing loss.

Prematurity, smallness-for-gestational age and later hospital admissions: a nation-wide registry study

INTRODUCTION

Being born premature or small for gestational age (SGA) is known to be associated with diseases later in life, such as gestational diabetes, hypertension and pre-eclampsia. In this study we examined the association between being born premature or SGA and all diseases diagnosed during hospital admissions later in life.

METHODS

Using Danish nation-wide registries we created a cohort of 1,348,106 persons born 1974-1996 and assessed all unique diagnoses registered in the Danish Patient Registry (DPR) for hospital admissions in the period 1994-2007 (n=27,910,558). We determined the odds ratios for persons born premature or SGA using multivariate logistic regression.

RESULTS

A total of 15,059 unique ICD-10 diagnosis codes were represented in the period. Only diagnoses used at least 100 times were included in the analysis (n=4175). Of these 838 showed an odds ratio that was statistically significantly different from unity for people born premature or SGA. After correcting for multiple testing, 250 remained significant. The diagnoses covered diseases in most organ systems, including cardiovascular, endocrinological, infectious, neurological/neurosurgical, obstetric, orthopedic, psychiatric, lung & urological diseases, and occurred throughout childhood and early adulthood. Novel findings included increased risks for delayed puberty, neurofibromatosis type 1 and ileus and decreased risks of mononucleosis, peritonsillar abscesses, chronic hypothyroidism and several types of fractures and contusions later in life.

CONCLUSION

Being born premature or SGA was associated with significantly altered risks of being admitted to a hospital with a wide range of diseases later in life, affecting almost all organ systems throughout childhood and early adulthood. Our findings may motivate testing in other cohorts and search for novel mechanisms of pathogenesis.

Visceral Fat Area Determined Using Bioimpedance Analysis Is Associated with Hearing Loss

BACKGROUND

Visceral fat area (VFA) using bioimpedance analysis (BIA) as a simple analyzer can be used to assess VFA, which may be associated with HL. The aim of the present study was to evaluate the clinical relevance and usefulness of VFA using BIA as a predictor of HL.

PATIENTS AND METHODS

In total, 18,415 patients were recruited into our study. VFAs were measured using multi-frequency BIA. VFAs were normalized by body mass index (BMI). Participants were divided into 3 tertiles based on their VFA/BMI for both sexes. For both ears of each participant, the low-frequency (Low-Freq), mid-frequency (Mid-Freq), and high-frequency (High-Freq) values were obtained calculating the pure tone averages at 0.5 and 1 kHz, 2 and 3 kHz, and 4 and 6 kHz, respectively. The average hearing threshold (AHT) was calculated as the pure tone average at the 4 frequencies (i.e., 0.5, 1, 2, and 3 kHz). HL was defined as AHT >40 dB.

RESULTS

The VFA/BMI had the greatest AUROC among VFA, BMI, and VFA/BMI in both sexes in this study. In both univariate and multivariate analyses, VFA/BMI tertiles were associated with all 4 hearing thresholds (i.e., Low-Freq, Mid-Freq, High-Freq, and AHT). The 4 hearing thresholds were positively correlated with VFA/BMI as a continuous variable. The odds ratio for HL increased as the VFA/BMI tertile increased.

CONCLUSION

VFA/BMI was associated with hearing impairment in the Asian population. The participants with high VFA/BMI should be closely monitored for hearing impairment.

Obesity is associated with sensorineural hearing loss in adolescents

OBJECTIVES/HYPOTHESIS

Childhood obesity, defined as body mass index (BMI) ≥ 95%, is a significant health problem associated with a variety of disorders, and in adults it has been found to be a risk factor for hearing loss. We investigated the hypothesis that obese children are at increased risk of sensorineural hearing loss (SNHL).

STUDY DESIGN

A complex, multistage, stratified geographic area design for collecting representative data from noninstitutionalized U.S. population.

METHODS

Relevant cross-sectional data from the National Health and Nutrition Examination Survey, 2005 to 2006, for 1,488 participants 12 to 19 years of age was examined. Subjects were classified as obese if their BMI ≥ 95 th percentile. SNHL was defined as average pure-tone level greater than 15 dB for 0.5, 1, and 2 kHz (low frequency) and 3, 4, 6, and 8 kHz (high frequency).

RESULTS

Compared to normal weight participants (BMI 5%-85%), obesity in adolescents was associated with elevated pure tone hearing thresholds and greater prevalence of unilateral low-frequency SNHL (15.2 vs. 8.3%, P = 0.01). In multivariate analyses, obesity was associated with a 1.85 fold increase in the odds of unilateral low-frequency SNHL (95% CI: 1.10-3.13) after controlling for multiple hearing-related covariates.

CONCLUSIONS

We demonstrate for the first time that obesity in childhood is associated with higher hearing thresholds across all frequencies and an almost 2-fold increase in the odds of unilateral low-frequency hearing loss. These results add to the growing literature on obesity-related health disturbances and also add to the urgency in instituting public health measures to reduce it.

Caracterização eletrofisiológica da audição em prematuros nascidos pequenos para a idade gestacional

OBJETIVO: Caracterizar as respostas do Potencial Evocado Auditivo de Tronco Encefálico em recém-nascidos pré-termo pequenos para idade gestacional, comparando-as às de recém-nascidos pré-termo adequados para idade gestacional, verificando se a condição de pequeno para a idade gestacional é indicador de risco para alteração auditiva retrococlear. MÉTODOS: Estudo multicêntrico transversal prospectivo. Avaliou-se 72 recém-nascidos pré-termo, 35 pequenos e 37 adequados para idade gestacional de ambos os gêneros, com idade gestacional de 30 a 36 semanas e avaliados na pré-alta hospitalar, com presença de emissões otoacústicas evocadas por estímulo transiente e timpanometria tipo A. A análise quantitativa dos dados foi feita baseada na média e desvio-padrão das latências das ondas I, III, V e interpicos I-III, III-V, I-V para cada grupo. Para análise qualitativa, os resultados dos potenciais evocados auditivos foram classificados em alterado ou normal mediante a análise das latências absolutas das ondas I, III, V e dos interpicos I-III, III-V, I-V, considerando-se a faixa etária no momento do exame. RESULTADOS: Evidenciaram-se alterações em 32 crianças (44,44% do total), sendo 15 recém-nascidos pequenos (43%) e 17 adequados (46%), não havendo diferença entre os grupos. Dos 15 recém-nascidos pequenos com potencial evocado auditivo alterado, seis tiveram como risco auditivo apenas o fato de ser pequeno para a idade gestacional. No grupo adequado para idade gestacional, houve maior ocorrência de alterações no gênero masculino. CONCLUSÃO: Não houve diferença nas respostas do potencial evocado auditivo entre os recém-nascidos pré-termo pequenos e adequados, de forma que a condição pequeno não se revelou risco para alteração retrococlear.

How the Newcastle Thousand Families birth cohort study has contributed to the understanding of the impact of birth weight and early life socioeconomic position on disease in later life

Much has been made of the potential influence of birth weight and early socioeconomic disadvantage in influencing adult health, but little has been published in terms of how important these associations may be with respect to exposures throughout the lifecourse. The objective of this review is to describe the contributions of the Newcastle Thousand Families Study in understanding the relative impacts of factors in early life, particularly birth weight and socio-economic position at birth, in influencing health in later life. The Newcastle Thousand Families Study is a prospective birth cohort established in 1947. It originally included all births to mothers resident in Newcastle upon Tyne, in northern England, in May and June of that year. Study members were followed extensively throughout childhood and intermittently in adulthood. At the age of 49-51 years, study members underwent a large-scale follow-up phase enabling an assessment of how early life may influence their later health, and also incorporating adult risk factors which enabled the relative contributions of factors at different stages of life to be assessed. While some findings from the study do support birth weight and early socio-economic position having influences on adult health status, the associations are generally small when compared to risk factors later in life. Using path analyses on longitudinal data of this nature enables mediating pathways between early life and later health to be assessed and if more studies were to take this approach, the relative importance of early life on adult disease risk could be better understood.

Electrophysiological study of hearing in full-term small-for-gestational-age newborns

PURPOSE: To describe the Brainstem Auditory Evoked Potential (BAEP) results of full-term small-for-gestational-age newborns, comparing them to the results of full-term appropriate-for-gestational-age newborns, in order to verify whether the small-for-gestational-age condition is a risk indicator for retrocochlear hearing impairment. METHODS: This multicentric prospective cross-sectional study assessed 86 full-term newborns - 47 small- (Study Group) and 39 appropriate-for-gestational-age (Control Group - of both genders, with ages between 2 and 12 days. Newborns with presence of transient evoked otoacoustic emissions and type A tympanometry were included in the study. Quantitative analysis was based on the mean and standard deviation of the absolute latencies of waves I, III and V and interpeak intervals I-III, III-V and I-V, for each group. For qualitative analysis, the BAEP results were classified as normal or altered by analyzing these data considering the age range of the newborn at the time of testing. RESULTS: In the Study Group, nine of the 18 (38%) subjects with altered BAEP results had the condition of small-for-gestational-age as the only risk factor for hearing impairments. In the Control Group, seven (18%) had altered results. Female subjects from the Study Group tended to present more central alterations. In the Control Group, the male group tended to have more alterations. CONCLUSION: Full-term children born small or appropriate for gestational age might present transitory or permanent central hearing impairments, regardless of the presence of risk indicators.

Auditory brainstem response (ABR) abnormalities across the life span of rats prenatally exposed to alcohol

BACKGROUND

Fetal alcohol syndrome (FAS) is a leading cause of neurodevelopmental impairments (NDIs) in developed countries. Sensory deficits can play a major role in NDI, yet few studies have investigated the effects of prenatal alcohol exposure on sensory function. In addition, there is a paucity of information on the lifelong effects of prenatal alcohol exposure. Thus, we sought to investigate the effects of prenatal alcohol exposure on auditory function across the life span in an animal model. Based on prior findings with prenatal alcohol exposure and other forms of adverse prenatal environments, we hypothesized that animals prenatally exposed to alcohol would show an age-dependent pattern of (i) hearing and neurological abnormalities as postweanling pups, (ii) a substantial dissipation of such abnormalities in young adulthood, and (iii) a resurgence of such abnormalities in middle-aged adulthood.

METHODS

Pregnant rats were randomly assigned to an untreated control (CON), a pair-fed control (PFC), or an alcohol-treated (ALC) group. The ALC dams were gavaged with 6 mg/kg alcohol daily from gestation day (GD) 6 to 21. The PFC dams were gavaged daily from GD6 to GD21 with an isocaloric and isovolumetric water-based solution of maltose-dextrins and pair-fed to the ALC dams. The CON dams were the untreated group to which the ALC and CON groups were compared. Hearing and neurological functions in the offspring were assessed with the auditory brainstem response (ABR) at the postnatal ages of 22, 220, and 520 days.

RESULTS

In accord with our hypothesis, ABR abnormalities were first observed in the postweanling pups, largely dissipated in young adulthood, and then resurged in middle-aged adulthood. This age-related pattern suggests that the ALC pups had a developmental delay that dissipated in young adulthood and an enhanced age-related deterioration that occurred in middle-aged adulthood. Such a pattern is consistent with the fetal programming hypothesis of adult-onset diseases (the Barker hypothesis).

CONCLUSIONS

Our findings have important clinical implications for the assessment and management of (i) childhood hearing disorders and their comorbidities (i.e., speech-and-language, learning, and attention deficit disorders) and (ii) enhanced age-related hearing and neurological degeneration in middle-aged adulthood that can result from prenatal alcohol exposure. We recommend hearing evaluation be a part of any long-term follow-up for FAS patients and patients exposed to any adverse prenatal environment.

Association of central obesity with the severity and audiometric configurations of age-related hearing impairment

To investigate the effect of central obesity on the severity and characteristics of age-related hearing impairment (ARHI), we recruited 690 adult subjects with normal or symmetrical sensorineural hearing loss (SNHL). The effects of age, gender, morphometry, habits, systemic diseases, and environmental noise exposure on average pure tone hearing level at low frequencies (pure tone audiometry (PTA)-low) and high frequencies (PTA-high) were analyzed. After adjusting for age, gender, systemic disease, and other variables, waist circumference (WC) showed a significant positive association with PTA-low and PTA-high. In females, PTA-low and PTA-high only showed significant positive association with age, but not with WC or other variables. However, PTA-high showed a positive association with borderline significance with WC in female subjects older than 55. In males, WC as well as age and noise exposure showed significant positive associations with both PTA-low and PTA-high, primarily in subjects younger than 55. When both WC and BMI were taken into account in a backward stepwise multivariate linear regression analysis, WC, but not BMI, showed a significant positive association with PTA-low and PTA-high in males younger than 55, and with PTA-high with borderline significance in females older than 55. However, the audiogram patterns were not significantly affected by central obesity in either age or gender. Our results suggest that WC was, even after adjustment for BMI, an independent risk factor of ARHI, particularly for low and high frequencies in males younger than 55 and for high frequencies in female subjects older than 55.

Occupational noise, smoking, and a high body mass index are risk factors for age-related hearing impairment and moderate alcohol consumption is protective: a European population-based multicenter study

A multicenter study was set up to elucidate the environmental and medical risk factors contributing to age-related hearing impairment (ARHI). Nine subsamples, collected by nine audiological centers across Europe, added up to a total of 4,083 subjects between 53 and 67 years. Audiometric data (pure-tone average [PTA]) were collected and the participants filled out a questionnaire on environmental risk factors and medical history. People with a history of disease that could affect hearing were excluded. PTAs were adjusted for age and sex and tested for association with exposure to risk factors. Noise exposure was associated with a significant loss of hearing at high sound frequencies (>1 kHz). Smoking significantly increased high-frequency hearing loss, and the effect was dose-dependent. The effect of smoking remained significant when accounting for cardiovascular disease events. Taller people had better hearing on average with a more pronounced effect at low sound frequencies (<2 kHz). A high body mass index (BMI) correlated with hearing loss across the frequency range tested. Moderate alcohol consumption was inversely correlated with hearing loss. Significant associations were found in the high as well as in the low frequencies. The results suggest that a healthy lifestyle can protect against age-related hearing impairment.

Is the relation of social class to change in hearing threshold levels from childhood to middle age explained by noise, smoking, and drinking behaviour?

Recent work shows that variation in adult hearing function is related both to social class of origin and current social class. This study examines how much of this relationship after adjustment for childhood hearing impairment is explicable by occupational noise, current smoking, and alcohol consumption. A cohort of 9023 persons born in the UK during one week in 1958 was followed periodically, and hearing threshold levels (HTLs) were measured at 1 kHz and 4 kHz at age 45 years. Most (71% and 68%, at 1 kHz and 4 kHz respectively) of the relation to social class of origin of adult HTLs remains after adjustment for these other factors. For the relation to current social class, corresponding values are 64% and 44% (though varying by gender). The magnitude of social class effect is comparable to that of occupational noise. Susceptibility to hearing impairment is likely to be appreciably determined in early childhood.

Childhood hearing is associated with growth rates in infancy and adolescence

It is known that shorter stature is associated with sensorineural hearing loss; and that cochlear development is associated with activity of IGF 1, as are many important aspects of neurodevelopment. We hypothesized that this relation might be extrapolated to a normally hearing group, and that the strongest relation between hearing level and growth rate would be in late puberty, when serum IGF-1 levels are highest. We examined the statistical relation between childhood hearing threshold and rate of growth in height at different times during the life course up to age 32. We found mixed support for the hypothesis. The strongest relations were observed in late puberty, at the ages which previous research shows are associated with the highest serum concentrations of IGF-1 in males and females, but also in infancy and early childhood. The association between hearing and height is present in a normally hearing, general population sample, and is associated with growth in late adolescence. Our findings support the idea that childhood hearing threshold may be predictive of IGF-1 mediated developmental characteristics.

No evidence for enhanced noise induced hearing loss after prenatal stress or dexamethasone

It was recently implied that prenatal stress and fetal exposure to glucocorticoids may interfere with hearing ability and noise induced hearing loss in adulthood. In the present study pregnant Wistar rats were stressed during gestation by Chronic Mild Stress (CMS, a variable schedule of different stressors) or by dexamethasone (a synthetic glucocorticoid, i.e. a pharmacological stressor). At birth, but not at weaning, the dexamethasone offspring exhibited significantly decreased body weight compared to both control offspring and progeny from dams exposed to CMS during pregnancy. As adults, male offspring were exposed to 105 dB sound pressure level (SPL) wide band noise either continuously for eight hours or for two hours per day on three consecutive days. Oto-acoustic emissions and auditory brainstem responses were recorded before and after exposure to noise. Neither prenatal chronic stress nor prenatal dexamethasone exposure was associated with significantly enhanced noise induced hearing loss compared to controls, and these results were consistent in both subsets of animals. Our data do not support previous reports that prenatal exposure to mild stress nor to dexamethasone is detrimental to the hearing organ per se. However, hearing may be modulated by prenatal stressors under certain circumstances, of which the timing and degree are probably the most important.

Peripheral insensate neuropathy--a tall problem for US adults?

The relation between height and lower extremity peripheral insensate neuropathy among persons with and without diabetes was examined by use of the 1999-2002 US National Health and Nutrition Examination Survey with 5,229 subjects aged 40 or more years. A monofilament was used to determine whether any of three areas on each foot were insensate. Peripheral insensate neuropathy was defined as the presence of one or more insensate areas. Its prevalence was nearly twice as high among persons with diabetes (21.2%) as among those without diabetes (11.5%; p < 0.001). Men (16.2%) had 1.7 times the prevalence of peripheral insensate neuropathy as did women (9.4%), but the difference was not significant after adjustment for height. Greater height was associated with increased peripheral insensate neuropathy prevalence among persons with and without diabetes (p < 0.001). This association was characterized by a sharp increase in prevalence among persons who were taller than 175.5 cm. Peripheral insensate neuropathy risk was significantly higher among those taller than 175.5 cm (adjusted odds ratio = 2.3, 95% confidence interval: 1.5, 3.5). The authors conclude that body height is an important correlate of peripheral insensate neuropathy. This association largely accounts for the difference in peripheral insensate neuropathy prevalence between men and women. Height may help health-care providers to identify persons at high risk of peripheral insensate neuropathy.