Is undernutrition a risk factor for sensorineural hearing loss in early infancy?

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.

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 association between malnutrition and childhood disability in low- and middle- income countries: systematic review and meta-analysis of observational studies

OBJECTIVE

The aim of this study was to evaluate the association between childhood disability and malnutrition in low- and middle- income countries (LMICs).

METHODS

Articles were identified from 1990 to August 2017 by searching nine electronic databases. Epidemiological studies, undertaken in LMICs that compared the prevalence of malnutrition in children with disabilities to children without disabilities were eligible for inclusion. Titles, abstracts, and full texts were screened by two reviewers, and data were extracted using a structured table for eligible papers. Meta-analyses for the association between childhood disability and undernutrition were performed.

RESULTS

The search generated 4678 results, from which 17 articles were eligible. Fifty-three per cent of these studies showed a positive association between childhood disability and undernutrition. Results varied when disaggregated by type of disability, with positive associations identified for 44% of studies focussed on neurodevelopmental disability, 60% of general disability studies and 67% of studies on hearing impairment. Only four studies were identified that considered overnutrition outcomes, and these showed variable results. Eighteen per cent of eligible studies were considered at low risk of bias, 53% had a medium risk, and 29% had a high risk of bias. Pooled ORs showed that children with disabilities were almost three times more likely to be underweight (OR 2.97, 95% CI 2.33, 3.79), and nearly twice as likely to experience stunting and wasting (Stunting: 1.82, 1.40, 2.36; Wasting: 1.90, 1.32-2.75), compared to controls.

CONCLUSIONS

Children with disabilities may be a vulnerable group for undernutrition in LMICs, which should be reflected in disability and nutritional programming and policy-making.

Protein energy malnutrition associates with different types of hearing impairments in toddlers: Anemia increases cochlear dysfunction

OBJECTIVES

This work aimed to highlight a challenging asymptomatic problem which is early detection of hearing impairment in toddlers with protein energy malnutrition (PEM) as a neuro-cognitive effect of PEM on developing brain in relation to hemoglobin level.

METHODS

100 toddlers, aged 6-24 months, fifty with moderate/severe PEM and fifty healthy children, were included in study. Both TEOAEs and ABR testing were used to assess auditory function.

RESULTS

Study reported an association between malnutrition and hearing impairment, 26% of cases had conductive deafness secondary to otitis media with effusion using tympanometry; 84.6% showed type B and 15.4% type C which may suggest developing or resolving otitis media. Their ABR showed 46% mild and 53% moderate impairment. 32% of PEM cases had sensory neural hearing loss and with type (A) tympanometry. Those were assessed using ABR; 58% had mild, 34% moderate and 8% profound impairment. 10% of PEM cases had mixed hearing loss with 50% type B and 50% type C tympanometry and their ABR showed moderate to profound impairment. TEOAEs latencies at different frequencies correlate negatively with hemoglobin level.

CONCLUSIONS

Toddlers with moderate/severe PEM had hearing impairments of different types and degrees. Neuro-physiological methods could be early and safe detectors of auditory disorders especially in high-risk toddlers. Anemia increases risk for auditory dysfunction.

Malnutrition and disability: unexplored opportunities for collaboration

There is increasing international interest in the links between malnutrition and disability: both are major global public health problems, both are key human rights concerns, and both are currently prominent within the global health agenda. In this review, interactions between the two fields are explored and it is argued that strengthening links would lead to important mutual benefits and synergies. At numerous points throughout the life-cycle, malnutrition can cause or contribute to an individual's physical, sensory, intellectual or mental health disability. By working more closely together, these problems can be transformed into opportunities: nutrition services and programmes for children and adults can act as entry points to address and, in some cases, avoid or mitigate disability; disability programmes can improve nutrition for the children and adults they serve. For this to happen, however, political commitment and resources are needed, as are better data.

Audiometric thresholds and auditory processing in children with early malnutrition: a retrospective cohort study

CONTEXT AND OBJECTIVE

Malnutrition is one of the causes of changes in cell metabolism. The inner ear has few energy reserves and high metabolism. The aim of this study was to analyze whether malnutrition at an early age is related to impairment of auditory processing abilities and hearing abnormalities.

DESIGN AND SETTING

Retrospective cohort study conducted in a tertiary public hospital.

METHODS

45 children participated, divided as follows: G1, children diagnosed with malnutrition in their first two years of life; G2, children without history of malnutrition but with learning difficulties; G3, children without history of malnutrition and without learning difficulties. Tympanometry, pure-tone audiometry and the Staggered Spondaic Word (SSW) test (auditory processing) were performed. Statistical inferences were made using the Kruskal-Wallis test (α = 5%) and the test of equality of proportions between two samples (α = 1.7%).

RESULTS

None of the 45 children participating in this study presented hearing deficiencies. However, at six of the eight frequencies analyzed, the children in G1 presented hearing thresholds lower than those of the other groups. In the auditory processing evaluation test, it was observed that 100% of the children in G1 presented abnormal auditory processing and that G1 and G2 had similar proportions of abnormalities (P-values: G1/G2 = 0.1; G1/G3 > 0.001; G2/G3 = 0.008).

CONCLUSIONS

Malnutrition at an early age caused lowering of the hearing levels, although this impairment could not be considered to be a hearing deficiency. Every child in this group presented abnormalities in auditory processing abilities.

Personally Modifiable Risk Factors Associated with Pediatric Hearing Loss: A Systematic Review

BACKGROUND

Pediatric hearing loss is an increasingly recognized problem with significant implications. Increasing our quantitative understanding of potentially modifiable environmental risk factors for hearing loss may form the foundation for prevention and screening programs.

OBJECTIVE

To determine whether specific threshold exposure levels of personally modifiable risk factors for hearing loss have been defined, with the overarching goal of providing actionable guidance for the prevention of pediatric hearing loss.

DATA SOURCES

A systematic review was performed. Computerized searches of PubMed, EMBASE, and the Cochrane Library were completed and supplemented with manual searches.

REVIEW METHODS

Inclusion/exclusion criteria were designed to determine specific threshold values of personally modifiable risk factors on hearing loss in the pediatric population. Searches and data extraction were performed by independent reviewers.

RESULTS

There were 38 criterion-meeting studies, including a total of 50,651 subjects. Threshold noise exposures significantly associated with hearing loss in youth included: (1) more than 4 hours per week or more than 5 years of personal headphone usage, (2) more than 4 visits per month to a discotheque, and (3) working on a mechanized farm. Quantified tobacco levels of concern included any level of in utero smoke exposure as well as secondhand exposure sufficient to elevate serum cotinine.

CONCLUSIONS

Specific thresholds analyses are limited. Future studies would ideally focus on stratifying risk according to clearly defined levels of exposure, in order to provide actionable guidance for children and families.

Societal-level Risk Factors Associated with Pediatric Hearing Loss: A Systematic Review

OBJECTIVE

To determine if the current body of evidence describes specific threshold values of concern for modifiable societal-level risk factors for pediatric hearing loss, with the overarching goal of providing actionable guidance for the prevention and screening of audiological deficits in children.

DATA SOURCES

Three related systematic reviews were performed. Computerized PubMed, Embase, and Cochrane Library searches were performed from inception through October 2013 and were supplemented with manual searches.

REVIEW METHODS

Inclusion/exclusion criteria were designed to determine specific threshold values of societal-level risk factors on hearing loss in the pediatric population. Searches and data extraction were performed by independent reviewers.

RESULTS

There were 20 criterion-meeting studies with 29,128 participants. Infants less than 2 standard deviations below standardized weight, length, or body mass index were at increased risk. Specific nutritional deficiencies related to iodine and thiamine may also increase risk, although data are limited and threshold values of concern have not been quantified. Blood lead levels above 10 µg/dL were significantly associated with pediatric sensorineural loss, and mixed findings were noted for other heavy metals. Hearing loss was also more prevalent among children of socioeconomically disadvantaged families, as measured by a poverty income ratio less than 0.3 to 1, higher deprivation category status, and head of household employment as a manual laborer.

CONCLUSIONS

Increasing our understanding of specific thresholds of risk associated with causative factors forms the foundation for preventive and targeted screening programs as well as future research endeavors.

Predictors of early-onset permanent hearing loss in malnourished infants in Sub-Saharan Africa

The objective of this study was to determine the predictors of early-onset permanent hearing loss (EPHL) among undernourished infants in a low-income country where routine screening for developmental disabilities in early childhood is currently unattainable. All infants attending four community-based clinics for routine immunization who met the criteria for undernutrition by the Growth Standards of the World Health Organization (WHO) based on weight-for-age, weight-for-length and body-mass-index-for-age were enlisted. EPHL was determined after two-stage screening with transient-evoked otoacoustic emissions, automated auditory brainstem response and diagnostic evaluation. Factors predictive of EPHL were explored with multivariable logistic regression analysis. Some 39 (1.7%) infants from 2254 undernourished infants were confirmed with hearing loss (>30 dB HL). Bilateral EPHL was mild in 7 (17.9%) and moderate-to-profound in 26 (66.7%). EPHL was unilateral in 6 (15.4%). Multiparity, chronological age of more than 30 days, the absence of skilled attendant at birth and severe neonatal jaundice were associated with an increased risk of EPHL while having a Christian mother and exclusive breast feeding had protective effect against EPHL. EPHL is highly prevalent among undernourished infants and associated with modifiable risk factors that can be addressed at the community-level and used as a basis for targeted intervention in resource-poor countries.