Hearing loss and use of personal stereos in young adults with antecedents of otitis media

Cortical representation of tympanic membrane movements due to pressure variation: an fMRI study

Middle ear sensory information has never been localized in the homunculus of the somatosensory cortex (S1). We investigated the somatosensory representation of the middle ear in 15 normal hearing subjects. We applied small air pressure variations to the tympanic membrane while performing a 3T-fMRI study. Unilateral stimulations of the right ear triggered bilateral activations in the caudal part of the postcentral gyrus in Brodmann area 43 (BA 43) and in the auditory associative areas 42 (BA 42) and 22 (BA 22). BA 43 has been found to be involved in activities accompanying oral intake and could be more largely involved in pressure activities in the oropharynx area. The tympanic membrane is indirectly related to the pharynx area through the action of tensor tympani, which is a Eustachian tube muscle. The Eustachian tube muscles have a role in pressure equalization in the middle ear and also have a role in the pharyngeal phase of swallowing. Activation of BA 42 and BA 22 could reflect activations associated with the bilateral acoustic reflex triggered prior to self-vocalization to adjust air pressure in the oropharynx during speech. We propose that BA 43, 42, and 22 are the cortical areas associated with middle ear function. We did not find representation of tympanic membrane movements due to pressure in S1, but its representation in the postcentral gyrus in BA 43 seems to suggest that at least part of this area conveys pure somatosensory information.

Sensorineural hearing loss in high school teenagers in Mexico City and its relationship with recreational noise

The aim of this study was to measure the frequency of hearing loss in a sample of typical public high-school students exposed to recreational noise, and determine associated risk factors. The sample was made up of 214 teenagers from a high-school in Mexico City; subjects were selected randomly per strata. We applied a questionnaire to identify risk factors for hearing loss and performed a battery of audiologic tests consisting of otoscopy, tympanometry, and pure-tone audiometry. The mean age of the sample was 16 +/- 1.07 years; 73% were male and 27%, female. Hearing loss was found in 21% of students. The main hearing loss-related risk factor was exposure to recreational noise: frequent attendance at discotheques and pop-music concerts; use of personal stereos; and noise exposure in school workshops. The high frequency of hearing loss in high school students from one Mexico City school (nearly one fifth of the sample) was found to be related to noise exposure mainly during recreational activities.

Long-term assessment of auditory changes resulting from a single noise exposure associated with non-occupational activities

We examined the long-term sequelae in both ears of 42 patients who reported the occurrence of auditory changes resulting from a single exposure to intense sound levels during non-occupational activities. We divided these patients into two groups, based upon noise exposures of either continuous duration or single high-energy impulse. Audiometric data were available for each of these subjects shortly after their noise-exposure events and follow-up examinations took place more than one year after the noise occurrence (range: 1-16 years). The initial median hearing loss for the continuous-type noise exposure group at 3-8 kHz was found to be 9 dB, relative to the age-appropriate norms, in the more affected ears, and hearing function was found to have returned to normal levels at follow-up. The same initial hearing loss was measured for the impulse-type noise group, but a residual hearing loss of 4 dB was measured at follow-up. Furthermore, the majority of the subjects from both groups reported tinnitus and hypersensitivity to sound at follow-up, but with minimal impact on their lives.

Choice of environmental components for a longitudinal birth cohort study

Various aspects of the environment of the mother and child may have major influences on the health and development of the child. Long-term influences can even affect chronic diseases of adulthood. Here we describe the major psychosocial and physical environmental factors that should be measured in longitudinal birth cohort studies.

Otoacoustic detection of risk of early hearing loss in ears with normal audiograms: a 3-year follow-up study

INTRODUCTION

Distortion product otoacoustic emissions (DPOAEs) are known to represent the contractile amplifier function of cochlear outer hair cells. It is known that low or absent DPOAEs are associated with hearing loss on audiograms. However, low DPOAEs can also be found associated with normal audiograms. It is unknown whether low DPOAEs in normal hearing ears are risk markers for subsequent early hearing loss when subjects are exposed to noise.

MATERIALS AND METHODS

A 3-year follow-up study was carried out on a population of pilots aged 20-40 years (n=521). Data collection consisted of tonal audiograms, DPOAEs measurements with a calculation of an index of abnormality (the IaDPOAE). Of the 521 pilots enrolled, 350 (67%) had follow-up data 3 years later. In pilots with normal audiograms (n=219, all frequencies=10dB HL), we observed the occurrence of hearing threshold shifts after 3 years depending on whether the IaDPOAE was initially high (group 1) or low (group 2). We used this index to test the hypothesis that reduced DPOAEs levels are potential ear vulnerability biomarkers in apparent normal hearing ears. After a 3-year follow-up, the initial IaDPOAE in normal hearing subjects was correlated with final noise-induced hearing threshold shifts at high frequencies (p<0.01). The occurrence of abnormal audiograms was significantly higher in group 1 compared to group 2 (p=0.003). In group 1, 13% of audiograms were found with at least one frequency 25dB HL compared to 3% of audiograms in group 2. In both groups, impairments occurred at high frequencies and hearing in the 4kHz frequency range was significantly more impaired in group 1 (p=0.035). Group 1 was associated with a relative risk of 2.29 (95% CI 1.26-4.16, p=0.005) of sustaining early hearing loss. There was no significant differences between groups for age and noise exposure.

DISCUSSION

In adults with a normal audiogram, ear vulnerability to noise could be elicited by the use of objective DPOAE measurements. A high IaDPOAE that corresponded to reduced DPOAE levels constitutes a risk for early hearing loss. This study emphasised the interest of DPOAE measurements in public health and occupational noise prevention policies. The IaDPOAE calculation may also be interesting for clinicians because no DPOAE index of abnormality is currently available.

An assessment of threshold shifts in nonprofessional pop/rock musicians using conventional and extended high-frequency audiometry

The clinical value of extended high-frequency audiometry for the detection of noise-induced hearing loss has not been established conclusively. The purpose of this study was to assess the relative temporary threshold shift (TTS) in two frequency regions (conventional versus extended high frequency). In this exploratory study, pure-tone thresholds from 0.5 to 14 kHz were measured in both ears of 16 nonprofessional pop/rock musicians (mean age, 35 yr; range, 27 to 49 yr), before and after a 90-minute rehearsal session. All had experienced repeated exposures to intense sound levels during at least 5 yr of their musical careers. After the rehearsal, median threshold levels were found to be significantly poorer for frequencies from 0.5 to 8 kHz (Wilcoxon signed rank test, p <or= 0.004) but were unchanged in the extended high-frequency range from 9 to 14 kHz. Decreases in the median threshold values measured before the rehearsal were present across the conventional frequency range, most notably at 6 kHz, but were not observed in the extended high-frequency range. On the basis of these results, extended high-frequency audiometry does not seem advantageous as a means of the early detection of noise-induced hearing loss.

Hearing in Nonprofessional Pop/Rock Musicians

OBJECTIVE

The purpose of this study was to evaluate the hearing and subjective auditory symptoms in a group of nonprofessional pop/rock musicians who had experienced repeated exposures to intense sound levels during at least 5 yr of musical activity.

DESIGN

An evaluation of both ears in 42 nonprofessional pop/rock musicians included pure-tone audiometry in the conventional and extended high-frequency range, the measurement of uncomfortable loudness levels, and an assessment of tinnitus and hypersensitivity to sound. Exclusion criteria were (a) the occurrence of acoustic trauma, (b) excessive noise exposure during occupational activities, (c) a history of recurrent otitis media, (d) previous ear surgery, (e) a fracture of the cranium, (f) ingestion of potentially ototoxic drugs, and (g) reported hearing difficulties within the immediate family. These audiometric results were then compared with a control group of 20 otologically normal young adults with no history of long-term noise exposure.

RESULTS

After adjusting for age and gender, relative to ISO 7029, the mean hearing threshold in the frequency range of 3 to 8 kHz was 6 dB in the musicians and 1.5 dB in the control group. This difference was statistically significant (Mann-Whitney rank sum test, p < 0.001). A significant difference was also observed between musicians using regular hearing protection during their activities (average 3 to 8 kHz thresholds = 2.4 dB) and musicians who never used such hearing protection (average 3 to 8 kHz thresholds = 8.2 dB), after adjusting for age and gender (Mann-Whitney rank sum test, p = 0.006). Eleven of the musicians (26%) were found to be hypersensitive to sound, and seven (17%) presented with tinnitus. Tinnitus assessment, however, did not reveal any clinically significant psychological distress in these individuals.

CONCLUSIONS

Tinnitus and hypersensitivity to sound were observed in a significant minority within a group of nonprofessional pop/rock musicians who had experienced repeated exposure to intense sound levels over at least 5 yr but with minimal impact on their lives. Moreover, hearing loss was minimal in the subjects who always used ear protection, being only 0.9 dB higher than the control group. In contrast, hearing loss was significantly more pronounced, at 6.7 dB higher than the control group, in those musicians who never used ear protection. Continued education about the risk to hearing and the benefits of the persistent use of ear protection is warranted for musicians who are exposed frequently to intense sound levels.

Moderate variations of mood/emotional states related to alterations in cochlear otoacoustic emissions and tinnitus onset in young normal hearing subjects exposed to gun impulse noise

This study was designed to test whether under impulse noise exposure mood and emotional states could play a role in the onset of tinnitus and/or could modify cochlear sensitivity objectively measured with distortion product otoacoustic emissions (DPOAEs). The experimental design consisted in a short follow-up study of 54 young military subjects (20+/-2 years old), psychologically normal, with normal hearing, during two consecutive days of target practice rounds. Data collection included an abbreviated version of the profile of mood states (POMSs) inventory [Profile of Mood States, Educational and Industrial Testing Service, San Diego, 1971], questionnaires on tinnitus perception (previous history and after shooting) and DPOAEs measurements before and after shooting. Higher scores of tension-anxiety were found in subjects having previous history of tinnitus. Association between tinnitus previous history and tinnitus after shooting was found significant. Perception of tinnitus after target practice rounds was associated with significantly lower DPOAEs at 3 kHz. The most tense-anxious subjects were found to have DPOAEs decreases of 3.35+/-6 dB at 3 kHz after shooting. This study clearly shows that, in young healthy population, psychologically normal and with normal hearing, moderate variations in mood and emotional states were related to tinnitus onset and DPOAEs alterations. It is possible that stronger variations in mood and/or emotional condition would increase risks of tinnitus and alterations of cochlear sensitivity.

The effect of noise on the health of children

The effects of noise on health, especially that of children, were reviewed. (1) From the point of view of disturbance of daily living, subjective recognition of "noisiness" is an important issue in relation to the study of noise. Concerning the effects of airplane noise on school children, while no effects on the hearing level were detected, a significant increase in the complaint of "noisiness" was observed. (2) Exposure of pregnant women to airplane noise was found to be associated with a decrease in the body weight of newborn babies. Moreover, the height of 3-year-old boys and girls was found to be significantly decreased in association with increase in the environmental noise. (3) Noise levels that seemed to have some influence on the sleep of adults did not affect the sleep of children. (4) In a group of children living in noisy districts exhibiting poor academic performance, the academic performance seemed to become progressively worse as the school grade advanced. (5) No consensus has been arrived at in regard to headphone-induced hearing impairment. Researches and studies effective enough to influence policy decisions must be continually conducted in the future, with appropriate control for related factors.

CAP amplitude after impulse noise exposure in guinea pigs

In this study, 21 guinea pigs were submitted to a single high energy impulse noise (gun shot with blank projectiles). The auditory function was evaluated over a 7-day recovery period by recording the compound action potential (CAP) from the round window. The threshold shift and input/output function (CAP amplitude and delay function of the stimulus intensity) were studied at different frequencies. CAP amplitude fell after the noise trauma, especially at the lower sound level, resulting in a threshold shift. Latency was significantly increased. During recovery, whereas latency returned to its initial value, CAP amplitude gradually increased and, in half the animals, exceeded the control value for the higher levels of stimulus. This could have been because of progressive disinhibition or recruitment, and may correspond clinically to hyperacusis. These results are discussed referring to those obtained by other authors using other methods.

Hearing deficits in young adults who had a history of otitis media in childhood: use of personal stereos had no effect on hearing

OBJECTIVE

To test the hypothesis proposed in a recent French study that a history of recurrent otitis media (OM) in childhood increases susceptibility to hearing loss from frequent exposure to a personal stereo (PS) during development to early adulthood.

METHODS

A subcohort of 358 young adults selected from a historic cohort study, all 18 years old and with a well-documented OM history (secretory and acute), provided data on the sound level and length of exposure to PSs. Four contrasting groups were formed: those with the highest or lowest PS exposure combined with a positive or negative history of OM (n = 238). The main outcome measure was hearing thresholds from pure-tone audiometry (0.5-8 kHz).

RESULTS

Young adults with a history of recurrent OM in childhood did not show greater susceptibility to hearing loss from PS use than their peers without a history of OM. However, a history of recurrent OM was associated with significant mean air-conduction hearing loss of 4 dB and a mean bone-conduction hearing loss of 2 dB compared with the participants without a history of OM (Fig 1).

CONCLUSIONS

Recurrent OM in childhood may have an irreversible effect on the middle ear and the cochlea and may lead to hearing deficits in later life. No interaction with PS exposure is seen.

DPOAEs in young normal-hearing subjects with histories of otitis media: evidence of sub-clinical impairments

To investigate the origin of the susceptibility to noise in subjects with histories of otitis media (OM), we assessed early sub-clinical impairments in normally hearing subjects with a history of OM using distortion product otoacoustic emissions (DPOAEs). DPOAEs of 213 normal-hearing subjects aged 18-24 years were obtained and comparisons of DPOAE levels in several groups as a function of OM past infections were tested by ANOVA. A main finding was that young normal-hearing subjects with a history of OM had significantly lower DPOAEs over all octaves tested compared to normal-hearing subjects without antecedent of OM. The mean difference was 3.5+/-1.1 dB in the 2-4 kHz zone, which was especially marked in subjects (n=21) that had undergone a myringotomy (6.6+/-1.5 dB) in the 4 kHz zone. The level of impairment seemed to depend on the severity of the past infection as characterised by the importance and the duration of the infectious effusions.

The impact of hearing disability on well-being and health

OBJECTIVES

The aim of the paper is to assess the significance of hearing disability as a public health problem through its association with multiple negative health outcomes: subjective health perception, mental health and social well-being.

METHODS

The data come from the participants of the 1997 national health survey in Belgium, who were 15 years and older (n = 8,560). The presence and severity of the hearing disability was estimated through self-reporting. The association of hearing disability with the studied health outcomes was assessed using logistic regression while controlling for confounding factors such as age, sex, co-morbidity and socio-economic status.

RESULTS

The prevalence of hearing disability is 7% in the population 15 years and older. The prevalence of subjective ill health (Odds Ratio (OR): 1.32), mental ill health (OR: 1.51), and a low appreciation of the social contacts (OR: 1.73) was higher in subjects with hearing disability. No association was found between hearing disability and the frequency of social contacts or with the functional content of the social contacts.

CONCLUSIONS

Given the health and social consequences of hearing disability, increased public health attention, including both strategies for prevention, for identification and treatment, is warranted.

Hyaluronic acid in incision wound fluid: a clinical study with the Cellstick device in children

When inserted into a human incision wound, the Cellstick device harvests inflammatory cells and collects wound fluid, reflecting time-related changes in cell populations and in wound fluid composition. Hyaluronic acid has been postulated to be an important factor in scar reduction in wound healing and in scarless fetal wound healing. The aim of this work was to determine the concentration and variation of hyaluronic acid and proportions of wound cells in closed surgical wounds in children at two time points. The Cellstick device was inserted subcutaneously into the wound at the end of an elective inguinal hernia operation on 37 healthy boys, and the devices were removed 3+/-1 or 24+/-3 hours after surgery. Haluronic acid concentration was measured from the wound fluid and a differential count of the wound cells was performed. There was a significant decrease in hyaluronic acid concentration from 3+/-1 to 24+/-3 hours after surgery (p<0.001, Kruskal-Wallis anova). The variance of hyaluronic acid concentration in wound fluid differed between the wounds at the two time points (p<0.01, Levene test for homogeneity of variance). A positive correlation between hyaluronic acid concentration and patient age (r=0.91, p<0.05, Spearman) at 3+/-1 hours post surgery and between HA and wound lymphocytes (r=0.38, p<0.05, Spearman) was also found. We conclude that the hyaluronic acid concentration in wound fluid peaks early in children and decreases significantly by 3 to 24 hours after surgery, and the concentrations in the wound fluid of healthy boys are more variable 3 hours than at 24 hours after surgery.