Bo Engdahl

The effect of noise exposure on the details of distortion product otoacoustic emissions in humans.

The effect of noise exposure on amplitude and phase of distortion product otoacoustic emissions (DPOAEs) was examined by five different paradigms: across a wideband of frequency, microstructure, input/output function, primary frequency ratio tuning curve, and group delay. The aim was to investigate the vulnerability of these different features to moderate levels of noise exposure. Nine subjects were exposed to third-octave-band noise. The DPOAE amplitude was reduced frequency specifically with the greatest reduction approximately half an octave above the frequency of the noise. The degree of amplitude reduction was greatest at low stimulus levels. There were no observed effects on the shape of the primary ratio tuning curve. A weak tendency to a decrease was seen in group delays. Distinct microstructure was seen in the amplitude against frequency of five out of seven subjects. The maximum to minimum ratio of the microstructure decreased, and the whole pattern shifted toward lower frequencies after noise exposure. Evidence of multiple internal reflection or interference was seen in the periodicity of the microstructure. Using a simple model of the microstructure based on multiple reflections, the noise-induced changes were reevaluated. A reduction in maximum to minimum microstructure ratio could be interpreted as a decrease in the internal reflection coefficient. The implications of these observations for the interpretation of the DPOAE measurements are considered.

Screened and unscreened hearing threshold levels for the adult population: Results from the Nord-Trøndelag Hearing Loss Study Niveles de umbrales auditivos tamizados y no tamizados en la población adulta. Resultados del estudio Nord-TrøndeIag sobre hipoacusias

This paper presents normative data of hearing threshold levels of a population screened with various criteria, as compared to unscreened population data. Computer-controlled pure-tone audiometry was administered to the adult population in Nord-Trøndelag County, Norway, during 1995–1997. The 51 975 participants also provided questionnaire information about occupational and leisure noise exposure, previous ear infections, and head injury. While screening had little effect on the median hearing threshold levels of young adults, there was a substantial effect when screening men above 40 years of age for a history of noise exposure. Screening for known ear-related disorders and diseases resulted in small effects on the mean hearing threshold levels. The median hearing thresholds of both the screened and the unscreened sample exceeded the age and sex specific thresholds specified by the ISO 7029.

Short- and Long-term Mortality Risk Associated with the Use of Antipsychotics Among 26,940 Dementia Outpatients: A Population-Based Study

OBJECTIVE To investigate short- and long-term mortality risk associated with the use of antipsychotics in dementia outpatients, assessing the risk over specific time frames and quantifying the risk by the individual antipsychotics. METHODS This population-based study used data from the Norwegian Prescription Database. The study sample included 26,940 dementia outpatients aged 65 years or older prescribed antidementia drugs and psychotropics from Norwegian pharmacies between 2004 and 2010. RESULTS Cox survival analyses, adjusted for age, gender, mean daily defined dose, and severe medical conditions, showed that antipsychotic use compared with other psychotropics involved approximately twice the mortality risk in outpatients with dementia. Furthermore, these results are consistent for all investigated time points after first dispensing the drugs (hazard ratio [HR]30 days = 2.1 [95% confidence interval {CI}: 1.6-2.9] to HR 730-2,400 days = 1.7 [95% CI: 1.6-1.9]). Haloperidol was associated with higher mortality risk (HR 30 days = 1.7 [95% CI: 1.0-3.0] to HR 730-2,400 days = 1.4 [95% CI: 1.0-1.9]) than risperidone. CONCLUSION This first study to observe antipsychotic use and mortality in dementia outpatients over more than 6 years clearly shows that antipsychotics involve increased short- and long-term mortality risk. Physicians may justly consider antipsychotics to be the best option for some dementia patients among available nonpharmacologic and pharmacologic treatments. However, although causal conclusions are precluded due to limited adjustments in the analyses, the findings support the current treatment recommendations that antipsychotics should be avoided or used with great caution.

Hearing loss induced by occupational and impulse noise: Results on threshold shifts by frequencies, age and gender from the Nord-Trøndelag Hearing Loss Study

The aim of the study was to compare the frequency-specific effects of noise on hearing acuity across the range 250–8000 Hz and the extent to which the patterns of frequency-specific threshold shifts differ between occupational noise and impulse noise. Pure-tone audiometry was administered to an adult general population sample with 51 975 subjects who also provided questionnaire information about noise exposure and other risk factors. Threshold shifts induced by life-long occupational noise and impulse noise (mostly shooting) were estimated separately in six age and sex groups for eight frequencies. Reported noise exposure, as well as observed threshold shifts, were moderate among women. Threshold shifts averaged over both ears among subjects in the higher 2% of exposure to occupational noise, reached 13 dB (3000 Hz, age 65 years + ) among men and were generally largest at 3000–4000 Hz. The shifts induced by impulse noise reached approximately 8 dB among men 45–64 years and men 65 years+. The effects of impulse noise were strongest at 3000–8000 Hz and varied little within this frequency range.

The effect of emotional distress on persistent pelvic girdle pain after delivery: a longitudinal population study

Objective  To study the prognosis for pelvic girdle pain, and to explore the association between presence of emotional distress during pregnancy and pelvic girdle syndrome 6 months after delivery.

Otoacoustic emissions in the general adult population of Nord-Trøndelag, Norway: I. Distributions by age, gender, and ear side

Transient evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) are described as a function of age, gender and ear side in an unscreened adult population of 6415 subjects comprising a subsample of the 51975 subjects from the Nord-Trøndelag Hearing Loss Study. While most descriptions of OAEs are from samples selected based on hearing threshold, the present sample is from a less selected general population. The OAEs were recorded as a part of the programme of a general health screening. The large sample size provided accurate estimations of mean values. TEOAEs were analysed at 1, 2 and 4 kHz. DPOAEs were measured with f2 frequencies of 2, 3, 4, 6, and 8 kHz. Signs of bimodality were seen in the OAE density distributions of the > or = 45-year age group. The OAEs declined as a function of age, with the steepest gradient between 30 and 65 years. OAEs were generally higher in females than in males and in right ears than in left ears. Controlling for pure-tone thresholds reduced some of the effects of age, gender and ear side.Transient evoked otoacoustic emissions (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) are described as a function of age, gender and ear side in an unscreened adult population of 6415 subjects comprising a subsample of the 51 975 subjects from the Nord-Trondelag Hearing Loss Study. While most descriptions of OAEs are from samples selected based on hearing threshold, the present sample is from a less selected general population. The OAEs were recorded as a part of the programme of a general health screening. The large sample size provided accurate estimations of mean values. TEOAEs were analysed at 1. 2 and 4 kHz. DPOAEs were measured with f2 frequencies of 2, 3, 4, 6, and 8 kHz. Signs of bimodality were seen in the OAE density distributions of the ±45-year age group. The OAEs declined as a function of age, with the steepest gradient between 30 and 65 years. OAEs were generally higher in females than in males and in right ears than in left ears. Controlling for pure-tone thresholds reduced some of the effects of age, gender and ear side. Sumario Se describen las emisiones otoacústicas evocadas por transitorios (TEOAEs) y las emisiones otoacústicas por productos de distorsiócute;n (DPOAEs) en funcion de la edad, el género y el oído estudiado, en una poblaciócute;n de 6415 adultos no estudiados previamente, que conformaban una submuestra de los 51, 975 sujetos del Estudio de Pérdidas Auditivas Nord-Trøndelag. Mientras la mayoria de las descripciones de EOAs vienen de muestras seleccionadas con base en los umbrales auditivos, esta proviene de una poblacion general menos seleccionada. Las EOAs se registraron como parte de un programa de estudios generales del estado dc salud. El gran tamaño de la muestra permitiócute; estimaciones precisas de los valores promedio. Las TEOAEs se analizaron en 1, 2 y 4 kHz. Las DPOAEs se midieron con las frecuencias f2 de 2, 3, 4, 6 y 8 kHz. Se vieron signos de bimodalidad en las distribuiciones de las EOA en el grupo de >45 anos. Las EOAs declinaron como funcion de la edad. con el gradientc más abrupto entre 30 y 65 años. Las EOAs fucron generalmente mayores en las mujeres que en hombres y en los oidos derechos que en los izquierdos. El control de los umbrales con tonos puros redujo algunos de los efectos de edad, genero y oido estudiado.

Occupation and the risk of bothersome tinnitus: results from a prospective cohort study (HUNT)

Objectives Estimates of occupation-specific tinnitus prevalence may help identify high-risk occupations where interventions are warranted. The authors studied the effect of occupation on prevalence of bothersome tinnitus and estimated the attributable fraction due to occupation. The authors also studied how much of the effect remained after adjusting for noise exposure, education income, hearing thresholds and other risk factors. Design A prospective cohort study. Setting A health survey of the Nord-Trøndelag county of Norway. Participants A sample of the general adult population (n=49 948). Primary outcome measure The primary outcome measure is bothersome tinnitus. Results Occupation had a marked effect on tinnitus prevalence. The effect of occupation on tinnitus was reduced in men by controlling for self-reported occupational noise exposure and in women by controlling for education and income. Adding hearing loss as a predictor increased the effect of occupation somewhat. In men, age-adjusted prevalence ratios of tinnitus ranged from 1.5 (workshop mechanics) to 2.1 (crane and hoist operators) in the 10 occupations with highest tinnitus prevalence. In women, the most important contribution to the tinnitus prevalence was from the large group of occupationally inactive persons, with a prevalence ratio of 1.5. Conclusion This study found a moderate association between occupation and bothersome tinnitus.

Otoacoustic emissions in the general adult population of Nord-Trøndelag, Norway: II. Effects of noise, head injuries, and ear infections.

Otoacoustic emissions (OAEs) have been suggested as a sensitive measure of cochlear function with the potential for preclinical detection of damage. The present work assesses the risk for decreased OAEs associated with occupational and leisure noise, head injuries and recurrent ear infections. The predictive power of the environmental factors on different OAE values is compared with the prediction of conventional pure-tone hearing thresholds (PTTs). The analyses are based on data from 5072 adult subjects comprising a subsample of the 51975 subjects from the Nord-Trøndelag Hearing Loss Study. The subjects participated in a general health screening, including an examination of pure-tone audiometry, transient OAEs and distortion-product OAEs, and completed a questionnaire regarding history of noise exposure and ear disease. The predictions of OAEs and PTTs were analysed using regression analysis for various sex and age groups (20-44 years, 45-64 years, > or = 65 years). The fraction of the variance explained by exposure was generally moderate (0-4%, varying with age, sex, and type of measurement). Males showed moderate effects of work noise, impulse noise and ear infection, while ear infection was the only significant predictor in females. There were no effects of music noise and head injuries. The effect of exposure on OAEs that remained after controlling for PTTs was small and similar to the effect of exposure on PTTs that remained after controlling for OAEs.Otoacoustic emissions (OAEs) have been suggested as a sensitive measure of cochlear function with the potential for preclinical detection of damage. The present work assesses the risk for decreased OAEs associated with occupational and leisure noise, head injuries and recurrent ear infections. The predictive power of the environmental factors on different OAE values is compared with the prediction of conventional pure-tone hearing thresholds (PTTs). The analyses are based on data from 5072 adult subjects comprising a subsample of the 51975 subjects from the Nord-Trondelag Hearing Loss Study. The subjects participated in a general health screening, including an examination of pure-tone audiometry, transient OAEs and distortion-product OAEs, and completed a questionnaire regarding history of noise exposure and ear disease. The predictions of OAEs and PTTs were analysed using regression analysis for various sex and age groups (20 44 years, 45–64 years, ±65 years). The fraction of the variance explained by exposure was generally moderate (0–4%, varying with age, sex, and type of measurement). Males showed moderate effects of work noise, impulse noise and ear infection, while ear infection was the only significant predictor in females. There were no effects of music noise and head injuries. The effect of exposure on OAEs that remained after controlling for PTTs was small and similar to the effect of exposure on PTTs that remained after controlling for OAEs. Sumario Se ha sugerido que las emisiones otoacústicas (EOAs) son una medida sensible para para medir la funciócute;n coclear y que tienen potencial para la detectiócute;n preclínica de daño. Este trabajo evalúa el riesgo de EOAs decrecientes, asociadas con ruido ocupacional o recreativo, lesiones craneoencefálicas e infecciones recurrentes del oído. El valor predictivo de los factores ambientales en los diferentes valores de las EOAs sc compara con la predicciócute;n hecha con umbrales auditivos por tonos puros (PTTs). El análisis se basa en datos de 5,072 adultos de una submuestra de 51,975 sujetos del Estudio Nord-Trøndelag de Pérdidas Auditivas. Los sujetos participaron en un estudio de salud general, incluyendo un examen de audiometría por tonos puros, TEOAEs y DPOAEs y completaron un cuestionario relacionado con historia de expositiócute;n al ruido o enfermedades otolócute;gicas. Las predicciones de las EOAs y de los PPTs se estudiaron usando análisis de regresiócute;n por grupos etáreos (20–44 años, 45–64 años y >65 anos) y de génera La fractiócute;n de la variancia explicada por la expositiócute;n fue generalmente moderada (0–4%, variando con la edad, sexo y tipo de mediciócute;n). Los hombres mostraron efectos modcrados del ruido laboral, ruido impulsivo e infection de oídos, mientras que éste último fue el único factor predictivo en las mujeres. No se vieron efectos de ruido por música o por lesiones cefálicas. El efecto de la expositiócute;n en las EOAs que permaneciócute; después del control con los PTTs fue pequeño, y similar al efecto de la expositiócute;n en los PPTs, que permaneciócute; después del control con las EOAs.

Childhood Otitis Media: A Cohort Study With 30-Year Follow-Up of Hearing (The HUNT Study).

Objectives: To study the extent to which otitis media (OM) in childhood is associated with adult hearing thresholds. Furthermore, to study whether the effects of OM on adult hearing thresholds are moderated by age or noise exposure. Design: Population-based cohort study of 32,786 participants who had their hearing tested by pure-tone audiometry in primary school and again at ages ranging from 20 to 56 years. Three thousand sixty-six children were diagnosed with hearing loss; the remaining sample had normal childhood hearing. Results: Compared with participants with normal childhood hearing, those diagnosed with childhood hearing loss caused by otitis media with effusion (n = 1255), chronic suppurative otitis media (CSOM; n = 108), or hearing loss after recurrent acute otitis media (rAOM; n = 613) had significantly increased adult hearing thresholds in the whole frequency range (2 dB/17–20 dB/7–10 dB, respectively). The effects were adjusted for age, sex, and noise exposure. Children diagnosed with hearing loss after rAOM had somewhat improved hearing thresholds as adults. The effects of CSOM and hearing loss after rAOM on adult hearing thresholds were larger in participants tested in middle adulthood (ages 40 to 56 years) than in those tested in young adulthood (ages 20 to 40 years). Eardrum pathology added a marginally increased risk of adult hearing loss (1–3 dB) in children with otitis media with effusion or hearing loss after rAOM. The study could not reveal significant differences in the effect of self-reported noise exposure on adult hearing thresholds between the groups with OM and the group with normal childhood hearing. Conclusions: This cohort study indicates that CSOM and rAOM in childhood are associated with adult hearing loss, underlining the importance of optimal treatment in these conditions. It appears that ears with a subsequent hearing loss after OM in childhood age at a faster rate than those without; however this should be confirmed by studies with several follow-up tests through adulthood.

Heritability of hearing loss.

Background: Hearing impairment is one of the most common permanent disabilities in the western world. Although hearing ability normally declines with age, there is great individual variation in age of onset, progression, and severity, indicating that individual susceptibility plays a role. The aim of the present study was to explore the relative importance of genetic and environmental effects in the etiology of impaired hearing. Methods: From August 1995 to June 1997, the total adult population of Nord-Trøndelag County, Norway, was invited to take part in the Nord-Trøndelag Health Study. The survey included as an integrated project the Nord-Trøndelag Hearing Loss Study with pure-tone audiometry assessment of the standard frequencies 0.25, 0.5, 1, 2, 3, 4, 6, and 8 kHz on 51,574 participants aged 20 to 101 years. We obtained information from Statistics Norway identifying 11,263 sibling pairs. After age stratification, we assessed similarity in hearing thresholds between siblings using polychoric correlations. The contribution of genetic effects in hearing ability was calculated. Results: The upper limit of the heritability of hearing loss was 0.36. We found little evidence for sex differences in the relative importance of genetic effects. Conclusions: There is a substantial genetic contribution to individual variation in hearing thresholds.