Piotr Kotylo

The prevalence and risk factors for occupational voice disorders in teachers.

Objective: Occupational voice disorders in Poland account for over 25% of all occupational diseases. The aim of the study was to assess the prevalence of voice problems in the general population of Polish teachers, and identify risk factors for developing voice pathology. Patients and Methods: The study group comprised 425 female full-time teachers (most of them primary and secondary school, age ranging from 23 to 61 years) and 83 non-teacher women (control) whose jobs did not involve vocal effort, matched for age to the study group. All participants were subjected to a survey using an extensive questionnaire, and to laryngological, phoniatric and videostroboscopic examinations. Results: The overall lifetime vocal symptoms were more frequent in the teachers than in the non-teachers (69 vs. 36%), and in particular it related to permanent and recurrent hoarseness, and dryness in the throat. Mean number of the voice symptoms was 3.21 in teachers and 1.98 in controls (p < 0.001). Abnormal (non-euphonic) voice, neck muscle hypertension during phonation and incorrect resonator function were also significantly more frequent in the teachers. Mean maximum phonation time was shorter in teachers than in the controls (14.3 vs. 15.9 s, p < 0.01). Occupational voice disorders and hyperfunctional dysphonia (that is thought to predispose to such pathology) were found in 32.7% of teachers and 9.6% of control subjects. The probability of developing incomplete glottal closure (odds ratio 13.2x; 95% CI: 1.8–96.8) and hyperfunctional dysphonia (odds ratio 2.7; 95% CI: 1.14–6.44) were significantly higher in the teacher group versus non-teachers. A significant positive relationship was found in teachers between the prevalence of hyperfunctional dysphonia and strained phonation, neck muscle hypertension, instability of voice, self-assessed hyperarousal, and lifetime vocal effort index (years of employment as a teacher × hours of professional activity/week). The prevalence of vocal nodules and incomplete glottal closure were correlated with incorrect phonation technique parameters, but not with psychological factors. No correlation was found with environmental variables, such as classroom temperature, humidity, airborne dust. Conclusion: The prevalence of self-reported symptoms and clinical signs of voice disorders is around 2–3 times more frequent in Polish female teachers than in non-teachers. Lifetime vocal effort, incorrect technique of phonation and psychological predisposition seem to constitute major risk factors for developing occupational voice disorders.

Ototoxic effects of occupational exposure to styrene and co-exposure to styrene and noise.

Learning ObjectivesRecall the reported effects of exposure to styrene and noise on the cochlear hair cells and hearing function in rats.Describe which possible confounding factors were and were not controlled for in this study, and what the results indicate about the respective ototoxic effects on humans of exposure to styrene and noise.Characterize the effects in humans of isolated and combined exposure to styrene and noise. Ototoxicity of styrene and the synergistic action of styrene and noise have been shown in rats. The respective data in humans are scarce and equivocal. This study evaluated the effects of occupational exposure to styrene and combined exposures to styrene and noise on hearing. The study group, comprised of 290-yacht yard and plastic factory workers, was exposed to a mixture of organic solvents, having styrene as its main compound. The reference group, totaling 223 subjects, included (1) white-collar workers, exposed neither to solvents nor noise and (2) metal factory workers, exposed exclusively to noise. All subjects were assessed by means of a detailed questionnaire and underwent otorhinolaryngological and audiometric examinations. Multiple logistic regression analysis revealed almost a 4-fold (or 3.9; 95% CI = 2.4–6.2) increase in the odds of developing hearing loss related to styrene exposure. The factors adjusted for were: age, gender, current occupational exposure to noise, and exposure to noise in the past. In cases of the combined exposures to styrene and noise, the odds ratios were two to three times higher than the respective values for styrene-only and noise-only exposed subjects. The mean hearing thresholds—adjusted for age, gender, and exposure to noise—were significantly higher in the solvent-exposed group than in the unexposed reference group at all frequencies tested. A positive linear relationship existed between an averaged working life exposure to styrene concentration and a hearing threshold at the frequencies of 6 and 8 kHz. This study provides the epidemiological evidence that occupational exposure to styrene is related to an increased risk of hearing loss. Combined exposures to noise and styrene seem to be more ototoxic than exposure to noise alone.

Effects of coexposure to noise and mixture of organic solvents on hearing in dockyard workers.

Questionnaire and audiometric data of 701 dockyard workers (517 noise and organic solvent mixture-exposed and 184 noise-only-exposed) were referred to 205 control subjects not exposed to either noise or solvents. The odds ratio (OR) of hearing loss was significantly increased by approximately 3 times in the noise-only group and by almost 5 times in the noise and solvent group. A moderate effect of solvent ototoxicity, in addition to noise, was observed on hearing threshold at a frequency 8 kHz. ORs for hearing loss were 1.12 for each increment of 1 year of age, 1.07 for every decibel of lifetime noise exposure (dB-A), and 1.004 for each increment of the index of lifetime exposure to solvents. The results suggest an additive damaging effect of coexposure to noise and organic solvents to the auditory organ.

The effectiveness of voice therapy for teachers with dysphonia.

Objective: An incorrect voice emission is a risk factor for developing occupational voice disorders. The study aimed at assessing the effectiveness of voice therapy in female teachers with dysphonia. Methods: The study comprised 133 subjects with voice disorders, taking part in a vocal training programme. A reference group for the present study included 53 teachers with dysphonia. Questionnaire surveys, phoniatric examination and videostroboscopic evaluation were conducted at initial and control examination. Results: In the study group, an improvement after the vocal training was noted in most of the reported symptoms and also in some quantitative parameters of phoniatric examinations compared to the findings for the reference group. The number of patients who assessed their voice as normal increased significantly after the vocal training (2.3 vs. 46.6%). A significant increase in the mean maximum phonation time, from 13.3 to 16.6 s, was observed. The same applied to voice frequency range (increase from 171 to 226.8 Hz). Conclusions: The outcomes of vocal training, such as a subjective improvement of voice quality and an increase in the quantitative parameters (prolonged maximum phonation time, extended voice range) seem to be important parameters for monitoring the effectiveness of training in correct voice emission.

Exacerbation of noise-induced hearing loss by co-exposure to workplace chemicals

BACKGROUND : Numerous organic solvents applied in industry, like toluene, styrene, xylene and n-hexane have been demonstrated to impair hearing in animals. However, the effects of exposure to a given organic solvent and the interaction of noise and solvents on hearing in humans are still not fully recognized. STUDY DESIGN : The study was aimed to assess the effects of occupational exposure to solvents alone or in combination with noise on hearing in 1117 employees of yacht, ship, plastic, shoe, and paint and lacquer industry. These persons were exposed either to the mixture of organic solvents with xylene as the main component, or predominantly to styrene, or to the mixture of n-hexane and toluene. Detailed questionnaire data and pure-tone audiometry were compared with data of the reference group that included white collar workers, exposed neither to solvents nor noise and metal factory workers exposed to noise only. In all statistics, the confounding factors were recognized as gender, age, exposure to noise, and other variables occurring at a different rate in study and reference group. RESULTS : Odds ratio (OR) of hearing loss related with the particular exposure to chemicals was 2.4 (95%CI 1.59-3.74) in case of solvent mixture, 3.9 (95%CI 2.4-6.2) in case of styrene and 5.3 (95%CI 2.6-10.9) in case of n-hexane and toluene exposure. The odds of developing hearing loss substantially increased in the case of combined exposure to organic solvents and noise as compared to isolated exposure to each of these hazards. The highest OR (over 20-fold) was demonstrated in subgroups of subjects exposed simultaneously to noise and two ototoxic solvents (i.e. styrene and toluene or n-hexane and toluene). The mean hearing thresholds were significantly higher in the solvent-exposed groups than in the reference group. The differences in thresholds were observed at high frequencies in the solvent mixture- and n-hexane + toluene-exposed groups and at all frequencies in the styrene-exposed group. A positive linear relationship existed between exposure to solvents and hearing thresholds at high frequencies. CONCLUSIONS : The results of the study provide the epidemiological evidence that exposure to organic solvents in humans is associated with an increased risk of hearing loss. The simultaneous exposure to organic solvents and noise seems to enhance the hearing deficit if compared with isolated exposures.

Acoustic analysis with vocal loading test in occupational voice disorders: outcomes before and after voice therapy.

OBJECTIVE To assess the usefulness of acoustic analysis with vocal loading test for evaluating the treatment outcomes in occupational voice disorders. METHODS Fifty-one female teachers with dysphonia were examined (Voice Handicap Index--VHI, laryngovideostroboscopy and acoustic analysis with vocal loading) before and after treatment. The outcomes of teachers receiving vocal training (group I) were referred to outcomes of group II receiving only voice hygiene instructions. RESULTS The results of subjective assessment (VHI score) and objective evaluation (acoustic analysis) improved more significantly in group I than in group II. The post-treatment examination revealed a decreased percentage of subjects with deteriorated jitter parameters after vocal loading, particularly in group I. CONCLUSIONS Acoustic analysis with vocal loading test can be a helpful tool in the diagnosis and evaluation of treatment efficacy in occupational dysphonia.

Occupational exposure to noise decreases otoacoustic emission efferent suppression

With the discovery of otoacoustic emissions (OAEs), the efferent cochlear system has become accessible for investigation in humans. Recently, it has been suggested that contralateral sound activated OAE efferent suppression may provide an early indication of auditory damage due to exposure to noise. In this study, OAE efferent suppression in normally hearing subjects, occupationally exposed to noise, was compared with respective effects in healthy, non-exposed subjects. The noise-exposed group exhibited higher mean hearing thresholds at frequencies 4, 6 and 10 kHz (p < 0.01) and lower-level transienl-evoked otoacoustic emission (TEOAE) and distortion-product otoacoustic emission (DPOAE) at a frequency of 4 kHz (not significant). TEOAE efferent suppression was moderately decreased, whereas DPOAE efferent suppression was negligible, in the exposed group compared to nonexposed subjects. The results of the study suggest that OAEs, particularly DPOAE contralateral suppression, are likely to become a valuable method for assessing early hearing damage caused by exposure to noise. Sumario Con el descubrimiento de las EOAs, el sistema eferente coclear se ha vuelto accesible para la investigación en humanos. Recientemente se sugirió que la supresión eferente de las EOAs activadas por sonidos contralaterales puede ser un indicador temprano de daño auditivo debido a la exposición al ruido. En este estudio, la supresión eferenle de las EOAs en sujetos normooyentes, expucstos laboralmente a ruido, se comparó con los respectivos efectos en sujetos sanos no expuestos a ruido. El grupo de sujetos expuestos mostró una media más alta de umbrales auditivos en las frecuencias de 4, 6 y 10 kHz (p < 0.01) y un nivel más bajo en las OEAs evocadas por transientes (TEOAE) y en las EOAs por productos de distorsión (DPOAE) en la frecuencia de 4 kHz (no significativa). La supresión eferente de las TEOAE resultó moderadamente disminuida mientras que la supresión eferente de las DPOAE fue casi nula, en el grupo de sujetos expuestos a ruido comparado con los que no lo estaban. Los resultados del estudio sugiercn que las EOAs y particularmente la supresión contralateral de las DPOAEs pueden convertirse en un método válido para evaluar tempranamente el daño audilivo causado por exposición a ruido.

Diagnostic value of voice acoustic analysis in assessment of occupational voice pathologies in teachers

It has been shown that teachers are at risk of developing occupational dysphonia, which accounts for over 25% of all occupational diseases diagnosed in Poland. The most frequently used method of diagnosing voice diseases is videostroboscopy. However, to facilitate objective evaluation of voice efficiency as well as medical certification of occupational voice disorders, it is crucial to implement quantitative methods of voice assessment, particularly voice acoustic analysis. The aim of the study was to assess the results of acoustic analysis in 66 female teachers (aged 40–64 years), including 35 subjects with occupational voice pathologies (e.g., vocal nodules) and 31 subjects with functional dysphonia. The acoustic analysis was performed using the IRIS software, before and after a 30-minute vocal loading test. All participants were subjected also to laryngological and videostroboscopic examinations. After the vocal effort, the acoustic parameters displayed statistically significant abnormalities, mostly lowered fundamental frequency (Fo) and incorrect values of shimmer and noise to harmonic ratio. To conclude, quantitative voice acoustic analysis using the IRIS software seems to be an effective complement to voice examinations, which is particularly helpful in diagnosing occupational dysphonia.

Analysis of inner ear potassium recycling genes as potential factors associated with tinnitus.

Tinnitus is defined as a perception of sound in the absence of an external acoustic stimulus. Several factors are known to influence tinnitus, e.g. hearing loss, noise exposure, age, and hypertension. As only certain individuals develop tinnitus in the presence of the above risks and in approximately 50% of cases tinnitus is not attributed to any particular cause, the question arose whether this inter-individual susceptibility to tinnitus could be explained by the influence of genetic factors.ObjectivesTo test the hypothesis that genetic variability in genes of the potassium recycling pathway is associated with increased susceptibility to tinnitus.Materials and MethodsThe study group consisted of 626 subjects exposed to occupational noise (128 with tinnitus and 498 without tinnitus). 99 single nucleotide polymorphisms were investigated in 10 genes involved in the potassium recycling pathway in the inner ear, previously selected as putative noise-induced hearing loss (NIHL) candidate genes.ResultsNominally significant associations were obtained for 2 variants in KCNE1 (potassium voltage-gated channel, Isk-related family, member 1) and SLC12A2 (solute carrier family 12, member 2) genes. The first gene contributed to tinnitus that developed independently of hearing loss, while the second one was associated with increased susceptibility to noise-induced hearing loss.ConclusionsPresent findings lend support to the notion of potassium recycling pathway genes as possible risk modifiers of tinnitus in individuals with and without hearing loss. Due to the lack of replication in other independent populations these results should be seen as suggestive.

Polish Translation and Validation of the Tinnitus Handicap Inventory and the Tinnitus Functional Index

Objective: The need for validated measures enabling clinicians to classify tinnitus patients according to the severity of tinnitus and screen the progress of therapies in our country led us to translate into Polish and to validate two tinnitus questionnaires, namely the Tinnitus Handicap Inventory (THI) and the Tinnitus Functional Index (TFI). Design: The original English versions of the questionnaires were translated into Polish and translated back to English by three independent translators. These versions were then finalized by the authors into a Polish THI (THI-Pl) and a Polish TFI (TFI-Pl). Participants from three laryngological centers in Poland anonymously answered the THI-Pl (N = 98) and the TFI-Pl (N = 108) in addition to the Polish versions of the Center for Epidemiologic Studies Depression Scale as a measure of self-perceived level of depression, and the Satisfaction With Life Scale to assess self-perceived quality of life. Both were used to determine discriminant validity. Two Visual Analog Scales were used to measure tinnitus annoyance and tinnitus loudness in order to determine convergent validity. Results: Similar to the original version of the THI, the THI-Pl showed a high internal consistency (Cronbach’s α = 0.93). The exploratory factor analysis revealed that the questionnaire has a three-factorial structure that does not correspond to the original division for functional, catastrophic, and emotional subscales. Convergent and discriminant validities were confirmed. The TFI-Pl showed high internal consistency (Cronbach’s α = 0.96) with the reliability ranging from 0.82 to 0.95 for its different subscales. Factor analysis confirmed an eight-factorial structure with factors assigning all items to appropriate subscales reported in the original version of the questionnaire. Discriminant and convergent validities were also confirmed for the TFI-Pl. Conclusion: We translated and validated the Polish versions of the THI and the TFI to make them suitable for clinical use in Poland.