Dental practitioners are prone to hearing loss due to noise exposure encountered in dental clinics. The aim of this study was to determine whether the persistent high-frequency sounds produced by the dental equipment could cause hearing decrement among the Saudi dental practitioners.This cross-sectional study included 38 randomly selected Saudi dentists from different specialties who were exposed to noise during working hours and 38 individuals as a control group. The participants underwent four audiometric tests that included an otoscopic examination, tympanometry, pure tone audiometry and the distortion product otoacoustic emissions (DPOAE) test.P=0.002), and between the right and left ears (P=0.005).The data revealed that ~15.8% of the dentists and 2.6% of the control group had some hearing loss. No significant difference was found between the two groups in the pure tone audiometry test; however, qualitative analysis revealed a higher percentage of hearing loss among the dentists’ group as compared with their control counterparts. A statistically significant difference was found in DPOAEs between the two groups in the left ear (et al., which revealed the prevalence of hearing loss in dental personnel to be 17.7%; however, no significant differences were observed compared to the control group in both studies. The otoacoustic emission test in the left ear exhibited significant changes. These changes could have been due to the presence and continuity of the sounds produced by high- and low-velocity suction devices on the left side of the dental unit knowing that 97% of the dentists are right handed.In the present cross-sectional study, the prevalence of hearing loss among dentists as assessed with the pure tone audiometry test was 15.8%. Which was in accordance with a previous study performed by Khaimook Evidence suggests that noise from dental clinics can cause hearing problems, which had a greater effect on the left ear than the right; however, these problems are not severe in nature. Noise-induced hearing loss was more prevalent among the dentists than the control group. Noise-induced hearing loss can be temporary following short-term exposure to noise, with the return of normal hearing after a period of rest.2 Injury to the ear due to noise occurs in two different manners that depend on the type of exposure. High-level short-duration exposures to more than 140 decibel  can stretch the delicate inner ear tissues beyond their elastic limits and then rip or tear them apart. This type of damage (acoustic trauma) develops rapidly and causes an immediate and permanent hearing loss. The second type of injury occurs because of exposure to noise between 90 and 140 dB, which causes metabolic rather than mechanical damage to the cochlea, and this damage is related to the level and duration of exposure.3 The factors that affect the degree and extent of hearing impairment include the intensity and type of noise, the period of exposure each day, total work duration, distance from the source, and individual age and susceptibility.4According to the national institute for occupational safety and health, noise has been identified as one of the 10 leading causes of work-related diseases or injuries.2The Occupational Safety and Health Administration of the United State Department of Labor demands that employers develop and implement a noise-monitoring programme when employees are exposed to noise equal to or exceeding 85 dB for more than eight working hours. If this situation occurs, Occupational Safety and Health Administration requires employers to inform employees to establish and maintain an audiometric testing protocol, and to train workers how to prevent occupational hearing loss. When hazardous noise have not yet been eliminated, Occupational Safety and Health Administration also requires employers to provide hearing protection and to ensure that the workers utilise that protection.6Pure tone audiometry is generally the first quantitative hearing test that is performed to assess the nature and degree of hearing loss in adults and children over 4 years of age to properly plan the most appropriate intervention because this test determines the faintest tones a person can hear at selected frequencies from low to high.7Otoacoustic emissions (OAEs) permit the early detection of inner ear abnormalities that are associated with a wide variety of diseases and disorders, including non-pathologic etiologies, such as noise exposure and aging. Changes in outer hair cell length generate energy within the cochlea that contributes to hearing sensitivity and the ability to distinguish small differences in the frequencies of sounds.8 Instruments in the dental office, such as high-speed turbine hand pieces, low-speed hand pieces and high-velocity suction devices, produce dangerously loud noises that may contribute to hearing loss. Long-term exposure to noise levels of greater than 80–85 dB is associated with an increased risk of hearing loss.9 Kilpatrick10 provided a list of the dB ratings of different office instruments and equipment and reported levels of 70–92 dB for high-speed turbine hand pieces, 86 dB for ultrasonic scalers and 74 dB for low-speed hand pieces.People are accustomed to everyday normal noise that is constantly present all around them. Similar to other working professionals, dental practitioners are exposed to many occupational hazards; hearing loss is definitely one such occupational hazard due to the noise that is constantly present during their work.et al.11 that sought to determine the prevalence of hearing problems among dentists in Saudi Arabia concluded that all dental personnel exhibit roughly the same incidence of symptoms, which include tinnitus, speech discrimination difficulties and difficulties with speech discrimination in the presence of background noise; moreover, dental technicians were found to be the most affected group.A previous study by Alwazzan The aim of this study was to determine whether the persistent high-frequency sounds produced by the dental equipment could cause hearing decrement among the Saudi dental practitioners.This cross-sectional study was conducted from March to December 2015. Thirty-eight dentists from different specialties who work at various governmental hospitals and private clinics that were exposed to occupational noise and a control group of thirty-eight matched non-dental professionals were recruited; matching was done based on age, gender and whether that participant was a smoker/non-smoker. Both sample groups were selected randomly while observing the matching criteria for the control group only12 history of chronic ear disease, ear surgery, ear trauma, ototoxic drugs, diabetes, previous sensorineural hearing loss, any hereditary factors and treatment with radiation or chemotherapy.The inclusion criteria for the experimental group included dentists who had been practicing dentistry for more than 5 years, which includes 2 years of preclinical practice. For the control group, the inclusion criterion was individuals who had not been exposed to noise during work hours. Both sample groups included individuals between the ages of 25 and 40 years. The exclusion criteria for both groups included daily loud music exposure for more than 3 h,This study has received a formal review and approval from the ethics committee of Riyadh Colleges of Dentistry and Pharmacy. The potential participants were approached either by telephone or in person to explain the effects of instrument noise on hearing and were asked to be part of this cross-sectional study. After providing written informed consent, the participants underwent an otoscopic examination and tympanometry by an audiology specialist at Magrabi Hospitals and Centers. If abnormal findings were observed, the individual was excluded from further testing. Subsequently, the participants who fulfilled the inclusion criteria completed a demographic questionnaire and underwent pure tone audiometry and distortion product otoacoustic emission (DPOAE) testing.The collected data included age group , gender, years of practice , actual number of hours exposed to loud noise each week , days of exposure per week  and whether the dentists are left-handed or right-handed .The audiometric examinations were performed using an audiometer  in a 2×2 m double-walled sound booth that was calibrated according to the standards of the International Standard Organization (1964). Air conduction hearing thresholds were measured by pure tone audiometry at the following frequencies: 250 Hz, 500 Hz, 750 Hz, 1 kHz, 2 kHz, 3 kHz, 4 kHz, 6 kHz and 8 kHz. The pure tone averages at 4, 6 and 8 kHz reflect the frequency range that is most susceptible to noise-induced hearing loss. Losses of more than 25 dB in these frequencies are usually considered abnormal see .13Otoacoustic emission tests  are used to determine cochlear status and particularly hair cell function.The IBM SPSS computer software  for Windows was used to perform the analyses. The 3Power G3.1 software  was used to conduct power analysis and determine the number of the required sample size, which was 25. Wilcoxon test was used to determine whether the differences in the pure tone audiometry and OAE test results were significantly different between the dentists and the control group. The level of significance was defined as equal to or less than 0.05.et al.,14 which was used to investigate noise-induced hearing loss among musicians of symphony orchestras. They adopted a rather strict criterion for normal hearing, and more specific criteria for the degree of the noise notch if present  and 23 participants from the control group (60%) had some type of hearing loss.The ages of the 38 dentists and the 38 participants of the control group ranged from 25 to 40 years, and the sample included 23 (61%) males and 15 (39%) females . The preNo significant difference was observed between the two groups in the pure tone audiometry results at the following frequencies: 500 Hz, 1 kHz, 2 kHz, 4 kHz, 6 kHz, and 8 kHz. Moreover, there were no significant differences between dentists and the matched control group in terms of noise-induced hearing loss in the right and left ears separately or in both ears combined .P=0.355), but a significant difference was found for the left ear (P=0.002) and in both ears combined (P=0.005)  . The meaet al.14 showed different patterns among the dentists as compared to their control counterparts. For the right ear, 5.2% of the dentists exhibited sloping loss, and 60.5% had flat loss. For the left ear, 7.8% had a moderate notch, and 50% had flat loss. On the other hand, 42.1% of the control group showed normal hearing in the right ear, and 52.6% had normal hearing in the left ear (see Qualitative analysis of the audiograms as proposed by Jensen  ear see .15Occupational noise-induced hearing loss is defined as bilateral sensorineural hearing loss that develops gradually over a period of several years because of exposure to continuous or intermittent loud noise in the work place.16 Unfortunately, none of the participants in this study were using any type of ear protection, potentially due to discomfort, fear that the protective device may interfere with communication, inconvenience, negative feedback from co-workers or patients and the belief that noise levels from dental instruments will not damage their hearing.16Hearing loss due to aging or genetic factors is not preventable. In contrast, noise-induced hearing loss can be prevented by the use of protective equipment in noisy environments, including ear plugs and ear muffs.11A study that sought to determine the prevalence of hearing problems among dentists in Saudi Arabia concluded that all dental personnel exhibit roughly similar incidences of symptoms; i.e., 16.6% had tinnitus, 14.7% had speech discrimination difficulties and 63% had problems with speech discrimination in the presence of background noise. The incidences of symptom were similar because all dental personnel are exposed to similar noise levels.17–19 Therefore, the noise generated in the dental clinic should not be underestimated.20 The sources of dental sounds that can be treated as potentially damaging to hearing include high-speed turbine hand pieces, high-velocity suction devices, ultrasonic scalers and other mixing devices.8The occurrence of hearing loss due to prolonged exposure to noise levels greater than 85 dB without the use of any type of ear protection is well documented in the literature.et al.21 noted that personnel who work in noisy environments should not engage in noisy activities immediately following the workday. These authors stated that ‘the ear begins to recover its hearing ability when it is allowed to rest’.Altinoz 22–24 The study performed by Khaimook et al.15 revealed the prevalence of hearing loss in dental personnel to be 17.7%; however, no significant differences were observed compared with the control group.The prevalence of noise-induced hearing loss among dental personnel has been reported to range from 7 to 16% in the literature.25In the present cross-sectional study, the prevalence of hearing loss among dentists as assessed with the pure tone audiometry test was 15.8%, which did not significantly differ from the results observed in the control group. Prevalence with more stringent criteria among dentists was 76%. A significant difference may have been observed with a larger sample. Regarding the DPOAEs that were used to compare the two groups, the left ear exhibited significant changes that could have been due to changes in the outer hair cell lengths. These changes could also have been due to the presence and continuity of the sounds produced by high- and low-velocity suction devices on the left side of the dental unit, considering that 97% of the dentists in this study were right-handed. Undoubtedly, the degree of risk to the dental practitioner depends upon certain factors such as the intensity of the sound and the duration of exposure.et al.,15 the authors stated that risk factors including the years of experience and the working hours per week influence hearing. Further study is recommended in the future to reveal risk factors related to dental specialty, working hours and years of experience.In an article written by Khaimook To decrease the risk of developing noise-induced hearing loss, dental practitioners are encouraged to follow the recommendation of the ADA council on dental materials and devices, which include the following:26Preventive measures for noise attenuation should be directed in three areas: optimum maintenance of rotary equipment, reduction of the ambient noise level in the operatory and personal protection through the use of ear plugs.26 This regular testing should identify those who have begun to lose their hearing before they acquire significant auditory impairments.27Dentists are advised to perform regular annual audiometry check-ups.27 During the construction and design of the dental clinic, consideration of the use of sound-absorbing materials is also recommended to decrease the noise level.21It is necessary to produce dental hand pieces with additional noise control. Manufactures are urged to improve quality in terms of decreasing the sound levels produced by high-speed dental hand pieces. Furthermore, friction increases in old and worn machinery, which results in increases in sound levels and highlights the importance of maintenance and periodic replacement.11Continuing education programmes would be beneficial in terms of decreasing the risk of noise-induced hearing loss among dental personnel. Moreover, dental school curricula ought to include education about the different occupational hazards.Within the limitations of this study, evidence suggests that noise from dental clinics can cause hearing problems, which had a greater effect on the left ear than the right; however, these problems are not severe in nature. Noise-induced hearing loss was more prevalent among the dentists than the control group.


Sudden sensorineural hearing loss (SSNHL) is an important otological emergency. Up to 90% of the cases are idiopathic. Cerebral venous thrombosis (CVT) is an extremely rare identifiable cause as it only represents 0.5% of all strokes.In this paper, an unusual case of bilateral SSNHL secondary to bilateral CVT with rapid and complete recovery is reported. The patient presented with sudden bilateral hearing loss associated with some neurological symptoms. Initial computed tomography (CT) venography revealed a CVT of bilateral transverse sinuses. The patient was started on an anticoagulant and imaging was repeated after five days, revealing the absence of the thrombosis. Serial pure tone audiometry (PTA) showed complete recovery of bilateral hearing within 10 days.Early detection and intervention may fasten hearing recovery and improve the quality of life. The immediate restoration of venous blood flow and intracranial pressure may lead to the complete recovery of bilateral hearing loss.  Bilateral sudden sensorineural hearing loss caused by bilateral cerebral venous thrombosis is uncommon. The majority of sudden onset sensorineural hearing loss presents itself unilaterally, while the incidence of bilateral involvement is less than 5% . Sudden A 27-year-old man came with a complaint of sudden onset bilateral hearing loss while he was attending a religious event in a mosque the night before. He was confused and unable to find his way back to his car. There was associated slurred speech, dizziness, and vomiting. Otherwise there was no ear pain, tinnitus, vertigo or ear discharge. He also denied any fever, headache or body weakness. There was no previous history of ear infection, trauma or exposure to a loud voice. He also denied taking any ototoxic medications. He had a childhood history of epilepsy with the last fitting episode occurring when he was 12-years-old. During his physical examination, the patient was alert and conscious. The vital signs were normal. Free field voice test showed that the patient had bilateral profound hearing loss. He was unable to hear a shout at 2 feet and he spoke in a loud voice with some degree of dysarthria. Tuning fork test was not administered since the patient had profound hearing loss. Otoscopic examination was also normal. He had a normal gait, no facial asymmetry, and his muscle power and reflexes were normal. His routine blood examinations showed a haemoglobin of 135 g/L, total white cell count of 8.51 x109/L, and an ESR 3 mm/hr. His coagulation profile was normal. Screening tests for Hepatitis and Syphilis infection were negative.Based on the patient’s history and physical examination, we referred him to the neuromedical team with the diagnosis of bilateral sudden sensorineural hearing loss secondary to central causes which could be stroke or meningitis. Computed tomography (CT) followed by CT venography, which were administered on the following day, revealed cerebral venous thrombosis (CVT) of bilateral transverse sinuses and torcular herophili with multifocal infarction of various ages . The neuOn the following day, the patient’s bilateral hearing started to improve. Free field voice test showed that he was able to hear a shout at 2 feet (80-90 dB hearing loss). Pure Tone Audiometry (PTA) was not performed upon admission because the patient had giddiness and was not fit for the procedure . The first PTA was administered on the third day after admission, which revealed moderate-to-severe sensorineural hearing loss (SNHL) at high frequencies  . The patient’s hearing continues to improve and he claims to have his normal bilateral hearing back 10 days after admission.Five days after the first imaging, an MRI of the brain was ordered for the patient to evaluate the progress of the CVT. The radiologist reported it as multifocal infarction of varying ages with no evidence of venous sinus thrombosis . The patient was discharged after 11 days with an oral anticoagulant (aspirin 75mg daily) and to complete oral prednisolone in total of 2 weeks. . Four weeks post-discharge, during the patient’s ORL clinic follow-up, he claimed having normal bilateral hearing and a subsequent PTA assessment showed normal findings .Sudden hearing loss (SHL) can be described as a rapid onset hearing impairment in one or both ears over a 72-hour period. Sudden sensorineural hearing loss (SSNHL) is a component of SHL that is sensorineural in nature and conforms to certain audiometric criteria (2). Sudden sensorineural hearing loss (SSNHL) is an otological emergency requiring prompt and thorough assessment in order to detect a possible etiology that may be life-threatening and that possesses reversible conditions. However, most of SSNHL, 85% to 90% of cases, is idiopathic . IdiopatThe unilateral condition is more common and usually idiopathic. About 65% of patients which presented with a unilateral condition spontaneously recovered their hearing . On the Cerebral venous thrombosis (CVT) has wide spectrum of clinical presentations. Classical symptoms of CVT include headache, seizures, and various focal neurological deficits including cranial nerve palsies . In thisRisk factors for central venous thrombosis (CVT) include changes in hormonal levels , mechanical causes , infections, cancer, acquired prothrombotic states , inflammatory diseases, haematological disorders, arteriovenous malformations, and drugs . HoweverCVT may have led to sensorineural hearing loss by inducing increased intracranial pressure. Increased pressure in the subarachnoid space may be conveyed to the perilymph and endolymphatic system via the cochlear aqueduct, causing increased fluid pressure in the internal ear which eventually causes cochlear dysfunction. Cranial nerve VIII function may also be disturbed by the increased intracranial pressure . ThromboIn this case, CT scan with contrast and CT venography which was performed one day after admission revealed that the patient had a cerebral venous thrombosis (CVT) of the bilateral transverse sinuses and torcular herophili with multifocal infarct of various age. He was immediately started on subcutaneous fondaparinux by the neurosurgical team. We also started him on intravenous prednisolone. Within one day, his bilateral hearing started to improve evidenced by clinical hearing assessment and later by serial PTA. However, the MRI of the brain administered five days after the first CT scan revealed only multifocal infarct with absence of CVT. The probability of hearing recovery has been reported to differ according the gravity of the hearing loss threshold level upon presentation. Patients with mild hearing loss usually achieve full recovery, those with moderate hearing loss occasionally have a full recovery unless treated, and patients with severe to profound hearing loss rarely show spontaneous improvement or make a full recovery -13. However, in this case, the patient presented with profound hearing loss and continues to have improvement of bilateral hearing and even achieved a full recovery after ten days. .Bilateral sudden sensorineural hearing loss is a rare presentation of cerebral venous thrombosis that is potentially reversible with prompt diagnosis and appropriate intervention. Early and accurate detection of CVT is possible with the help of CT scan and MRI. Successful management requires anticipation of related etiology, early recognition, and an optimal treatment of CVT.


The purpose of this retrospective study is to present the clinical experience of a single institution on the recovery of ABR thresholds in a large population of neonates and infants at risk of hearing loss. Potential prognostic factors associated with this phenomenon were also investigated. Out of 2248 high risk infants, 384 had abnormal ABR at initial hearing evaluation and 168 of them had absent ABR or a threshold ≥80 dBnHL. From this subgroup, a significant percentage showed complete or partial recovery on reexamination , performed 4–6 months later. The presence of normal otoacoustic emissions was associated with the ABR restoration on reexamination. Moreover, the very young age at the initial hearing screening seems to be related to higher probabilities of false positive ABR. The potential recovery of hearing in HR infants raises concerns about the very early cochlear implantation in HR infants less than one year. Such a treatment modality should be decided cautiously and only after obtaining valid and stable objective and subjective hearing thresholds. This holds especially true for infants showing an auditory neuropathy profile, as they presented a much greater probability of ABR recovery. It is largely accepted among physicians that sensorineural hearing loss is caused by irreversible damage to the hearing organ, showing a permanent or progressively deteriorating character.However, there are reports of recovered hearing thresholds in children. These reports first appeared in the early 1980s, when changes of the hearing status could be validated for the first time by using the Auditory Brainstem Responses (ABR), as a newly introduced technique of hearing evaluation. At that time, researchers reported on the changes of ABR thresholds in jaundiced infants. Those changes concerned not only the restoration of prolonged latencies after therapy but also the appearance of normal waveforms in cases with completely absent responses . More reA number of neonates and infants at risk of hearing loss who showed restoration of their objective hearing thresholds have been gathered in our institution during the last two decades. Some of them (years 1992–2008) have already been reported .Our purpose is to present a single institution's experience on the restoration of objective hearing thresholds in high risk (HR) infants. We have carried out a multivariate analysis to determine whether there are any indicators that can predict the recovery of auditory function. Illustrative cases are presented.n = 2248) who were admitted to the neonatal intensive care unit (NICU) of our institution between 1992 and 2014. All children had one or more risk factors for hearing loss, as they have been defined and modified by the American Joint Committee on Infant Hearing during the study years [We reviewed retrospectively the audiological charts of all HR neonates  and a Biologic System AEP Version 1.3.0 (years 2004–2014) were used . Alternating clicks at a rate of 31.1/sec were presented monaurally through a shielded TDH-39 headphone. Responses were collected using four silver cup electrodes and then were amplified  and filtered ; 2048 samples were averaged and replicated. A replicable waveform at 40 dBnHL within the expected latencies was considered as “normal” or “pass” response, suggesting a normal hearing threshold. Babies who failed to produce a “pass” response uni- or bilaterally were scheduled for reevaluation 4–6 months later. In some cases, a third ABR session was necessary. Any improvement of ABR threshold by ≥10 dBnHL, compared to the initial ABR test, was considered as “recovery.”Click-evoked OAEs were measured by a regularly calibrated ILO88 Otodynamic Analyzer  in its default settings , 21. An t-test for categorical and continuous variables, respectively. For multivariate analysis we used a logistic regression model and created a binary outcome variable describing the improvement of ABRs in follow-up studies; it was based on whether improvement in ABRs was at least 10 dBnHL. As predictors in the model we used OAE responses, sex, and risk factors that have been reported in the literature to cause hearing loss in the neonatal period, such as intake of ototoxic medications, birth weight, hyperbilirubinemia requiring exchange transfusions, and severe birth asphyxia.In univariate analysis we used chi-square and Continuous variables are expressed as mean ± SD. Results are expressed as odds ratios (OR) and their corresponding 95% confidence intervals (CI).Prognostic significance of OAEs has been based on the TEOAEs recordings from 69 out of 107 infants included in the statistical analysis. For the rest of 38 children, OAEs data were either missed or unreliable .In order to categorically exclude all ABR threshold elevations due to pure conductive losses , only infants demonstrating ABR thresholds ≥80 dBnHL were included in the analysis.This research was conducted according to the rules of the institutional ethical committee.From the total HR population tested, 384 cases or 17.1% showed abnormal ABR findings, ranging from ABR elevation by 10 dBnHL to absent waveforms at maximum stimulation level (90/95 dBnHL), uni- or bilaterally, and they were scheduled for reexamination, after 4–6 months. Two hundred five appeared on follow-up assessment while 179 did not . From those presented, 103 showed complete ABR recovery, 15 showed partial recovery, and 87 remained stable or deteriorated . In thesAs most cases of mild to moderate hearing loss are expected to be due to middle ear problems, we focused on infants with initial ABR threshold ≥80 dBnHL through our statistical analysis. Overall, 168 infants showed ABR thresholds ≥80 dBnHL or no response at maximum stimulation level at initial screening. In this specific subgroup, 107 infants presented on reexamination and a substantial percentage of them showed full recovery to normal (32.7%) while 10 (9.3%) restored their ABR thresholds partially. From the same group, in 56 cases (52.3%) the ABR thresholds remained unchanged, whereas 6 (5.6%) cases showed threshold deterioration. The outcome of the hearing assessment is summarized in Figures One hundred seven infants with ABR thresholds ≥80 dBHL at the first measurement were finally included in our analysis. Their clinically important characteristics and the results of univariate analysis are shown in p = 0.004). Sex , intake of ototoxic medications , birth weight , hyperbilirubinemia requiring exchange transfusions , and existence of severe birth asphyxia  were not statistically significant.In multivariate analysis, only the presence of OAEs proved statistical significant predictor of ABR improvement  were included. However, there were infants with ABR thresholds between 45 and 75 dBnHL, who showed full or partial restoration of a purely sensorineural ABR abnormality. In these cases, a temporary conductive hearing loss could not be held responsible for this phenomenon because otoscopy and the presence of otoacoustic emissions confirmed that their middle ears were free of disease. These infants were excluded from the analysis on the basis of our inclusion criteria.Early hearing loss detection and intervention are paramount for the development of linguistic, cognitive, and social skills. Worldwide, thousands of hearing handicapped children enjoy the benefits of this approach, having attained educational and professional standards comparable to those of their normal hearing peers. Even today, however, and despite the substantial advances in diagnostic audiology, a valid diagnosis of hearing loss in neonates and infants presents considerable difficulties. The inherent weakness of objective tests to assess the real hearing thresholds, inability to employ subjective tests in many cases, middle ear problems, and comorbidities are the primary reasons for uncertainty in diagnosis. Moreover, low and mid frequency serviceable residual hearing can be hardly detected in the routine audiological evaluation of the very young child while pathologies with an auditory neuropathy profile further complicate the diagnostic process.Apart from the above, a new confounding parameter has emerged from a number of reports; the potential of complete or partial recovery of auditory thresholds over time in neonates and infants with high risk factors for hearing loss. Such findings have been confirmed in several pediatric centers. Coenraad et al.  found siExcept for the HR infants, complete or partial restoration of abnormal ABRs has also been reported in pediatric patients suffering from a variety of medical conditions, such as meningitis , metabolTo this point, we can only speculate the underlying etiology of this phenomenon. Delayed CNS maturation seems to be a reasonable explanation for HR neonates. Restoration of a normal CNS function after the resolution of harmful factors  could also justify such findings. Unfortunately, in these cases prognosis is impossible because no predictor for hearing recovery had been found so far.Making use of our past experience on the possibility of ABR recovery in HR infants, in this study we included the presence of otoacoustic emissions to the potential predictors for partial or complete restoration of hearing in HR infants. In both uni- and multivariate analyses, the OAEs proved statistical significant predictor of ABR improvement, whereas the rest of potential predictors under investigation failed at this task. From a clinical viewpoint, it is much more likely that children who demonstrate typical otoacoustic emissions and abnormal or absent ABR at initial screening will show hearing improvement compared to those without OAEs.Given that the combination of present OAEs in patients with abnormal ABR signifies an auditory neuropathy/dyssynchrony hearing pathology, we can state that, in HR infants showing an auditory neuropathy profile, partial or full ABR recovery may possibly take place in the following months. Specifically, we found that these infants have, on average, almost 5.5 times higher ABR recovery probabilities than those who do not show normal cochlear function at initial screening. Similar clinical reports but without statistical documentation have been described by other researchers, as well. Madden et al. observed improvement in behavioral thresholds over time in 9 out of 18 children with AN . PsarommTherefore, there is sufficient evidence that the abnormal hearing thresholds can be improved or restored in some HR infants within a few months and this is especially true for infants suffering from hearing loss of auditory neuropathy type. The impact of such notion could be substantial for clinical practice.The results in Moreover, the potential recovery of hearing in HR infants raises concerns about the very early cochlear implantation in children less than one year. Reports on very early cochlear implantation (5–12 months) have recently appeared in the medical literature –33. EvenAlthough we favor the fastest auditory stimulation possible in the hard of hearing child, the intervention in the form of cochlear implantation in the HR infant should be recommended only after the ABR thresholds have been stabilized and reliable behavioral tests have been obtained. Infants suffering from diseases which can harm CNS , sequential ABR, and imaging studies to monitor the progression of brain myelination are recommended. In such cases, the decision for cochlear implantation should not be based on an “early” ABR test. Instead, repeating the ABR test shortly before the cochlear implantation is strongly suggested.Particularly, the HR infants with an auditory neuropathy profile should be treated less aggressively than the other HR infants, in view of the fact that partial or complete ABR recovery is more likely to take place in this group during the following months. In such cases, the indication for cochlear implantation should be made well after the first year of life and only after the subjective and objective hearing thresholds have been repeatedly confirmed. Bilateral cochlear implantation should probably be avoided within the first year in infants suffering from auditory neuropathy.A significant number of HR infants with absent ABR or ABR thresholds ≥80 dBnHL showed complete or partial recovery on reexamination , after 4–6 months.The younger the age at first ABR evaluation is, the greater the likelihood of false positive results appears to be.Normal otoacoustic emissions recordings should be considered as an important predictor of ABR recovery since they remained significantly correlated with ABR recovery even after having taken into account a number of confounding factors.The decision for a very early cochlear implantation (<1 year) in HR infants should be made cautiously and only after obtaining valid and stable objective and subjective hearing thresholds.This is especially true for infants showing an auditory neuropathy profile, because they showed a much greater probability of partial or complete hearing recovery.Fast-track sequential or simultaneous bilateral cochlear implantation in HR infants younger than 1 year of age should be recommended only in exceptional cases with absolute indication.Any modification in the existing protocols should account for certain exceptions, such as neonates and infants with meningitis or CMV infection, which, according to the current level of knowledge, should be treated early.


Ambiguous results have been reported regarding the effects of training on resting metabolic rate (RMR), and the importance of training type and intensity is unclear. Moreover, studies in subjects with type 2 diabetes (T2D) are sparse. In this study, we evaluated the effects of interval and continuous training on RMR in subjects with T2D. Furthermore, we explored the determinants for training-induced alterations in RMR.n = 14) completed three, 2-week interventions  separated by washout periods. Training included 10 supervised treadmill sessions, 60 min/session. CWT was performed at moderate walking speed [aiming for 73% of walking peak oxygen uptake (VO2peak)], while IWT was performed as alternating 3-min repetitions at slow (54% VO2peak) and fast (89% VO2peak) walking speed. Study 2 was a single-arm training intervention study where subjects (n = 23) were prescribed 12 weeks of free-living IWT . Before and after interventions, RMR, physical fitness, body composition, and glycemic control parameters were assessed.Data from two studies, both including T2D subjects, were encompassed in this manuscript. Study 1 was a randomized, crossover study where subjects , fat-free mass (FFM), and fat mass were all associated with RMR. Changes in RMR were associated with changes in TBM and fat mass, and subjects who decreased body mass and fat mass also decreased their RMR. No associations were seen between changes in physical fitness, glycemic control, or FFM and changes in RMR.Neither short-term continuous or interval-type training, nor longer term interval training affects RMR in subjects with T2D when no overall changes in body composition are seen. If training occurs concomitant with a reduction in fat mass, however, RMR is decreased.NCT02320526 and NCT02089477. Most subjects with type 2 diabetes (T2D) are overweight or obese, and overweight/obesity is considered to be a central component of the pathogenesis and pathology of T2D , 2. Inde2max is an important determinant for changes in RMR  of short-term (2 weeks) IWT/CWT and the effects of longer term (12 weeks) IWT on RMR in subjects with T2D. Moreover, we aimed to assess the associations between potential determinants for RMR  and RMR, both at baseline and in relation to the changes induced with 12 weeks of IWT.Exercise intensity is an important determinant for training-induced changes in body composition , and we ial EPOC , the maiy on RMR . As such2peak test with indirect calorimetry  and a familiarization VO2max test performed on a treadmill  with indirect calorimetry  as previously described  and (NCT02089477).This manuscript builds on data from two different studies, both including subjects with T2D . Exclusiescribed , 27. Wri2peak); IWT [ten 60-min walking sessions performed with cycles of alternating 3-min slow (54% of VO2peak) and 3-min fast (89% of VO2peak) walking]; control (CON) , and interventions were performed in randomized order. All walking sessions were performed at a treadmill (Katana Sport) and controlled with indirect calorimetry at the first and sixth session . Between interventions, washout periods , where subjects returned to their habitual activity level, were applied to ensure that any intervention-induced effects disappeared before initiation of the next intervention. Other data from this study have previously been published , and data from training sessions were uploaded to a central server . Carbon dioxide concentrations in the system were kept below 1% to avoid excess breathing (Before (pre) and after (post) interventions, subjects underwent one experimental day . Subjects met fasting  in the laboratory, by means of passive transport . After confirming that no subjective feeling of acute disease and no fever was present, subjects voided. Subjects were then weighted, had an antecubital vein catheter inserted, and were placed in a bed in a temperature controlled (20°C) and calm room. After an acclimatization period of at least 30 min, the RMR measurements commenced: a standardized head tilt (15°) was applied to the bed and a ventilated hood  was placed over the subject’s head and connected to an indirect calorimetric system (Cosmed Quark) 2max test comparable to the one performed at the screening day.Following the RMR measurements, fasting blood samples (lithium-heparin and EDTA tubes) were obtained and subjects included in Study 1 underwent supine resting whereas subjects in Study 2 underwent a 2 h standard OGTT  with bedside blood glucose measurements  obtained every 30 min. Finally, following resting/OGTT procedures, all subjects were given a light meal and underwent a dual-energy X-ray absorptiometry scan  and a VOPost-intervention investigations were in Study 1 initiated 39–43 h after the last exercise bout (in CWT/IWT interventions), and in Study 2 at least 48 h after the last exercise bout.via Electrochemiluminescence immunoassay . EDTA plasma was analyzed for HbA1c via absorption photometry .Fasting blood samples were centrifuged . Lithium-heparin plasma was analyzed for thyroid hormones  and insulin Mean oxygen uptake and carbohydrate excretion rates were calculated from the indirect calorimetric measurements. RMR was calculated according to the equations by Weir .t-test (Study 2).First, intervention-induced effects on RMR were compared using two-way (time × intervention) repeated-measures (RM) ANOVA (Study 1) and Student’s paired 2max, body composition, and glycemic control variables) and RMR were performed on baseline data (both studies) and on post–pre intervention (delta) values (Study 2). To avoid regression toward the mean, all delta values were controlled for baseline values, and this did not change the results of the regression analyses.Next, simple linear regression analyses between potential determinants of RMR  decreased RMR (≥ 10% decrease); (2) unchanged RMR; (3) increased RMR (≥10% increase). The specific cutoff levels were chosen to ensure that subjects categorized in group 1 and 3 with certainty had intervention-induced alterations in RMR and that the differences measured were not just due to imprecision of the measurements or biological day-to-day variation , 32. Strp < 0.05.Data are reported as mean ± SEM or delta values with confidence intervals (CI). All analyses were performed using Prism v6.03  and statistical significance was accepted when N = 14 subjects were included in Study 1 with all subjects being included in the analyses. N = 32 subjects were included in Study 2, but only 23 subjects underwent RMR measurements. As such, N = 37 subjects were overall included in the current analyses. No subjects changed glucose-lowering medication during the study period. In Study 1, glucose-lowering medication was continued unchanged during the entire study, whereas, in Study 2, glucose-lowering medication was paused from 2 days before each experimental day and until the end of the experimental day.Baseline data are given in Table In Study 1, training adherence (amount of training performed relative to prescribed) was 99% in both CWT and IWT. As previously published , mean oxIn Study 2, the mean uploaded IWT time was 68 ± 9 min/week, corresponding to 75% of the minimal volumes of prescribed training. There were, however, substantial between-subject differences in uploaded IWT time, with six individuals uploading less than 30% of the minimal volumes of prescribed training. If excluding these six, apparently non-adherent, subjects from the analyses, mean uploaded IWT time was 85 ± 7 min/week, corresponding to 94% of the minimal amounts of prescribed training. It was not possible to assess training intensity from the uploaded data.p > 0.05 for all comparisons] , did not change this. Moreover, no association was seen between uploaded IWT time and changes in RMR  However, intervention-induced changes in RMR varied considerably between subjects , n = 9 subjects did not change RMR and n = 7 subjects increased RMR (≥10%) with the intervention. Normalization of RMR to total body mass (TBM) or FFM did not alter the above-standing results.In Study 1, no effect of any intervention was found on RMR , whereas neither body compositional nor glycemic control variables improved with the intervention .In Study 2, physical fitness improved with the intervention [delta VO2max were positively correlated with RMR , were all positively correlated with RMR at baseline. When analyzing delta values, the associations between TBM/fat mass and RMR were maintained, whereas no association between FFM and RMR was seen. The association between changes in fat mass and RMR was maintained when a sequential correction for changes in the other potential RMR-determinants was performed.No associations between glycemic control variables  and RMR were seen, neither at baseline nor when analyzing delta values.2max, body compositional variables, glycemic control variables) were seen between strata   Table .2max and glycemic control, no intervention-induced changes within strata were seen, nor were there any intervention-induced differences between strata.For measures of VOp < 0.05 for both).An intervention-induced reduction in body mass was seen in subjects who also decreased RMR, and a between-strata difference in body mass was seen between subjects who decreased and subjects who increased RMR .In Study 1, no intervention-induced effects on fasting insulin or thyroid hormones were seen with any of the interventions .In Study 2, fasting insulin and thyroid hormones did not change with the intervention, and likewise, no differences were seen in the stratified analyses . Since EPOC is increased with IWT compared to both CON and CWT , we find this unlikely.In contrast to previous observations , 20, we  and RMR , 15, waswith T2D , it woulvia increased physical activity (The strong baseline associations we found between FFM and fat mass on one side and RMR on the other side have previously been reported . Interesactivity , 43. Wheactivity , it is p2max, however, indicating that some effect of the training was seen. Still, when compared to our previous study, where 17 weeks of IWT resulted in considerable weight loss and improvements in glycemic control and a much greater increase in VO2max (2max (While Study 1 was fully supervised efficacy trial with high training adherence, Study 2 was a free-living effectiveness trial without supervision. Whereas the training adherence in Study 2, in terms of volume, was fairly good compared to other free-living training studies , 46, then VO2max , it is cn VO2max , indicatn VO2max  and greaax (2max , 15 may Given that the analyses in this paper were secondary to other analyses , 28 and In summary, neither short-term continuous or interval-type training, nor longer term interval training affects RMR in subjects with T2D when no overall changes in body composition are seen. Whereas both FFM and fat mass are important determinants of RMR at baseline, only training-induced changes in fat mass and not in FFM seem to be important for training-induced changes in RMR.KK designed the studies, analyzed and interpreted the data, and wrote the manuscript. MR-L contributed to the study design. KK, CB, IT, and JN researched the data. All authors reviewed and revised the manuscript, approved the final version, and agreed to be accountable for the content of the work.The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer, OS, and handling editor declared their shared affiliation, and the handling editor states that the process nevertheless met the standards of a fair and objective review.


The aim of this study was to investigate the association between insomnia and hearing impairment among workers exposed to occupational noise.This study included 809 male workers exposed to occupational noise. The participants underwent audiometric testing, and their insomnia was examined based on the Insomnia Severity Index test. Hearing impairment was defined as hearing threshold >25 dB hearing level in the range of 1–4 kHz.p = 0.042) after adjustment for age, working period, noise level, snoring, use of protection devices, diabetes mellitus, hypertension, smoking, alcohol consumption, regular exercise, waist circumference, total cholesterol, triglyceride and high density lipoprotein cholesterol.According to analysis of covariance, it was observed that pure tone audiometry thresholds at 1–2 kHz in the right ear and at 1 kHz in the left ear were significantly higher among workers with insomnia compared to those with no insomnia. Multiple logistic regression analysis of insomnia for hearing impairments was performed, which showed the odds ratio was 1.806 (95% confidence intervals: 1.022–3.188, Insomnia could be associated with hearing impairment in workers who are exposed to occupational noise. Additionally, insomnia may be associated with decreased hearing at low frequencies. Especially, more efforts are required to improve the quality of sleep for workers who are exposed to loud occupational noise. Further well- designed prospective studies are needed to clarify the relationship between insomnia and hearing impairment. Noise-induced hearing loss (NIHL) is one of the most prevalent occupational disorders worldwide. It is estimated that about 16% of the cases of adult-onset hearing loss are due to induced by noise .NIHL has deleterious effects on workers such as social disconnection, depression, and increased risks of accidents. Further, it raises social expenditure for treatment, compensation, and rehabilitation . VariousInsomnia is a common problem in adults and is defined as a subjective feeling of having difficulty in initiating or maintaining sleep or having poor sleep quality . It has Only few studies have been conducted to examine the association between sleep and hearing loss. A study in Sweden indicated poorer sleep quality is associated with higher prevalence of hearing problems. However, this study focused on not only hearing loss but also considering subjective hearing complaints as hearing problems . AnotherWe therefore conducted this study to examine the relationship between insomnia by using the Insomnia Severity Index (ISI) and hearing impairment objectively assessed by audiometric device among occupational noise exposed workers.This study was conducted on 840 male workers, aged between 25 and 60 years, at a tire-manufacturing factory. They underwent specific health examinations from October 2014 to November 2014. We excluded 31 workers with a history of ear diseases or with abnormal lesions observed during otoscopy. Finally, we enrolled 809 workers in the current study and conducted the ISI, audiometric, clinical, and tests. We provided each subject for written informed consent for participation. Moreover, physicians who conducted clinical examination explained the method and purpose of this study to the participants. After obtaining informed consent from each subject, tests were performed.The participants were interviewed by trained physicians using a well-established questionnaire. We examined their age, working period, use of hearing protection devices, snoring, smoking, drinking, physical exercise, medical history, current medical problems, and drug administrations. Each subject was questioned about the use of hearing protection devices. Based on all the responses, we divided the subjects into “No or seldom” and “Always” groups. With respect to snoring, the subjects were asked, “Do you snore when you are sleeping or have you heard from family or friends that you snore when you are sleeping?”. The subjects who answered “Yes” were classified into snoring group, while the rest were classified into non-snoring group. With respect to the smoking status, subjects who were smoking currently were defined as current smokers, and those who had stopped smoking were defined as ex-smoker; the subjects who had never smoked were regarded as non-smokers. Further, subjects who consumed alcohol once or more per week were assigned to the drinking group. Subjects who exercised for 30 min or longer at least three times a week were classified into the physical activity group.The height, weight, waist circumference, and blood pressure were measured. Height and weight were measured to the nearest 0.1 cm and 0.1 kg, respectively. Waist circumference was measured at the mid-point between the twelfth rib and anterior superior iliac spine. The body mass index (BMI) was calculated by dividing the weight (kg) by the squared height (meter). Blood pressure was measured in the right arm in the sitting position by using digital blood pressure monitor under stable conditions.Blood samples  of all the participants were collected after 12-h fasting. Total cholesterol, high-density lipoprotein (HDL) cholesterol, triglyceride, and fasting glucose levels were measured. Hypertension was defined as systolic blood pressure ≥ 140 mmHg or diastolic blood pressure ≥ 90 mmHg or antihypertensive medication. Diabetes mellitus was defined as fasting glucose ≥126 g/dL or medication for diabetes.We reviewed the data of working environment noise measured in 2014, which were provided by the company, and the mean noise level of each department to which the workers belonged was regarded as the noise level of the worker.For evaluating insomnia, we conducted the ISI test, which is regarded as a validating measurement worldwide , 22. The(1) Difficulty in falling asleep; (2) Difficulty staying asleep; (3) Problems on waking up too early; (4) How satisfied/dissatisfied are you with your current sleep pattern?; (5) How noticeable to others do you think your sleep problem is in terms of impairing the quality of your life?; (6) How worried/distressed are you about your current sleep problem?; (7) To what extent do you consider your sleep problem to interfere with your daily functioning currently?All the participants answered these questions in the form of ratings from 0 to 4 . We added the scores for all seven questions and obtained a total score ranging from 0 to 28. The total score is interpreted as follows: absence of insomnia (0–7), sub-threshold insomnia (8–14), moderate insomnia 15–21), and severe insomnia (22–28) [, and sevAudiometry was performed for measuring the hearing thresholds of participants. Air conduction pure tone thresholds for the frequencies 1–4 kHz were obtained bilaterally by using an Itera II audiometer with TDH-39P headphones by experienced testers. An audiometric device was calibrated according to the guidelines for audiometry of the Korean Occupational Safety and Health Agency . We consAge, working period, noise level, waist circumference, BMI, blood pressure, total cholesterol, triglyceride, HDL cholesterol, glucose, smoking, alcohol consumption, exercise, hypertension, diabetes mellitus, snoring, use of protection devices, and pure tone audiometry results were compared for those with and without insomnia. The Student t-test for continuous variables and chi-square test for categorical variables were performed. We compared hearing thresholds according to insomnia by using analysis of covariance (ANCOVA) with adjustment for covariates including age, working period, noise level, snoring, use of protection devices, hypertension, diabetes mellitus, smoking, alcohol consumption, regular exercise, waist circumference, and total cholesterol, triglyceride, HDL cholesterol levels.Multiple logistic regression was applied to examine the relationship between insomnia and hearing impairments with four different models. The models were as follows: (1) adjusted for age; (2) adjusted for age, working period, noise level, use of protection devices, and snoring; (3) adjusted for age, working period, noise level, use of protection devices, snoring, diabetes mellitus, and hypertension; (4) adjusted for age, working period, noise level, snoring, use of protection devices, diabetes mellitus, hypertension, smoking, alcohol consumption, regular exercise, waist circumference, total cholesterol, triglyceride, and HDL cholesterol.p-value < 0.05. The SPSS version 23.0 software was utilized for all statistical tests .Additionally, we performed multiple logistic regression analysis to evaluate the relationship between the ISI test score and hearing impairments with same models as mentioned above. The ISI test score was analyzed as a continuous variable. Continuous variables were presented as means ± standard deviation (SD), and categorical variables were presented as numbers and percentages. Results were shown as odds ratio (OR) with 95% confidence intervals (CI). Statistical significance was set at All the 809 subjects that participated in this study were men. The number of subjects those who were classified as normal hearing were 277 and as hearing impairment were 532. General characteristics of the subjects were presented by hearing status. Age, working period, noise level, snoring, protection device use, ISI score and insomnia were statistically different between two groups. No statistically significant differences were observed between two groups in waist circumference, BMI, blood pressure, total cholesterol levels, triglyceride levels, HDL cholesterol levels, glucose levels, smoking, alcohol consumption, regular exercise, hypertension and diabetes mellitus Table .Table 1GBased on insomnia, pure tone audiometry thresholds at 1–4 kHz at both ears were presented. The pure tone audiometry thresholds at all frequencies for both the ears were higher for the non-insomnia group compared to the insomnia group. No significant correlation was observed between the hearing thresholds for the left ear, 3 and 4 kHz in the right ear, and insomnia status. However, at 1–2 kHz in the right ear, the hearing thresholds were significantly high for the insomnia group  after adjustment for age. However, in three different models, the OR of the ISI test scores for hearing impairments were 1.026 (95% CI: 0.994–1.060), 1.026 (95% CI: 0.994–1.060), and 1.025 (95% CI: 0.992–1.059), respectively, which were statistically insignificant . Additional adjustment for working period, noise level, use of protection devices, and snoring was performed, and the OR of insomnia for hearing impairments was found as 1.834 (95% CI: 1.043–3.225). After additionally adjusting for diabetes mellitus and hypertension, the OR of insomnia for hearing impairments changed to 1.842 (95% CI: 1.046–3.242).Finally, adjustment for age, working period, noise level, snoring, use of protection devices, diabetes mellitus, hypertension, smoking, alcohol consumption, regular exercise, waist circumference, and total levels of cholesterol, triglyceride, HDL cholesterol revealed that the OR of insomnia for hearing impairments was 1.806 (95% CI: 1.022–3.188) Table .Table 4OIn this study, we focused on the influence of insomnia on hearing impairment and showed that the presence of insomnia  elevated the risk of hearing impairment after adjustment for covariates . Further, pure tone audiometry thresholds at low frequency levels (1 kHz in the left ear and 1–2 kHz in the right ear) were significantly high in workers with insomnia.No previous studies have been conducted to examine the association of insomnia and hearing loss owing to the exposure to noise. Only few studies have suggested the relationship between sleep and hearing problems including hearing loss and hearing complaints. A large-scale study with 9756 working individuals in Sweden indicated statistically significant differences in the prevalence of hearing problems among individuals with different levels of sleep quality, and poor sleep quality was found to be associated with hearing problems in both men and women. However, this study used questionnaire-based subjective hearing complaints as an outcome variable, and the actual hearing loss was not evaluated . AnotherYamane H showed that superoxide levels increased along with the luminal membrane of the marginal cells of the stria vascularis after an exposure to high-intensity rock and roll music [The nature of the association between insomnia and hearing impairment is unclear, and the underlying mechanism of insomnia in the pathogenesis of hearing impairment is not elucidated. A plausible mechanism linking insomnia and hearing impairment is oxidative stress. An experimental study by ll music . Furtherll music –29. Morell music . In simill music . TherefoAnother mechanism that might explain the association of insomnia and hearing impairment is the change in the sympathetic tone. Insomnia, shortness of sleep, and sleep deprivation increase the sympathetic activity and can lead to alteration of blood flow , 33. TheIn our study, although pure tone audiometry thresholds at 1–4 kHz were high among workers with insomnia, only thresholds at 1–2 kHz in the right ear and at 1 kHz in the left ear were statistically significant. The arteries, which feed the stria vascularis located in the lateral wall of the cochlea are few in number at the apex than at the base. Thus, the hair cells at the apex, which react to the relatively low frequency sounds, could be more vulnerable to ischemia .Many studies suggest that shift work and sleep deprivation or insomnia are relevant , 37. AllThe strength of our study was the homogeneity of the participants who worked in the same workplace; this allowed comparisons of hearing impairment and insomnia under similar circumstances. Another strength was that all 809 participants were tested by the same method and equipment. Adjustment of noise-exposure level is very important for evaluation of hearing loss since noise is one of the most significant risk factors for the development of hearing loss. In this study, we utilized the objective noise exposure measurement data that were provided by each department; this could possibly be another strength of our study.Our study has several limitations. First, owing to the cross-sectional design, we could not confirm whether insomnia precedes and leads hearing impairment; hence, we could not clarify the exact order of the relationship. Possibly, insomnia is triggered by hearing impairments and tinnitus. Second, we attempted to control several confounding factors, which could affect hearing loss; however, not all possible factors could be controlled, which included the environmental noise near the residence of participants. Third, since all the workers in the tire-manufacturing factory were men, our study included all male participants. Sex is one of the most clearly identified demographic risk factors of insomnia. Moreover, insomnia is more prevalent in women than in men . FurtherThe present study is the first to examine the association between insomnia and hearing impairment in workers exposed to occupational noise. Although there are some limitations as mentioned above, we have attempted to demonstrate the relationship between insomnia and degree of hearing impairment. Further long-term prospective studies are necessary to supplement the limitations of this study.In conclusion, our study showed that insomnia could be associated with hearing impairment and might affect the degree of hearing loss in workers who are exposed to occupational noise. Additionally, it was shown that insomnia may be associated with decreased hearing at lower frequencies. Especially, more efforts are required to improve the quality of sleep for workers who are exposed to loud occupational noise. However, the precise mechanisms of effects of insomnia on hearing impairment have not been established. In the future, additional prospective investigation is required to identify the mechanism of the development of hearing impairment in workers with insomnia.


There is a lack of data on the prevalence of hearing impairment in South Africa. Current data is unreliable as it is based on national census information which tends to underestimate the prevalence of hearing impairment.The aim of this study was to estimate the prevalence of hearing impairment in the Cape Town Metropolitan area and to determine factors associated with hearing impairment.A cross-sectional household survey involving 2494 partcipants from 718 households was conducted between the months of February and October 2013. Random cluster sampling was used to select four health sub-districts from eight health sub-districts in the Cape Town Metropolitan area using a method of probability proportional to size (PPS). The survey was conducted according to the World Health Organization (WHO) Ear and Hearing Disorders Survey Protocol and the classifcation of hearing impairment matched the WHO’s criteria for the grading of hearing impairment.The overall prevalence of hearing impairment in the population of this study was 12.35% (95% CI: 11.06% – 13.64%) and prevalence of disabling hearing impairment was 4.57% (95% CI: 3.75% – 5.39%) amongst individuals ≥ 4 years old. The following factors were found to be associated with hearing impairment; male gender, age, hypertension, a history of head and neck trauma and a family history of hearing impairment.Based on the data from communities surveyed during this study, hearing impairment is more prevalent than previously estimated based on national population census information. Interventions for the prevention of hearing impairment in these communities should focus on individuals with associated risk factors. Hearing impairment at any stage of life can compromise the communication process and influence an individual’s quality of life  sub-districts. The most recent national population census data of 2011 indicated that this metropolitan area has a population of 3 740 025 people evenly spread across these eight health sub-districts  were only included in the study if their parents or legal guardians gave consent. For older children (≥ 12 years old) parental consent and assent from the child were obtained prior to being included in this study. Individuals were excluded from the study if they refused to give consent, were not at home after a second visit, were unable to understand either written or verbal instructions, or had cognitive impairment or communication difficulties.Random cluster sampling was used to select four sub-districts (cluster) from the eight health sub-districts within the Cape Town Metropolitan area through a method of probability proportional to size (PPS). An aerial map of each of the health sub-districts to be surveyed was used to aid in selecting the households to be sampled. The distribution of types of residences for each sub-district was obtained from the national census database to determine the proportion of each residence type within the health sub-district  approached selected households; explained the purpose of the study and procedures to be followed to the members of selected household with an invitation to participate. The research team entered the household and followed the following protocol, in households where the members (i.e. head of household or a guardian over the age of 18 years old) agreed and consented to be part of this study.Obtain consent: The research team requested consent from each member of the household eligible to participate in this study. For young children (< 12 years old), the parent or legal guardian was asked to give consent on behalf of the child to participate in the study. For older children , assent and consent was obtained from the child before being tested. Participants were asked to sign a consent form (or assent form where applicable) to indicate their willingness to participate in the study.Assessment: Audiometric assessments proceeded in the following sequence: measurement of ambient noise levels in the room, obtaining pertinent background history information , whether otoscopy, tympanometry and audiometry were done. The verification process showed good agreement (Kappa = 98%) between data collected by different research teams and therefore the data was considered was reliable. Finally, all decisions regarding the diagnosis of hearing loss were made by a qualified audiologist and all decisions involving a diagnosis of hearing loss were forwarded to the second qualified audiologist for cross-checking. There was also good agreement between the two audiologists (kappa = 0.96). All of the equipment used in this study were calibrated prior to the start of this study and also underwent a daily biological calibration check prior to data collection sessions. Test procedures used in this study were routine audiological tests with established validity.Data was captured on the hard copy version of the WHO/PDH Ear and Hearing Disorders Examination Form (Version 7.1A), then transferred into an excel spread sheet by four research assistants. To ensure consistency when entering the data into an excel spread sheet, at least 10% of the data entered by each one of the research assistants was double checked by a different person to ensure accurate capturing of the data.t-test (p = 0.05) was used to compare hearing thresholds obtained under different ambient noise levels, whilst binomial logistic regression was used to model the relationship between hearing impairment and several explanatory variables; age, gender, level of education, a family history of hearing impairment, a history of stroke, a self-reported history of hypertension, a self-reported history of diabetes, smoking, a history of respiratory difficulties and a history of head and neck trauma. Binomial logistic regression was also done to estimate the probability (odds) of occurrence of hearing as a function of these explanatory variables.Data analysis was performed using the STATA Data Analysis and Statistical Software package  or no one was home on a second visit (52 households). It was not possible to find out the number of household members for 49 of the 73 households that were eligible but did not participate in this study. However, for the remaining 24 households in which household members were not assessed, the number of individuals per household ranged from 3 to 7. The number of non-respondent households was distributed evenly across all the health districts surveyed (i.e. there was no district with a markedly high number of non-respondent households).Ultimately 718 households participated in this study and 2494 individuals  from those households had their hearing screened; women comprised the majority of the participants (60.9%) and individuals in the 10–19 years old age category constituted 22.9% of the sample, whilst individuals 60+ years old constituted 7.6% of the sample (refer to t-test for independent samples (p = 0.05) showed no statistically significant relationship between the level of ambient noise during testing and the different categories of hearing impairment in this study (p = 0.163).The average level of ambient noise during testing was 52.6±3.4 dBA. A Of the total number of participants to this study, 12.35% (95% CI: 11.06% – 13.64%) had some degree of hearing impairment. See The prevalence of disabling hearing impairment amongst individuals who participated in this study was 4.57% (95% CI: 3.75% – 5.39%). As a group, males and participants older than 60 years old had a higher proportion of individuals with disabling hearing impairment than other groups of participants.The prevalence of unilateral hearing impairment in this study was 2.3% (95% CI: 1.71% – 2.89%). Tympanometry assessment also showed that participants in the 0–3 and 4–9 year old age categories had higher rates of abnormal tympanometry findings than other age categories. Refer to p < 0.05) , a self-reported history of hypertension, a self-reported history of diabetes, a prior history of respiratory difficulties, whether participant smokes or not, and a prior history of head and neck trauma. The results of this study showed that increased age, male gender, a family history of hearing impairment, a self-reported history of hypertension, and a prior history of head and neck trauma were associated with hearing impairment  then a hearing assessment was not done at all or was terminated. Furthermore, an analysis of the results also revealed that there was no association between a participant being diagnosed with hearing impairment or having a particular degree of hearing impairment and the level of noise in the room.Another limitation of this study was the small sample size which compromised the representativeness of the study sample. The calculated sample for this study was 5924 participants. However, only 42% (2494 participants) of this sample was achieved during this study. Data collection for this study had to be terminated prematurely before achieving the required sample size due to a flare-up of gang-related violence in the areas selected for this survey. This may have led to the resultant study sample being biased in favour of female participants and participants under the age of 20 years old, and this may have potentially introduced a bias that could have led to an underestimation of the prevalence of hearing impairment in this study. However, despite a possibly biased sample, the trends revealed by the data in this study were consistent with those reported in previous studies, i.e. more hearing impairment in males than females, as well as an association between hearing impairment and advanced age.This study showed that the prevalence of hearing impairment in the communities surveyed is much higher than current estimates obtained through national census. Main factors associated with hearing impairment were also identified. Therefore, in spite of its limitations, this study represents one of the few population-based surveys of hearing impairment done in South Africa. The findings of this study could therefore be useful in planning for prevention and interventions services for hearing impairment, especially in the Cape Town Metropolitan area. It is also hoped that the findings of this study will stimulate interest among the South African research community to conduct similar research studies in other parts of the country  to obtain a more complete picture of the magnitude of hearing impairment on a national scale. This will yield information that could be used to lobby for resources that are required for prevention and intervention services for hearing impairment.


Hearing loss is fairly a common disorder which is usually treated with corticosteroids via systemic administration and/or intra-tympanic injection. This study aimed to compare the effectiveness of intra-tympanic injections of dexamethasone with its combination with hyaluronic acid in patients with sudden sensorineural hearing loss.In this clinical trial, 40 patients were randomly assigned to two groups; in the first group, 20 patients received 2.4 mg intra-tympanic dexamethasone, while in the second group patients received injections of 2.4 mg of dexamethasone plus 2 mg of hyaluronic acid in combination. Patients in both groups were injected every other day to a total of three injections. The hearing status of patients was evaluated by pure tone audiometry (bone conduction threshold) before and 2 weeks after the intervention.Assessment of hearing threshold before and after treatment in the two groups showed a significant difference between hearing thresholds at frequencies of 4,000 to 8,000 Hz (P<0.001). The difference at other frequencies was not meaningful; however, in general, we found a better therapeutic effect in patients who received the combination of dexamethasone and hyaluronic acid.A combination of dexamethasone and hyaluronic acid in patients with sudden sensorineural hearing loss may be more effective than dexamethasone alone. Because hyaluronic acid lacks certain side effects, and also makes it possible to reduce the steroid dose, we recommend the use of this combination in the treatment of patients with sudden sensorineural hearing loss. In sudden sensorineural hearing loss, a person with normal or near-normal hearing loses his or her hearing in a short period of time, and maximally within 3 days. The defect can be partial or total. By definition, the drop in hearing should be at least 30 dB in three consecutive frequencies. The incidence of the disorder is estimated at one in 5,000 population per year -3. If leThe expected time for recovery is usually about 2 weeks to allow response to treatment, while some patients treated with systemic steroids for 2 weeks have shown no improvement in hearing thresholds. The mechanism of action for steroid therapy in this disease is not yet fully known, but previous studies have shown that corticosteroid effects on the cochlea include the reduction of ischemia, increase in blood flow and reduction of inflammation ,24. It iThis double-blind clinical study was conducted at Ayatollah Kashani Hospital in Isfahan, Iran in 2015 in patients with a diagnosis of sudden sensorineural hearing loss. Inclusion criteria consisted of unilateral hearing loss (occurring within 72 hours), a hearing threshold average greater than 50 dB, appearance of symptoms within 7 days from the intervention, age between 18 and 80 years, and provision of consent to participate in the study. Exclusion criteria were history of acoustic tumor, middle ear diseases, autoimmune diseases, vestibular problems (including Menier disease), cardiovascular disorders, diabetes mellitus and previous ear surgery. A patient’s refusal to attend follow-up visits on time as well as any limitation on injecting into the intra-tympanum via the external auditory canal, such as stenosis, anatomical deformities or external and middle ear infections, were considered exclusion criteria. Bone and air conduction pure tone audiometry were performed in all patients before treatment. Taking into account the 95% confidence level, 80% statistical power, improvement in hearing equivalent to 0.5 and a desired 0.5 difference between the two groups, it was calculated that 16 patients were required in each study group. For greater reliability, 20 patients were assigned randomly into each group. All patients initially underwent an ear examination and audiometric assessment. The first group received dexamethasone and the second group was injected with dexamethasone plus hyaluronic acid  in combination. Injectable solutions were previously prepared and coded. For Group 1, 0.6 ml of dexamethasone solution (8 mg in 2 ml), equivalent to 2.4 mg of dexamethasone plus 0.2 ml distilled water, was loaded into an insulin syringe. For Group 2, 0.6 ml of dexamethasone solution (8 mg in 2 ml), equivalent to 2.4 mg of dexamethasone, plus 0.2 ml hyaluronic acid 0/1%, equivalent to 2 mg, were similarly loaded. For local anesthesia, the superior part of the anterior and posterior-external auditory canal walls were injected with xylocaine 2%.Positioning the patient in the supine position with the head rotated upward and at a 45° angle toward the opposite ear allowed the round window niche to be set at the deepest and the Eustachian tube at the highest level of the tympanum cavity. Then, under microscopic vision, the prepared solution in the insulin syringe was injected into the posterior inferior tympanic membrane via a 26-gage needle. This procedure was repeated three times, with injections every other day. After 2 weeks, a second audiogram was obtained and compared with the first. A 30-db improvement in bone conduction threshold in pure tone audiometry was considered a significant improvement, while improvements of 10–30 dB and <10 dB were considered as partial recovery and non-recovery, respectively. Finally, data were entered into SPSS version 23 and analyzed using the Chi-square test, T-test, paired T-test and analysis of variance (ANOVA) with repeated observations.In this study, 40 patients with sudden deafness were divided in two groups of 20 and received dexamethasone alone or dexamethasone plus hyaluronic acid, respectively. A comparison of hearing thresholds before and after treatment between the two groups using the T-test showed that the average hearing thresholds at frequencies of 4,000 and 8,000 Hz was statistically meaningful. Finally, the ANOVA with repeated observations showed that the hearing threshold difference between the two groups was significant and that improvement of hearing was greater in the hyaluronic acid plus dexamethasone group than in the dexamethasone-only treatment group. At the present time, the treatment of sudden hearing loss is considered a major challenge in otolaryngologic practice. Further, because of the relatively high prevalence of the disease and its impact on patient quality of life, there is a need for a therapeutic modality with few complications and a general acceptance by practitioners and researchers. In a 2011 study by Rauch et al, in which 250 subjects were followed for 6 months, both oral and intra-tympanic corticosteroid were shown to have a meaningful therapeutic effect in sudden hearing loss. In another study, conducted in Italy by Dalen et al, use of intra-tympanic corticosteroid as a salvage therapy after failure of oral corticosteroids was shown to be an effective modality in the treatment of sudden hearing loss.We believe that the addition of the highly viscous hyaluronic acid may prolong the time the corticosteroid remains within the middle ear cavity, which, in turn, may lead to a better therapeutic effect. It is noteworthy that there are few studies on the effect of hyaluronic acid in combination with a corticosteroid in this type of treatment for sudden hearing loss. Many studies have shown that treatment with corticosteroids is currently the best supporting treatment for sudden deafness. In addition to the greater effectiveness of the drug when used locally, this method also prevents the systemic side effects of oral or parenteral prescription. Other studies have also shown that hyaluronic acid can be helpful in the treatment of sudden deafness . TherefoIn this study, there were no significant differences between the two groups in terms of demographic and clinical variables at baseline, eliminating any confounding effect of these factors on hearing and recovery of the patients. The results showed that adding hyaluronic acid to dexamethasone in patients had a significant effect on hearing and increased the speed of recovery, especially at high frequencies. Although the process had non-significant changes in hearing threshold at low frequencies, the improvement at these frequencies was numerically better in the group receiving dexamethasone plus hyaluronic acid. In a study conducted in 2011 by Ulfendahl, it was shown that introduction of corticosteroid within the tympanic cavity can significantly improve symptoms in low frequency sounds (500 Hz) . The mixConsidering that hyaluronic acid has no major side effects, is able to reduce essential steroid dosage, and results in better treatment outcomes, we recommend the combination of dexamethasone and hyaluronic acid as an effective therapeutic modality in patients with sudden sensorineural hearing loss.


Mucormycosis is a rare but devastating fungal infection primarily affecting immunocompromised patients such as those with hematological malignancy, bone marrow and solid organ transplantation, and patients with diabetes, and, even more rarely, immunocompetent patients. The objective of this study was to assess the prevalence and burden, both clinical and economic, of mucormycosis among hospitalized patients in the U.S.TM Comparative Database, with more than 560 participating hospitals covering 104 million patients (January 2005-June 2014). All hospitalizations in the database were evaluated for the presence of mucormycosis using either an ICD-9 code of 117.7 or a positive laboratory result for Mucorales. Hospitalizations were further required to have prescriptions of amphotericin B or posaconazole to be considered as mucormycosis-related hospitalizations. The prevalence of mucormycosis-related hospitalizations among all hospital discharges was estimated. Mortality rate at discharge, length of hospital stay, and readmission rates at 1 and 3 months were evaluated among mucormycosis-related hospitalizations. Cost per hospital stay and average per diem cost (inflated to 2014 USD) were reported.This is a retrospective study using the Premier PerspectiveThe prevalence of mucormycosis-related hospitalizations was estimated as 0.12 per 10,000 discharges during January 2005-June 2014. It increased to 0.16 per 10,000 discharges if the definition of mucormycosis was relaxed to not require the use of amphotericin B or posaconazole. The median length of stay was 17 days, with 23% dead at discharge; readmission rates were high, with 30 and 37% of patients readmitted within one and three months of discharge, respectively. The average cost per hospital stay was $112,419, and the average per diem cost was $4,096.The study provides a recent estimate of the prevalence and burden of mucormycosis among hospitalized patients. The high clinical and economic burden associated with mucormycosis highlights the importance of establishing active surveillance and optimizing prophylactic and active treatment in susceptible patients.The online version of this article (doi:10.1186/s12879-016-2023-z) contains supplementary material, which is available to authorized users. Mucormycosis (formerly known as zygomycosis) is an uncommon, opportunistic fungal infection primarily caused by Mucorales, a filamentous fungus of the Mucormycetes class. This particular fungal infection typically shows a rapid progression and primarily affects patients with diabetes mellitus or compromised immune systems, such as those with hematologic malignancies, stem cell and solid organ transplants , 2. InfoAmphotericin B , posaconazole and the recently approved triazole, isavuconazole, in conjunction with surgery, are the only active agents against mucormycosis, and are recommended by treatment guidelines –13. EvenIn addition to the high mortality rate, mucormycosis is also associated with long hospital stays and substantial costs. Based on a study published in 2012, the average direct cost per episode of mucormycosis was estimated to be $113,511 (2004 USD), which was higher than more common invasive infections such as aspergillosis  and candidiasis  .To provide an up-to-date overview on the epidemiology and burden of mucormycosis in the general population of hospitalized patients in U.S., we sought to estimate the prevalence of mucormycosis and to assess the clinical and economic burden associated with mucormycosis-related hospitalizations using data from recent years.The study used the Premier’s Perspective™ Comparative Database (Premier), spanning from January 2005 to June 2014. Premier is a large, U.S. hospital-based database covering more than 560 participating hospitals and 104 million patients. Participating hospitals represent all regions of the U.S., are mainly non-teaching facilities, and mostly serve urban patient population. Information collected includes patient demographics , principal and secondary diagnoses, principal and secondary procedures, length of stay, drug utilization , and cost of care. Laboratory results are available from the SafetySurveillor™ product from 2009 and on for about 37% of the hospitals.Mucormycosis-related hospitalizations were identified as hospitalizations with an International Classification of Diseases 9th Edition (ICD-9) code of 117.7 (either primary or secondary) or a positive laboratory microbiology result for Mucorales, the organisms that cause mucormycosis . To decrPrevalence of mucormycosis was estimated annually by dividing the number of mucormycosis-related hospitalizations by the total number of all hospital discharges observed in the same year. An alternative calculation of the prevalence was conducted by relaxing the definition of mucormycosis-related hospitalizations to require only the ICD-9 code or a positive laboratory microbiology test, without the antifungal drug use restriction.Characteristics of hospitals and patients with mucormycosis-related hospitalizations were summarized. Hospital characteristics included region, bed size, teaching facilities, and urban/rural setting. Patient characteristics included age, gender, race, and underlying conditions, and were summarized based on disease history present in the data within 12 months preceding the admission with mucormycosis.The clinical and economic outcomes assessed included death at discharge, length of stay, and readmission rates at 1 and 3 months. Death at discharge was identified using discharge status ‘expired’. The cost for hospitalization included all supplies, labor, depreciation of equipment, etc. All costs were inflated to 2014 USD using the medical care component of the Consumer Price Index. Continuous variables were summarized by mean, standard deviation, median, and range; proportions were reported for categorical variables. All analyses were conducted using SAS 9.3.A total of 555 mucormycosis-related hospitalizations were identified among 47,131,360 total inpatient encounters in the Premier data during January 2005 to June 2014.  with a bed size > 300, and 42% of the hospitals were affiliated with teaching facilities. Our sample was predominantly from urban hospitals, accounting for more than 90% of the inpatient mucormycosis encounters included in this study , followed by hematological malignancies (40%) (Table N = 775).  patients were admitted to intensive care units (ICUs) during the mucormycosis-related hospitalizations. The death rate at discharge was high, with 23% of the patients dead at discharge. The rate was somewhat higher among patients with hematological malignancies than those with diabetes (23 vs. 19%). Nearly one third of the patients (30%) were readmitted into hospitals within a month after the discharge, and 37% were readmitted within 3 months of the discharge  with a range of $1,912 to $1,395,163. The mean per diem cost during hospitalization was $4,096, with a range of $768 to $19,728  [In our study, the economic burden associated with a mucormycosis-related hospitalization was substantial, with average cost per stay at $112,419, which was comparable to the cost of mucormycosis reported in the literature , and higher than the average cost reported for both aspergillosis-related hospitalizations and candidiasis-related hospitalizations , reflecting the significant morbidity and mortality of mucormycosis . SpecifiAmphotericin B lipid complex (52%) was the most commonly used treatment, followed by liposomal amphotericin B (45%) and posaconazole (45%) among patients with mucormycosis-related hospitalizations observed in the present study. Although Mucorales have been shown to be resistant to drugs such as fluconazole and voriconazole, they were used in 21% and 23% of the mucormycosis-related hospitalizations. Due to lack of time stamps of the drug prescriptions, it was not clear if these fluconazole and voriconazole prescriptions were intended to treat mucormycosis or were intended to serve as prophylaxis treatment for patients with high risk of various invasive fungal infections, such as patients with leukemia and recipients of stem cell transplantation , 23. GivOur study has several limitations that should be taken into consideration when interpreting the results. First, only a subset of hospitals in Premier submitted laboratory microbiology results, and laboratory microbiology results were not available before 2009. In addition, it is possible that some of the hospitalizations without use of amphotericin B or posaconazole were true mucormycosis cases, or that some mucormycosis cases were identified post-mortem, which might not have been completely captured by the data , 25. DueThe low prevalence of mucormycosis, its high clinical and economic burden, and the fact that commonly used antifungal therapies such as fluconazole and voriconazole are not effective against mucormycosis, indicate a need to increase the awareness of mucormycosis among physicians who routinely treat patients at high risk mucormycosis for the infection, and the necessity of active surveillance and optimized prophylactic treatment in susceptible individuals.