Instrumental and Non-Instrumental Measurements in Patients with Peripheral Vestibular Dysfunctions.

Vestibular dysfunction is a disturbance of the body's balance system. The control of balance and gait has a particular influence on the quality of life. Currently, assessing patients with these problems is mainly subjective. New assessment options using wearables may provide complementary and more objective information. Posturography makes it possible to determine the extent and type of posture dysfunction, which makes it possible to plan and monitor the effectiveness of physical rehabilitation therapy. This study evaluates the effectiveness of non-instrumental clinical tests and the instrumental mobile posturography MediPost device for patients with unilateral vestibular disorders. The study group included 40 patients. A subjective description of the symptoms was evaluated using a questionnaire about the intensity of dizziness using the Dizziness Handicap Inventory (DHI) and Vertigo Syndrome Scale-short form (VSS-sf). The clinical protocol contained clinical tests and MediPost measurements using a Modified Clinical Test of Sensory Interaction on Balance. All patients underwent vestibular rehabilitation therapy (VRT) for four weeks. The non-instrumental measurement results were statistically significant, and the best was in the Timed Up and Go test (TUG). In MediPost, condition 4 was the most valuable. This research demonstrated the possibilities of using an instrumental test (MediPost) as an alternative method to assess balance.

Innovative System for Evaluation and Rehabilitation of Human Imbalance.

<b>Introduction:</b> Mobile posturography is based on wearable inertial sensors; it allows to test static stability (static posturography) and gait disturbances. </br> </br> <b>Aim:</b> The aim of this work was to present the results of research on the innovative MEDIPOST system used for diagnosis and rehabilitation of balance disorders. </br> </br> <b>Material and methods:</b> Fourteen articles published in influenced foreign journals were presented and discussed. The deve-lopment and construction of the device was preceded by a literature review and methodological work. The Dizziness Handi-cap Inventory (DHI) questionnaire was translated and validated. The methodology of posturography with head movements with a frequency of 0.3 Hz was also developed in the group with chronic vestibular disorders. Simultaneous measurements were performed (static posturogrphy vs. MEDIPOST) in the CTSIB-M (Modified Clinical Test of Sensory Interaction in Balance) test in healthy subjects and patients with unilateral peripheral dysfunction.</br> </br> <b>Results:</b> In the posturography with head movements the improvement of sensitivity (67 to 74%) and specificity (65 to 71%) was noted. In the CTSIB-M test the intraclass correlation coefficients for both methods were 0.9. The greatest differences between examinations were observed for the mean angular velocity in the tests on the foam (trials no. 3 and 4), in particular on the foam with eyes closed (trial no. 4 - sensitivity 86.4%, specificity 87.7%). Two functional tests were analyzed: the Swap Seats test and the 360 degree turn test. In the former, the results are studied from 6 sensors - 86% of the true positives and 73% of the true negatives for the fall/ no-fall group classification. The second test differentiates people with vestibular impairment and healthy people. It can be analyzed with 1 (sensitivity 80%) and 6 sensors (sensitivity 86%, specificity 84%). Currently, the MEDIPOST device is in the development and certification phase.

Detection of balance disorders using rotations around vertical axis and an artificial neural network.

Vestibular impairments affect patients' movements and can result in difficulties with daily life activities. The main aim of this study is to answer the question whether a simple and short test such as rotation about a vertical axis can be an objective method of assessing balance dysfunction in patients with unilateral vestibular impairments. A 360˚ rotation test was performed using six MediPost devices. The analysis was performed in three ways: (1) the analytical approach based only on data from one sensor; (2) the analytical approach based on data from six sensors; (3) the artificial neural network (ANN) approach based on data from six sensors. For approaches 1 and 2 best results were obtained using maximum angular velocities (MAV) of rotation and rotation duration (RD), while approach 3 used 11 different features. The following sensitivities and specificities were achieved: for approach 1: MAV-80% and 60%, RD-69% and 74%; for approach 2: 61% and 85% and RD-74% and 56%; for approach 3: 88% and 84%. The ANN-based six-sensor approach revealed the best sensitivity and specificity among parameters studied, however one-sensor approach might be a simple screening test used e.g. for rehabilitation purposes.

[Use of the posturography in balance system evaluation in occupational medicine]. / Zastosowanie posturografii dla oceny ukladu równowagi dla potrzeb medycyny pracy.

BACKGROUND: The posturography test allows assessment of the entire function of balance system and quantitative, device-based verification of the clinical Romberg test. Therefore, the aim of this study is assessment of usefulness of posturography as primary test for balance disorders in occupational medicine. MATERIAL AND METHODS: The study is cross-sectional, analyzing anonymous results of 1030 patients reporting dizziness and balance disorders. Based on symptoms, clinical examination and videonystagmography patients were classified into subgroups: benign paroxysmal positional vertigo (BPPV [N = 130]), non compensated (NS [N = 82]) and compensated (S [N = 174]) peripheral vestibular, bilateral vestibular (BV [N = 63]), Ménière's disease (MD [N = 53]), central dizziness (central [N = 293]), migraine (migr. [N = 132]), psychogenic dizziness (psychog. [N = 232]), Persistent postural-perceptual dizziness (PPPD [N = 150]). Besides, 129 healthy people were included in the study. RESULTS: Ninety nine percent of abnormal static posturography (SP) and 94% of abnormal dynamic posturography (PD) results were found in diseased patients. Normal results were found both in healthy group (59% PS, 67% PD) and in diseased group (24% PS, 31% PD). Static posturography's abnormal results were more frequent in NS, BV and PPPD patients. In PD the differences were visible in the central, psychog. and PPPD subgroups. In NS subgroup the high negative predictive values of static and dynamic tests (82-87%) were calculated in relation to caloric test. CONCLUSIONS: Static tests are the basic test used in examinations of employees for occupational medicine purposes. Posturography is a quantitative record of sways in relation to normative values. Abnormal posturography results most likely indicate the presence of pathologies of the balance system, including psychofunctional disorders. Normal posturography results do not indicate the lack of pathology of balance system what should be included in the work ability assessment. Med Pr. 2022;73(2):143-50.

Utility of the Novel MediPost Mobile Posturography Device in the Assessment of Patients with a Unilateral Vestibular Disorder.

Balance disorders are a growing problem worldwide. Thus, there is an increasing need to provide an inexpensive and feasible alternative to standard posturographic platforms (SP) used for the assessment of balance and to provide a possible solution for telemonitoring of patients. A novel mobile posturography (MP) MediPost device was developed to address these issues. This prospective study used a Modified Clinical Test of Sensory Interaction on Balance to evaluate healthy individuals and patients with a unilateral vestibular disorder through SP and MP simultaneously. The control group included 65 healthy volunteers, while the study group included 38 patients diagnosed with a unilateral vestibular deficit. The angular velocity values obtained from both methods were compared by intraclass correlation coefficients (ICC) and Bland−Altman plot analysis. Diagnostic capabilities were measured in terms of sensitivity and specificity. The ICC between the two methods for conditions 2−4 was indicative of excellent reliability, with the ICC > 0.9 (p < 0.001), except for Condition 1 (standing stance, eyes open) ICC = 0.685, p < 0.001, which is indicative of moderate reliability. ROC curve analysis of angular velocity for condition 4 represents the most accurate differentiating factor with AUC values of 0.939 for SP and 0.953 for MP. This condition also reported the highest sensitivity, specificity, PPV, and NPV values with 86.4%, 87.7%, 80%, and 90.5% for SP, and 92.1%, 84.6%, 77.8%, and 94.8% for MP, respectively. The newly developed MediPost device has high sensitivity and specificity in distinguishing between healthy individuals and patients with a unilateral vestibular deficit.

A comparison of head movements tests in force plate and accelerometer based posturography in patients with balance problems due to vestibular dysfunction.

This study compares HS posturography on inertial sensors (MediPost) with force platform posturography in patients with unilateral vestibular dysfunction. The study group included 38 patients (age 50.6; SD 11.6) with unilateral vestibular weakness (UV) and 65 healthy volunteers (48.7; SD 11.5). HS tests were performed simultaneously on the force plate and with MediPost sensor attached at L4. Four conditions applied: eyes open/closed, firm/foam. The tests were performed twice, with the head moving at the frequency of 0.3 Hz (HS 0.3) and 0.6 Hz (HS 0.6). Mean sway velocity was significantly lower for MediPost than force plate in 4th condition both in UV and healthy group. For HS 0.3 the differences between devices were marginal; the highest sensitivity (87%) and specificity (95%) were in 4th condition. For HS 0.6 MediPost revealed lower sensitivity than force plate although the surface parameter improved results. MediPost IMU device and force platform posturography revealed a similar ability to differentiate between patients with balance problems in course of vestibular pathology and healthy participants, despite the differences observed between measuring methods. In some tests surface parameter may be more appropriate than sway velocity in improving MediPost sensitivity.

Dizziness Handicap Inventory in Clinical Evaluation of Dizzy Patients.

(1) Objectives: The evaluation of dizzy patients is difficult due to nonspecific symptoms that require a multi-specialist approach. The Dizziness Handicap Inventory (DHI) is widely used in the assessment of dizziness-related disability, but its clinical efficacy needs further expansion. The aim of this study was to identify the subscales of DHI that may correlate with some vestibular or nonvestibular dysfunctions. (2) Material and methods: This observational study included 343 dizzy patients with one of the following clinical conditions: Vestibular impairment noncompensated or compensated, central or bilateral, benign paroxysmal positional vertigo (BPPV), migraine and psychogenic dizziness. Principal component analysis was used to examine the factorial structure of the questionnaire. (3) Results: The DHI questionnaire total scoring and its vestibular subscale distinguished between patients with compensated and uncompensated vestibular dysfunction with positive predictive values of 76% and 79%, respectively. The DHI items composing the F3 (positional) subscale revealed the highest scoring in the BPPV group with 75% sensitivity and 92% negative predictive value (NPV) in reference to Dix-Hallpike tests. The DHI total score and the subscales scores correlated with anxiety-depression, and the highest correlation coefficients were calculated for vestibular (F2 0.56) and anxiety (F5 0.51) subscales. (4) Conclusions: Our analysis revealed that the DHI vestibular subscale distinguishes between patients with compensated and uncompensated vestibular dysfunction. The positional subscale showed the highest scoring in the BPPV group with high sensitivity and low specificity of the test. The DHI is highly correlated with patients' psychological status.

Fully Automatic Fall Risk Assessment Based on a Fast Mobility Test.

This paper presents a fall risk assessment approach based on a fast mobility test, automatically evaluated using a low-cost, scalable system for the recording and analysis of body movement. This mobility test has never before been investigated as a sole source of data for fall risk assessment. It can be performed in a very limited space and needs only minimal additional equipment, yet provides large amounts of information, as the presented system can obtain much more data than traditional observation by capturing minute details regarding body movement. The readings are provided wirelessly by one to seven low-cost micro-electro-mechanical inertial measurement units attached to the subject's body segments. Combined with a body model, these allow segment rotations and translations to be computed and for body movements to be recreated in software. The subject can then be automatically classified by an artificial neural network based on selected values in the test, and those with an elevated risk of falls can be identified. Results obtained from a group of 40 subjects of various ages, both healthy volunteers and patients with vestibular system impairment, are presented to demonstrate the combined capabilities of the test and system. Labelling of subjects as fallers and non-fallers was performed using an objective and precise sensory organization test; it is an important novelty as this approach to subject labelling has never before been used in the design and evaluation of fall risk assessment systems. The findings show a true-positive ratio of 85% and true-negative ratio of 63% for classifying subjects as fallers or non-fallers using the introduced fast mobility test, which are noticeably better than those obtained for the long-established Timed Up and Go test.

Posturography with head movements in the assessment of balance in chronic unilateral vestibular lesions.

The aim of our study was to validate the method of head-shake static posturography (HS-posturography) in healthy individuals and to establish the value of this novel method in the diagnostics of patients with unilateral vestibular lesion (UV). The study included 202 participants divided into two groups, one consisting of 133 patients with canal paresis CP > 19% and one of 69 healthy subjects. Participant was tested according to the standard protocol of static posturography (SP), and with head movements of 0.3 Hz (HS 40), 0.6 Hz (HS 70) in random order controlled by a metronome. HS-posturography revealed a similar repeatability and internal consistency as the standard posturography. In patients with UV, 4th condition revealed higher sensitivity (74%) and specificity (71%) in HS 40 than in the standard posturography (67%, 65% respectively) and HS 70 (54%, 70% respectively). Static posturography and HS- posturography revealed a high reliability of the testing method. The head movements added to static posturography improve the sensitivity and specificity of the method in group with vestibular impairment. The most important test for that purpose seems to be the one on unstable surface with the eyes closed, with low frequency of head movements.

Usefulness of Mobile Devices in the Diagnosis and Rehabilitation of Patients with Dizziness and Balance Disorders: A State of the Art Review.

OBJECTIVE: The gold standard for objective body posture examination is posturography. Body movements are detected through the use of force platforms that assess static and dynamic balance (conventional posturography). In recent years, new technologies like wearable sensors (mobile posturography) have been applied during complex dynamic activities to diagnose and rehabilitate balance disorders. They are used in healthy people, especially in the aging population, for detecting falls in the older adults, in the rehabilitation of different neurological, osteoarticular, and muscular system diseases, and in vestibular disorders. Mobile devices are portable, lightweight, and less expensive than conventional posturography. The vibrotactile system can consist of an accelerometer (linear acceleration measurement), gyroscopes (angular acceleration measurement), and magnetometers (heading measurement, relative to the Earth's magnetic field). The sensors may be mounted to the trunk (most often in the lumbar region of the spine, and the pelvis), wrists, arms, sternum, feet, or shins. Some static and dynamic clinical tests have been performed with the use of wearable sensors. Smartphones are widely used as a mobile computing platform and to evaluate the results or monitor the patient during the movement and rehabilitation. There are various mobile applications for smartphone-based balance systems. Future research should focus on validating the sensitivity and reliability of mobile device measurements compared to conventional posturography. CONCLUSION: Smartphone based mobile devices are limited to one sensor lumbar level posturography and offer basic clinical evaluation. Single or multi sensor mobile posturography is available from different manufacturers and offers single to multi-level measurements, providing more data and in some instances even performing sophisticated clinical balance tests.

Cochlear dysfunction is associated with styrene exposure in humans.

AIM: Occupational exposure to styrene has been shown to be associated with an increased probability of developing hearing loss. However, the sites of lesions in the auditory system in humans remain unknown. The aim of this study was to investigate the possible adverse effects of styrene exposure on the cochlea of human subjects. DESIGN: The hearing function of 98 styrene-exposed male workers from the glass fibre-reinforced plastics industry (mean concentration of 55 mg/m3) was evaluated bilaterally using pure-tone audiometry (1000-16000 Hz), distortion product otoacoustic emissions (DPOAEs), and auditory brainstem response (ABR). The results were compared to a group of 111 male workers exposed to noise (above 85 dBA) and 70 male white-collar workers exposed to neither noise nor solvents. Age and noise exposure levels were accounted for as confounding variables in all statistical models. RESULTS: Styrene exposure was significantly associated with poorer pure-tone thresholds (1-8 kHz), lower DPOAE amplitudes (5-6 kHz), and shorter wave V latencies in both ears compared to control-group subjects. Similar results were found among noise-exposed subjects. A further analysis with wave V latency showed that styrene-exposed subjects showed significantly shorter latencies than expected according to normative data. These results suggest that occupational exposure to styrene at moderate concentrations is associated with cochlear dysfunction, at least at high frequencies. DPOAEs may be considered a valuable diagnostic tool in hearing conservation programs in workers exposed to styrene.

Vertigo and Severe Balance Instability as Symptoms of Lyme Disease-Literature Review and Case Report.

Lyme disease is caused by a tick-borne bacterium Borrelia sp. This zoonotic infection is common in the Northern Hemisphere, e.g., Europe. Clinical presentation may involve multisystem symptoms and depends on the stage of the disease. The involvement of nervous system in Lyme disease is commonly referred to as neuroborreliosis. Neuroborreliosis may involve meningitis, mononeuritis multiplex, or cranial neuritis including the inflammation of vestibulocochlear nerve. In the late or chronic stage of Lyme disease, vestibular involvement may be the sole presentation, although such cases are rare. Our study was designed to present our own case and review the available literature reporting cases of neuroborreliosis with vertigo/dizziness and severe balance instability as a main disease symptom. The studies were obtained by searching the following databases: PubMed, Medline, and Embase. We included case reports of Lyme disease presenting with vertigo or gait disorders as the main symptom, written in the English language. Initially, 60 papers were identified. After analyzing the abstracts, seven manuscripts focusing on 13 clinical cases were included in this review. We conclude that the patients with neuroborreliosis sometimes present vertigo/dizziness, but rarely gait ataxia as a sole symptom. These complaints are usually accompanied by a hearing loss. Antibiotic treatment is usually effective. Balance instability in the patients with neuroborreliosis may persist but it responds well to vestibular rehabilitation.

Cervico-ocular reflex upregulation in dizzy patients with asymmetric neck pathology.

OBJECTIVES: The aim of this study was to investigate whether the restriction in neck rotation and increased neck muscle tension could be causally related to vertigo and dizziness. MATERIAL AND METHODS: Seventy-one patients reporting vertigo and/or imbalance were divided into 2 groups: 45 subjects with unilateral restriction (R+) and 26 without restriction (R-) of cervical rotation and muscle tension in the clinical flexion-rotation test. The normal caloric test was the inclusion criterion. The control group comprised 36 healthy volunteers with no history of vertigo. The vestibulo-ocular reflex (VOR) and the cervico-occular reflex (COR) were measured through the videonystagmography (VNG) sinusoidal pendular kinetic test in the conditions of not inactivated head and immobilized head, respectively. The VNG-head torsion test (VNG-HTT) nystagmus was recorded. RESULTS: Among the reported complaints, neck stiffness, headaches and blurred vision were more frequent in the R+ group than in both the R- group and the control group. VNG revealed an increased COR gain and the presence of VNG-HTT nystagmus in the R+ group only. Similarly, only in the R+ group a positive relationship between COR and VOR was observed. CONCLUSIONS: Patients with asymmetric restriction in neck rotation and increased neck muscle tension reveal the tendency to have an increased response of the vestibular system, along with co-existing COR upregulation. Further research is needed to investigate the relationships between the activation of cervical mechanoreceptors and dizziness pathomechanisms. Int J Occup Med Environ Health. 2019;32(5):723-33.

Validation of the Polish version of the Dizziness Handicap Inventory.

BACKGROUND: The Dizziness Handicap Inventory (DHI) was established to assess the impact of dizziness and balance problems on the quality of life. The aim of the study was to validate the Polish version of DHI for patients with vestibular disorders. MATERIAL AND METHODS: Two hundred and thirty patients diagnosed with vestibular impairment and/or positional vertigo were included in the study. The mean age of the study group was 56.2 years (SD = 13.6). The factor structure (the principal component analysis - PCA), internal consistency (Cronbach's α), and discrimination ability (the receiver operating characteristic [ROC] curve) were examined. RESULTS: satisfactory internal consistency was found (Cronbach's α coefficient = 0.92), while no floor or ceiling effect was revealed. The Dizziness Handicap Inventory demonstrated a good ability to discriminate between patients with and without the handicap (sensitivity and specificity about 80%, the cutoff point = 56). In PCA a 3-factor solution was obtained, with the factors related to restrictions in daily life, positional symptoms and visual-vestibular symptoms, which was not in agreement with the subscales provided in the original version. CONCLUSIONS: The Polish version of DHI demonstrates satisfactory measurement properties and can be used to assess the impact of dizziness on handicap and the quality of life. The functional, emotional, and physical subscales were not confirmed. In particular, the functional subscale revealed no satisfactory internal consistency which provides an indication for further studies. Med Pr. 2019;70(5):529-34.

[Functional assessment of patients with vertigo and dizziness in occupational medicine]. / Badanie czynnosciowe osób z zawrotami glowy i zaburzeniami równowagi dla potrzeb medycyny pracy.

BACKGROUND: Balance assessment relies on symptoms, clinical examination and functional assessment and their verification in objective tests. Our study was aimed at calculating the assessment compatibility between questionnaires, functional scales and objective vestibular and balance examinations. MATERIAL AND METHODS: A group of 131 patients (including 101 women; mean age: 59±14 years) of the audiology outpatient clinic was examined. Benign paroxysmal positional vertigo, phobic vertigo and central dizziness were the most common diseases observed in the study group. Patients' symptoms were tested using the questionnaire on Cawthworne-Cooksey exercises (CC), Dizziness Handicap Inventory (DHI) and Duke Anxiety-Depression Scale. Berg Balance Scale (BBS), Dynamic Gait Index (DGI), the Tinetti test, Timed Up and Go test (TUG), and Dynamic Visual Acuity (DVA) were used for the functional balance assessment. Objective evaluation included: videonystagmography caloric test and static posturography. RESULTS: The study results revealed statistically significant but moderate compatibility between functional tests BBS, DGI, TUG, DVA and caloric results (Kendall's W = 0.29) and higher for posturography (W = 0.33). The agreement between questionnaires and objective tests were very low (W = 0.08-0.11).The positive predictive values of BBS were 42% for caloric and 62% for posturography tests, of DGI - 46% and 57%, respectively. CONCLUSIONS: The results of functional tests (BBS, DGI, TUG, DVA) revealed statistically significant correlations with objective balance tests but low predictive values did not allow to use these tests in vestibular damage screening. Only half of the patients with functional disturbances revealed abnormal caloric or posturography tests. The qualification to work based on objective tests ignore functional state of the worker, which may influence the ability to work. Med Pr 2018;69(2):179-189.

AUDITORY TEMPORAL PROCESSING TESTS - NORMATIVE DATA FOR POLISH-SPEAKING ADULTS.

BACKGROUND: Several subjects exposed to neurotoxins in the workplace need to be assessed for central auditory deficit. Although central auditory processing tests are widely used in other countries, they have not been standardized for the Polish population. The aim of the study has been to evaluate the range of reference values for 3 temporal processing tests: the duration pattern test (DPT), the frequency pattern test (FPT) and the gaps in noise test (GIN). MATERIAL AND METHODS: The study included 76 normal hearing individuals (38 women, 38 men) at the age of 18 to 54 years old (mean ± standard deviation: 39.4±9.1). All study participants had no history of any chronic disease and underwent a standard ENT examination. RESULTS: The reference range for the DPT was established at 55.3% or more of correct answers, while for the FPT it stood at 56.7% or more of correct answers. The mean threshold for both cars in the GIN test was defined as 6 ms. In this study there were no significant associations between the DPT, FPT and GIN results and age or gender. Symmetry between the ears in the case of the DPT, FPT and GIN was found. CONCLUSIONS: Reference ranges obtained in this study for the DPT and FPT in the Polish population are lower than reference ranges previously published for other nations while the GIN test results correspond to those published in the related literature. Further investigations are needed to explain the discrepancies between normative values in Poland and other countries and adapt tests for occupational medicine purposes.

Bedside examination for vestibular screening in occupational medicine.

OBJECTIVES: The aim of the study was to assess the usefulness of bedside examination for screening of vestibular and balance system for occupational medicine purposes. Study group comprised 165 patients referred to Audiology and Phoniatric Clinic due to vestibular and/or balance problems. Caloric canal paresis of 19% was the cut off value to divide patients into 43 caloric-positive vestibular subjects and 122 caloric-negative patients. The latter group comprised 79 subjects revealing abnormalities of videonystagmographic (VNG) oculomotor tests (central group) and 43 subjects with normal VNG. MATERIAL AND METHODS: Vestibular and balance symptoms were collected. Five tests were included to bedside examination: Romberg and Unterberger tests, Head Impulse Test (HIT), Dynamic Visual Acuity (DVA) and gaze nystagmus assessment. RESULTS: Vestibular and balance symptoms were reported by 82% of vestibular, 73% of central and 40% of VNG-normal patients. Thirteen out of 18 VNG-normal but symptomatic subjects (73%) had abnormal tests in clinical assessment. The sensitivity of bedside test set for vestibular pathology was 88% as compared to caloric test and 68% for central pathology as compared to VNG oculomotor tests. CONCLUSIONS: The combination of 5 bedside tests reveal satisfactory sensitivity to detect vestibular abnormalities. Bedside examination abnormalities are highly correlated with vestibular/balance symptoms, regardless the normal results of VNG. Thus, this method should be recommended for occupational medicine purposes.

Mobile telephone use effects on perception of verticality.

Low-level radiofrequency (RF) signals may produce disorientation and nausea. In experiment I, we assessed mobile phone effects on graviception in nine symptomatic subjects after mobile telephone use and 21 controls. The mobile handset was strapped to each ear for 30 min in pulsed emission, continuous RF emission, or no emission test mode, respectively. The subjective visual vertical and horizontal (SVV/SVH) were tested from min 25 of exposure. There was no exposure effect; however, there was an ear effect, with the SVV/SVH being shifted to the opposite direction of the ear exposed. This could be due to thermal or RF effects or handset weight. In experiment II, we assessed the handset weight effect on 18 normal controls. After baseline SVV/SVH, the switched off handset was strapped to either ear; the SVV/SVH was repeated 25 min later. A significant ear effect was found. We compared the observed ear effect SVV/SVH change in the experiment II group to the continuous exposure ear effect change in the experiment I group, and the difference was not significant. The ear effect was attributed to a minor head tilt due to the handset weight, or proprioceptive stimulation of neck muscle affecting the perception of verticality.

[The influence of organic solvents on hearing and balance: a literature review]. / Dzialanie wybranych rozpuszczalników organicznych na narzad sluchu i uklad równowagi.

This manuscript presents an overview of current knowledge on the influence of organic solvents on the hearing and balance systems. The authors analyzed--the literature data concerning the results of all human and the most relevant animal studies, published untill 2012. Moreover, the guidelines for occupational medicine specialists were proposed on the basis of literature review and the authors' own scientific experience. The literature data and our studies revealed the increased risk of hearing loss in workers exposed to organic solvents only, and well documented potentiation of harmful effects of combinedexposure to organic solvents and noise. Hearing impairment is mainly observed in high frequencies, but lower frequencies can also be involved (0.5-4 kHz). The impairment induced by exposure to organic solvents is mild, up to several dBs. In the combined exposure to noise and solvents, the noise effect predominates. Organic solvents affect the central pathways of vestibular system although unilateral or bilateral vestibular hypofunction might also be a possible consequence of solvent exposure. Occupational exposure to organic solvents is a risk factor for hearing and balance impairments. Therefore, workers exposed to solvents should be covered by hearing loss prevention programs. Speech in noise test (HINT) and posturography seem to be the most suitable tests for hearing and balance prevention programme for organic solvent exposed workers.

Vestibular and balance findings in nonsymptomatic workers exposed to styrene and dichloromethane.

OBJECTIVE: The aim of our study was to assess the vestibular and balance system in non-symptomatic workers exposed to styrene and dichloromethane at the workplace. DESIGN: Subjects underwent videonystagmography including saccades, smooth pursuit (SP), optokinetic test (OKN), gaze nystagmus assessment, bithermal caloric test, and static posturography. STUDY SAMPLE: Study groups included 74 workers in plastics manufacturing, aged 40 (SD 8) years, exposed to styrene and dichloromethane, and the reference group of 49 non-exposed subjects, aged 36 (SD 10) years. RESULTS: More than 60% of exposed and non-symptomatic workers revealed abnormal results of vestibular tests. Saccadic latency elongation (p = 0.0098), lower gain in SP (p = 0.0037) and OKN (p = 0.0000) were more common in the exposed group, as well as lower reactivity (p = 0.0337) and mean slow phase velocity of caloric nystagmus. Static posturography revealed higher sway velocities in the test with eyes closed, on foam and worse results of three from five limit of stability tests. No relationship between chemicals exposure and vestibular and balance test results was found. CONCLUSIONS: In principle, our findings indicate the possibility of high-level deficits in the central part of vestibular system. Lower vestibular reactivity may suggest that bilateral vestibular hypofunction might also be the possible consequence of solvent exposure.