Imaging of Temporal Bone.

Multidetector computed tomography has been the benchmark for visualizing bony changes of the ear, but has recently been challenged by cone-beam computed tomography. In both methods, all inner ear bony structures can be visualized satisfactorily with 2D or 3D imaging. Both methods produce ionizing radiation and induce adverse health effects, especially among children. In 3T magnetic resonance imaging, the soft tissue can be imaged accurately. Use of gadolinium chelate (GdC) as a contrast agent allows the partition of fluid spaces to be visualized, such as the bulging of basilar and Reissner's membranes. Both intravenous and intratympanic administration of GdC has been used. The development of positive endolymph imaging method, which visualizes endolymph as a bright signal, and the use of image subtraction seems to allow more easily interpretable images. This long-awaited possibility of diagnosing endolymphatic hydrops in living human subjects has enabled the definition of Hydropic Ear Disease, encompassing typical Meniere's disease as well as its monosymptomatic variants and secondary conditions of endolymphatic hydrops. The next challenge in imaging of the temporal bone is to perform imaging at the cellular and molecular levels. This chapter provides an overview of current temporal bone imaging methods and a review of emerging concepts in temporal bone imaging technology.

Tinnitus complaint behaviour in long-standing Menière's disorder: its association with the other cardinal symptoms.

OBJECTIVE: To explore factors that determines tinnitus complaint behaviour in patients with chronic long-standing Menière's disorder. DESIGN AND SETTING: A questionnaire-based cross-sectional investigation. This included the Oto-neurological questionnaire, the Hearing Disability and Handicap Scale (HDHS), Hearing Measurement Scale (HMS) on sound localisation and the Dizziness Handicap Questionnaire (DHQ). PARTICIPANTS: Randomly selected 183 members of the Finnish Menière's Federation. INTERVENTION: Postal questionnaire. MAIN OUTCOME MEASURE: International Tinnitus Inventory and impact of tinnitus. RESULTS: The 183 patients,[36 men and 147 women; mean age, 63 years] had their Meniere's disorder-like symptoms, with a mean of 18 years [range, 1-43], 19% of patients ranked tinnitus as their most severe symptom, and 10% experienced tinnitus as causing a severe or very severe impact. Regression analysis indicated that 41% of International Tinnitus Inventory variance and 28% of tinnitus impact variance were explained by the cardinal symptoms of Menière's disorder. Furthermore, 40% of International Tinnitus Inventory and 25% of tinnitus impact variance were explained by symptom-related disabilities (HDHS, HMS and DHQ). Aural pressure, hearing loss and gait problems were the most important predictors of tinnitus complaint. Understanding what people say and limitation of activities because of vertigo were the most important related disabilities. CONCLUSION: Tinnitus shares a significant variance with the other cardinal symptoms in patients with long-standing Menière's disorder. As the impact is significantly related to activity limitations based on hearing disability and vertigo, the results suggest that therapeutic efforts to reduce tinnitus in Menière's disorder should include the alleviation of balance and hearing problems.

Modelling stabilograms with hidden Markov models.

Hidden Markov models are an effective computational method for modelling and interpreting digital signals of biological, as well as other, origin. In the current investigation, we explored whether hidden Markov models can be used to control and represent phenomena in human balance signals recorded from subjects standing on a force platform. Additionally, our aim was to classify healthy controls and patients who suffered from Meniere's disease into their own classes. Hidden Markov models were capable of these tasks and of overcoming such disturbances as noise and other unforeseen perturbations in balance signals, which are inherently complex and possibly difficult to visually specify.

Do viruses cause inner ear disturbances?

The association of viral infection to inner ear disease is controversial. Experiments on animals show that several viruses are capable of causing hearing loss, if applied into the perilymph. Some of these have specific affinity to the cellular type of the inner ear, as sensory epithelia and cochlear nerve. Some viruses as adenoviruses and Coxsackie virus B have specific CAR receptors that are identified in different cell types, whereas other act by attaching onto nonspecific cellular surface receptors. Some viruses such as varicella zoster virus (VZV) do not cause disease in rodents. We assessed 273 patients with clinical, serological, neuro-otologic and endoscopic evaluations. Of the 273 patients, 43 served as control subjects. The patients either had Ménière's disease (n = 158), recurrent vertigo of unknown etiology (n = 56), or hearing loss (n = 17). Antibodies against neurotropic and common viruses were evaluated. VZV, influenza B, CBV5 and RSV titers were significantly elevated in patients with inner ear disease when compared with the control group. In analyzing the internal relationship, VZV and influenza B were intercorrelated. We did not find a correlation between hearing loss and viral titers. In conclusion, VZV, Coxsackie virus B5 and influenza B virus may be the main causes of inner ear disorder. The spiral and Scarpa's ganglion are potential sites harboring viral DNA for possible latent infection.

Contribution of the N-acetyltransferase 2 polymorphism NAT2*6A to age-related hearing impairment.

BACKGROUND: Age-related hearing impairment (ARHI) is the most common sensory impairment in older people, affecting 50% of those aged 80 years. The proportion of older people is increasing in the general population, and as a consequence, the number of people affected with ARHI is growing. ARHI is a complex disorder, with both environmental and genetic factors contributing to the disease. The first studies to elucidate these genetic factors were recently performed, resulting in the identification of the first two susceptibility genes for ARHI, NAT2 and KCNQ4. METHODS: In the present study, the association between ARHI and polymorphisms in genes that contribute to the defence against reactive oxygen species, including GSTT1, GSTM1 and NAT2, was tested. Samples originated from seven different countries and were combined into two test population samples, the general European population and the Finnish population. Two distinct phenotypes for ARHI were studied, Z(low) and Z(high), representing hearing in the low and high frequencies, respectively. Statistical analysis was performed for single polymorphisms (GSTM1, GSTT1, NAT2*5A, NAT2*6A, and NAT2*7A), haplotypes, and gene-environment and gene-gene interactions. RESULTS: We found an association between ARHI and GSTT1 and GSTM1 in the Finnish population sample, and with NAT2*6A in the general European population sample. The latter finding replicates previously published data. CONCLUSION: As replication is considered the ultimate proof of true associations in the study of complex disorders, this study provides further support for the involvement of NAT2*6A in ARHI.

Method for detecting small changes in vibrotactile perception threshold related to tactile acuity.

Two metrics, expressing the change in mechanoreceptor-specific vibrotactile thresholds at a fingertip over a time interval of months or years, and the shift in threshold from the mean values recorded from the fingertips of healthy persons, have been constructed for thresholds measured from individual fingers. The metrics assume the applicability of the acute adaptation property of mechanoreceptors, which has been confirmed by thresholds obtained from 18 forest workers on two occasions, separated by 5 years. Hence, when expressed in decibels, both threshold changes and threshold shifts may be averaged at frequencies mediated by the same receptor population to improve precision. Differences between threshold changes at frequencies mediated by the same receptor population may be used to identify inconsistent subject performance, and hence potentially erroneous results. For this group of subjects, the threshold changes and threshold shifts at frequencies believed mediated by the slowly adapting type I (SAI) (4 and 6.3 Hz) and rapidly adapting type I (FAI) (20 and 32 Hz) receptors within each finger were correlated. In these circumstances, which may be expected to occur for some work-induced and systemic peripheral neuropathies, both threshold changes and threshold shifts may be summed over SAI and FAI receptors to improve precision, and hence the potential for interpretation.

Application of metrics constructed from vibrotactile thresholds to the assessment of tactile sensory changes in the hands.

Two tools for assessing tactile sensory disturbances in the hands have been constructed from mechanoreceptor-specific vibrotactile threshold shifts, and thresholds changes with time, and employed in a prospective study of forest workers (N=18). Statistically significant positive threshold shifts (i.e., reductions in sensitivity compared to the hands of healthy persons) were found in five hands at study inception (13.9%), and 15 hands at follow-up (41.7%). Four patterns of threshold shift could be identified, involving selectively the median and/or ulnar nerve pathways and/or end organs. Statistically significant positive threshold changes (i.e., reductions in sensitivity with time) were recorded in 69.4% of the hands over a five-year period, even though a majority of the workers remained symptom free. If the thresholds recorded from subjects not working with power tools are used to control for aging, lifestyle, and environmental factors during the five year period, then 40% of the remaining subjects are found to be experiencing work-related threshold changes in their hands. The ability of the threshold shift metric to predict the numbness reported by these subjects shows that it is closely associated with the tactile sensory changes occurring in their hands.

Familial aggregation of tinnitus: a European multicentre study.

INTRODUCTION AND AIM: Tinnitus is a common condition affecting approximately 20% of the older population. There is increasing evidence that changes in the central auditory system following cochlear malfunctioning are responsible for tinnitus. To date, few investigators have studied the influence of genetic factors on tinnitus. The present report investigates the presence of a familial effect in tinnitus subjects. METHODS: In a European multicentre study, 198 families were recruited in seven European countries. Each family had at least 3 siblings. Subjects were screened for causes of hearing loss other than presbyacusis by clinical examination and a questionnaire. The presence of tinnitus was evaluated with the question "Nowadays, do you ever get noises in your head or ear (tinnitus) which usually last longer than five minutes". Familial aggregation was tested using three methods: a mixed model approach, calculating familial correlations, and estimating the risk of a subject having tinnitus if the disorder is present in another family member. RESULTS: All methods demonstrated a significant familial effect for tinnitus. The effect persisted after correction for the effect of other risk factors such as hearing loss, gender and age. The size of the familial effect is smaller than that for age-related hearing impairment, with a familial correlation of 0.15. CONCLUSION: The presence of a familial effect for tinnitus opens the door to specific studies that can determine whether this effect is due to a shared familial environment or the involvement of genetic factors. Subsequent association studies may result in the identification of the factors responsible. In addition, more emphasis should be placed on the effect of role models in the treatment of tinnitus.

Value of imaging studies in vertiginous children.

OBJECTIVE: Imaging of the head is expensive and can be stressful for children, some of whom need anesthesia for the procedure. The aim of this study was to determine which vertiginous children benefit most from head imaging. METHODS: We conducted a retrospective chart review of all children aged under 18 years who were referred to the Helsinki University Children's Hospital Radiology Department (tertiary referral center) for head computerized tomography (CT) or magnetic resonance imaging (MRI) over a 1-year period. We analyzed and reviewed the medical records of 87 children who had undergone imaging of the head due to vertigo. RESULTS: Altogether 978 children underwent imaging of the head for various indications. Of these, 87 aged 0-16 years (mean age 8 years) were imaged because of vertigo. Abnormalities were seen in the images of 37 children; 23 were new findings and 14 showed no change in comparison to earlier deviant images. The most common abnormalities in head imaging were brain tumors, infections, multiple sclerosis lesions, and other lesions in T2-weighted images. Of the 23 vertiginous children with a new finding, 19 also had neurological deficits. While four children had no neurological symptoms, three had intense headaches. CONCLUSIONS: Head imaging is necessary for vertiginous children with neurological deficits or persistent headaches or who have sustained a head trauma. If vertigo is the only symptom without trauma, imaging studies will not aid diagnostic work-up.

The use of hearing protectors among forest, shipyard and paper mill workers in Finland--a longitudinal study.

From 1953 to 1995 the usage rate of hearing protective devices (HPD) was tracked at a paper mill, a shipyard, and in selected areas of forestry work. For each work period, observations were made of HPD use among workers. In the paper mill, the usage rate increased steadily from 1965. In 1990, 39% of workers used HPDs full-time. At the shipyard, the usage rate remained low up to the mid-1980s, but thereafter the proportion of full-time users rose to 70%. A similar trend was noted in forest workers, with the full-time use at 97% by the 1990s. Due to the increased usage rate in all measured industries, the mean effective noise level at the ear has decreased to below 85 dB.

Postural instability in Meniere's disease.

In order to characterize the postural instability by duration of Meniere's disease (MD) we present the results of 180 MD patients tested on posturography. The duration of the disease varied from 4 weeks to 36 years. The patients were clinically examined and they had filled a questionnaire concerning their symptoms. Postural instability was examined by a force platform posturography and the results are expressed as sway velocities (SV). There was no statistically significant difference in the mean SV between groups of different duration of MD. The number of the patients with normal eyes open SV declined by duration of the illness from 73% to 38% but the decline was not statistically significant. The mean age in the different duration groups of MD varied from 47 to 61 years. In general 58% of the patients had their eyes open SV in normal range and 55% when measured eyes closed. When examining the SV between the 4 different hearing stages of MD we found that those belonging into the group III (pure tone average [PTA] 41-70 dB) had significantly higher eyes open and eyes closed SV's than the patients in the group I (PTA under 25 dB).

Can low frequency sound stimulation during posturography help diagnosing possible perilymphatic fistula in patients with sensorineural hearing loss and/or vertigo?

Perilymphatic fistula (PLF) is often difficult to diagnose because of the similar symptomatology, such as vertigo, tinnitus and hearing loss, which is found in several inner ear diseases. We attempted to correlate a positive result of low frequency sound (LFS) stimulation tests in posturography with the presence or absence of a PLF confirmed by transtympanic endoscopy in 209 patients with various inner ear diseases (Meniere's disease ( n=128), vestibulopathy ( n=41), cochleopathy ( n=28) and sudden deafness ( n=12). LFS provoked unsteadiness in posturography without PLF in 24 patients with Meniere's disease, in 5 patients with vestibulopathy, in 3 patients with cochleopathy and in 2 patients with sudden deafness. In one patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In four cases there was abnormal light reflex in the round window but without PLF. In eight cases, Hennebert's sign was present with nystagmus, without PLF. We conclude that pathological responses to the LFS test in posturography can also be encountered in other inner ear diseases without PLF.

Impulse noise and risk criteria.

Impulse noise causes evidently more severe hearing loss than steady state noise. The additional effect of occupational impulse noise on hearing has been shown to be from 5 to 12 dB at 4 kHz audiometric frequency. Reported cases for compensated for hearing loss are prevalent in occupations where noise is impulsive. For impulse noise two measurement methods have been proposed: the peak level method and energy evaluation method. The applicability of the peak level method is difficult as even the recurrent impulses have different time and frequency characteristics. Various national risk criteria differ from international risk criteria. In France the maximum A-weighted peak level is 135 dB, and in the United Kingdom the C-weighted peak sound pressure is limited to 200 Pa (140 dB). This criterion of unweighted 200 Pa (140 dB) is used in European Union (EU) directive 86/188 and ISO 1999-1990 regardless of the number of impulses. The American Conference of Governmental Industrial Hygienists (ACGIH) has recommended that no exposure in excess of a C-weighted peak sound pressure level of 140 dB should be permitted. At work places these norms do not cause any practical consequences since the impulses seldom exceed 140 dB peak level. In several occupations the impulses are so rapid that they contribute only a minimal amount to the energy content of noise. These impulses can damage the inner ear even though they cause reduced awareness of the hazard of noise. Based to the present knowledge it is evident that there is the inadequacy of the equal energy principle in modelling the risk for hearing loss. The hearing protectors attenuate industrial impulse noise effectively due to the high frequency contents of impulses. Directive regarding the exposure of workers to the risks arising from noise requires that in risk assessment attention should be paid also to impulsive noise. So far there is no valid method to combine steady state and impulse noise. A statistical method for the measurements of industrial impulse noise is needed to get a preferably single number for risk assessment. There is an urgent task to develop risk assessment method and risk criteria for impulsive noise to meet the requirements of the upcoming European Union noise directive.

Role of transtympanic endoscopy of the middle ear in the diagnosis of perilymphatic fistula in patients with sensorineural hearing loss or vertigo.

BACKGROUND: The diagnosis of perilymphatic fistula (PLF) is often difficult, and therefore the condition can be overlooked. Tympanoscopy presents an alternative procedure for visualising the middle ear anatomy, and it may help to diagnose PLF. AIM: The aim of this study was to evaluate the use of middle ear endoscopy in establishing the diagnosis of PLF and in defining its incidence in patients with sensorineural hearing loss and/or vertigo and tinnitus. SUBJECTS AND METHODS: Two hundred and sixty-five patients (22-80 years of age, mean 48 years) were prospectively and consecutively referred for middle ear examination with tympanoscopy. Tympanoscopy was performed using endoscopes with visual angles of 5 and 25 degrees and an outer diameter of 1.7 mm. The round window niche (with its secondary membrane), the oval window with a stapes superstructure, a part of the facial recess and the area in the fissula ante fenestram were examined and video-recorded. RESULTS: For 1 patient, tympanoscopy revealed fistula in the round window membrane that was covered with a fibrinous layer. In 4 cases abnormal mucosal shining appeared in the round window, but no PLF was present. In 7 cases the tympanic cavity could not be visualised because of the adhesive tympanic membrane, abnormal anatomy or the prominent exostoses of the external ear canal. In 6 cases a postendoscopic middle ear infection was found. No permanent tympanic membrane perforation occurred in any of the patients in this study. CONCLUSIONS: Tympanoscopy is a rapid examination tool with which to verify certain areas of the middle ear anatomy, but it is of limited value for ruling out the presence of PLF.

Hearing loss and tinnitus in Meniere's disease.

OBJECTIVES: To characterize hearing loss, tinnitus and associative factors in Meniere's disease. METHODS: From our vertigo database consisting of 1356 patients, we retrieved 243 patients with Meniere's disease (MD). RESULTS: Hearing loss was the initial symptom in 13% of cases. Altogether 64% (n=133) of the patients stated that their hearing was reduced during the vertigo attack. The hearing deteriorated more likely during the vertigo attack if the vertigo attack was very intense [r(206)=0.19]. Tinnitus was the initial symptom in 5% of cases. The tinnitus was mild in 38% (n=90), moderate in 32% (n=76) and severe in 30% (n=72) of patients. The intensity of tinnitus correlated with the occurrence of drop attacks [r(237)=0.29], vertigo provoked by head positioning [r(235)=0.25], by physical activity [r(230)=0.33], or by pressure changes [r(239)=0.27]. CONCLUSION: Prolonged disease causes deterioration of hearing. Intense tinnitus is common in MD and is more often seen in late stage of the disease.

[Effects of peak levels and number of noise impulses on hearing among forge hammering workers]. / Vliianie pikovogo urovnia i chisla impul'sov shuma na slukh kuznetsov goriachei kovki.

The work was aimed (1) to compare actual and expected values of hearing loss in forge hammering workers, using risk evaluation patterns based on impulse noise measurements, and (2) to simulate harmful hearing changes caused by impulse noise. Study of exposure to noise and hearing loss covered forge hammering workers in 2 major blacksmith workshops of automobile enterprise, where equivalent levels of acoustic pressure (104 and 106 dB) were equal, but peak levels and impalse degrees reliably differed. Hearing thresholds for 2 selected groups of workers (97 and 235 subjects) were evaluated. When compared, actual and expected values of hearing loss calculated according to ISO standard appeared different with excess of 1 dB and 3 dB for the workers in shops 1 and 2 respectively. Excessive hearing loss corresponds to noise exposure increased by 3.5 years. Hearing loss in the workers subjected to less impulsive noise were readily forecasted by ISO standard 1999-1990. Hearing loss in the workers subjected to more impulsive noise were in reliable correlation with combination of peak level and impulses number.

On classification capability of neural networks: a case study with otoneurological data.

We investigated the capability of multilayer perceptron neural networks and Kohonen neural networks to recognize difficult otoneurological diseases from each other. We found that they are efficient methods, but the distribution of a learning set should be rather uniform. Also it is important that the number of learning cases is sufficient. If the two mentioned conditions are satisfied, these neural networks are similarly efficient as some other machine learning methods. The conditions are known in the theory of neural networks [1,2], but not often taken seriously in practice. Both networks functioned as well, excluding the case with several input variables, where the Kohonen neural networks surpassed the perceptron.

Towards virtual reality stimulation in force platform posturography.

We developed a stimulation technique on the basis of virtual reality methods for balance investigation performed in balance laboratories of otorhinolaryngological clinics and institutes of occupational health. Such a stimulation technique is greatly progressive in the sense that by creating virtual moving views and "virtual worlds" inside which the subject is located it is possible to make effective stimuli that would be very difficult or even impossible to set in any real environment. We tested our system on healthy subjects and found out that this kind of virtual reality stimulation system is very useful for balance analysis.