Audiovestibular Function Deficits in Vestibular Schwannoma

Introduction. Vestibular schwannomas (VS) are benign tumours of the vestibular nerve and can lead to hearing loss, tinnitus, vertigo, facial palsy, and brainstem compression. Audiovestibular diagnostic tests are essential for detection and treatment planning. Methods. Medline was used to perform a systematic literature review with regard to how audiovestibular test parameters correlate with symptoms, tumour size, and tumour location. Results. The auditory brainstemresponse can be used to diagnose retrocochlear lesions caused by VS. Since hearing loss correlates poorly with tumour size, a retrocochlear lesion is probably not the only cause for hearing loss. Also cochlear mechanisms seem to play a role. This can be revealed by abnormal otoacoustic emissions, despite normal ABR and new MRI techniques which have demonstrated endolymphatic hydrops of the inner ear. Caloric and head impulse tests show frequency specific dynamics and vestibular evoked myogenic potentials may help to identify the location of the tumour regarding the involved nerve parts. Conclusion. In order to preserve audiovestibular function in VS, it is important to stop the growth of the tumour and to avoid degenerative changes in the inner ear. A detailed neurotological workup helps to diagnose VS of all sizes and can also provide useful prognostic information

Analysis of intrathecal antibody production against Chlamydia pneumoniae in multiple sclerosis patients

Multiple Sclerosis (MS) is one of the most frequent organic diseases of the nervous system, with a prevalence of 30-60 per 100,000 inhabitans. It is charcterized by an inflammatory destruction of the myelin sheaths in the white matter of the central nervous system, which may lead to severe disability and death. The underlying mechanism has not been clearly elucidated yet, but involves an attack of the body’s immune system against some of its own neural tissue antigens. One of the immunopathologic hallmarks of MS is the chronic intrathecal production of immunoglobulin (Ig). This contains IgG of very restricted variability, i.e. oligoclonal IgG, and in addition, recognizes a panel of different pathogens such as measles, rubella, and herpes zoster virus. While the antigen-specificity of the largest part of oligoclonal IgG in multiple sclerosis is unknown, the oligoclonal IgG arising during CNS infections are reactive against the specific pathogen. Recently, a link between Chlamydia (C.) pneumoniae and multiple sclerosis has been claimed. To test the possible role of C. pneumoniae in multiple sclerosis, we analyzed a) whether there is intrathecal IgG production against C. pneumoniae in multiple sclerosis and b) whether the oligoclonal IgG in the CSF of multiple sclerosis patients recognize C. pneumoniae. By studying paired serum/CSF samples from 120 subjects (definite multiple sclerosis: 46; probable multiple sclerosis: 12; OIND: 35; OND: 27) by ELISA, we found that 24% of all patients with definite multiple sclerosis, but only 5% of patients with other inflammatory or non-inflammatory diseases produced IgG specific for C. pneumoniae intrathecally (definite multiple sclerosis versus OIND: p = 0.027). The presence of intrathecal IgG to C. pneumoniae was independent of the duration of disease and relatively stable over time. The major CSF oligoclonal IgG bands from multiple sclerosis-patients with an intrathecal Ig-production to C. pneumoniae did not react to C. pneumoniae by IEF-Western as seen by isolectric focusing and subsequent affinity-mediated immunoblot (IEF-Western) towards purified elementary bodies and reticulate bodies of C. pneumoniae. By contrast, the IgG in the CSF of control patients with neuroborreliosis strongly reacted with their specific pathogen, Borrelia burgdorferi by IEF-Western. Concomitant analysis of the CSF of 23 patients with a nested PCR for C. pneumoniae was negative in all cases. Together, these findings strongly suggest that the immune response to C. pneumoniae is part of a polyspecific intrathecal Ig production, as is commonly observed with other pathogens. This argues against a specific role of C. pneumoniae in multiple sclerosis

Relationship Between the Extent of Endolymphatic Hydrops and the Severity and Fluctuation of Audiovestibular Symptoms in Patients With Meniere's Disease and MRI Evidence of Hydrops

Objective:To characterize the short-, middle-, and long-term occurrence of vertigo attacks in a large population of Meniere's disease (MD) and to investigate the relationship between the extent of endolymphatic hydrops (ELH) and the severity of audiovestibular symptoms. Study Design:Prospective observational study. Methods:One hundred ninety-two patients with clinically definite MD participated in this study. The degree of ELH was visualized by locally enhanced inner ear magnetic resonance imaging. The occurrence and intensity of vertigo attacks, hearing loss, tinnitus, and aural fullness were documented in patient diaries. Results:There was no significant correlation between the extent of cochlear or vestibular hydrops and the number of definite vertigo days, neither with regard to a short-term nor with regard to a middle-term time period. There was also no correlation between the extent of ELH and the intensity or activity of the coexisting aural symptoms hearing loss, tinnitus, and aural fullness. The duration of the disease significantly correlated with the extent of both cochlear and vestibular hydrops, but not with the number of definite vertigo days. Conclusion:The ELH was progressive in the long-term course of the disease in this large population of definite MD patients, but short-term and middle-term fluctuations of the symptom severity did not involve measurable variations of the ELH. Furthermore, the symptom severity did not decrease with increasing disease duration

Tinnitus in Normal-Hearing Participants after Exposure to Intense Low-Frequency Sound and in Meniere's Disease Patients

Tinnitus is one of the three classical symptoms of Meniere's disease (MD), an inner ear disease that is often accompanied by endolymphatic hydrops. Previous studies indicate that tinnitus in MD patients is dominated by low frequencies, whereas tinnitus in non-hydropic pathologies is typically higher in frequency. Tinnitus of rather low-frequency (LF) quality was also reported to occur for about 90 s in normal-hearing participants after presentation of intense, LF sound (120 dB SPL, 30 Hz, 90 s). LF sound has been demonstrated to also cause temporary endolymphatic hydrops in animal models. Here, we quantify tinnitus in two study groups with chronic (MD patients) and presumably transient endolymphatic hydrops (normal-hearing participants after LF exposure) with a psychophysical procedure. Participants matched their tinnitus either with a pure tone of adjustable frequency and level or with a noise of adjustable spectral shape and level. Sensation levels of matching stimuli were lower for MD patients (mean: 8 dB SL) than for normal-hearing participants (mean: 15 dB SL). Transient tinnitus after LF-exposure occurred in all normal-hearing participants (N = 28). About half of the normal-hearing participants matched noise to their tinnitus, the other half chose a pure tone with frequencies below 2 kHz. MD patients matched their tinnitus with either high-frequency pure tones, mainly above 3 kHz, or with a noise. Despite a significant proportion of MD patients matching low-pass (roaring) noises to their tinnitus, the range of matched stimuli was more heterogeneous than previous data suggested. We propose that in those participants with noise-like tinnitus, the percept is probably generated by increased spontaneous activity of auditory nerve fibers with a broad range of characteristic frequencies, due to an impaired ion balance in the cochlea. For tonal tinnitus, additional mechanisms are conceivable: focal hair cell loss can result in decreased auditory nerve firing and a central auditory overcompensation. Also, normal-hearing participants after LF-exposure experience alterations in spontaneous otoacoustic emissions, which may contribute to a transient tonal tinnitus

Low-frequency sound affects active micromechanics in the human inner ear

Noise-induced hearing loss is one of the most common auditory pathologies, resulting from overstimulation of the human cochlea, an exquisitely sensitive micromechanical device. At very low frequencies (less than 250 Hz), however, the sensitivity of human hearing, and therefore the perceived loudness is poor. The perceived loudness is mediated by the inner hair cells of the cochlea which are driven very inadequately at low frequencies. To assess the impact of low-frequency (LF) sound, we exploited a by-product of the active amplification of sound outer hair cells (OHCs) perform, so-called spontaneous otoacoustic emissions. These are faint sounds produced by the inner ear that can be used to detect changes of cochlear physiology. We show that a short exposure to perceptually unobtrusive, LF sounds significantly affects OHCs: a 90 s, 80 dB(A) LF sound induced slow, concordant and positively correlated frequency and level oscillations of spontaneous otoacoustic emissions that lasted for about 2 min after LF sound offset. LF sounds, contrary to their unobtrusive perception, strongly stimulate the human cochlea and affect amplification processes in the most sensitive and important frequency range of human hearing

Atmospheric Pressure and Onset of Episodes of Meniere’s Disease - A Repeated Measures Study

External changes of air pressure are transmitted to the middle and inner ear and may be used therapeutically in Menière's disease, one of the most common vertigo disorders. We analyzed the possible relationship of atmospheric pressure and other meteorological parameters with the onset of MD vertigo episodes in order to determine whether atmospheric pressure changes play a role in the occurrence of MD episodes.Patients of a tertiary outpatient dizziness clinic diagnosed with MD were asked to keep a daily vertigo diary to document MD episodes (2004-2009). Local air pressure, absolute temperature and dew point temperature were acquired on an hourly basis. Change in meteorological parameters was conceptualized as the maximum difference in a 24 hour time frame preceding each day. Effects were estimated using additive mixed models with a random participant effect. We included lagged air parameters, age, sex, weekday and season in the model.A total of 56 persons (59% female) with mean age 54 years were included. Mean follow-up time was 267 days. Persons experienced on average 10.3 episodes during the observation period (median 8). Age and change in air pressure were significantly associated with vertigo onset risk (Odds Ratio = 0.979 and 1.010). We could not show an effect of sex, weekday, season, air temperature, and dew point temperature.Change in air pressure was significantly associated with onset of MD episodes, suggesting a potential triggering mechanism in the inner ear. MD patients may possibly use air pressure changes as an early warning system for vertigo attacks in the future

Different mutation patterns of Plasmodium falciparum among patients in Jimma University Hospital, Ethiopia

<p>Abstract</p> <p>Background</p> <p>The emergence of drug resistance is a major problem in malaria control. Combination of molecular genotyping and characterization of mutations or single nucleotide polymorphisms (SNPs) correlated with drug resistance can provide information for subsequent surveillance of existing and developing drug resistance patterns. The introduction of artemether/lumefantrine (AL) as first-line treatment, never used before in Ethiopia, allowed the collection of baseline data of molecular polymorphisms before a selection due to AL could occur.</p> <p>Method</p> <p>97 patients with uncomplicated falciparum malaria were recruited from April to June 2006 and treated with either AL, quinine (Q) or atovaquone/proguanil (AP) in Jimma University Hospital, Ethiopia. Mutations or SNPs associated with resistance to these drugs were analysed by RFLP (<it>pfdhfr</it>, <it>pfmdr1</it>) and sequencing of the target genes (<it>pfcytb</it>, <it>pfserca </it>).</p> <p>Results</p> <p>SNPs previously reported to be associated with resistance to the study drugs were identified in recrudescent and treatment sensitive isolates. A total of seven recrudescences were obtained. The <it>pfmdr1 </it>N86Y mutation was found in 84.5% of isolates. The triple mutation 51I,59R,108N of the <it>pfdhfr </it>gene occured in high frequency (83.3%) but no <it>pfcytb </it>mutation was detected. Sequencing showed a variety of previously described and new mutations in the <it>pfserca </it>gene.</p> <p>Conclusion</p> <p>The prevalence of mutations was in accordance with the expected patterns considering recent drug regimens. The broad introduction of AL and the cessation of former drug regimens might probably change the current distribution of polymorphisms, possibly leading to decreased sensitivity to AL in future. Continuous surveillance of molecular patterns in this region is, therefore, recommended.</p

A Comparison of Distortion Product Otoacoustic Emission Properties in Meniere's Disease Patients and Normal-Hearing Participants

Objectives: Postmortem examination of temporal bones of Meniere's disease patients consistently show dilated endolymphatic spaces of the inner ear, for which the term endolymphatic hydrops has been coined. During the past decade, magnetic resonance imaging techniques for the inner ear appeared, advancing the diagnosis of Meniere's disease. They require, however, a field-strength of at least 3 T, are costly and not universally available. Alternative, noninvasive, cost-effective tests with high sensitivity and specifity for endolymphatic hydrops are desirable. In this study, we test the suitability of distortion product otoacoustic emissions (DPOAEs) for endolymphatic hydrops detection. Previous measurements of the commonly recorded cubic DPOAEs mainly register cochlear hearing loss and are not specific for Meniere's disease. Simultaneous recordings of cubic and quadratic DPOAEs might be more suitable to detect endolymphatic hydrops, because both DPOAE orders react differently to changes of the cochlear operating point as they might occur in Meniere's disease patients. Design: Cubic and quadratic DPOAEs were recorded in normal-hearing participants (N = 45) and in the affected and unaffected ears of patients with a diagnosis of definite Meniere's disease (N = 32). First, to assess the integrity of DPOAE-generating mechanisms, cubic DPOAE-grams were obtained with primary tone frequencies f(2) between 1 and 8 kHz with primary tone levels l(1) = 60 dB SPL and l(2) = 50 dB SPL, and a fixed primary tone frequency ratio of 1.22. Then, cubic and quadratic DPOAEs were simultaneously recorded with primary tone levels l(1) = l(2) = 65 dB SPL and at primary tone frequencies f(2) = 4 and 5 kHz, where f(1) was successively varied such that the ratio f(2)/f(1) ranged between 1.1 and 1.6 in 0.04 steps while quadratic and cubic DPOAE levels were extracted from the same recording. Results: Cubic DPOAEs were significantly reduced in the affected ears of Meniere's disease patients, and slightly reduced in the unaffected ears of Meniere's disease patients, relative to the ears of normal-hearing participants. In contrast, no significant changes could be seen in quadratic DPOAEs across the ears of normal-hearing participants and Meniere's disease patients. Conclusions: We could identify a relatively good preservation of quadratic DPOAE levels in relation to a reduction of cubic DPOAE levels as a potential noninvasive diagnostic approach in the early stage of suspected Meniere's disease. Future studies validating the differential diagnostic power of this parameter in control groups with nonhydropic forms of hearing loss are warranted