Forms Of Sensorineural Hearing Loss Research Articles

Otosyphilis mimics immune disorders of the inner ear

Syphilis is a well established cause of hearing loss. Sensorineural hearing loss may develop in the congenital or acquired form. The clinical course of the early acquired and late congenital forms are similar: sudden or rapidly progressive bilateral sensorineural hearing loss with mild vestibular symptoms. Cochleovestibular involvement in early acquired syphilis has been related to a basilar meningitis with lymphocytic infiltration of the labyrinth and VIIIth nerve. However, neurosyphilis and inner ear syphilis are not the same disease. Prompt diagnosis and treatment with corticosteroids and penicillin are mandatory to reduce the immune response and fibrosis of the labyrinth and the endolymphatic sac. Unfortunately, early acquired syphilis is frequently overlooked in the differential diagnosis of other forms of sensorineural hearing loss, particularly autoimmune inner ear disease. Given the increasing number of luetic infection cases, especially in immunocompromised patients, this condition should be considered in any sexually active patients affected by sudden hearing loss. Cases of inner ear syphilis are presented. Immunopathology of luetic inner ear infection is discussed and compared with immune disorders of the inner ear.

TNFα blockers do not improve the hearing recovery obtained with glucocorticoid therapy in an autoimmune experimental labyrinthitis

The effectiveness of etanercept [tumour necrosis factor-alpha (TNFalpha) blocker] and corticoids in treating immuno-mediated inner ear disease (IMIED) was compared in an animal model of autoimmune labyrinthitis. IMIED is one of the few forms of sensorineural hearing loss that is reversible with proper medical treatment. While the effectiveness and usefulness of immunomodulating agents (corticosteroids) in treating IMIED have been demonstrated, TNFalpha antagonists, which inhibit granuloma formation in rheumatoid arthritis and other autoimmune diseases, have been considered as an alternative therapy. The efficacy of etanercept (anti-TNFalpha) was evaluated in a guinea pig model of experimental autoimmune labyrinthitis in which 25 guinea pigs were divided in a control group, which was used to document the rise in hearing thresholds following immunisation, and two experimental groups, which were treated with steroids (6-methylprednisolone) and anti-TNFalpha (etanercept), respectively, after the immunisation. Comparison of the auditory thresholds obtained by means of auditory brainstem response (ABR) revealed that the auditory thresholds of the two experimental groups were not statistically different (6-methylprednisolone: 41.5 dB, SD: 8.51; etanercept: 37.5 dB, SD: 7.91) and that both compared favourably with that of the control group (60 dB, SD: 7.91) at p=0.001. We therefore conclude that etanercept is as effective as glucocorticoids in an animal model of autoimmune labyrinthitis; however, the potential adverse effects and high price of the former advise against its use as an initial therapy for IMIED.

Functional analysis of R75Q mutation in the gene coding for Connexin 26 identified in a family with nonsyndromic hearing loss

Mutations in the gene (GJB2) coding for Connexin 26 (Cx26) are responsible for genetic forms of sensorineural hearing loss. This article describes a family characterized by congenital profound hearing loss, inherited in an autosomal dominant fashion and associated to a R75Q substitution in Cx26. Cell transfection and fluorescence imaging, dye transfer experiments and dual patch clamp recording showed that the mutant completely prevents the formation of functional channels despite assembling into junctional plaques, in communication incompetent HeLa cells. The disease is not associated with palmar and plantar keratosis in any of the family members, suggesting that R75Q substitution is not sufficient for the development of the complete syndromic phenotype. The association of palmar and plantar keratosis with profound hearing loss may be dependent on genetic background, requiring a functional interaction between the mutated Cx26 and other epidermally expressed connexins.

Molecular pathogenetic mechanism of maternally inherited deafness.

Mutations in the mitochondrial DNA (mtDNA) have been shown to be one important cause of deafness. In particular, mutations in the mtDNA have been associated with both syndromic and nonsyndromic forms of sensori-neural hearing loss. The deafness-linked mutations often occur in the mitochondrial 12S rRNA gene and in tRNA genes. Mutations in the 12S rRNA gene account for most of the cases of aminoglycoside ototoxicity. The other hot spot for mutations associated with hearing impairment is the tRNA(Ser(UCN)) gene, as five deafness-linked mutations have been identified in this gene. Nonsyndromic deafness-linked mtDNA mutations are often homoplasmic or at high levels of heteroplasmy, indicating a high threshold for pathogenicity. Phenotypic expression of these mtDNA mutations requires the contribution of other factors such as nuclear modifier gene(s), environmental factor(s), or mitochondrial haplotype(s).

Autoimmune sensorineural hearing loss.

Autoimmune sensorineural hearing loss has been increasingly recognized as a clinical entity since its description by McCabe in 1979. Recognition and proper management of this condition is important, as it is one of the very few forms of sensorineural hearing loss that can be successfully treated by medical therapy. Recent studies have provided experimental evidence to suggest that immune processes can cause sensorineural hearing loss in animals and humans. However, antigenic targets within the inner ear are diverse and as a result conclusive evidence for specific autoimmune damage to the inner ear has been elusive. This review focuses on the recent progress in understanding of the aetio-pathogenesis of autoimmune hearing loss along with a description of the various clinical conditions in which they occur. Recent advances in the laboratory diagnosis and management of this interesting condition are also described.

Preparing Future Professionals—What’s the Real Story?

Preparing Future Professionals—What’s the Real Story?

Immune response and immunopathology of the inner ear: an update.

Immune-mediated inner-ear disease includes clinical conditions associated with unilateral or bilateral rapidly progressive forms of sensorineural hearing loss. A systemic autoimmune disorder can be present in less than one-third of cases. Because of the lack of well defined detection methods to identify immune-mediated processes within the inner ear, and the fact that the human inner ear is not amenable to diagnostic biopsy, there has been great interest in developing animal models. Experimental models of sterile and virus-induced labyrinthitis support the participation of the immune system in the aetiopathogenesis of inner-ear disorders: interleukin-2 emanates from the endolymphatic sac and assists in changing the spiral modiolar vein, as in the expression of intercellular adhesion molecule 1, which allows the egrees of immune cells from the circulation. The formation of a fibro-osseous matrix ultimately results in degeneration of the inner ear. These investigations have allowed us to alter the immune response for the purpose of regulating its intensity and the subsequent damage to patients.

Sensorineural hearing loss in children

Advances in audiologic testing of young children and more widespread implementation of neonatal hearing screening are providing a better understanding of the epidemiology of pediatric sensorineural hearing loss (SNHL). SNHL in children is caused by many acquired and inherited factors. New discoveries in the molecular genetics of hereditary hearing impairment help us understand the physiology of normal hearing and the pathophysiology of many forms of SNHL. Cochlear implants offer children with profound SNHL the ability to perceive acoustic stimuli, when amplification with hearing aids is not helpful.

Autoimmune hearing loss

Immune-mediated inner ear disease describes a variety of clinical conditions associated with unilateral or bilateral rapidly progressive sensorineural hearing loss. Typically, the hearing loss occurs over weeks to months. Although it may affect both sexes and all ages, it occurs most commonly in middle-aged female patients. Frequently, the patient may experience Meniere's disease-like symptoms including episodic vertigo, aural fullness, otalgia and disequilibrium, although the hearing loss is more progressive. A history of systemic autoimmune disorders (eg, systemic lupus erythematosis, Wegener's granulomatosis, or rheumatoid arthritis) can be elicited in less than one-third of the time. Recent experimental evidence supports the existence of a group of organ-specific and nonspecific antibodies that target the inner ear tissues, leading to inflammatory insults of the cochlea. This class of cochleovestibular disorder is unique because it represents one of the few forms of sensorineural hearing loss that can be treated with immunosuppressive therapy. Therefore, it is important that the clinician maintains a high index of suspicion, obtain laboratory validation, and promptly initiate therapy to preserve cochleovestibular function.

Can sensitized lymphocytes retain reactivity to inner ear antigens after retrieval from frozen storage?

Immune inner ear disease results in rapidly progressive, bilateral sensorineural hearing loss and is one of the few forms of sensorineural hearing loss that can be treated medically. The purpose of this study is to identify and preserve several populations of sensitized lymphocytes from patients with immune inner ear disease as a first step toward cloning autoreactive T cells, in order to study the pathogenesis of disease. Lymphocytes from four patients with high reactivity (stimulation index of 2.5 or greater) were placed in frozen storage. At 8 to 14 months they were thawed and restimulated. All four samples were viable. Two reacted again to inner ear homogenate, but with different intensities. Some lymphocytes sensitized to inner ear antigens can retain reactivity after frozen storage. This methodology may be useful to clone highly reactive T cells.

Non-syndromic dominant sensorineural hearing loss: from a few phenotypes to many genotypes

Sensorineural hearing loss affects approximately 1 in 2 persons at about 80 years of age and 1 in 750 in childhood. The best known forms of hearing loss with an autosomal dominant pattern of inheritance are the syndromic-mediated ones. At present, the non-syndromic autosomal dominant inherited forms can only be distinguished by the shape of the tone-audiogram. Based on gene linkage studies twelve different genotypes for autosomal dominant hereditary non-syndromic forms of sensorineural hearing loss have been recognized in a period of almost 2 years. In view of the great diversity of types that have been recognized in such a short period, it can be expected that over the next 10 years, several dozens genetically-mediated forms of autosomal dominant inherited sensorineural hearing loss will be detected. Similar developments are taking place in the non-syndromic autosomal recessive hereditary forms of sensorineural hearing loss and deafness. The above indicates clearly that before too long, new genetic investigation techniques will enable us to distinguish between forms of sensorineural hearing loss that could not be distinguished in the past.

Changes in otoacoustic emissions in patients with idiopathic sudden deafness.

Transiently click-evoked (TEOAE), distortion product (DPOAE) and spontaneous otoacoustic emissions (SOAE) were recorded and changes in these tests were studied during the recovery process in 15 cases of idiopathic sudden deafness (ISD). In all these cases the amplitudes of TEOAEs and DPOAEs increased concurrently with the recovery of the hearing threshold. Ears with ISD were not different in their OAE characteristics from ears with other forms of sensorineural hearing loss (SNHL). In 4 of the 15 cases, SOAEs could be detected when hearing had recovered. These results suggest that the function of outer hair cells (OHCs) had deteriorated when the hearing threshold was elevated and that OHC activity recovered as hearing improved to nearly normal levels in ISD cases with good outcome.

A method for determining interaural attenuation in animal models of asymmetric hearing loss.

Asymmetric or unilateral sensorineural hearing loss is an important hall-mark of various forms of sensorineural hearing loss. Animal research regarding the etiology and mechanism of these disorders often requires hearing estimates in each ear of experimental animals. Monaural auditory testing of animals with experimentally induced unilateral hearing loss therefore requires prior knowledge of interaural attenuation (IAA) to facilitate contralateral masking. The purpose of this study is to describe a method of determining frequency-specific IAA data and to present relevant information obtained in the rats--a frequently used animal in studies of acquired sensorineural hearing loss. A custom-made sound source was designed to accomplish threshold determination at important frequencies in the dynamic range of rats. Six male Long-Evans rats were surgically monauralized by ablation/obliteration of the cochlea. Auditory brainstem response (ABR) thresholds were determined for ipsilateral and contralateral presentations of 2-kHz, 10-kHz, and 40-kHz toneburst. IAA was calculated by subtracting the frequency-specific ABR threshold obtained from the normal ear from that obtained following tone presentation to the 'dead' ear, and was found to average 65.0 +/- 10.5 dB at 2 kHz, 45.0 +/- 8.4 dB at 10 kHz, and 47 +/- 15.1 dB at 40 kHz (+/- standard deviation). Using data obtained from the animal demonstrating the smallest IAA, masking is not needed until a threshold asymmetry of 50 dB at 2 kHz and 30 dB at 10 and 40 kHz is observed. In order to obtain bilateral auditory threshold information in any animal model of asymmetric hearing loss, data regarding IAA are needed in order to know when to apply contralateral masking and therefore avoid crossover stimulation of the non-test ear. The protocol presented herein provides guidelines for use in any animal model of sensorineural hearing loss which may demonstrate unilateral or asymmetric deficits.

The Clinical Utility of Distortion-Product Otoacoustic Emissions

Otoacoustic emissions permit, for the first time, an unbiased means of examining the preneural elements of the peripheral auditory pathway that make the initial contribution to the perception of acoustic stimuli. Distortion-product otoacoustic emissions (DPOAEs) represent one type of evoked emission that has significant potential for becoming an important test in the audiometric evaluation of hearing capacity. In the present review, selected examples of several forms of sensorineural hearing loss demonstrate that DPOAEs have the ability to act as objective indicators of the frequency/level configuration of the conventional audiogram in cases in which hearing impairment results primarily from damage to the outer hair cells. In contrast, normal DPOAE functioning, in the presence of a significant hearing loss, indicates a locus of damage central to the region of the outer hair cells. Like the other emitted responses, DPOAEs can be measured noninvasively, are highly repeatable, under test-retest conditions, and are simple and rapid to detect using microcomputer-based instrumentation. Further, DPOAEs test both the "threshold" and suprathreshold levels of outer hair-cell activity in the form of response/growth functions, over a 30- to 40-dB stimulus range. In combination, these attributes indicate that DPOAEs can provide an objective and comprehensive assessment of the cochlear reserve of a given ear.

Cochlear and Retrocochlear Immune-Mediated Inner Ear Disorders

Three different forms of immune-mediated sensorineural hearing loss are described. The pathogeneses of these three cases with severe audiovestibular deficits are completely different. To make an appropriate diagnosis remains a dilemma. Autoimmunity plays a certain role, but is not always present. Vascular and neural tissue can become involved. Immune-mediated forms of sensorineural hearing loss can be of cochlear or retrocochlear origin.

Die Bedeutung des Glycerol-Testes für die Diagnostik von Schallempfindungsschwerhörigkeiten*

140 patients with various forms of sensorineural hearing loss were examined via the glycerol test (Klockhoff). In 66% of the cases with Menière's disease, a typical temporary threshold shift could be seen. 17 patients with fluctuating hearing loss of unknown etiology without vestibular symptoms showed a similar effect; they were classified as belonging to the group of the cochlear type of Menière's disease. In 34% of cases with clinically assured diagnosis of Ménière's disease, glycerol did not induce improvement in hearing. Repeated glycerol tests revealed varying results; shortly after a Menière attack, the glycerol test was usually negative, whereas shortly before the next attack the glycerol test changed to positive. These data support the specificity of the glycerol test: The results depend on the presence of endolymphatic hydrops at the time of examination. Positive results of the glycerol test were also seen in the cases of reduced sensorineural hearing associated with syphilis, as well as in cases of cerebrospinal pressure changing synchronously with fluctuating hearing loss (Lindsay and Zajtschuk). In all other cases of sensorineural hearing losses, no positive effect of the glycerol test has been found.

Problematik einer frequenzspezifischen Schwellenmessung mit den Hirnstammpotentialen unter Verwendung des otometrischen Signals (DWT)

This study aimes at investigating if the damped wavetrain stimulus (Victoreen) may be used in the evaluation of frequency specific thresholds using brainstem potentials. Stimulus frequencies were 1, 4, and 8 kHz. Starting with a control group (10 persons) latency curves for the brainstem potentials were established. The test group included patients with various forms of sensorineural hearing loss in the audiogram. Threshold measurements at the three stimulus frequencies were done with these patients using the potential IV (Jewet V). The latency curves of the normal hearing control group reveal a frequency-specific information being present in the brainstem potentials. This can be derived from latency shifts at different stimulus frequencies. However, investigating patients with a steep slope or a notch in the pure-tone audiogram introduces some difficulties in the ERA-threshold evaluation.

Cochlear Initiation Site of the Frequency-Following Response: a Study of Patients with Sensorineural Hearing Loss

The cochlear initiation of the frequency-following response (FFR) was assessed by comparing the FFR thresholds to the pure-tone thresholds in four groups of patients suffering from different forms of sensorineural hearing loss. The groups consisted of patients suffering from (1) pure high-frequency hearing losses; (2) high-frequency hearing losses mixed with moderate low-frequency losses; (3) flat hearing losses, and (4)low-frequency hearing losses. Across groups, the pattern of thresholds of the FFR evoked by 500-Hz tome bursts paralleled the pattern of pure-tone thresholds only for the low frequencies- not the high frequencies. In order to clarify the interpretation of this result, a high-pass masking experiment was performed on patients with low-frequency hearing losses. High-pass masking noise did not affect the FFR thresholds to 500-Hz tone burst, but it produced a phase shift of the FFR at stronger intensity levels. The data are interpreted as strongly supporting the view that the FFR at low levels is initiated primarily by activity in the apical portion of the cochlea.

BIOFLAVONOID THERAPY IN SENSORINEURAL HEARING LOSS: A DOUBLE-BLIND STUDY.

Purpose THE PURPOSE of this paper is to report the effects of lemon bioflavonoid therapy in three forms of sensorineural hearing loss. A double-blind technique was followed throughout the study. Introduction H. L. Williams, 1 in August 1962, reported the successful use of the lemon bioflavonoids in Meniere's disease. In a paper presented before the Otologic Society in August 1963, Williams reported the beneficial effects of lemon bioflavonoid complex in Meniere's disease in 95 of 122 patients. Forty five of the 95 had experienced improved hearing of at least 10 db in three continguous frequencies. 2 Williams also reported that 11 of 52 patients with sensorineural hearing loss (exclusive of Meniere's disease) treated with the same preparation showed a similar hearing improvement. Although Williams 3,4 stressed the use of the medication in Meniere's disease, clinicians began to prescribe, and have continued to prescribe, the medication for various forms of