Immune-mediated sensorineural hearing loss

A glance into the future of anti-neutrophil cytoplasmic antibody-associated vasculitis

In the past decade, unprecedented progress has been made in understanding the pathogenesis, diagnosis, assessment, and treatment of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs). International collaborations and input from several fields (e.g. immunology, rheumatology, and nephrology) have been critical for analyzing demographics, disease manifestations, and outcomes in clinical research studies. Such efforts opened new avenues for generating novel questions and rationale to design better clinical trials. In addition, clinical research has been a source of several biological discoveries and the starting point for knowledge seeking on the pathophysiology of AAV. Interestingly, the blending of clinical and basic research provides a platform for personalized medicine. Despite recent revisions on AAV classification, the incorporation of new findings on disease genetics and immunologic responses may soon result in changes in clinical practice. These advances will enhance the selection of more specific and targeted therapies. However, current unmet needs in the management of AAV are still sizable and heavily impact long-term survival. Especially, frequent relapses, damage accrual, and high morbidity contribute to poor outcomes. Finally, the lack of defined biomarkers for disease activity and the prognosis is a permanent challenge in AAV research. Our work provides an overview of the current state of the art in AAV literature and suggests bridges for the remaining knowledge gaps. It offers potential future directions for the clinical assessment, management, and research in the field toward a more personalized medicine approach.

Age-related changes in the number of cresyl-violet-stained, parvalbumin and NMDAR 2B expressing neurons in the human spiral ganglion

Animal-studies associate age-related hearing loss (presbycusis) with decreasing number of spiral ganglion neurons (SGNs) in Rosenthal's canal (RC) of cochlea. The excitatory neurotransmitter for SGNs is glutamate (through its receptor NMDAR 2B), which can be neurotoxic through Ca²⁺ overload. Neurotoxicity is balanced by calcium-binding proteins (CBPs) like Parvalbumin (PV), which is the predominant CBP of the SGNs. To estimate the volume of the RC and total number of SGNs that are immunoreactive to PV and NMDAR 2B, we used unbiased stereology in 35 human cochleae derived from cadavers of persons from 2nd to 8th decade of life (subsequently statistically divided into two groups) and compared them to the total number of cresyl violet (CV) stained SGNs. We also estimated the volume of individual neurons and their nuclei. Regression analysis was made on estimated parameters against age. Hierarchical-cluster analysis was done on the neuronal against neuronal nuclear volumes.The average volume of the RC did not change with increasing age (p = 0.4115). The total number of SGNs (CV-stained and those separately expressing PV and NMDAR 2B) significantly decreased with age (p < 0.001). We identified three distinct populations of neurons on the basis of their volumes among SGNs. Thus, there is significant age-related decline in the total number of SGNs, which starts early in life. It may be due to ambient noise and inadequate neutralisation of excitotoxicity.

Association Between Psoriasis with Arthritis and Hearing Impairment in US Adults: Data from the National Health and Nutrition Examination Survey

Objective.

Emerging data has linked inflammatory arthritis with hearing impairment (HI). The objective of this study was to investigate the relationship between psoriasis with arthritis (PsA) and HI in the US population. Given the known association of HI and depression, a secondary aim is to investigate the effect of PsA on mental well-being.

Methods.

Cross-sectional study using the National Health and Nutrition Examination Survey for adults aged ≥ 20 years (n = 10,747). Association of PsA with above outcomes was examined using multivariable generalized linear and ordinal logistic regression models, adjusted for demographics and medical comorbidities. Structural equation models examined the extent to which HI mediated the effect of PsA on mental health.

Results.

Individuals with PsA were more likely to report hearing difficulties (OR 1.50, p = 0.043), visit a mental health provider (OR 1.62, p = 0.084), have 1.62 more days of poor mental health over the previous month (p = 0.033), and have depression (OR 2.01, p = 0.015) compared to controls. HI mediated 6.5%, 8.3%, and 5.0% of the effect of PsA on the above mental health outcomes, respectively.

Conclusion.

PsA is independently associated with a significantly increased risk of HI, which partially mediates an association with worsened psychiatric outcomes.

Microscopic polyangiitis: Advances in diagnostic and therapeutic approaches

Microscopic polyangiitis (MPA) is an idiopathic autoimmune disease characterized by systemic vasculitis. The disease predominantly affects small-calibre blood vessels and is associated with the presence of antineutrophil cytoplasmic autoantibodies (ANCA). Microscopic polyangiitis was considered to be a disease entity by Savage et al. in 1985. Microscopic polyangiitis has a reported low incidence and a slight male predominance. The aetiology of MPA remains unknown. There is, however, increased evidence that MPA is an autoimmune disease in which ANCAs, particularly those reacting with MPO, are pathogenic. MPA belongs to the systemic vasculitides, indicating that multiple organs can be affected. The major organs involved in MPA are the kidneys and the lungs. As expected for an illness that affects multiple organ systems, patients with MPA can present with a myriad of different symptoms. Ear, nose and throat (ENT) manifestations are not considered to be clinical symptoms of MPA, but in the majority of populations described, ENT involvement was found in surprisingly high percentages. MPA is part of the ANCA-associated vasculitides, which are characterized by necrotizing vasculitis of small vessels. Diagnosis is mainly established by clinical manifestations, computed tomography (TC), ANCA antibody detection and renal and pulmonary biopsy. The introduction of aggressive immunosuppressive treatment has substantially improved the prognosis. The standardized therapeutic regimen is based on cyclophosphamide and corticosteroids. Using this regimen, remission can be achieved in most of the patients. Rituximab may represent an important alternative to cyclophosphamide for patients who may not respond adequately to antimetabolite therapies.

Hearing loss and kidney dysfunction: finding a unifying diagnosis

Microscopic polyangiitis (MPA) is a systemic vasculitis that affects small caliber vessels, with renal and lung compromise. Diagnosis can be challenging; timely diagnosis and treatment are important to prevent devastating complication, particularly renal failure. We present a case of a patient with microscopic polyangiitis presented with renal and pulmonary involvements with concomitant sensorineural hearing loss. We provide diagnostic, therapeutic, and prognostic keys to microscopic polyangiitis.

Functional and molecular expression of epithelial sodium channels in cultured human endolymphatic sac epithelial cells

HYPOTHESIS

Epithelial sodium channels are expressed in cultured human endolymphatic sac (ES) epithelial (HESE) cells and epithelial sodium channel (ENaC) expression is suppressed by interleukin 1beta.

BACKGROUND

The ES is part of the membranous labyrinth in the inner ear that plays an important role in maintaining homeostasis of the endolymphatic fluid system. However, the exact mechanism of fluid volume regulation is not yet known.

METHODS

The ES specimens were harvested during acoustic neuroma surgery (n = 13) using the translabyrinthine approach and were subcultured with high-epidermal growth factor (25 ng/mL) media.

RESULTS

The serially passaged HESE cells differentiated into a monolayer of confluent cells and some of the cultured cells had features of mitochondria-rich cells. Reverse transcription-polymerase chain reaction revealed that ENaC subunits are expressed in the cultured HESE cells. We also confirmed the presence of an ENaC-dependent short-circuit current in the cultured HESE cells. Interestingly, ENaC mRNA expression and ENaC-dependent current decreased after treatment with interleukin 1beta (10 nmol/L for 24 h).

CONCLUSION

These findings suggest that ENaC plays an important role in fluid absorption in the human ES and that its function may be altered during inflammatory conditions.

Diagnostic tests for immunomediated hearing loss: a systematic review

OBJECTIVE

To quantitatively evaluate the diagnostic accuracy of diagnostic tests for immunomediated hearing loss.

DATA SOURCES

We searched Medline and the Cochrane Database of Systematic Reviews for potentially relevant studies.

STUDY SELECTION

Twenty-five studies met the inclusion criteria of this systematic review. The diagnosis of immunomediated hearing loss was based on the clinical presentation and the response to corticosteroid administration.

DATA EXTRACTION

The following data were extracted from the selected studies and entered into a standardised database: population demographics; exclusion and inclusion criteria; diagnostic tests; sensitivity; specificity; the number of true positive, true negative, false positive and false negative values; therapy used, including dose and duration; and delay between symptom onset and therapy commencement.

DATA SYNTHESIS

This systematic review combined data from 679 patients with immunomediated hearing loss, reported by 22 research teams. Substantial heterogeneity was found among the included studies; for this reason, summary sensitivity and specificity values were not computed.

CONCLUSIONS

The results of diagnostic tests for immunomediated hearing loss depend on many factors, and there is a risk of potential bias. This is the first time that such a systematic review has been presented; such a review is a more rigorous method of demonstrating the utility of the available diagnostic tests.

Methylenetetrahydrofolate reductase gene mutations as risk factors for sudden hearing loss

Sudden hearing loss (SHL) can be caused by vascular disorders favoring impaired cochlear perfusion. Several inherited prothrombotic risk factors have been considered in the pathogenesis of vascular impairment, and the possible role of genetic alterations has recently been suggested. Methylenetetrahydrofolate reductase (MTHFR) gene mutations at nucleotides 677 and 1298 cause reduced MTHFR enzyme activity, which leads to increased homocysteine and reduced serum folate levels that are known to be involved in vascular impairment. We studied the relationship between SHL and MTHFR C677T and A1298C gene polymorphisms in 67 patients with SHL and 134 controls. Wild-type MTHFR CC677/AA1298 was significantly more frequent in the controls (P = .05), and gene mutations were significantly more frequent in the patients (P = .001; P = .001 for trend). Fifty-three patients (79.1%) and 56 controls (41.8%) (P = .012) had a double mutation (homozygosis 677TT or 1298CC; compound heterozygosis for both polymorphisms). Homocysteine levels were significantly higher and serum folate levels significantly lower in the patients than in the controls (P < .0001). These data suggest that MTHFR gene polymorphisms may be involved in the pathogenesis of SHL.

Estudio estadístico y resultados clínicos de la comparación de dos protocolos diferentes en el tratamiento de la hipoacusia brusca

Sudden deafness goes on being a clinical entity of unknown cause for which several theories and treatments have been proposed. We are reporting a comparative study of two different protocols that we have performed on 60 patients (divided in two groups of 30) diagnosed and admitted with sudden hearing loss between 1989 and 2003. The main goal is to prove if there is a statistical and significant difference among both, in respect of the audiologic improvement obtained, after two weeks of therapy at east. We have applied the normal approximation of Mann-Whitney's test and we can argue, after its result, our current protocol (piracetam, pentoxifiline, metilprednisolone), which includes 4 days of endovenous treatment another 10 days at home. The presence of vestibular symptoms darkens the prognosis since about 95% of the patients with them have not improved significantly (p<0.05).

Autoimmune sensorineural hearing loss: Clinical course and treatment outcome

BACKGROUND

Autoimmune sensorineural hearing loss (ASHL) originally was defined both by the presence of progressive hearing loss (with or without vertigo) and a positive response to glucocorticoid therapy. Subsequently, antibodies to a 68-kd inner-ear antigen were identified in a high percentage of patients with ASHL.

OBJECTIVE

To analyze the disease progression and treatment outcome of ASHL.

METHODS

Retrospective chart review of 30 patients with a diagnosis of ASHL referred to Texas Tech Rheumatology Clinic. All subjects were tested for anti-68-kd antibody, had audiometric evidence of hearing loss, and were treated with glucocorticoids.

RESULTS

The median duration from onset of symptoms to audiometric testing was 25.5 weeks (mean, 144 weeks; range, 3-1,040 weeks), and to testing for anti-68-kd antibody was 40 weeks (mean, 157.3; range, 4-1,092 weeks). Ninety percent of subjects tested positive for anti-68-kd antibodies. By audiometric testing, 50% of subjects were steroid-responsive; minimal improvement or no change was recorded in 12%, and worsening occurred in 39% after steroid therapy. The 3 subjects who were anti-68-kd antibody-negative were steroid-unresponsive, and 1 progressed to complete deafness.

CONCLUSIONS AND RELEVANCE

This series of patients with ASHL suggests a more variable and benign course with a better prognosis than previously reported. Immunosuppressive therapy other than steroids rarely was required, and rapid progression to complete hearing loss was very uncommon in this cohort.

Electrocochleographic findings in cases of autoimmune disease with sensorineural deafness

OBJECTIVES

To present electrocochleographic findings in patients with autoimmune disease (AD) with sensorineural deafness (ADSD), and to discuss the etiologies of sensorineural hearing loss (SNHL) in cases of ADSD.

METHODS

Study design is a retrospective review of electrocochleographic results of 26 patients with ADSD. To evaluate the electrocochleographic results, average SP/AP ratios were compared between ADSD and normal subjects. In the ADSD group, audiologic pattern, fluctuations in hearing and results of the glycerol test were also reviewed. Electrocochleography (ECoG) was recorded using the extratympanic method, and the SP to AP ratio (SP/AP ratio) was analyzed.

RESULTS

The mean of average SP/AP ratios in the ADSD groups (0.46) was significantly higher than that in normal subjects (0.27). Further, 17 of 29 affected ears in patients with ADSD showed fluctuating hearing loss. Eighteen ears showed low tone loss (rising and peak audiologic patterns). Only 5 of 26 ears (19.2%) showed positive results on glycerol test. There was no correlation between glycerol test results and hearing fluctuation or between glycerol test results and the SP/AP ratio on chi(2)-test. There was no tendency between audiologic pattern and glycerol test results or between audiologic pattern and the SP/AP ratio.

CONCLUSION

These results suggest the etiologies of SNHL in cases of ADSD remain unclear. However, some cases showed clinical findings similar to endolymphatic hydrops. We should bear in mind that clinical Meniere's syndrome involves ADSD. Further investigation is needed to resolve the etiology of SNHL of ADSD.

Platelet GPIaC807T polymorphism is associated with negative outcome of sudden hearing loss

To determine the relevance of inherited prothrombotic risk factors in sudden hearing loss, we investigated 85 patients with sudden hearing loss of >/= 60 dB for the presence of inherited prothrombotic risk factors. The FV G1691A, FII G20210A, GPIa C807T, GPIIIa PIA1/A2, PAI-1 4G/5G, t-PA Alu repeat ID, MTHFR C677T and CBS 844ins68 genotypes were investigated. Allele frequencies found in patients were compared to those of 85 healthy control subjects of the same ethnic background using Chi-squared and odds-ratio analysis. The frequency of the GPIa807T allele was significantly elevated in patients compared to controls. In addition, allele frequency and genotype distribution of GPIa was significantly elevated in the patient group without recovery after 3 months of sudden hearing loss onset. Allele frequencies of all other prothrombotic risk factors investigated here did not differ from those of the control subjects. The single-nucleotide polymorphism of GPIa C807T seems to play a role as a prognostic factor in recovery from sudden hearing loss.

The emotional ear in stress

Stress of some kind is encountered everyday and release of stress hormones is essential for adaptation to change. Stress can be physical (pain, noise exposure, etc.), psychological (apprehension to impending events, acoustic conditioning, etc.) or due to homeostatic disturbance (hunger, blood pressure, inner ear pressure, etc.). Persistent elevated levels of stress hormones can lead to disease states. The aim of the present review is to bring together data describing morphological or functional evidence for hormones of stress within the inner ear. The present review describes possible multiple interactions between the sympathetic and the complex feed-back neuroendocrine systems which interact with the immune system and so could contribute to various inner ear dysfunctions such as tinnitus, vertigo, hearing losses. Since there is a rapidly expanding list of genes specifically expressed within the inner ear this clearly allows for possible genomic and non-genomic local action of steroid hormones. Since stress can be encountered at any time throughout the life-time, the effects might be manifested starting from in-utero. These are avenues of research which remain relatively unexplored which merit further consideration. Progress in this domain could lead towards integration of stress concept into the overall clinical management of various inner ear pathologies.

Intravenous infusion of recombinant tissue plasminogen activator for the treatment of patients with sudden and/or chronic hearing loss

Seventeen patients with sudden hearing loss and 10 patients with chronic hearing loss were treated with intravenous infusion of tissue plasminogen activator. For sudden hearing loss, the recombinant tissue plasminogen activator was used, and 3 mg (in 3 mL of diluent) was diluted into 250 mL of physiological saline solution and given intravenously every 12 hours. Sixteen patients of the sudden hearing loss group and all 10 patients of the chronic hearing loss group showed an improvement after this treatment. No patients had side effects from the treatment. The results indicate that this would be an excellent mode of therapy for patients with hearing loss.

Experimental autoimmune inner ear disease: an electrocochleographic and histophysiologic study

Systemic immunization with swine inner ear antigens in complete Freund's adjuvant induces functional disturbances in the cochlea. Morphometric data indicate that an endolymphatic hydrops develops within 2 weeks. It diminishes 6 weeks after immunization. A progressive decrease in the compound action potential amplitude is observed from 2 to 6 weeks after immunization. Enhancement of the amplitude of the summating potential is present without a clear overall correlation to the presence of endolymphatic hydrops. The amplitude of the cochlear microphonics shows no significant changes after immunization. Western blot analysis of the sera performed 2 and 6 weeks after immunization shows enhanced reactivity at 68, 50, 45, and 27 kd molecular weights, as compared to controls. The same spectrum of cross-reacting antibodies is believed to be instrumental in immune-mediated sensorineural hearing loss in patients. Apparently, cross-reacting antibodies and released mediators disturb cochlear homeostasis, resulting in the observed changes in the electrophysiological responses. However, these changes are not clearly related to structural changes at the light and electron microscopic levels.