Cochlear function in ears with immunomediated inner ear disorder

Hearing impairment in systemic sclerosis patients-what do we really know?

Background

Systemic sclerosis (SSc) is a disease of a very heterogeneous clinical picture and immunological profile with progression rate that varies between individuals. Although hearing deterioration is not a complaint that comes to the fore in SSc patients, as it is not life-threatening compared to many other more severe symptoms of this disease, it can significantly impair the quality of life. Medical literature concerning this problem is rather scarce.

Materials and methods

In this article we systematically reviewed the medical publications concerning hearing impairment in patients with systemic sclerosis to evaluate current understanding of this complex problem. Following PRISMA guidelines a total of 19 papers were found and analysed including 11 original studies and 8 case reports.

Results

Although it seems that hearing impairment in SSc patients is relatively more common than in the general population, based on the analysis of available literature, no firm conclusions regarding its frequency and pathomechanism can be drawn yet. Microangiopathy leading to damage to the sensory cells of the inner ear is suspected to be the main mechanism of hearing loss, although damage to the higher levels of the auditory pathway appears to be underestimated due to incomplete audiological diagnosis.

Conclusion

Undoubtedly, the reason for the difficulty in such an evaluation are the complex and still not fully elucidated pathomechanism of SSc, the individually variable dynamics of the disease and the unique heterogeneity of symptoms. Nevertheless, further studies in larger and appropriately selected groups of patients, focused more on the dynamics of microangiopathy and not solely on clinical symptoms could provide answers to many key questions in this regard.

Current understanding of the pathogenesis of autoimmune inner ear disease: a review

BACKGROUND

Autoimmune inner ear disease (AIED) is a poorly understood form of sensorineural hearing loss that causes bilateral, asymmetric, progressive hearing loss, sometimes with vestibular symptoms, often associated with a systemic autoimmune disease, which is noteworthy as the only sensorineural loss responsive to medical therapy. Despite much research interest of the past 25 years, its aetiopathogenesis is still unproven.

OBJECTIVE OF REVIEW

To succinctly consolidate research and opinion regarding the pathogenesis of autoimmune inner ear disease, in ongoing efforts to elucidate the molecular and intracellular pathways that lead to inner ear damage, which may identify new targets for pharmacotherapy.

TYPE OF REVIEW

Systematic review

SEARCH STRATEGY

PubMed/MEDLINE search using key terms to identify articles published between January 1980 and Apr 2014. Additionally, any landmark works discussed in this body of literature were obtained and relevant information extracted as necessary.

EVALUATION METHOD

Inclusion criterion was any information from animal or human studies with information relevant to possible aetiopathogenesis of AIED. Studies that focused on diagnosis, ameliorating symptoms or treatment, without specific information relevant to mechanisms of immune-mediated injury were excluded from this work. Articles meeting the inclusion criteria were digested and summarised.

RESULTS

A proposed pathogenic mechanism of AIED involves inflammation and immune-mediated attack of specific inner ear structures, leading to an excessive Th1 immune response with vascular changes and tissue damage in the cochlea. Studies have identified self-reactive T cells and immunoglobulins, and have variously implicated immune-complex deposition, microthrombosis and electrochemical disturbances causing impaired neurosignalling in the pathogenesis of AIED. Research has also demonstrated abnormalities in the cytokine milieu in subjects with AIED, which may prove a target for therapy in the future.

CONCLUSION

Ongoing research is needed to further elucidate the aetiopathogenesis of AIED and discern between various mechanisms of tissue injury. Large-cohort clinical studies employing IL-1 receptor blockade are warranted to determine its potential for future therapy.

Sudden sensorineural hearing loss in lupus erythematosus associated with antiphospholipid syndrome: case report and review

Systemic lupus erythematosus is a disease of unknown cause that manifests with tissue and cellular alterations due to the deposition of antibodies and pathogenic immune complexes. The disease can be associated with anticardiolipin antibody syndrome, a disorder of recurrent vascular thrombosis and thrombocytopenia associated with a persistent anticardiolipin test positivity. In this report, we describe the case of a young woman affected by lupus erythematosus and positive for anticardiolipin antibodies who was brought to our observation for a sudden sensorineural hearing loss in the right ear. The patient was successfully treated with osmotic therapy and, 13 months after the initial symptom, is now in good clinical condition with no recurrence of the hearing loss and normal bilateral hearing. Together with a critical review of the pertinent literature, this rare clinical case led us to formulate some original comments.

Surdités brusques idiopathiques

Idiopathic Sudden Sensorineural Hearing Loss (ISSHL) remains one of the major unsolved otologic emergencies. It is characterized by the onset of an unilateral sensorineural hearing loss developing within 24 hours, and averaging on pure tone audiogram at least 30 dB HL for three subsequent octave steps, with no marked vestibular symptoms and no identifiable cause. ISSHL is a syndrome covering several heterogeneous entities resulting from different pathogenetic mechanisms. At this time, the audiogram is the unique tool which may help clinicians to identify these entities and provide a classification based on 5 types of hearing loss. Numerous experimental and clinical studies have investigated the mechanisms by which infectious, ischemic, mechanic or immunologic insults may induce cochlear dysfunction. However, extrapolation to humans and rationale therapeutic approaches to ISSHL remain uncertain. SSHL being a diagnosis of exclusion, retrocochlear and neurologic etiologies should be eliminated. No argument allows to consider ISSHL a therapeutic emergency. More precisely, the experimental data presently available on cochlear physiology suggests that a treatment could have some chance to be effective if undertaken within minutes following the onset of ISSHL, a condition never encountered in daily practice. Conversely, it is not justifiable to impute the absence of hearing recovery to a delay in therapy. The various therapeutic strategies currently recommended are highly empirical and should be questionned in terms of cost-effectiveness, the most common being high-dose corticosteroids. New investigation tests are required for improving our approach to ISSHL.