Plasma exchange in the treatment of immune complex-associated sensorineural deafness

Thyroid Dysfunction in Ménière's Disease: A Comprehensive Review

INTRODUCTION

The precise etiology of Ménière's disease (MD) remains unknown; however, given the association of MD with serum antibodies and human leukocyte antigen (HLA) complex, several studies have proposed a relationship between MD and thyroid disorders. Similarly, multiple hypotheses exist regarding the metabolic disturbances of fluctuating thyroid hormone as a potential contributing agent in the development of MD.

METHODS

A total of 171 abstracts were identified and screened by 2 independent reviewers. Based on inclusion and exclusion criteria, 8 studies were selected for final analysis. Due to heterogeneity of clinical data, meta-analysis was not feasible.

RESULTS

The prevalence of autoimmune thyroid disease and hypothyroidism in MD varied significantly from 1 to 38%. Notable bias was introduced given the lack of standardization of diagnostic criteria across studies. Articles that described autoimmune thyroid-specific antibodies and HLA types also presented inconclusive results. Multiple studies noted a potential etiologic role of hypothyroidism in MD, which was often confounded by thyroxine supplementation.

CONCLUSIONS

Despite a potential correlation in the medical literature between thyroid disorders and MD, there is currently no definitive causal relationship. Although most of the present medical literature focuses on autoimmunity, dysregulated thyroid hormone levels may also be implicated in the association of MD with thyroid disorders.

Mechanism of Immune Complex—Mediated Inner Ear Diseases

Tissues of the stria vascularis of normal rabbits were collected as cochlear antigen and injected into the foot pad of guinea pigs. The mechanism of development of endolymphatic hydrops was studied by the tracer method. Damage to the capillary endothelium and an increase in vascular permeability were found in the stria vascularis. Therefore, we studied patients with a raised level of immunoglobulin (Ig) G—class circulating immune complexes (CICs). Hearing loss was found in 3 of 22 patients with significantly elevated IgG CIC levels (13.6%). The relationship between inner ear disease and the presence of CIC was considered to be very significant. The possible mechanism of CIC-mediated inner ear diseases is discussed.

T cells infiltrating from the systemic circulation proliferate in the endolymphatic sac

It has been reported that autoimmune mechanisms are involved in the development of inner ear disorders such as Meniere's disease and steroid-responsive sensorineural hearing loss. In the present study, using an animal model for graft-versus-host disease, we investigated the immune regulatory mechanism in the endolymphatic sac and demonstrated that donor T cells injected into the systemic circulation of recipients infiltrate and proliferate in the perisaccular region. These findings suggest that immunocompetent cells are supplied from the systemic circulation through blood-labyrinth and blood-endolymph barriers into the endolymphatic sac, and that the endolymphatic sac allows these cells to proliferate locally as a local immune defense. It therefore seems likely that the endolymphatic sac plays a crucial role in not only graft-versus-host disease but also autoimmune inner ear disorders.

Study of systemic lupus erythematosus in temporal bones

Despite some reports of sensorineural hearing loss with systemic lupus erythematosus (SLE), its pathologic correlate has remained unidentified due to the scarcity of human temporal bone studies. We here present findings in 14 temporal bones from 7 patients with SLE, examined histologically and immunohistochemically for pathologic conditions in the cochlea that might relate to their otologic histories. Blue-staining concretions were seen in the stria vascularis of 6 ears. Most of the cases showed a loss of spiral ganglion cells, with various degrees of hair cell loss and atrophy of the stria vascularis. One ear demonstrated formation of fibrous tissue and bone throughout the cochlea, with complete loss of the membranous labyrinth. Cochlear hydrops was found in only 1 ear. These findings in temporal bones from patients with SLE are discussed in relation to autoimmune disease of the inner ear.

Breakdown of Stria Vascularis Blood-Labyrinth Barrier in C3H/lpr Autoimmune Disease Mice

Sensorineural hearing loss related to autoimmune disease is a well-recognized condition, although the exact pathophysiologic mechanisms remain unclear. One current theory postulates immune complex-induced interference with blood-labyrinth barrier integrity in the stria vascularis. The C3H/ lpr autoimmune mouse was chosen to study the permeability of capillaries in the stria vascularis because this mouse model has demonstrated abnormalities of the stria vascularis and shifts in the auditory brain stem response threshold during active disease. C3H/ lpr mice with active disease were compared with younger mice without disease, as well as age-matched C3H/HeJ control mice. The mice were injected with the tracer ferritin and examined by transmission electron microscopy to evaluate the integrity of the capillary tight junctions in the stria vascularis. Four of five mice with active disease were noted to have extensive leakage of ferritin into the perivascular tissues. Neither the young, disease-free autoimmune mice nor the nonautoimmune control mice demonstrated vessel leakage. Thickening of the basement membrane was also noted in the diseased animals. The results imply that active disease leads to a breakdown in the blood-endolymph barrier, which could underlie the hearing loss accompanying autoimmune and other immune diseases.

Medical Management of Meniere's Disease

The management of Meniere's disease often creates a formidable clinical challenge. Drugs may be helpful in treating the acute attacks of vertigo, and in more long-term management. These remedies are largely symptomatic and there are few properly controlled studies of their efficacy. A critical overview of the scientific and clinical basis for these various pharmacological agents is discussed.

The pharmacological treatment of Menière's disease

The management of Menière's disease often provides a formidable clinical challenge largely because its precise aetiology is unknown. There is no known 'cure' once the condition is established, but drugs may be helpful in treating both the acute attacks of vertigo, and in more long-term management, particularly in the earlier fluctuant stage. These remedies are largely symptomatic and there are few if any properly controlled studies of their efficacy. Suppressant drugs may act centrally at neurotransmitter sites, or peripherally on the labyrinth. Conventional diuretics and osmotically acting agents have been given to reduce the endolymph fluid volume. Histamine analogues directly reduce inner ear fluid pressure mainly by increasing the cochlear blood flow, and are probably the treatment of choice. Otovestibulotoxic drugs given systemically to cause chemical labyrinthine ablation are frequently effective in abolishing attacks of vertigo but often resulted in disabling oscillopsia and ataxia. There is now evidence that local administration by intratympanic injection may well be more efficacious resulting in selective partial end organ ablation. To date innovative immune modifying regimes have not proved helpful.

The possible association of pyoderma gangrenosum and progressive sensorineural deafness

Deafness is known to be associated with certain autoimmune disorders. This article describes a hitherto unreported possible association between pyoderma gangrenosum and progressive bilateral sensorineural deafness.

Stria vascularis ultrastructural pathology in the C3H/lpr autoimmune strain mouse: a potential mechanism for immune-related hearing loss

The stria vascularis in the C3H/lpr autoimmune strain mouse was ultrastructurally examined in order to better understand the potential mechanisms by which systemic autoimmune disease affects the ear. The inner ear from C3H/lpr mice before disease onset and C3H/HeJ controls showed no apparent pathology. However, the stria vascularis from older C3H/lpr mice after systemic autoimmune disease onset showed considerable intercellular edema around the stria capillaries and thickening of the capillary basement membrane, compared to controls. These observations suggest that perivascular abnormalities, which are the hallmark of systemic autoimmune diseases, may underlie the stria dysfunction and hearing loss seen in autoimmune diseases in humans.

Polyarteritis nodosa presenting as bilateral sudden onset cochleo-vestibular failure in a young woman

Sudden onset sensorineural hearing loss is an otological emergency. Although deafness is recognised as being associated with polyarteritis nodosa (PAN) only very rarely does it herald the disease. We describe a case of bilateral, sudden onset vestibulo-cochlear failure which with thorough investigation proved to be the presenting complaint of PAN. This diagnosis enabled definitive management of a multi-system disorder and resulted in an improvement of the initial symptom with the chemotherapeutic regime discussed. We review the involvement of PAN in deafness and hope this case will remind otolaryngologists of the need for full investigation of the above mentioned emergency, in an attempt to discover and hence direct management towards a specific underlying pathology.

Immune status in patients with Menière's disease

Sera of 164 patients with classical Meniere's disease were screened for autoantibodies, immune complexes and HLA status. Increased thyroid microsomal antibodies were significant in those patients in the 40- to 60-year age range. Raised IgM complexes and C1q component of complement were significant in all age groups. Low levels of IgA complexes were a consistent finding and were significantly lower in the HLA Cw7 group. Patients with migraine had no increased incidence of immune disturbances.