Hearing Loss, by Rodney Tailor

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An autoimmune disease is a disorder in which an individual’s immune system attacks its own cells. In the case of autoimmune inner ear disease, the individual’s immune system (T-cell lymphocytes, antibodies and immunologic cells) attacks the cells within its own inner ear. This can cause tinnitus, vestibular dysfunction, and fluctuating hearing loss (Arnold, Pfaltz & Altermatt, 1985; McCabe & McCormick, 1984).
The exact reason for why the body’s immune system attacks the inner ear is unclear, although some theories have been proposed. It is possible that the immune system attacks the inner ear due to the ear sharing common antigens with a harmful virus or bacteria. It is also possible that the immune system may not be aware of all inner ear antigens in some people, and may attack that particular antigen, leading to inner ear damage. Finally, we know that genetic factors are involved, and those genetic factors that predispose an individual to other autoimmune disorders would also predispose them to autoimmune inner ear disease as well (Hain, 2012).
There are two types of autoimmune inner ear disease: primary disease, which occurs when the disease process originates within the inner ear itself, and secondary disease, in which the individual has a systemic autoimmune disease which affect other parts of the body, but may affect the inner ear secondarily. Examples of such diseases include ulcerative colitis (which primarily affects the colon), rheumatoid arthritis (which primarily affects the joints), Hashimoto’s thyroiditis (which primarily affects the thyroid), and Wegener’s granulomatosis (which primarily affects the blood vessels) (Hughes, Barna, Calabrese & Koo, 1993).
Bilateral sensorineural fluctuating hearing loss is the most common type of hearing loss seen as a result of autoimmune inner ear disease. However, conductive losses may occur from secondary autoimmune inner ear disease; when the disease processes involved in Wegener’s granulomatosis attack the outer and middle ears, for example. Hearing losses caused by autoimmune inner ear disease typically progress over the course of several months. It is very common for tinnitus to accompany the hearing loss (Musiek, Baran, Shinn & Jones, 2012). Approximately 50% of patients with autoimmune inner ear disease will have accompanying symptoms related to balance (Ruckenstein, 2004).
Autoimmune inner ear disease accounts for less than 1% of all cases of hearing loss and dizziness. We know that it is more common amongst those who have other autoimmune diseases, such as systemic lupus erythematosus and Crohn’s disease (Musiek et al., 2012). The precise incidence and prevalence is controversial (Hain, 2012).
There is little information regarding the exact site of lesion within the auditory system in autoimmune inner ear disease. This is due to the lack of temporal bone samples from patients with the disorder (Musiek et al., 2012). However, Harris & Sharp (1990) have found evidence which appears to point to the cochlea as the primary site of lesion.
Autoimmune inner ear disease is diagnosed by performing serial audiograms (to document the fluctuating nature of the hearing loss), blood tests (to record general autoimmune disease markers, such as erythrocyte sedimentation rate and rheumatoid factor), vestibular tests, documenting a positive response to corticosteroids, and more. The case history is of particular importance in the diagnosis of this disorder, as it may help to differentiate autoimmune inner ear disease from other disorders which present with similar symptomatology, such as perilymph fistula and Ménière’s disease (Hain, 2012; Musiek et al., 2012).
Drug treatment for autoimmune inner ear disease falls into two categories: acute treatments, designed to provide immediate relief and prevent a flare up from causing permanent damage, and long term treatment, which seeks to provide lasting remission, preventing flare ups from happening in the first place (Hain, 2012; Musiek et al., 2012).
An example of an acute treatment would be corticosteroids such as Prednisone. Although steroid use is known to be highly effective in treating autoimmune conditions of all sorts, their long term use is not recommended due to the associated side effects. As such, disease-modifying antirheumatic drugs (DMARDs), such as Methotrexate, are often the medication of choice for long term maintenance of remission in autoimmune inner ear disease. These drugs build up in the body over the course of several months and provide a resistance against the disease, preventing flare ups from happening. They are less toxic than steroids in the long term and are therefore a wiser choice for prolonged treatment of autoimmune diseases (Hain, 2012; Musiek et al., 2012).
Audiologic management of the patient with autoimmune inner ear disease can be challenging due to the fluctuating nature of the hearing loss. If DMARD treatment succeeds in keeping the patient’s hearing loss stable, then the patient would be managed as any other patient would. Should the hearing loss continue to fluctuate, however, then the patient would be managed similar to one with Ménière’s disease (multiple programs, volume controls, frequent visits to the audiologist for testing and reprogramming, etc.) (Musiek et al., 2012).
Prognosis of patients with autoimmune inner ear disease depends greatly on how rapidly the initial treatment begins following the initial symptoms. Corticosteroids have the ability to reverse much of the damage caused by the disease if administered shortly after onset of the first flare up. See figure 1 for a real life example of the effectiveness of steroids when administered promptly. In addition, DMARDs take several months to reach full effectiveness. Because of this, the sooner treatment of autoimmune inner ear disease begins, the better the prognosis will be (Musiek et al., 2012).
Figure 1. Pre- and post-steroid audiograms for a 60 year old female diagnosed with autoimmune inner ear disease. Taken from Musiek et al. (2012).

References
Arnold, W., Pfaltz, R., & Altermatt, H. J. (1985). Evidence of serum antibodies against inner ear tissues in the blood of patients with certain sensorineural hearing disorders. Acta Otolaryngologica, 99(3-4), 437-444.
Hain, T. C. (2012). Autoimmune Inner Ear Disease (AIED). Retrieved March 4, 2016, from http://american-hearing.org/disorders/autoimmune-inner-ear-disease-aied/
Harris, J. P., & Sharp, P. A. (1990). Inner ear autoantibodies in patients with rapidly progressive sensorineural hearing loss. Laryngoscope, 100(5), 516-524.
Hughes, G. B., Barna, B. P., Calabrese, L. H., & Koo, A. (1993). Immunologic disorders of the inner ear. In B. J. Bailey (Ed.), Head and Neck Surgery-Otolaryngology (pp. 1883-1842). Philadelphia, PA: Lippincott.
McCabe, B. F., & McCormick, K. J. (1984). Tests for autoimmune disease in otology. American Journal of Otology, 5(6), 447-449.
Musiek, F. E., Baran, J. A., Shinn, J. B., & Jones, R. O. (2012). Disorders of the Auditory System. San Diego: Plural Publishing Inc.
Ruckenstein, M. J. (2004). Autoimmune innear ear disease. Current Opinion in Otolaryngology & Head and Neck Surgery, 12(5), 426-430

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