Autoimmune Sensorineural Hearing Loss (2007)

GOOD HEARING HEALTH IS ALMOST as important to a singer as good vocal health. A great many conditions can cause hearing impairment.1 Those that involve the outer and/or middle ear produce a mechanical impediment to sound transmission. This type of impairment is called a conductive hearing loss. Conductive hearing loss makes sounds heard seem softer, but it does not usually cause distortion of sounds. On occasion, those with a conductive hearing loss may hear an echo or feel their voices resonate during phonation. Conductive hearing losses are usually curable through medical or surgical treatment. Sensorineural hearing loss (SNHL) involves the cochlear hair cells of the inner ear, or the eighth cranial nerve that travels from the inner ear to the brain. SNHL decreases volume and clarity of sounds that an individual hears. In addition to distortion of words, SNHL also can cause pitch distortion (diplacusis) or loudness distortion (recruitment). With loudness recruitment, sounds that increase in loudness just slightly, may be perceived as extremely loud, or even painful. It is generally believed that sensorineural hearing loss is permanent; however, this is not necessarily true. There are many treatable causes of sensorineural hearing loss, including infections such as syphilis or Lyme disease, some cases of Meniere's disease, and other conditions. Autoimmune sensorineural hearing loss (AISNHL) is one treatable cause that is fairly common but infrequently diagnosed. Autoimmune diseases are conditions in which the body's immune system attacks a part of its own body. The most commonly recognized autoimmune diseases include rheumatoid arthritis, thyroiditis, psoriasis, and multiple sclerosis (MS). For example, in rheumatoid arthritis, patients make antibodies that attack their joints; in thyroiditis, the antibodies are against the thyroid gland; in psoriasis, antibodies attack the skin; and in multiple sclerosis, the antibodies attack a portion of the nerve sheaths. In AISNHL, the body makes antibodies against the sensory hair cells and their supporting cells within the cochlea. The cochlear nerve, a division of the eighth cranial nerve, transmits information from the sensory hair cells to the brain where it is interpreted as sound. Typically, AISNHL affects the sensory hair cells and not the cochlear nerve. Autoimmune inner ear disease most often is characterized by a bilateral progressive (BPSNHL) or unilateral progressive sensorineural hearing loss (UPSNHL) that occurs gradually over a period of weeks to months, with or without vestibular (balance) symptoms and tinnitus (ear noises). This disease can also cause sudden sensorineural hearing loss (SSNHL).2 An audiogram (hearing test) measures an individual's ability to hear and interpret sounds and words. Both puretone average (PTA) and speech discrimination scores (SDS) can be affected severely; therefore the affected individual may have difficulty hearing and understanding speech. A predilection toward females has been reported, and the disease appears to have a higher incidence in patients who have known autoimmune disease.3 Autoimmune diseases are not curable; however, an individual's symptoms can be controlled. It is possible for an individual to have more than one autoimmune disease, all of which can be characterized by periods of exacerbation (active symptomatology) and remission (less active). The diagnosis of autoimmune sensorineural hearing loss (AISNHL) is ascertained by the history, clinical findings, serial audiograms, and response to immunosuppressive medications (such as steroids), and an immunologic evaluation of the patient's serum. Among the diagnostic blood tests that have been advocated are the lymphocyte transformation assay, the Western blot analysis for inner ear antibodies, and, most recently, supporting-cell immunofluorescence.4 The latter has been reported to be the most sensitive.5 An association between AISNHL and the presence of human leukocytic antigen (HLA) markers also has been proposed. …