Unilateral Slowly Progressive Hearing Loss

9 Unilateral Slowly Progressive Hearing Loss

Eric L. Slattery, Timothy E. Hullar, and Lawrence R. Lustig

Unilateral slowly progressive sensorineural hearing loss is perhaps one of the most common presentations of hearing loss. The key to differentiating the etiology is to determine how long hearing has been lost (days, weeks, months, or years), and whether or not there are any associated features, such as vertigo or other neurologic symptoms. Past history is important, particularly with regard to prior noise exposure. Radiographic evaluation is important for all cases of unilateral hearing loss to rule out a retrocochlear etiology, such as vestibular schwannoma.

Sensorineural Hearing Loss: Inner Ear

Autoimmune Inner Ear Disease/Autoimmune Hearing Loss

Autoimmune hearing loss most commonly presents as a rapidly progressive (as opposed to sudden) hearing loss occurring over weeks to months. However, at times the hearing loss may be sudden. The sensorineural hearing loss may be associated with vestibular dysfunction and vertigo if the vestibular organs are also affected. There may also be symptoms or signs of a systemic autoimmune disorder, such as relapsing polychondritis, rheumatoid arthritis, systemic lupus, Cogan syndrome, or a vasculitis. Corticosteroids (systemic and/or parenteral) are used for treatment, and a beneficial response is also used to confirm the diagnosis. Laboratory testing for HSP (heat shock protein) 68 kD may be suggestive of the diagnosis but not pathognomonic. Although autoimmune hearing loss may be unilateral, it is usually bilateral.

Ototoxicity

The most common cochlear ototoxic medications are aminoglycoside and macrolide antibiotics, loop diuretics, quinine, and platinum chemotherapeutic compounds. Hearing loss from ototoxicity varies in its time course, depending on the offending ototoxic agent, and though usually slow and cumulative in onset, it may be sudden in some instances. With most aminoglycoside antibiotics, there is typically vestibular dysfunction before hearing loss. Otherwise, there are no other associated symptoms except tinnitus. Higher frequencies are affected first in ototoxicity, progressing to lower frequencies as the damage continues. As a result, screening for ototoxicity also involves testing of frequencies above 8 kHz. Although ototoxic sensorineural hearing loss may be unilateral, it is usually bilateral.

Meniere Disease

Patients with Meniere disease present with fluctuating, sudden, usually low-frequency sensorineural hearing loss in association with spells of vertigo, aural fullness, and roaring tinnitus. The diagnosis is made after excluding other potential etiologies, as there is no definitive test to identify the disease. In the early stages, the hearing will often be normal between spells, whereas in the later stages of the disease, there may be a permanent sensorineural hearing loss, which can occur gradually. Hearing loss may be unilateral or bilateral.

Radiation-Induced Inner Ear Injury

Radiation administered for nasopharyngeal, skull base, or intracranial pathologies may involve the inner ear. This can lead to both sensorineural hearing loss and tinnitus in one or both ears.

Hereditary Hearing Impairment

Most of the syndromic hereditary hearing impairments do not present as adults, and most are associated with comorbidities (this topic will be discussed further in section III). Nonsyndromic hereditary hearing loss, as seen in patients with connexin 26 anomalies, may present as adults. This is more commonly bilateral than unilateral.

Spirochetal Diseases

Both congenital and acquired syphilis may cause sensorineural hearing loss leading to deafness and tinnitus. One or both ears may be affected, with poor discrimination scores a hallmark in association with a progressive sensorineural hearing loss. Rarely, the hearing loss may present as a sudden deafness. Vestibular complaints are also commonly associated with the hearing loss. Diagnosis is based on the history and presence of associated symptoms of syphilis and suggested by serologic testing (the fluorescent treponemal antibody absorption test), but cerebrospinal fluid (CSF) analysis may be required. Similarly, Lyme disease may lead to vertigo and fluctuating sensorineural hearing loss. Lyme disease would be expected only in endemic areas.

Collagen Vascular Diseases

Collagen vascular diseases may lead to dizziness, tinnitus, and sensorineural hearing loss. Usually otologic symptoms are a relatively minor and late manifestation of disease. Specific disease entities include:

Rheumatoid arthritis