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- May affect patients of all ages
- For patients who have unilateral hearing loss
- Weber tuning fork test lateralizes to the unaffected side
- Rinne tuning fork test demonstrates air conduction greater than bone conduction
- Pure-tone thresholds result in equally diminished air and bone conduction
- Speech discrimination testing less than 90% correct.
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Hearing loss is extremely common and has a wide spectrum ranging from a nearly undetectable degree of disability to a profound loss of ability to function in society. Nearly 10% of the adult population has some hearing loss. Often, this impairment presents early in life. One to three of every 1000 newborn in the United States is completely deaf, and more than 3 million children have hearing loss. However, hearing loss can present at any age. Between 30% and 35% of individuals over the age of 65 have a hearing loss sufficient to require a hearing aid. Forty percent of people over the age of 75 have hearing loss.
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Hearing loss can result from disorders of the auricle, external auditory canal, middle ear, inner ear, or central auditory pathways. In general, lesions in the auricle, external auditory canal, or middle ear cause conductive hearing loss. The focus of this chapter is sensorineural hearing loss that tends to result from lesions in the inner ear or eighth nerve. See Table 52–1 for a list of the common causes of hearing loss.
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Sensorineural hearing loss may result from damage to the hair cells caused by intense noise, viral infections, fractures of the temporal bone, meningitis, cochlear otosclerosis, Meniere disease, and aging. The following drugs can also produce sensorineural hearing loss: ototoxic drugs (eg, salicylates, quinine, and the synthetic analogs of quinine), aminoglycoside antibiotics, loop diuretics (eg, furosemide and ethacrynic acid), and cancer chemotherapeutic agents (eg, cisplatin).
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Age-Related Hearing Loss (Presbycusis)
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Presbycusis, age-associated hearing loss, is the most common cause of hearing loss in adults. Initially, it is characterized by symmetric, high-frequency hearing loss that eventually progresses to involve all frequencies. More important, the hearing loss is associated with a significant loss in clarity.
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Congenital Hearing Loss
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Congenital malformations of the inner ear cause hearing loss in some adults. Genetic predisposition alone or in concert with environmental influences may also be responsible.
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