Presbycusis

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Saumya Easaw, M.B.B.S.[2]

Presbycusis, or age-related hearing loss, is the cumulative effect of aging on hearing. Also known as presbyacusis, it is defined as a progressive bilateral symmetrical age-related sensorineural hearing loss. The hearing loss is confined to higher frequencies.

Recently, this condition has led to the development of technologies to stop younger people from loitering near British stores (The Mosquito), and the development of a cell phone ringtone, Teen Buzz, for students to use in school, that many older instructors are unable to hear. In September 2006 this technique was used to make a dance track called ‘Buzzin’. The track had two melodies, one that everyone could hear and one that only younger people could hear.

Hearing loss usually begins gradually after the age of sixty, and is usually found more often in men than women. This can be miscontributed to men having a greater exposure to environmental noise. However, exposure to environmental noise can lead to noise-induced hearing loss (NIHL), a hearing issue that is separate from presbycusis. Over time, the detection of high-pitched sounds becomes more difficult and both ears tend to be affected.

The physical examination is usually normal with exception of cerumen which is a common problem in elderly people and a frequent cause of hearing loss and hearing aid malfunction.^[1] The physical examination includes otoscopy, whispered ear test and tuning forks for the assessment of hearing loss. The physical examination of the outer ears is usually normal in presbycusis. The otoscopic examination is helpful for finding other potential causes of hearing loss such as cerumen impaction, tympanic membrane perforation, infection or tumors.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Farman Khan, MD, MRCP [2], Saumya Easaw, M.B.B.S.[3]

Examples of microscopic changes seen in this condition are hair cell degeneration of the cochlea and giant stereociliary degeneration.

Hearing loss is broadly subdivided into two categories: Sensorineural and conductive. Conductive hearing loss is characterized by the inability to mechanically transmit sound vibrations from the environment to the inner ear. Sensorineural hearing loss is caused by the inability to effectively transduce sound information into usable neural signals. Mostly sensorineural hearing loss is the result of disorders of the inner ear itself. Presbycusis is sensorineural hearing loss, in which cochlear hair cells and, to a lesser extent, the spiral ganglion cells in the vestibulocochlear nerve can be affected.^[1][2]

In the histopathology classification system there are three main types of presbycusis.

• Sensory: High-frequency hearing deficit caused by loss of hair cells.

• Metabolic: Low-frequency hearing deficit caused by loss of stria vascularis.

• Neural: Variable pattern of hearing loss caused by loss of ganglion cells.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Saumya Easaw, M.B.B.S.[2]

• Hereditary: Features like early aging of the cochlea and susceptibility of the cochlea for drug insults are genetically determined.
• Atherosclerosis: May diminish vascularity of the cochlea, thereby reducing its oxygen supply.
• Dietary habits: Increased intake of fatty diet may accelerate atherosclerotic changes in old age.
• Diabetes: May cause vasculitis and endothelial proliferation in the blood vessels of the cochlea, thereby reducing its blood supply.
• Noise trauma: Exposure to loud noise on a continuing basis stresses the already hypoxic cochlea, hastening the presbycusis process.
• Smoking: Is postulated to accentuate atherosclerotic changes in blood vessels aggravating presbycusis.
• Hypertension: Causes potent vascular changes, like reduction in blood supply to the cochlea, thereby aggravating presbycusis.
• Ototoxic drugs: Ingestion of ototoxic drugs like aspirin may hasten the process of presbycusis.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Farman Khan, MD, MRCP [2]

Presbycusis should be differentiated from other causes of hearing loss:

• Acoustic neuroma
• Meningioma
• Multiple sclerosis
• Autoimmune disease
• Multiple sclerosis
• Perilymphatic or labyrinthine fistula
• Occupational noise-induced hearing loss
• Meniere’s disease
• Viral cochleitis
• Hearing loss secondary to ototoxic drugs
• Barotrauma

• Otosclerosis
• Otitis media
• Otosclerosis
• Perforation of tympanic membrane
• Glomus tumors
• Granulomatous diseases

• Otitis externa
• Exostosis
• Cerumen
• Squamous cell carcinoma

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1], Farman Khan, MD, MRCP [2]

Hearing impairment is the third most commonly reported chronic problem affecting the aged population.^[1]In one study in the United States, the prevalence of hearing loss (defined by audiometry) increased steadily with age. It is about 11 percent in ages 44 to 54, 25 percent in ages 55 to 64 and 43 percent in ages 65 to 84. The World Health organization (WHO) estimates that in 2025, there will be 1.2 billion people over 60 years of age worldwide, with more than 500 million individuals who will suffer significant impairment from presbycusis. The incidence of presbycusis for people aged 75 years and older is thought to to have risen to 40-50%.

The prevalence of hearing loss increases with age. Presbycusis affects more than half of all adults by age 75 years.

There is no difference in the prevalence of presbycusis between the sexes.

No known difference exists in the prevalence of presbycusis based on race.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Farman Khan, MD, MRCP [2]

The onset and severity of presbycusis is influenced by multiple factors such as:^[1]

• A genetic component that predisposes individuals to age-related hearing loss
• Diabetes
• Hypertension
• Infections
• Low socioeconomic status
• Noise exposure
• Ototoxins
• Smoking
• Vascular disease

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Saumya Easaw, M.B.B.S.[2]

Recently, this condition has led to the development of technologies to stop younger people from loitering near British stores (The Mosquito), and the development of a cell phone ringtone, Teen Buzz, for students to use in school, that many older instructors are unable to hear. In September 2006 this technique was used to make a dance track called ‘Buzzin’. The track had two melodies, one that everyone could hear and one that only younger people could hear.

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