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Age-related Hearing Loss
ALTERNATIVE NAMES: Presbycusis.
DEFINITION: Age-related hearing loss is thought to be a decline in the nerve function of the ear as individuals age.
WHAT IS GOING ON IN MY BODY? There are three different kinds of hearing loss. The first type is an abnormality in the eardrum or the bones for hearing that transmit sound from the environment into the inner ear. Anything that prohibits the eardrum (tympanic membrane) or the hearing bones (ossicles: malleus, incus, stapes) from moving effectively will result in a conductive hearing loss. The second type of hearing loss is when the eardrum and the ossicles function normally, but there is a loss of nerve sensitivity of the inner ear (sensorineural hearing loss). The third type of hearing loss is a combination of both conductive and sensorineural deficits and is termed a mixed loss. There have been some interesting studies trying to determine whether or not the hearing loss seen with aging is actually a consequence of aging or a result of ambient environmental noise. Nomadic Sudanese tribes in the Sahara dessert have had their hearing tested; and interestingly there is very little, if any, change in hearing abilities with age. Another study was done of inhabitants of Easter Island, which is located far off the coast of South America. Easter Island is non-industrial and until recently had very little automobile traffic and no industry. Individuals who had never left the island maintain excellent hearing over their full life span; but those individuals who had left Easter Island and lived in industrialized cities within Chile started to demonstrate nerve-related hearing loss. The severity of the sensorineural loss correlated with the length of time the individual had been away from the island and lived in an industrialized environment. Therefore, there is some question as to whether or not hearing loss seen with aging is truly a genetically programmed process or whether it is the accumulation of environmental noise trauma over the life span of an individual.
The main area of injury in "age-related hearing loss" is in the cochlea, a snail-shell-shaped structure which generates the first electrical impulse for hearing. There is usually a loss of cells that pick up the tones, particularly in the high-frequency portion of the cochlea. As these cells are damaged, they lose their ability to transmit sound in the form of pitches. The loss of these cells accounts for the high-frequency hearing loss identified on hearing tests.
WHAT ARE THE SIGNS AND SYMPTOMS? The individual with a hearing loss often is unaware that there is a gradual decline in their ability to perceive words or sound. One of the first clues that there is a loss is the complaints from other individuals that the person is unable to hear them when they are speaking. They may turn the television up more loudly than is comfortable for others. Patients suffering from hearing loss often complain that it is difficult for them to pick out conversation in the presence of background noise. Frequently there is associated ringing in the ears (tinnitus).
WHAT ARE THE CAUSES AND RISKS? The main cause, as mentioned above, is thought to be an accumulation of noise trauma over time. Individuals who are involved in noisy occupations are therefore at a greater risk. There seems to be differences from one individual to another in their degree of noise susceptibility, which raises the possibility that there are genetic factors which determine the degree of injury that occurs with noise exposure. There clearly are families that have heritable sensorineural deafness that begins in middle age, which suggests that genetics plays some role in some cases of presbycusis.
HOW TO PREVENT THE DISEASE: Certainly the genetic component cannot be changed. but the best way to prevent the disease is to limit the amount of noise that enters the inner ear. The use of headphones to listen to music or programs should be discouraged. Moderating the amount of music volume is important. Wearing hearing protection in the form of foam ear plugs or ear muffs when using lawn mowers or power equipment limits the amount of noise exposure of the ear.
HOW IS IT DIAGNOSED: Hearing loss is diagnosed with a hearing test (audiogram), which can determine how much of the hearing loss is a result of nerve injury and how much is consequent to abnormalities in the sound conduction mechanism (tympanic membrane and ossicles).
WHAT ARE THE LONG-TERM EFFECTS? Individuals with diminished hearing often go on to suffer from social isolation. Hearing loss can aggravate some forms of dementia, such as Alzheimer's disease.
AM I PUTTING OTHERS AT RISK? No.
WHAT ARE THE TREATMENTS? Unfortunately, there are no medical treatments for age-related hearing loss. Hearing aids are the mainstay of treatment.
WHAT ARE THE SIDE EFFECTS TO THE TREATMENTS? N/A.
WHAT HAPPENS AFTER TREATMENT? N/A.
HOW DO I MONITOR THE DISEASE? Regular audiograms may be necessary if the hearing loss progresses to not only quantify the deficit but help determine if and what type of hearing aid may be most beneficial.
WHAT ARE THE RESOURCES AND SUPPORT AVAILABLE? Most communities have otolaryngologists (ear, nose, and throat specialists) or audiologists (hearing specialists) who are able to diagnose the type of hearing loss and provide the appropriate treatment.
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