Hearing Loss: A Silent Epidemic

Harvard Health Watch

Everyone experiences hearing loss from time to time: ear wax, ear infections, and the ear-popping sensation that bothers air passengers during takeoff are common causes of temporary hearing loss. And a mild degree of permanent hearing impairment is an inevitable part of the aging process. But for millions of people, the problem is more serious. Major hearing loss becomes more common with increasing age, particularly after age 65, and men are 5.5 times more likely than women to have hearing loss that makes communication difficult.

Fortunately, modern medical care can help.

HOW YOU HEAR

The ear is divided into three parts. The outer portion consists of the external ear and the ear canal. The middle ear consists of the eardrum, or tympanic membrane, and three small bones, or ossicles (the malleus, incus, and stapes). The inner ear, or labyrinth, is the most complex. It includes the cochlea, the three semicircular canals, which are responsible for balance, and one end of the auditory nerve, which connects to the brain.

The external ear collects sound waves, and the ear canal funnels them to the eardrum. As sound waves strike the eardrum, they cause it to vibrate. The vibrations are relayed along the chain of tiny bones in the middle ear until they reach the third bone, which connects to the cochlea.

The cochlea is a busy little world of its own. It's filled with fluid that surrounds the 10,000 to 15,000 tiny hair cells (cilia). Vibrations of the stapes send fluid waves through the spiral-shaped cochlea. The fluid waves produce swaying movements of the hair cells. In turn, these cells release chemical neurotransmitters that activate the auditory nerve, sending miniature electric currents to your brain, which interprets them as sound.

Your ear is a complex apparatus that converts sound waves into electrical impulses that travel to the brain.

COMPLEX AND DELICATE

The human ear is the envy of even the most sophisticated acoustic engineer. Without a moment's thought or the slightest pause, you can hear the difference between a violin and a clarinet, you can tell if a sound is coming from your left or right, and if it's distant or near. You can tell if a human voice is male or female, young or old. And you can discriminate between words as similar as hear and near, sound and pound.

As every computer user knows, sophistication and complexity have a dark side. In broad terms, there are three major types of hearing loss:

1. Conductive hearing loss, which results from anything that reduces the amount of sound that reaches the inner ear

2. Sensorineural hearing loss, which results from problems involving the inner ear, including the cochlea and auditory nerve

3. Mixed hearing loss, which results from a combination of conductive and sensorineural problems.

CONDUCTIVE HEARING LOSS

A blockage of the ear canal can prevent sound waves from reaching the eardrum. Tightly packed ear wax (impacted cerumen) is the leading culprit. It's also the easiest to treat -- but only if you do it right. Other causes of conductive hearing loss include boney overgrowths, inflammation of the external ear, and the material that some people use in ill-advised attempts to clean their ears.

But even if sound waves make it through the external ear, a perforated or scarred eardrum may not vibrate properly and may fail to conduct sound onward. A collection of fluid in the middle ear will also block normal conduction.

Finally, boney overgrowth of the stapes (otosclerosis) can prevent the third and final middle ear bone from functioning as a piston that converts vibrations in the middle ear into fluid waves in the cochlea.

Conductive hearing loss affects mainly low-frequency sounds. Medical or surgical treatments can often help; examples range from simply removing ear wax to draining fluid from the middle ear, repairing a damaged eardrum, and surgical reconstruction of the stapes.

Ear wax

Ear wax, cerumen, is part of the human condition, and it's very democratic, affecting men and women, rich and poor, old and young.

Although ear wax is normal, it can cause itching and ear discomfort. It's also blamed for ringing in the ears (tinnitus) and dizziness (vertigo), but in most cases it doesn't deserve the rap. But ear wax can cause conductive hearing loss if it blocks the ear canal, and it can interfere with a hearing aid.

There's no way to stop your ears from making wax but you can keep it from building up by using drops like Debrox. Never try to dig out impacted cerumen on your own; it won't work, and you might injure your eardrum. Instead, see a doctor or nurse. You may have to use softening drops for three to five days before the wax gets cleaned out by irrigating the ear with warm water.

Cerumen seems like a simple problem, but men with impaired hearing will wax eloquent when it is removed.

SENSORINEURAL HEARING LOSS

The most common problem is presbycusis, a fancy name for age-related dysfunction of the cochlea and its hair cells. With presbycusis, hearing loss begins gradually, progresses slowly, and usually affects both ears equally. Most people with presbycusis (literally "older hearing") have difficulty with high-frequency sounds first, then gradually experience problems with mid- and then low-frequency sounds.

The only way to prevent presbycusis is to avoid getting old. But you can and should prevent the other leading cause of sensorineural hearing loss, acoustic trauma, or noise-induced hearing loss. Loud sounds damage the hair cells of the cochlea; and if the damage is severe enough, hearing loss is permanent. Although a single loud sound, such as a shotgun blast, can do the deed, noise-induced hearing loss usually results from repeated exposure to excessive loudness. iPod generation beware!

The many other causes of sensorineural hearing loss include smoking, diabetes, exposure to certain drugs (aminoglycoside antibiotics, the anticancer drug cisplatin, the diuretics furosemide and ethacrinic acid, quinidine, and high-dose aspirin), Ménière's disease. multiple sclerosis, skull trauma, acoustic nerve tumors, and hereditary hearing loss.

Sudden sensorineural hearing loss deserves special mention because it's a true emergency. When severe hearing loss, usually in one ear, comes on abruptly without apparent cause, experts suspect a viral infection. Treatment with corticosteroids may help restore hearing, but only if the medication is administered promptly.

Sensorineural hearing loss usually affects high-pitched sounds first. That's why it's responsible for the somewhat facetious diagnosis of "wife deafness." A man with presbycusis may be unable to decipher his wife's high-pitched words, while his similarly affected spouse can still hear her low-pitched husband. Failing to hear a woman or child is bad enough, but missing a whistling kettle, doorbell, telephone, or wailing siren can be even more dangerous.

Many people with sensorineural hearing loss try to compensate by turning up the volume. Unfortunately, it rarely helps. Patients can usually hear that someone is speaking but they cannot understand what is being said because speech discrimination is poor. Shouting only makes the problem worse, and competition from background noise, as in a busy restaurant, is very troublesome. Understanding consonants is particularly difficult, so similar words are confused with each other (someday and Sunday, fish and this, map and mat). A sense of humor can only go so far in dealing with such fundamental barriers to communication.

LOUDER, PLEASE

Hearing tests are accurate and simple, but they require expensive equipment, a skilled audiologist, and about a half hour of your time. Before you ask your doctor to refer you for an audiogram, try to figure out if you need one. The key is to ask yourself if you have a hearing problem -- but before you shrug off the question with a macho "not me," be a bit more specific:

Are you always turning up the volume on your TV or radio?

Do you shy away from social situations or meeting new people because you're worried about understanding them?

Do you get confused or feel "out of it" at restaurants or dinner parties?

Do you ask people to repeat themselves?

Do you miss telephone calls -- or have trouble hearing on the phone when you do pick up the receiver?

Do the women in your world complain that you never listen to them (even when you're really trying)?

You can ask a friend to test you by whispering a series of words or numbers. After all this, if you think you have a hearing problem, you should have a test.

TINNITUS: THE BUZZ THAT BOTHERS

Although ringing in the ears can plague people with normal hearing, it's particularly common in people with hearing loss. The sound is often described as buzzing or ringing, but it can also be a whistling, humming, clicking, or whooshing sound that can be loud or soft, constant or intermittent, present in one ear or both.

Tinnitus can occur with sensorineural hearing loss, acoustic trauma, Ménière's disease, auditory nerve damage, or certain medications. More often, though, it occurs without obvious cause.

Patients who are bothered by tinnitus deserve an evaluation by a specialist. If no specific cause is identified, the treatment aims to reduce symptoms. White noise machines can help. And in most cases, people can simply learn to live with tinnitus.

YOUR AUDIOGRAM

Comprehensive hearing evaluations are conducted by doctors specializing in the ear, nose, and throat (called otolaryngologists, or ENTs) and audiologists. The first step is a medical interview and examination of your ears, nose, and throat, followed by a few simple office hearing tests.

Next comes your audiogram. You'll sit in a soundproof booth wearing earphones that will allow each ear to be tested separately. A series of tones at various frequencies will be piped to your ear, and you'll be asked to indicate the softest tone you can hear in the low-, mid-, and high-frequency ranges. People with excellent hearing can generally hear tones as soft as 20 decibels (dB) or less. If you can't hear sounds softer than 45 to 60 dB, you have moderate hearing loss, and if you don't hear sound until it's ramped up to 76 to 90 dB, you have severe hearing loss.

Hearing tones is nice, but hearing and understanding words is crucial. The audiologist plays tape-recorded words at various volumes to find your speech reception threshold, the lowest dB level at which you can hear and repeat half the words. Finally, you'll be tested with a series of similar sounding words to evaluate your speech discrimination.

Depending on the results of your audiogram, you may be referred for additional tests to pinpoint your hearing problem, perhaps including a CT scan or MRI to look for structural abnormalities in your ears or nervous system.

FEELING DIZZY

When doctors speak of dizziness, they don't mean a lightheaded or foggy feeling. Instead, they mean vertigo, a spinning sensation that's often accompanied by nausea. Vertigo is like being seasick without the sea. Many things can cause vertigo. Most often, the problem originates in the body's gyroscope in the inner ear, known as the labyrinthine apparatus.

Benign positional vertigo (BPV) is quite common. It produces dizziness that's triggered by certain head positions, such as tilting your head to look up or turning it on your pillow. The dizziness usually last for less than 30 seconds, but it returns when your head moves the "wrong" way again. BPV is caused by small bits of debris in the inner ear's semicircular canals. Doctors or physical therapists can perform special head movement maneuvers to float the particles out of the way, resolving most cases.

Viral infections of the inner ear, called vestibular neuritis, can cause dizziness or nausea that lasts for days or sometimes weeks. The inflammation settles down on its own, but until it does, antinausea or antimotion sickness medications may help.

Méniere's disease produces episodes of dizziness and nausea, often with buzzing in the ear. It's a chronic condition that's more common in older adults. Doctors believe it's the result of excessive fluid in the inner ear canals. A low-salt diet, diuretics ("water pills"), and medications for nausea and motion sickness may help. In most cases, the symptoms come and go without creating too much difficulty, but in very severe cases, surgery may be considered.

The many other causes of dizziness range from migraines to much less common things like strokes and tumors (usually benign). So if your head takes you for a spin, see your doctor for diagnosis and treatment.

HEARING AIDS

Men are 5.5 times more likely than women to have hearing loss that makes communication difficult. However, many men deny they have hearing loss because they don't want to be seen wearing a hearing aid. Although young, hip guys fill their ears with Bluetooth receivers and iPod ear buds, a hearing aid may still be stigmatized as a sign of old age.

Vanity notwithstanding, it's important for men to face up to hearing loss. For one thing, conductive hearing losses can often be corrected by procedures as simple as removing ear wax or as delicate as operating on a recalcitrant stapes bone in the middle ear. For another, hearing aids have come a long way, both in looks and performance.

People whose main problem is volume respond best, but men with impaired speech discrimination may also benefit. The trick is to find the device that's best for you.

All hearing aids work on the same basic principle. A microphone captures sound, converts it to electrical impulses, and relays these signals to an amplifier. The amplifier boosts the volume, and it can also fine-tune the signals to make them easier for you to process. Finally, the altered signals are sent to a tiny receiver that converts them back to sound waves that are directed to your ear.

Although they all share this basic plan, today's digital hearing aids come in a wide range of styles, including tiny, custom-fitted devices that fit entirely inside the ear canal, somewhat larger models that extend from the canal into the external ear, models that sit behind the ear and carry sound into the canal through a thin tube, and open-fit aids that fit behind the ear and carry sound to tiny earbuds that leave most of the ear canal unobstructed.

Adding to the complexity, some aids come with volume controls or other programmable adjustments. Best of all, sophisticated electronics have reduced (but not eliminated) problems of feedback, interference, and whistling that bedeviled older devices.

All of these advances come at a price, quite a high price, in fact. Although costs vary, don't be surprised to find that a digital hearing aid may set you back $1,000 to $4,000 -- per ear. And in most cases, neither Medicare nor private insurance will be much help. That means you need an accurate prescription, a reputable company, and a trial period so you can return a device that doesn't live up to its promise.

NEW HORIZONS FOR HEARING

Physicians, engineers, and physicists have collaborated to produce amazing advances in medicine. Compared to some space-age devices, hearing aids seem pretty humble. But the team approach has gone beyond the hearing aid to the development of new treatments.

The cochlear implant is the most important example. It has helped thousands of children with severe hearing loss, and it's finding a role for some adults with severe sensorineural hearing loss in both ears that does not improve with hearing aids. Unlike a hearing aid, a cochlear implant replaces the normal hearing mechanism. An external microphone picks up sound and transmits it to a receiver implanted under the skull.

Electrical impulses are relayed along wires to electrodes coiled inside the cochlea that connect to the auditory nerve itself. It's like a hearing bypass -- sound is transmitted from the outside world to the auditory nerve without involving the eardrum, bones of the middle ear, or hair cells of the cochlea.

A cochlear implant is a big deal, and it's only indicated for a small minority of the many millions of adults with hearing loss. And hope for fancy progress in the future should not distract you from the things that can help today. Preserve your hearing in every way possible, particularly by protecting yourself from loud sounds. If your hearing is impaired, do the simple things that make life easier, including using an amplified telephone and assist devices at plays, movies, concerts, and religious services.

Consider getting a flashing light hooked up to your telephone, door bell, and smoke alarms. Plan social and professional gatherings in quiet places. Practice good communication skills: get away from competing sounds, make conversation a face-to-face affair, and don't be shy about asking people to speak slowly, clearly, and even a bit louder. Repeat back important information to be sure you got it right. And don't fail to get your hearing tested so you can have a professional evaluation for the hearing aid that's best for you. - Harvard Men's Health Watch

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