Ear, nose and throat disorder

Hearing Loss and Deafness

Text.

Hearing loss is deterioration in hearing; deafness is profound hearing loss.

Hearing loss may be caused by a mechanical problem in the ear canal or middle ear that blocks the conduction of sound (conductive hearing loss) or by damage to the inner ear, auditory nerve, or auditory nerve pathways in the brain (sensorineural hearing loss). The two types of hearing loss can be distinguished by comparing how well a person hears sounds conducted by air with how well the person hears sounds conducted by bones.

Sensorineural hearing loss is categorized as sensory when the inner ear is affected or as neural when the auditory nerve or auditory nerve path­ways in the brain are affected. Sensory hearing loss may be hereditary, or it may be caused by very loud noise (acoustic trauma), a viral infection of the inner ear, certain drugs, or Meniere's diseases. Neural hearing loss may be caused by brain tumors that also damage nearby nerves and the brain stem. Other causes include infections various brain and nerve disorders such as stroke, and some hereditary diseases such as Refsum's disease. In childhood, the auditory nerve can be damaged by mumps, German measles (rubella), meningitis, or inner ear infections. Auditory nerve pathways in the brain can be damaged by demyelinating diseases (diseases that destroy the nerve covering).

Diagnosis

Hearing tests with tuning forks can be con­ducted in a doctor's office, but hearing is best tested in a soundproof booth by an audiologist (a specialist in hearing loss) using an electronic de­vice that produces sounds at specific pitches and volumes. Hearing by air conduction in adults is tested by placing a vibrating tuning fork near the ear so that sound has to travel through the air to reach the ear. A hearing loss or a subnormal au­ditory threshold (the faintest sound that can be heard) can indicate a problem in any part of the hearing apparatus—the ear canal, middle ear, in­ner ear, auditory nerve, or auditory nerve path­ways in the brain.

In adults, hearing by bone conduction is tested by placing the base of a vibrating tuning fork against the head. The vibration spreads through­out the skull, including through the bony cochlea in the inner ear. The cochlea contains hair cells that convert the vibrations to nerve impulses, which then travel along the auditory nerve. This test bypasses the outer and middle ear, evaluating only the inner ear, auditory nerve, and auditory nerve pathways in the brain. Tuning forks with a variety of pitches (frequencies) are used because a person may be able to hear sounds at some pitches but not others.

If hearing by air conduction is reduced but hearing by bone conduction is normal, the hear­ing loss is conductive. If hearing by air and bone conduction is reduced, the hearing loss is senso­rineural. Occasionally, hearing loss is both con­ductive and sensorineural.

Audiometry measures hearing loss precisely with an electronic device (an audiometer) that produces sounds at specific pitches (pure tones) and specific volumes. The auditory threshold for a range of tones is determined by decreasing the volume of each tone until a person can no longer hear it. Each ear is tested separately. Earphones are used to measure air conduction hearing, and a vibrating device is held against the bone behind the ear (mastoid process) to measure bone con­duction hearing. Because loud tones presented to one ear may also be heard by the other ear, the test tone is masked by presenting a different sound, usually noise, to the ear not being tested. This way, the person hears the test tone only in the ear being tested.

Speech threshold audiometry measures how loudly words have to be spoken to be understood. A person listens to a series of two-syllable, equally accented words—such as railroad, staircase, and baseball—presented at specific volumes. The vol­ume at which the person can correctly repeat half of the words (spondee threshold) is recorded.

Discrimination, the ability to hear differences be­tween words that sound similar, is tested by pre­senting pairs of similar one-syllable words. The discrimination score (the percentage of words correctly repeated) is usually in the normal range when hearing loss is conductive, below normal when hearing loss is sensory, and far below nor­mal when hearing loss is neural.

Tympanometry, a type of audiometry, measures the impedance (resistance to pressure) of the middle ear. It's used to help determine the cause of conductive hearing loss. This procedure doesn't require the active participation of the per­son being tested and is commonly used in chil­dren. A device containing a microphone and a sound source that produces continuous sound is placed snugly in the ear canal. The device detects how much sound passes through the middle ear and how much is reflected back as pressure changes in the ear canal. The results of this test indicate whether the problem is a blocked eu­stachian tube (the tube that connects the mid­dle ear and back of the nose), fluid in the middle ear, or a disruption in the chain of three bones (ossicles) that transmit sounds through the middle ear.

Tympanometry also detects changes in the contraction of the stapedius muscle, which is at­tached to the stirrup (stapes), one of the three bones in the middle ear. This muscle normally contracts in response to loud noises (acoustic reflex), reducing the transmission of sound and thus protecting the inner ear. The acoustic reflex changes or decays if the hearing loss is neural.

When the acoustic reflex is decayed, the stape­dius muscle can't remain contracted during con­tinuous exposure to loud noise.

Auditory brain stem response is another test that can distinguish between sensory and neural hear­ing loss. It measures nerve impulses in the brain resulting from stimulation of the auditory nerves. Computer enhancement produces an image of the wave pattern of the nerve impulses. If the cause of hearing loss appears to be in the brain, mag­netic resonance imaging (MRI) of the head may be performed.

Electrocochleography measures the activity of the cochlea and the auditory nerve. This test and the auditory brain stem response can be used to measure hearing in people who can't or won't respond voluntarily to sound. For example, these tests are used to find out whether infants and children have profound hearing loss and whether a person is faking or exaggerating hearing loss (psychogenic hypacusis). Sometimes the tests can help determine the cause of sensorineural hearing loss. Auditory brain stem response also can be used to monitor certain brain functions in people who are comatose or in those undergoing brain surgery.

Some hearing tests can detect disorders in the auditory processing areas of the brain. These tests measure the ability to interpret and under­stand distorted speech, to understand a message presented to one ear when a competing message is presented to the other ear, to fuse incomplete messages to each ear into a meaningful message, and to determine where a sound is coming from when sounds are presented to both ears at the same time.

Because the nerve pathways from each ear cross to the other side of the brain, an abnormal­ity on one side of the brain affects hearing in the ear on the other side. Brain stem lesions can im­pair the ability to fuse incomplete messages into a meaningful message and to pinpoint where sounds are coming from.

Treatment

Treatment of hearing loss depends on the cause. For example, if fluid in the middle ear or wax in the ear canal is causing a conductive hear­ing loss, the fluid is drained or the wax removed. Often, no cure is available. In these cases, treat­ment involves compensating for the hearing loss as much as possible. Most people use a hearing aid. Rarely, a cochlear implant is used.

Notes:

deterioration ухудшение

profound абсолютный, полный, совершенный

tuning fork камертон

soundproof booth звукоизолированная кабина; заглушённая кабина

pitch высота (тона, звука и т. п.)

threshold of hearing порог слышимости

earphone слуховой аппарат

discrimination различение, выделение, дифференциация, разграничение;

a sound source источник звука

disruption разрушение

ossicle косточка

 

Outer Ear Disorders

 

The outer ear consists of the external part of the ear (pinna or auricle) and the ear canal (ex­ternal auditory meatus). Disorders of the outer ear include blockages, infections, injuries, and tumors.

Text A. Blockages

 

Earwax (cerumen) may block the ear canal and cause itching, pain, and a temporary loss of hearing. A doctor may remove the earwax by gently flushing out the ear canal with warm water (irri­gation). However, if a person has ever had a dis­charge from the ear, a perforated eardrum, or re­curring outer ear infections, irrigation isn't used. When the eardrum is perforated, water can enter the middle ear and possibly worsen a chronic infection. In these situations, a doctor may re­move earwax with a blunt instrument, an instru­ment with a loop at the end, or a vacuum device. These procedures are generally less messy and more comfortable than irrigation. A doctor usu­ally doesn't use earwax solvents because they often irritate the skin of the ear canal, cause aller­gic reactions, and don't dissolve the wax adequately.

Children may put all kinds of foreign objects into the ear canal, particularly beads, erasers, and beans. Usually, a doctor removes such objects with a blunt hook. Objects that go deep into the canal are more difficult to remove because of the risk of injuring the eardrum and small bones of the middle ear. Sometimes metal and glass beads can be flushed out by irrigation, but water causes some objects, such as beans, to swell, complicat­ing removal. A general anesthetic is used when a child doesn't cooperate or when removal is par­ticularly difficult.

Insects may enter the ear canal. Filling the canal with mineral oil kills the insect, providing imme­diate relief, and also helps with the removal.

Notes:

pinna ушная раковина

earwax серная пробка, ушная сера

eardrum барабанная перепонка

blunt тупой, тупоконечный

solvent растворитель

blunt hook тупой крючок

Text B. External Otitis

 

External otitis is an infection of the ear canal.

The infection may affect the entire canal, as in generalized external otitis, or just one small area as a boil (furuncle). External otitis, often called swimmer's ear, is most common during the summer swimming season.

Causes

A variety of bacteria, or rarely, fungi, can cause generalized external otitis; the bacterium Staphylococcus usually causes boils. Certain people, including those who have allergies, psoriasis, ec­zema, or scalp dermatitis, are particularly prone to external otitis. Injuring the ear canal while cleaning it or getting water or irritants such as hair spray or hair dye in the canal often leads to external otitis.

The ear canal cleans itself by moving dead skin cells from the eardrum out through the canal as if they were on a conveyor belt. Attempting to clean the canal with cotton swabs interrupts this self-cleaning mechanism and can push debris to- ward the eardrum, where it accumulates. Accumulated debris and earwax tend to trap water that gets into the ear canal during a shower or while swimming. The resulting wet, softened skin in the ear canal is more easily infected by bacteria or fungi.

Symptoms

Symptoms of generalized external otitis are itching, pain, and a malodorous discharge. If theear canal swells or fills with pus and debris, hear­ing is impaired. Usually, the canal is tender and hurts if the external ear (pinna) is pulled or if pressure is placed on the fold of skin in front of the ear canal. To a doctor looking into the ear canal through an otoscope (a device for viewing the canal and eardrum), the skin of the canal appears red, swollen, and littered with pus and debris.

Boils cause severe pain. When they rupture a small amount of blood and pus may leak from the ear.

Treatment

To treat generalized external otitis, a doctor first removes the infected debris from the canal with suction or dry cotton wipes. After the ear canal is cleared, hearing frequently returns to nor­mal. Usually, a person is given antibiotic ear drops to instill in the ear several times a day for up to a week. Some ear drops also contain a corticoste­roid to reduce swelling. Sometimes ear drops con­taining diluted acetic acid are prescribed to help restore the acidity of the ear canal. Analgesics such as acetaminophen or codeine may help re­duce pain for the first 24 to 48 hours, until the inflammation begins to subside. An infection that has spread beyond the ear canal (cellulitis) may be treated with an antibiotic given by mouth.

Boils are allowed to drain on their own because cutting them open can spread the infection. Antibiotic ear drops are not effective. A heating pad applied for a short time and analgesics can help, relieve pain and speed healing.

Notes:

conveyor belt лента конвейера, конвейерная лента

malodorous неприятный запах, зловонный

debris осколки; обломки; остатки

suction отсасывание

wipe вытирать

Text C. Injury

An injury such as a blunt blow to the external ear can cause bruising between the cartilage and the layer of connective tissue around it (peri­chondrium). When blood collects in this area, the external ear becomes a misshapen, reddish pur­ple mass. The collected blood (hematoma) can cut off the blood supply to the cartilage, leading to a deformed ear. This deformity, called a cauli­flower ear, is common among wrestlers and box­ers. Usually, a doctor uses suction to remove the hematoma, and suction is continued until all evi­dence of the hematoma is gone, usually 3 to 7 days. Treatment causes the skin and perichon­drium to return to their normal positions, allow­ing blood to reach the cartilage again.

If a cut (laceration) goes all the way through the ear, the skin is sewn back together and a splint is attached to the cartilage to allow healing.

A forceful blow to the jaw may fracture the bones surrounding the ear canal and distort the canal's shape, often narrowing it. The shape can be corrected surgically; general anesthesia is re­quired.

Notes:

misshapen уродливый

laceration разрыв; рваная рана

sew down пришивать

splint лонгета, шина

 

Text D. Tumors

 

Tumors of the ear may be noncancerous (be­nign) or cancerous (malignant).

Noncancerous tumors may develop in the ear canal, blocking it and causing a buildup of earwax and hearing loss. Such tumors include sebaceous cysts (small sacs filled with skin secretions), os­teomas (bone tumors), and keloids (growths of excess scar tissue after an injury). The best treat­ment is removal of the tumor. After treatment, hearing usually returns to normal.

Ceruminoma (cancer of the cells that produce earwax) develops in the outer third of the ear canal and can spread. Treatment consists of surgical removal of the cancer and the surrounding tissue.

Basal cell and squamous cell cancers are com­mon skin cancers that often develop on the exter­nal ear after repeated and prolonged exposure to the sun. When these cancers first appear, they can be successfully treated by excising them or by applying radiation therapy. More advanced can­cers may require surgical removal of a larger area of the external ear. When the cancer has invaded the cartilage of the ear, surgery is more effective than radiation therapy.

Basal cell and squamous cell cancers also may develop in or spread to the ear canal. Their treatment consists of surgically removing the cancer and a wide margin of the surrounding tissue, fol­lowed by radiation therapy.

Notes:

benign доброкачественный (напр. об опухоли)

margin прилежащая, приграничная полоса, край