Middle & Inner Ear Disorders

Introduction

The middle ear consists of the eardrum (tympanic membrane) and an air-filled chamber containing a chain of three bones (ossicles) that connect the eardrum to the inner ear. The fluid-filled inner ear (labyrinth) consists of two major parts: the organ of hearing (cochlea) and the organ of balance (vestibular system, which consists of the semicircular canals, the saccule, and the utricle). The middle ear acts as an amplifier of sound, while the inner ear acts as a transducer, changing mechanical sound waves into an electrical signal that is sent to the brain via the nerve of hearing (statoacoustic nerve). Middle and inner ear disorders cause many of the same symptoms, and a disorder of the middle ear may affect the inner ear and vice versa.

An auditory nerve tumor (acoustic neuroma, acoustic neurinoma, vestibular schwannoma, eighth nerve tumor) is a noncancerous (benign) tumor that originates in the cells that wrap around the auditory nerve (Schwann cells).

 

Auditory nerve tumors usually grow from the vestibular (balance) nerve. Early symptoms include noise in the ear (tinnitus), hearing loss, and imbalance or unsteadiness when the person turns quickly. If the tumor grows larger and compresses other parts of the brain, such as the facial nerve or the trigeminal nerve, weakness and numbness of the face may result. Early diagnosis is based on a magnetic resonance imaging (MRI) scan and hearing tests.

 

Tumors are removed by surgery, which may be performed with a microscope (microsurgery) to avoid damaging the facial nerve.

Barotrauma (barotitis media or aerotitis media) is damage to the middle ear caused by unequal air pressure on the two sides of the eardrum.

 

The eardrum separates the ear canal and the middle ear. If air pressure in the ear canal from outside air and air pressure in the middle ear are unequal, the eardrum can be damaged. Normally, the eustachian tube, which connects the middle ear and the back of the nose, helps maintain equal pressure on both sides of the eardrum by allowing outside air to enter the middle ear. When outside air pressure changes suddenly—for example, during the ascent or descent of an airplane or a deep-sea dive —air must move through the eustachian tube to equalize the pressure in the middle ear.

A perforation is a hole in the eardrum.

  • Eardrum perforations are often caused by middle ear infections.
  • Perforation causes sudden ear pain, sometimes with bleeding from the ear, hearing loss, or noise in the ear.
  • Doctors can see the perforation with an otoscope.
  • Usually the eardrum heals on its own, but sometimes surgical repair is needed.

A middle ear infection (otitis media) is the most common cause of eardrum perforation. The eardrum can also be perforated by a sudden change in pressure—either an increase, such as that caused by an explosion, a slap, or diving underwater; or a decrease, such as occurs while flying in an airplane. Another cause is burns from heat or chemicals. The eardrum may also be perforated (punctured) by objects placed in the ear, such as a cotton-tipped swab, or by objects entering the ear accidentally, such as a low-hanging twig or a thrown pencil. An object that penetrates the eardrum can dislocate or fracture the chain of small bones (ossicles) that connect the eardrum to the inner ear. Pieces of the broken ossicles or the object itself may even penetrate the inner ear. A blocked eustachian tube, which connects the middle ear and the back of the nose, may lead to the perforation because of severe imbalance of pressure (barotrauma).

 

Symptoms and Diagnosis

Perforation of the eardrum causes sudden severe pain, sometimes followed by bleeding from the ear, hearing loss, and noise in the ear. The hearing loss is more severe if the chain of ossicles has been disrupted or the inner ear has been injured. Injury to the inner ear may also cause vertigo (a whirling sensation). Pus may begin to drain from the ear in 24 to 48 hours, particularly if water or other foreign material enters the middle ear. A doctor diagnoses eardrum perforation by looking in the ear with a special instrument called an otoscope. Sometimes formal hearing tests are performed.

 

Treatment

The ear is kept dry. An antibiotic given by mouth may be used if the ear becomes infected. Ear drops may be given for contaminated injuries. Usually, the eardrum heals without further treatment, but if it does not heal within 2 months, surgery to repair the eardrum (tympanoplasty) may be needed. People with a severe injury, particularly one accompanied by marked hearing loss, severe vertigo, or both, may need to have more immediate surgery. If a perforation is not repaired, the person may develop a smoldering infection—chronic otitis media—in the middle ear.

 

A persistent conductive hearing loss occurring after perforation of the eardrum suggests a disruption or fixation of the ossicles, which may be repaired surgically. A sensorineural hearing loss or vertigo that persists for more than a few hours after the injury suggests that something has injured or penetrated the inner ear.

Infectious myringitis is infection of the eardrum by a virus or bacteria.

 

Myringitis is caused by a variety of viruses and bacteria. The bacteria Mycoplasma is a common cause. The eardrum becomes inflamed, and small, fluid-filled blisters (vesicles) form on its surface. Blisters may also be present in otitis media; however, in myringitis, there is no pus or fluid in the middle ear.

 

Pain begins suddenly and lasts for 24 to 48 hours. There may be some hearing loss.

 

Doctors diagnose myringitis by looking at the eardrum with an otoscope. Because it is difficult to tell whether the infection is viral or bacterial, most people are treated with antibiotics and analgesics. A doctor may need to rupture the vesicles with a small blade to relieve the pain.

Mastoiditis is a bacterial infection in the mastoid process, the prominent bone behind the ear.

 

This disorder usually occurs when untreated or inadequately treated acute otitis media spreads from the middle ear into the surrounding bone—the mastoid process.

 

Usually, symptoms appear days to weeks after acute otitis media develops, as the spreading infection destroys the inner part of the mastoid process. A collection of pus (abscess) may form in the bone. The skin covering the mastoid process may become red, swollen, and tender, and the external ear is pushed sideways and down. Other symptoms are fever, pain around and within the ear, and a creamy, profuse discharge from the ear. The pain tends to be persistent and throbbing. Hearing loss can become progressively worse.

 

Computed tomography (CT) shows that the air cells (spaces in bone that normally contain air) in the mastoid process are filled with fluid. As mastoiditis progresses, the spaces enlarge. Inadequately treated mastoiditis can result in deafness, blood poisoning (sepsis), infection of the tissues covering the brain (meningitis), brain abscess, or death.

 

Treatment is with antibiotics given by vein. A sample of ear discharge is examined to identify the organism causing the infection and to determine the antibiotics most likely to eliminate the bacteria. Antibiotics may be given by mouth once the person starts to recover and are continued for at least 2 weeks. If an abscess has formed in the bone, surgical drainage (mastoidectomy) is required.

Meniere's disease is a disorder characterized by recurring attacks of disabling vertigo (a whirling sensation), hearing loss, and noise in the ear (tinnitus).

  • Symptoms include sudden, unprovoked attacks of severe, disabling vertigo, nausea, and vomiting.
  • Doctors usually perform hearing tests and sometimes magnetic resonance imaging.
  • A low-salt diet and a diuretic may lower the frequency of attacks.

Meniere's disease (also called endolymphatic hydrops) is thought to be caused by an imbalance in the fluid that is normally present in the inner ear. This fluid is continually being secreted and reabsorbed, maintaining a constant amount. Either an increase in production of inner ear fluid or a decrease in its reabsorption results in an imbalance of fluid. Why either happens is not known.

 

Symptoms include sudden, unprovoked attacks of severe, disabling vertigo, nausea, and vomiting. These symptoms usually last for 2 to 3 hours but can (rarely) last up to 24 hours. Periodically, a person may feel a fullness or pressure in the affected ear. Hearing tends to fluctuate but progressively worsens over the years. Tinnitus, which may be constant or intermittent, may be worse before, during, or after an attack of vertigo. Both hearing loss and tinnitus usually affect only one ear.

 

In one form of Meniere's disease, hearing loss and tinnitus precede the first attack of vertigo by months or years. After the attacks of vertigo begin, hearing may improve.

 

Diagnosis and Treatment

A doctor suspects Meniere's disease because of the typical symptoms of vertigo with tinnitus and hearing loss in one ear. Doctors usually perform hearing tests and sometimes magnetic resonance imaging (MRI) to look for other causes. A low-salt diet and a diuretic (a drug that increases the excretion of urine) may lower the frequency of attacks in some people. When attacks do occur, vertigo may be relieved temporarily with drugs given by mouth, such as meclizine.

 

Several procedures are available for people who are disabled by frequent attacks of vertigo despite drug treatment. The procedures aim to either reduce fluid pressure in the inner ear or destroy inner ear balance function. The endolymphatic shunt procedure, in which a thin sheet of flexible plastic material is placed in the inner ear, is the least destructive of these procedures. To destroy inner ear balance function, a solution of gentamicin can be injected through the eardrum into the middle ear. Gentamicin selectively destroys balance function before affecting hearing, but hearing loss is still a risk. The risk of hearing loss is lower if doctors inject the gentamicin only once and wait several weeks before repeating if necessary. Cutting the vestibular nerve permanently destroys inner ear balance, while preserving hearing, and is successful 95% of the time in controlling vertigo. This procedure is usually performed on people whose symptoms do not lessen after an endolymphatic shunt or on people who never want to experience another spell of vertigo. Finally, when vertigo is disabling and hearing has deteriorated in the involved ear, the entire semicircular canals can be drilled away in a procedure called a labyrinthectomy.

 

None of the surgical procedures that treat vertigo are useful in treating the hearing loss that often accompanies Meniere's disease.

Acute otitis media is a bacterial or viral infection of the middle ear.

 

Acute otitis media results from infection by viruses or bacteria, often as a complication of the common cold or of allergies. Acute otitis media is more common among children than adults. Symptoms and treatment are similar in adults and older children.

 

The infected ear is painful, with a red, bulging eardrum. Most people with acute otitis media get better without treatment. However, because it is hard to predict whose symptoms will not lessen, some doctors treat all people with antibiotics.

 

If a person has severe or persistent pain and fever, and the eardrum is bulging, a doctor may perform a myringotomy, in which an opening is made through the eardrum to allow fluid to drain from the middle ear. The opening, which does not affect hearing, usually heals without treatment. People who have repeated bouts of otitis media may need to have drainage tubes (tympanostomy tubes) placed in their eardrums.

Chronic otitis media is a long-standing infection of the middle ear.

  • Chronic otitis media is caused by a cholesteatoma or by an eardrum perforation that has not healed.
  • A flare up may occur after an ear infection or after water enters the middle ear.
  • The person may have a persistent discharge of foul-smelling pus.
  • Doctors clean the ear canal and give eardrops.

Chronic otitis media is usually caused by eustachian tube dysfunction but may also result from a hole (perforation) in the eardrum that failed to heal after trauma or an acute infection of the middle ear. It can also result in a noncancerous (benign) growth of white skinlike material (cholesteatoma). People may have a perforation without ever getting any symptoms, but sometimes a chronic bacterial infection develops.

 

Chronic otitis media may flare up after an infection of the nose and throat, such as the common cold, or after water enters the middle ear while bathing or swimming. Usually, flare-ups result in a painless discharge of pus, which may have a very foul smell, from the ear. Persistent flare-ups may result in the formation of protruding growths called polyps, which extend from the middle ear through the perforation and into the ear canal. Persistent infection can destroy parts of the ossicles—the small bones in the middle ear that connect the eardrum to the inner ear and conduct sounds from the outer ear to the inner ear—causing conductive hearing loss. Other serious complications include inflammation of the inner ear, facial paralysis, and brain infections. Some people with chronic otitis media develop a cholesteatoma in the middle ear. A cholesteatoma, which destroys bone, greatly increases the likelihood of other serious complications. A doctor diagnoses chronic otitis media when seeing pus or skinlike material accumulating in a hole or in a pocket in the eardrum that often drains.

 

Treatment

When chronic otitis media flares up, a doctor thoroughly cleans the ear canal and middle ear with suction and dry cotton wipes, then prescribes a solution of acetic acid with hydrocortisone or antibiotic ear drops. Water must be kept out of the ear when a perforation is present.

 

Usually, the eardrum can be repaired by a procedure called tympanoplasty. If the ossicular chain has been disrupted, it may be repaired at the same time. A cholesteatoma must be removed surgically. Otherwise, serious complications can develop.

Secretory otitis media is an accumulation of fluid in the middle ear.

  • Secretory otitis media occurs when acute otitis media has not completely resolved or allergies cause blockage of the eustachian tube.
  • People may have fullness and some temporary hearing loss in the affected ear.
  • Doctors examine the ear and use tympanometry to diagnose this disorder.
  • Doctors may need to make an opening in the eardrum to let fluid drain.

Secretory (serous) otitis media can develop from acute otitis media that has not completely cleared or from a blocked eustachian tube (which connects the middle ear and the back of the nose). Allergies are a common cause of eustachian tube blockage. Secretory otitis media can occur at any age but is particularly common among children.

 

Normally, pressure in the middle ear is equalized 3 or 4 times a minute as the eustachian tube opens during swallowing. If the eustachian tube is blocked, pressure in the middle ear tends to decrease as oxygen is absorbed into the bloodstream from the middle ear. As the pressure decreases, fluid accumulates in the middle ear, reducing the eardrum's ability to move. Usually, although not always, the fluid contains some bacteria, but symptoms of active infection (such as redness, pain, and pus) are rare. People usually notice a fullness in the affected ear and may hear a popping or crackling sound when they swallow. Some hearing loss commonly develops.

 

A doctor examines the ear to make the diagnosis. Tympanometry helps determine whether fluid is in the middle ear.

 

Treatment

Decongestants, such as phenylephrine and ephedrine, and, in people with allergies, antihistamines, can be taken to reduce nasal congestion but do not help the secretory otitis media. Antibiotics are not helpful. Low pressure in the middle ear can be temporarily increased by forcing air past the blockage in the eustachian tube. To do this, the person breathes out with the mouth closed and the nostrils pinched shut.

 

If symptoms become chronic (lasting more than 3 months), a doctor may perform a myringotomy, in which an opening is made through the eardrum to allow fluid to drain from the middle ear. A tiny drainage tube can be inserted into the opening in the eardrum to help fluid drain and allow air to enter the middle ear.

The temporal bone (the skull bone containing part of the ear canal, the middle ear, and the inner ear) can be fractured by a blow to the head.

 

Temporal bone fractures frequently rupture the eardrum and may also damage the ossicles (the chain of small bones that connects the eardrum to the inner ear) and the cochlea (the organ of hearing).

 

Symptoms include facial paralysis on the side of the fracture and profound hearing loss, which may be conductive, sensorineural, or both. People may have bleeding from the ear, blood behind the eardrum, or patchy bruising of the skin behind the ear. Sometimes, cerebrospinal fluid leaks from the brain through the fracture and appears as clear fluid draining from the ear or nose. Leakage of this fluid indicates that the brain is exposed to infection.

 

Diagnosis is made with computed tomography (CT). Treatment usually requires an antibiotic given intravenously to prevent infection of the tissues covering the brain (meningitis). Sometimes, persistent facial paralysis caused by pressure on the facial nerve can be relieved by surgery. Damage to the eardrum and structures of the middle ear is repaired surgically weeks or months later if necessary.

Tinnitus is noise originating in the ear rather than in the environment.

  • Tinnitus can be a symptom of ear damage, an ear infection, eustachian tube blockage, or hearing loss.
  • People have a ringing or buzzing in the ears, especially in quiet environments.
  • Hearing tests and imaging tests are used to try to find the cause.
  • People may use hearing aids or tinnitus maskers to decrease the sound.

Tinnitus is a symptom and not a specific disease. It is very common—10 to 15% of people experience some degree of tinnitus.

 

More than 75% of ear-related problems include tinnitus as a symptom, including injury from loud noises or explosions, ear infections, a blocked ear canal or eustachian tube (which connects the middle ear and the back of the nose), otosclerosis (a type of hearing loss), tumors of the middle ear, and Meniere's disease. Certain drugs (such as aminoglycoside antibiotics and high doses of aspirin also may cause tinnitus.

 

Tinnitus may also occur with disorders outside the ears, including anemia, heart and blood vessel disorders such as hypertension and arteriosclerosis, an underactive thyroid gland (hypothyroidism), and head injury. Tinnitus that is only in one ear or that pulsates is a more serious sign. A pulsating sound may result from certain tumors, a blocked artery, an aneurysm, or other blood vessel disorders.

 

The noise heard by people with tinnitus may be a buzzing, ringing, roaring, whistling, or hissing sound. Some people hear more complex sounds that vary over time. These sounds are more noticeable in a quiet environment and when the person is not concentrating on something else. Thus, tinnitus tends to be most disturbing to people when they are trying to sleep. However, the experience of tinnitus is highly individual. Some people are very disturbed by their symptoms, whereas others find them quite bearable.

 

Diagnosis and Treatment

Because a person who has tinnitus usually has some hearing loss, thorough hearing tests are performed as well as magnetic resonance imaging (MRI) of the head and computed tomography (CT) of the temporal bone (the skull bone that contains part of the ear canal, the middle ear, and the inner ear).

 

Attempts to identify and treat the disorder causing tinnitus are often unsuccessful. Various techniques can help make tinnitus tolerable, although the ability to tolerate it varies from person to person. Often a hearing aid helps suppress tinnitus. Many people find relief by playing background music to mask the tinnitus. Some people use a tinnitus masker, a device worn like a hearing aid that produces a constant level of neutral sounds. For the profoundly deaf, an implant in the cochlea (the organ of hearing) may reduce tinnitus.

Tinnitus is noise originating in the ear rather than in the environment.

  • Tinnitus can be a symptom of ear damage, an ear infection, eustachian tube blockage, or hearing loss.
  • People have a ringing or buzzing in the ears, especially in quiet environments.
  • Hearing tests and imaging tests are used to try to find the cause.
  • People may use hearing aids or tinnitus maskers to decrease the sound.

Tinnitus is a symptom and not a specific disease. It is very common—10 to 15% of people experience some degree of tinnitus.

 

More than 75% of ear-related problems include tinnitus as a symptom, including injury from loud noises or explosions, ear infections, a blocked ear canal or eustachian tube (which connects the middle ear and the back of the nose), otosclerosis (a type of hearing loss), tumors of the middle ear, and Meniere's disease. Certain drugs (such as aminoglycoside antibiotics and high doses of aspirin also may cause tinnitus.

 

Tinnitus may also occur with disorders outside the ears, including anemia, heart and blood vessel disorders such as hypertension and arteriosclerosis, an underactive thyroid gland (hypothyroidism), and head injury. Tinnitus that is only in one ear or that pulsates is a more serious sign. A pulsating sound may result from certain tumors, a blocked artery, an aneurysm, or other blood vessel disorders.

 

The noise heard by people with tinnitus may be a buzzing, ringing, roaring, whistling, or hissing sound. Some people hear more complex sounds that vary over time. These sounds are more noticeable in a quiet environment and when the person is not concentrating on something else. Thus, tinnitus tends to be most disturbing to people when they are trying to sleep. However, the experience of tinnitus is highly individual. Some people are very disturbed by their symptoms, whereas others find them quite bearable.

 

Diagnosis and Treatment

Because a person who has tinnitus usually has some hearing loss, thorough hearing tests are performed as well as magnetic resonance imaging (MRI) of the head and computed tomography (CT) of the temporal bone (the skull bone that contains part of the ear canal, the middle ear, and the inner ear).

 

Attempts to identify and treat the disorder causing tinnitus are often unsuccessful. Various techniques can help make tinnitus tolerable, although the ability to tolerate it varies from person to person. Often a hearing aid helps suppress tinnitus. Many people find relief by playing background music to mask the tinnitus. Some people use a tinnitus masker, a device worn like a hearing aid that produces a constant level of neutral sounds. For the profoundly deaf, an implant in the cochlea (the organ of hearing) may reduce tinnitus.