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Description
Ménière's disease is an abnormality of
the inner ear causing a host of symptoms, including
vertigo or severe dizziness, tinnitus or a roaring sound
in the ears, fluctuating hearing loss, and the sensation
of pressure or pain in the affected ear. The disorder
usually affects only one ear and is a common cause of
hearing loss. Named after French physician Prosper Ménière
who first described the syndrome in 1861, Ménière's
disease is now also referred to as endolymphatic hydrops.
Causes/Diagnosis
The symptoms of Ménière's
disease are associated with a change in fluid volume
within a portion of the inner ear known as the labyrinth.
The labyrinth has two parts: the bony labyrinth and
the membranous labyrinth. The membranous labyrinth,
which is encased by bone, is necessary for hearing and
balance and is filled with a fluid called endolymph.
When your head moves, endolymph moves, causing nerve
receptors in the membranous labyrinth to send signals
to the brain about the body's motion. An increase in
endolymph, however, can cause the membranous labyrinth
to balloon or dilate, a condition known as endolymphatic
hydrops.
Many experts on Ménière's disease think
that a rupture of the membranous labyrinth allows the
endolymph to mix with perilymph, another inner ear fluid
that occupies the space between the membranous labyrinth
and the bony inner ear. This mixing, scientists believe,
can cause the symptoms of Ménière's disease.
Scientists are investigating several possible causes
of the disease, including environmental factors, such
as noise pollution and viral infections, as well as
biological factors.
Scientists estimate that there are 3 to 5 million
people in the United States with Ménière's
disease, with nearly 100,000 new cases diagnosed each
year. Proper diagnosis of Ménière's disease
entails several procedures, including a medical-history
interview and a physical examination by a physician
or ENT; hearing and balance tests; and medical imaging
with magnetic resonance imaging (MRI). Accurate measurement
and characterization of hearing loss are of critical
importance in the diagnosis of Ménière's
disease.
Through the use of several types of hearing tests,
physicians can characterize hearing loss as being sensory,
arising from the inner ear, or neural arising from the
hearing nerve. An auditory brain stem response, which
measures electrical activity in the hearing nerve and
brain stem, is useful in differentiating between these
two types of hearing loss. And under certain circumstances,
electrocochleography, recording the electrical activity
of the inner ear in response to sound, helps confirm
the diagnosis.
To test the vestibular or balance system, physicians
irrigate the ears with warm and cool water. This flooding
of the ears, known as caloric testing, results in nystagmus,
rapid eye movements that can help a physician analyze
a balance disorder. And because tumor growth can produce
symptoms similar to Ménière's disease,
magnetic resonance imaging is a useful test to determine
whether a tumor is causing the patients vertigo and
hearing loss.
Symptoms
The symptoms of Ménière's disease occur
suddenly and can arise daily or as infrequently as once
a year. Vertigo, often the most debilitating symptom
of Ménière's disease, forces the sufferer
to lie down. Vertigo attacks can lead to severe nausea,
vomiting, and sweating and often come with little or
no warning.
Some individuals with Ménière's disease
have attacks that start with tinnitus, a loss of hearing,
or a full feeling or pressure in the affected ear. It
is important to remember that all of these symptoms
are unpredictable. Typically, the attack is characterized
by a combination of vertigo, tinnitus and hearing loss
lasting several hours. But people experience these discomforts
at varying frequencies, durations, and intensities.
Some may feel slight vertigo a few times a year. Others
may be occasionally disturbed by intense, uncontrollable
tinnitus while sleeping. And other Ménière's
disease sufferers may notice a hearing loss and feel
unsteady all day long for prolonged periods. Other occasional
symptoms of Ménière's disease include
headaches, abdominal discomfort and diarrhea. A person's
hearing tends to recover between attacks but over time
becomes worse.
Treatment
There is no cure for Ménière's disease.
Medical and behavioral therapy, however, are often helpful
in managing its symptoms. Although many operations have
been developed to reverse the disease process, their
value has been difficult to establish. And, unfortunately,
all operations on the ear carry a risk of hearing loss.
The most commonly performed surgical treatment for
Ménière's disease is the insertion of
a shunt, a tiny silicone tube that is positioned in
the inner ear to drain off excess fluid.
In another more reliable operation, a vestibular neurectomy,
the vestibular nerve, which serves balance, is severed
so that it no longer sends distorted messages to the
brain. But the balance nerve is very close to the hearing
and facial nerves; thus, the risk of affecting a patient's
hearing or facial muscle control increases with this
type of surgical treatment. Also, older patients often
have difficulty recovering from this type of surgery.
A labyrinthectomy, the removal of the membranous labyrinth,
is an irreversible procedure that is often successful
in eliminating the dizziness associated with Ménière's
disease. This procedure, however, results in a total
loss of hearing in the operated ear, an important consideration
since the second ear may one day be affected. Also,
labyrinthectomies themselves may result in other balance
problems.
Some physicians recommend a change of diet to help
control Ménière's symptoms. Such as:
- eliminating caffeine,
- eliminating alcohol and salt (can relieve the frequency
and intensity of attacks in some people),
- eliminating tobacco use,
- reducing stress levels (can lessen the severity
of the symptoms),
- and medications that control allergies, reduce fluid
retention or improve blood circulation in the inner
ear may also help.
Research
Scientists are investigating environmental and biological
factors that may cause Ménière's disease
or induce an attack. They are also studying how fluid
composition and movement in the labyrinth affect hearing
and balance. And by studying hair cells in the inner
ear, which are responsible for proper hearing and balance,
scientists are learning how the ear converts the mechanical
energy of sound waves and motion into nerve impulses.
Insights into the mechanisms of Ménière's
disease will enable scientists to develop preventive
strategies and more effective treatment.
Source: National Institute on Deafness & Other
Communication Disorders, 2000.
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