Balance Disorders

A balance disorder is a disturbance that causes an individual to feel unsteady, giddy, woozy, or have a sensation of movement, spinning, or floating. An organ in our inner ear, the labyrinth, is an important part of our vestibular (balance) system. The labyrinth interacts with other systems in the body, such as the visual (eyes) and skeletal (bones and joints) systems, to maintain the body's position. These systems, along with the brain and the nervous system, can be the source of balance problems.

Three structures of the labyrinth, the semicircular canals, let us know when we are in a rotary (circular) motion. The semicircular canals, the superior, posterior, and horizontal, are fluid-filled. Motion of the fluid tells us if we are moving. The semicircular canals and the visual and skeletal systems have specific functions that determine an individual's orientation. The vestibule is the region of the inner ear where the semicircular canals converge, close to the cochlea (the hearing organ). The vestibular system works with the visual system to keep objects in focus when the head is moving. Joint and muscle receptors also are important in maintaining balance. The brain receives, interprets, and processes the information from these systems that control our balance.

How does the balance system work?

Movement of fluid in the semicircular canals signals the brain about the direction and speed of rotation of the head--for example, whether we are nodding our head up and down or looking from right to left. Each semicircular canal has a bulbed end, or enlarged portion, that contains hair cells. Rotation of the head causes a flow of fluid, which in turn causes displacement of the top portion of the hair cells that are embedded in the jelly-like cupula. Two other organs that are part of the vestibular system are the utricle and saccule. These are called the otolithic organs and are responsible for detecting linear acceleration, or movement in a straight line. The hair cells of the otolithic organs are blanketed with a jelly-like layer studded with tiny calcium stones called otoconia. When the head is tilted or the body position is changed with respect to gravity, the displacement of the stones causes the hair cells to bend.

The balance system works with the visual and skeletal systems (the muscles and joints and their sensors) to maintain orientation or balance. For example, visual signals are sent to the brain about the body's position in relation to its surroundings. These signals are processed by the brain, and compared to information from the vestibular and the skeletal systems. An example of interaction between the visual and vestibular systems is called the vestibular-ocular reflex. The nystagmus (an involuntary rhythmic eye movement) that occurs when a person is spun around and then suddenly stops is an example of a vestibular-ocular reflex.

What are the symptoms of a balance disorder?

When balance is impaired, an individual has difficulty maintaining orientation. For example, an individual may experience the "room spinning" and may not be able to walk without staggering, or may not even be able to arise. Some of the symptoms a person with a balance disorder may experience are:

A sensation of dizziness or vertigo (spinning).
Falling or a feeling of falling.
Lightheadedness or feeling woozy.
Visual blurring.
Disorientation.

Some individuals may also experience nausea and vomiting, diarrhea, faintness, changes in heart rate and blood pressure, fear, anxiety, or panic. Some reactions to the symptoms are fatigue, depression, and decreased concentration. The symptoms may appear and disappear over short time periods or may last for a longer period of time.

What causes a balance disorder?

Infections (viral or bacterial), head injury, disorders of blood circulation affecting the inner ear or brain, certain medications, and aging may change our balance system and result in a balance problem. Individuals who have illnesses, brain disorders, or injuries of the visual or skeletal systems, such as eye muscle imbalance and arthritis, may also experience balance difficulties. A conflict of signals to the brain about the sensation of movement can cause motion sickness (for instance, when an individual tries to read while riding in a car). Some symptoms of motion sickness are dizziness, sweating, nausea, vomiting, and generalized discomfort.

Balance disorders can be due to problems in any of four areas:

Peripheral vestibular disorder, a disturbance in the labyrinth.
Central vestibular disorder, a problem in the brain or its connecting nerves.
Systemic disorder, a problem of the body other than the head and brain.
Vascular disorder, or blood flow problems.

What are some types of balance disorders?

Benign Paroxysmal Positional Vertigo (BPPV)--a brief, intense sensation of vertigo that occurs because of a specific positional change of the head. An individual may experience BPPV when rolling over to the left or right upon getting out of bed in the morning, or when looking up for an object on a high shelf. The cause of BPPV is not known, although it may be caused by an inner ear infection, head injury, or aging.

Labyrinthitis--an infection or inflammation of the inner ear causing dizziness and loss of balance.

Ménière's disease--an inner ear fluid balance disorder that causes episodes of vertigo, fluctuating hearing loss, tinnitus (a ringing or roaring in the ears), and the sensation of fullness in the ear. The cause of Ménière's disease is unknown.

Vestibular neuronitis--an infection of the vestibular nerve, generally viral.

Perilymph fistula--a leakage of inner ear fluid to the middle ear. It can occur after head injury, physical exertion or, rarely, without a known cause.

Ménière's Disease

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.

What causes Ménière's disease?

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.

What are the symptoms of Ménière's disease?

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, typically involves a whirling dizziness that 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 (ear noises), 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. 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. Ménière's disease sufferers may also 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.

How is Ménière's disease diagnosed?

Based on a recent study, NIDCD estimates that there are currently approximately 615,000 individuals with diagnosed Ménière's disease in the United States and 45,500 newly diagnosed cases each year. Proper diagnosis of Ménière's disease entails several procedures, including a medical history interview and a physical examination by a physician, 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. Recording the 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. 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 or air. This procedure, known as caloric testing, results in nystagmus, rapid eye movements that can help a physician analyze a balance disorder. Since tumor growth can produce symptoms similar to Ménière's disease, an MRI is a useful test to determine whether a tumor is causing the patient's vertigo and hearing loss.

How is Ménière's disease treated?

There is no cure for Ménière's disease. However, the symptoms of the disease are often controlled successfully by reducing the body’s retention of fluids through dietary changes (such as a low-salt or salt-free diet and no caffeine or alcohol) or medication. Changes in medications that either control allergies or improve blood circulation in the inner ear may help. Eliminating tobacco use and reducing stress levels are more ways some people can lessen the severity of their symptoms.

Different surgical procedures have been advocated for patients with persistent, debilitating vertigo from Ménière's disease. Labyrinthectomy (removal of the inner ear sense organ) can effectively control vertigo, but sacrifices hearing and is reserved for patients with nonfunctional hearing in the affected ear. Vestibular neurectomy, selectively severing a nerve from the affected inner ear organ, usually controls the vertigo while preserving hearing, but carries surgical risks. Recently, the administration of the ototoxic antibiotic, gentamycin directly into the middle ear space has gained popularity worldwide for the control of the vertigo of Ménière's disease.