The vestibular system includes the parts of the inner ear and brain that process the sensory information involved with controlling balance and eye movements. If disease or injury damages these processing areas, vestibular disorders can result. Vestibular disorders can also result from or be worsened by genetic or environmental conditions, or occur for unknown reasons.
Balance is the ability to maintain the body’s center of mass over its base of support. A properly functioning balance system allows humans to see clearly while moving, identify orientation with respect to gravity, determine direction and speed of movement, and make automatic postural adjustments to maintain posture and stability in various conditions and activities.
Balance is achieved and maintained by a complex set of sensorimotor control systems that include sensory input from vision (sight), proprioception (touch), and the vestibular system (motion, equilibrium, spatial orientation); integration of that sensory input; and motor output to the eye and body muscles. Injury, disease, or the aging process can affect one or more of these components.
Not all symptoms will be experienced by every person with an inner ear disorder, and other symptoms are possible. An inner ear disorder may be present even in the absence of obvious or severe symptoms. It is important to note that most of these individual symptoms can also be caused by other unrelated conditions.
The type and severity of symptoms can vary considerably, and be frightening and difficult to describe. People affected by certain symptoms of vestibular disorders may be perceived as inattentive, lazy, overly anxious, or seeking attention. They may have trouble reading or doing simple arithmetic. Functioning in the workplace, going to school, performing routine daily tasks, or just getting out of bed in the morning may be difficult for some people.
Doctors use information from a person’s medical history and findings from a physical examination as a basis for ordering diagnostic tests to assess the vestibular system function and to rule out alternative causes of symptoms.
Good balance and clear vision rely on a close linkage between the vestibular organs and the eyes. Head movement or other stimulation of the inner ear sends signals to the muscles of the eyes via the nervous system; this is called the vestibulo-ocular reflex, or VOR. The VOR normally generates eye movements that maintain clear vision with head movement.
ENG is a battery (group) of eye-movement tests that look for signs of vestibular dysfunction or neurological problems by measuring nystagmus (a type of involuntary eye movements) and other eye movements. ENG tests are the most common ones administered to people with dizziness, vertigo, and/ or balance disorders, although the test battery and some testing methods vary widely.
During ENG, eye movements are recorded and analyzed via small electrodes placed on the skin around the eyes. The electrodes attach to the skin with an adhesive, much like a small bandage. Alternatively, eye movements may be recorded by videonystagmography (VNG) using an infrared video camera mounted inside goggles that the patient wears instead of sticky-patch electrodes.
One ENG/VNG test evaluates the movement of the eyes as they follow a moving target. Another observes eye movements as the head is positioned in different directions. During the caloric test (sometimes called bi-thermal caloric or mono-thermal caloric), warm or cold water or air is circulated in the ear canal to test the nystagmus response stimulated by the temperature change.
Rotation tests are another way of evaluating how well the eyes and inner ear work together. For every head movement in one direction, there is eye movement in the opposite direction.
With rotation tests (which employ the same type of sticky-patch electrodes or goggles used for ENG/VNG), the examiner can record eye movements while the head is moving at various speeds. This provides additional information, beyond the ENG/VNG, about how well the balance organs are functioning, along with their connections to the eye muscles. Not all people in the diagnosis phase will need rotation tests.
VEMP testing is used to evaluate whether the saccule and the inferior vestibular nerve are intact and functioning normally. During VEMP testing, headphones are placed over the ears and small electrodes are attached with an adhesive to the skin over the neck muscles. When sound is transmitted through the headphones, the electrodes record the response of the muscle to the vestibular stimuli.
CDP tests postural stability. While ENG/VNG and rotation tests assess visual-vestibular interactions, CDP provides information about motor control or balance function under varying environmental conditions. This is important because the ability to maintain balance depends not only on sensory information from the vision and the vestibular systems, but also on sensory information that the brain receives from the muscles and joints. These somatosensory signals provide clues such as the direction of head turn and the texture and slope of the walking surface. CDP tests the relationships among these three sensory inputs and records the balance and posture adjustments made by a person in response to variations in reliable information provided by the vision and somatosensory systems.
The test involves standing on a platform, typically with some form of visual target to watch. The platform and/or the visual target move while pressure gauges under the platform record shifts in body weight (body sway) as the person being tested maintains balance. A safety harness is worn to prevent falling during the test.
Audiometry measures hearing function. Hearing evaluations are an important part of vestibular diagnostics, because of the close relationship between the inner ear hearing and balance organs. Several different audiometry tests, performed by an audiologist, may be required. These tests are carried out in a sound-treated room with a set of headphones which also allow voice contact with the audiologist through a microphone.
A person with a vestibular disorder sometimes has his/her hearing monitored at intervals over time, especially when there is evidence of hearing loss, a sensation of fullness in the ears, or tinnitus (ringing or noise in the ears).
The form of treatment prescribed for vestibular disorders depends upon symptoms, medical history and general health, a physical examination by a qualified doctor, and diagnostic test results. In addition to being treated for any underlying disease that may be contributing to the balance disorder, treatment can include:
VRT uses specific head, body, and eye exercises designed to retrain the brain to recognize and process signals from the vestibular system and coordinate them with information from vision and proprioception. The choice and form of VRT exercises will differ from person to person.
A specialized form of VRT is available to treat benign paroxysmal positional vertigo (BPPV). This treatment is often referred to as the Epley maneuver, and involves a series of specifically patterned head and trunk movements to move tiny displaced otoliths to a place in the inner ear where they can’t cause symptoms.
Home exercises are often a vital part of treatment. Appropriate VRT exercises will be assigned by the physical or occupational therapist to be performed at a prescribed pace, along with a progressive fitness program to increase energy and reduce stress.
Many people with Ménière’s disease, secondary endolymphatic hydrops, and migraine-associated dizziness find that certain modifications in diet are helpful in managing their disorder. Avoidance of non-dietary substances such as nicotine and some types of medications may also reduce symptoms.
Symptoms from vestibular disorders are invisible and unpredictable. This does not mean that they are imaginary, but that they often contribute to a wide range of psychological impacts. People who have a vestibular disorder often need support and may benefit from counseling to cope with lifestyle changes, depression, guilt, and grief that comes from no longer being able to meet their own or others’ expectations.
The use of medication in treating vestibular disorders depends on whether the vestibular system dysfunction is in an initial or acute phase (lasting up to 5 days) or chronic phase (ongoing).
When medical treatment isn’t effective in controlling vertigo and other symptoms caused by vestibular system dysfunction, surgery may be considered. The type of surgery performed depends upon each individual’s diagnosis and physical condition. Surgical procedures for peripheral vestibular disorders are either corrective or destructive. The goal of corrective surgery is to repair or stabilize inner ear function. The goal of destructive surgery is to stop the production of sensory information or prevent its transmission from the inner ear to the brain. Read more, including a description of specific surgical procedures.
Dizziness in the elderly can be a result of problems with the vestibular, central (brain-related), and vision systems, as well as from neuropathy, psychological causes, and unknown (idiopathic) causes. Vestibular disorders, however, are thought to be the most common cause of dizziness in older people, responsible for approximately 50% of the reported dizziness in the elderly.
BPPV is a common vestibular disorder that causes vertigo, dizziness, and other symptoms due to debris that has collected within a part of the inner ear. This debris, called otoconia, is made up of small crystals of calcium carbonate (sometimes referred to informally as “ear rocks”). With head movement, the displaced otoconia shift, sending false signals to the brain.
Labyrinthitis and vestibular neuritis are disorders resulting from an infection that inflames the inner ear or the vestibulo-cochlear nerve (the eighth cranial nerve), which connects the inner ear to the brain. Neuritis (inflammation of the nerve) affects the vestibular branch of the vestibulo-cochlear nerve, resulting in dizziness or vertigo but no change in hearing. Labyrinthitis (inflammation of the labyrinth) occurs when an infection affects both branches of the nerve, resulting in hearing changes as well as dizziness or vertigo.
Ménière’s disease is a vestibular disorder that produces a recurring set of symptoms as a result of abnormally large amounts of a fluid called endolymph collecting in the inner ear. The exact cause of Ménière’s disease is not known. The four classic symptoms are vertigo, tinnitus, a feeling of fullness or pressure in the ear, and fluctuating hearing.
Migraine, a disorder usually associated with headache, is extremely common and can cause several vestibular syndromes. Studies suggest that about 25 percent of migraineurs experience dizziness or migraine during attacks. Migraine-associated vertigo (MAV) can occur with or without pain.
Mal de débarquement literally means “sickness of disembarkment.” This term originally referred to the illusion of movement felt as an aftereffect of travel by ship or boat. Some experts now include other types of travel, such as by train and airplane, and situations with new and different movement patterns, such as reclining on a waterbed.
A perilymph fistula is a tear or defect in one of the small, thin membranes that separate the middle ear from the fluid-filled inner ear. When a fistula is present, changes in middle ear pressure will directly affect the inner ear, stimulating the balance and/or hearing structures and causing symptoms.
Superior semicircular canal dehiscence syndrome results from an opening (dehiscence) in the bone overlying the superior (uppermost) semicircular canal within the inner ear. With this dehiscence, the fluid in the membranous superior canal (which is located within the tubular cavity of the bony canal) can be displaced by sound and pressure stimuli, creating certain vestibular and/or auditory signs and symptoms.
Tinnitus is a symptom that can be experienced with some types of vestibular disorders and is not vestibular disorder by itself. Tinnitus is abnormal noise perceived in one or both ears or in the head. Tinnitus (pronounced either “TIN-uh-tus” or tin-Ny-tus” may be intermittent, or it might appear as a constant or continuous sound. It can be experienced as a ringing, hissing, whistling, buzzing, or clicking sound and can vary in pitch from a low roar to a high squeal.
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