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In addition to serving as the organ of hearing, the ears have a significant role in the control of balance. The inner ears house the semicircular canals and otolithic organs - the sensory organs of the vestibular system - the most rapid sensors of the body’s motion.
As the ears sense movement, they send signals to the muscles of the eyes, neck, trunk, arms and legs. These signals allow those organs to maintain a stable position even as the body and head undergo complex motions. Were it not for the vestibulo-ocular reflex (the reflexive control of eye position in response to signals from the ear) we would not be able to keep our gaze fixed on an object as we moved about. In fact, certain patients with loss of inner ear function experience oscillopsia, i.e. the abnormal perception of movement of their visual field as they move about in their daily activities.
A more common symptom that arises from disturbances of the inner is vertigo. Vertigo is either the perception of motion when no movement is present, or the abnormal perception of motion in response to movement. When the vestibular system functions improperly, a person may feel like they are moving even when they are not. There may also be unsteadiness while moving, because the experience of each movement - and the sensation that is felt - is not what the body and brain are used to feeling.
Vertigo is not a disease; it is a symptom of disease. Just like pain in your leg can be caused by many different things - bumping into something, fracture of the bone, clogged blood vessels… - so too can the sensation of vertigo be produced in many different ways.
Disorders That Can Cause Vertigo
There are scores of disorders that can cause vertigo. These are some of the more common ones:
Some less common causes of vertigo are:
After injury to the inner ear, the brain undergoes a complex set of changes that allow it to adapt to the altered sensory input and abolish the perception of vertigo. This process is called “vestibular compensation.” After a sudden injury to the inner ear, the continuous perception of vertigo is usually controlled in about 3 days. It can take another 4-6 weeks, on average, for the brain to adapt to the new input with motion.
In some people this process is never completed, and they have vertigo due to incomplete vestibular compensation. It is important to distinguish this process from ongoing alterations and fluctuations in the inner ear itself, in order to properly tailor the treatment. Certain patients can achieve complete compensation initially only to have episodes of “decompensation” later in life, frequently in response to new physical or emotional stresses. It is likewise important to distinguish this “central decompensation” from a recurrence of the original ear problem that precipitated it.
Treatment of vertigo depends on its cause. If a specific causative disease is identified, therapy can be tailored for that disorder. Frequently there can be multiple, coincident causes of vertigo, and each needs to be treated individually. Surgery can be helpful and even curative for many causes of vertigo. There are a number of different operations that can eliminate vertigo from various inner ear diseases. In general, surgery is reserved for patients in whom more conservative treatments have failed to control the symptoms. Medications are often helpful in controlling the acute symptoms of vertigo, but can frequently be counter-productive for people with more chronic problems.
In certain cases, one specific cause of vertigo cannot be identified, but, depending on the nature of the vertigo treatment may still be provided with good hope for improvement. In many such instances, vestibular rehabilitation therapy (VRT) is the recommended approach.
Vestibular Rehabilitation Therapy (VRT)
VRT is a specialized mode of physical therapy that strengthens the vestibular sensory system. This contrasts with traditional physical therapy which strengthens motor systems. VRT has three different general approaches to improving balance:
Other conditioning programs such as Tai Chi have also been shown to benefit people with chronic vestibular and balance disorders. Although they can be helpful, since they may not take place in a closely supervised setting, people who are at risk for falls should use caution when trying such approaches.