Friday, June 2

VERTIGO

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VERTIGO is a sense of rotation, rocking, or the world spinning, experienced even when someone is perfectly still.

Many children attempt to create a sense of vertigo by spinning around for a time; this type of induced vertigo lasts for a few moments and then disappears. In comparison, when vertigo occurs spontaneously or as a result of an injury it tends to last for many hours or even days before resolving.

Sound waves travel through the outer ear canal until they reach the ear drum. From there, sound is turned into vibrations, which are transmitted through the inner ear via three small bones -- the incus, the malleus, and the stapes -- to the cochlea and finally to the vestibular nerve, which carries the signal to our brain. Another important part of the inner ear is the collection of semicircular canals. These are positioned at right angles to each other, and are lined with sensitive cells to act like a gyroscope for the body. This distinctive arrangement, in combination with the sensitivity of the hair cells within the canals, provides instantaneous feedback regarding our position in space.


WHAT CAUSE VERTIGO

There are a number of different causes of vertigo. Vertigo can be defined based upon whether the cause is peripheral or central. Central causes of vertigo arise in the brain or spinal cord while peripheral vertigo is due to a problem within the inner ear. The inner ear can become inflamed because of illness, or small crystals or stones found normally within the inner ear can become displaced and cause irritation to the small hair cells within the semicircular canals, leading to vertigo. This is known as benign paroxysmal positional vertigo (BPPV).

Meniere's disease, vertigo associated with hearing loss and tinnitus (ringing in the ear), is caused by fluid buildup within the inner ear; the cause of this fluid accumulation is unknown. Head injuries may lead to damage to the inner ear and be a cause of vertigo. Infrequently, strokes affecting certain areas of the brain, multiple sclerosis, or tumors may lead to an onset of vertigo. Some patients with a type of migraine headache called basilar artery migraine may develop vertigo as a symptom.

What are the risk factors for vertigo?

Head injuries may increase the risk of developing vertigo, as can different medications, including some antiseizure medications, blood pressure medications, antidepressants, and even aspirin. Anything that may increase your risk of stroke (high blood pressure, heart disease, diabetes, and smoking) may also increase your risk of developing vertigo. For some people, drinking alcohol can cause vertigo.

Studies of the incidence of vertigo find that between 2% to 3% of a population is at risk of developing BPPV; older women seem to have a slightly higher risk of developing this condition.





Rujukan :

http://www.medicinenet.com/vertigo_overview/article.htm

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