Dizziness is an impairment in spatial perception and stability. The term dizziness is imprecise: it can refer to vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness.
Dizziness is a common medical complaint, affecting 20-30% of persons. Dizziness is broken down into 4 main subtypes: vertigo (~25-50%), disequilibrium (less than ~15%), presyncope (less than ~15%) and nonspecific dizziness (~10%).Vertigo is the sensation of spinning or having one's surroundings spin about them. Many people find vertigo very disturbing and often report associated nausea and vomiting. Presyncope describes lightheadedness or feeling faint; the name relates to syncope, which is actually fainting. Disequilibrium is the sensation of being off balance and is most often characterized by frequent falls in a specific direction. This condition is not often associated with nausea or vomiting. Non-specific dizziness may be psychiatric in origin. It is a diagnosis of exclusion and can sometimes be brought about by hyperventilation.
According to the USA National Ambulatory Medical Care Survey for 1991, dizziness-vertigo is among the 25 most common reasons Americans visit the doctor. U.S. physicians report a total of more than 5 million dizziness-vertigo visits a year.