Syncope (Fainting)

One out of every 4 persons experiences a faint during his or her lifetime. In the US syncope is such a common complaint that each year as many as 1 million people seek medical treatment at a cost of $1 billion. It is estimated that as many as 6% of hospitalizations and 3% of emergency visits are prompted by transient loss of consciousness. In additional, 75% of patients with recurring syncope will alter their daily lives, nearly 40% will change jobs, and 75% will suffer from depression or anxiety, especially if not diagnosed and treated.

Syncope (Greek: synkope = cut-off) is a brief transient loss of consciousness (fainting) and postural tone (collapse) with rapid spontaneous recovery. Syncope is due to transient decrease in blood flow to the brain, an organ that cannot tolerate a brief deprivation of oxygen and blood-derived nutrients. Prolonged states of impaired consciousness without spontaneous rapid recovery are termed coma or shock rather than syncope. The mechanisms of syncope range from nearly normal (physiological) to abnormal and life threatening. Management may extend from simple reassurance to life-saving emergency intervention. For some persons with heart disease and complicated by arrhythmias, syncope today may represent tomorrow's sudden cardiac death.

Although individual differences in susceptibility to syncope exist, almost any healthy person can faint given the proper circumstances. The fact that simple faints are so common probably reflects incomplete evolutionary adaptation of humans to the upright body position. Giraffes have done an excellent job of mastering gravity and can raise their head from the ground to an elevation of 18 feet in one second without passing out. Standing upright requires special blood pressure regulation to drive blood against gravity up to the head. Most patients experience warning symptoms telling them they are about to pass out (pre-syncope or "gray-out"). Premonitory symptoms such as palpitations, weakness, confusion, and nausea allow an individual to "prepare" for collapse without bodily harm. However, elderly patients may be prone to serious injury such as hip fractures.