What is the definition of "syncope"?

Syncope is defined as a temporary loss of consciousness that occurs as a result of insufficient blood flow to the brain. This can happen due to various reasons, such as a sudden drop in blood pressure, dehydration, or certain medical conditions that affect blood flow. During syncope, the brain is briefly deprived of the oxygen it requires to function normally, which can lead to the individual fainting or experiencing a brief lapse in awareness.

The other choices describe different medical conditions or symptoms that do not accurately represent syncope. For example, a sudden onset of a severe headache may indicate a migraine or another type of headache, but it does not involve loss of consciousness. Prolonged periods of unconsciousness could refer to conditions like a coma or vegetative state, which are much more severe and longer-lasting than syncope. Lastly, loss of motor function after a stroke pertains to neurological deficits following a cerebrovascular accident, which is a separate medical issue from syncope.