Source:http://linkedlifedata.com/resource/umls/id/C0039070
MSH: A transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., BRAIN ISCHEMIA). Presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp367-9),CSP: fainting due to a sudden fall of blood pressure below the level required to maintain oxygenation of brain tissue.,NCI: Extremely weak; threatened with syncope.,MEDLINEPLUS: <p>If you've ever fainted, you are not alone - at least one third of people faint sometime in their lives. Fainting is a temporary loss of consciousness. You lose muscle control at the same time, and may fall down. Most people recover quickly and completely. </p><p>Fainting usually happens when your blood pressure <a href='http://www.nlm.nih.gov/medlineplus/lowbloodpressure.html'>drops</a> suddenly, causing a decrease in blood flow to your brain. This is more common in older people. Some causes of fainting in