syncope
Meaning of syncope: The recovery is what defines it: consciousness returns on its own, quickly and completely, with nothing done to bring it back.
Definition of syncope
Syncope is a sudden, brief loss of consciousness and muscle tone caused by a temporary drop in blood flow to the brain, from which a person recovers fully and on their own. The everyday word for it is fainting. Because the blackout is short and self correcting, syncope names the event itself rather than any single cause behind it.
Why does consciousness fail so fast?
Brain tissue stores almost no oxygen or fuel of its own. It depends on continuous delivery, and an interruption lasting only seconds is enough to switch consciousness off. What reaches the brain depends on blood pressure, which is set by how much blood the heart pushes out with each beat and how firmly the arteries hold their tone. Anything that lowers either one far enough produces the same result. Standing pools blood in the legs, which is why most faints happen upright and why falling to the floor is itself corrective: lying flat restores flow within seconds. That is the reason recovery is quick and complete, and the reason an episode that does not resolve by itself is something other than syncope.
What are the main kinds?
| Type | What sets it off |
|---|---|
| Reflex, also called vasovagal | Pain, fear, the sight of blood, long periods standing, heat, coughing, swallowing or straining |
| Orthostatic | Rising to stand when blood volume is low or when the reflex that tightens each blood vessel is blunted by medicines or nerve disease |
| Cardiac | A rhythm too fast or too slow to move blood, or an obstruction such as a narrowed valve |
The three carry very different weight. Reflex faints are much the commonest and are not dangerous in themselves, though the fall can be. Cardiac syncope is the group that matters, and the features that raise concern are recognized ones: collapse during exertion rather than after it, collapse while lying down or seated, no warning at all beforehand, and a family history of sudden death.
How is it told apart from a seizure?
Both end in a person on the floor, and brief twitching during a faint is common enough to confuse the two. Several details separate them. A faint is usually preceded by warmth, nausea, sweating, dimming or graying vision and muffled hearing, and awareness returns almost at once. After a seizure, confusion typically lasts many minutes, and tongue biting along the side and loss of bladder control are more suggestive of it. The account given by someone who watched is often worth more than any test, since the person who fainted remembers nothing of the interval.
Also known as
Used in a sentence
The clinician asked about symptoms immediately before the episode of syncope.
Good to know
Causes range from a harmless reflex faint to serious heart disease, so the circumstances of the episode and any warning symptoms carry more weight than the collapse itself.
Word origin
Where “syncope” comes from
From Greek synkope, meaning a cutting short, formed from syn-, meaning together, and koptein, meaning to strike or cut off.