What is syncope?
Syncope is temporary loss of consciousness and posture, described as "fainting" or "passing out." It's usually related to temporary insufficient blood flow to the brain. It most often occurs when the blood pressure is too low (hypotension) and the heart doesn't pump a normal supply of oxygen to the brain.
What causes syncope?
It may be caused by emotional stress, pain, pooling of blood in the legs due to sudden changes in body position, overheating, dehydration, heavy sweating or exhaustion. Syncope may occur during violent coughing spells (especially in men) because of rapid changes in blood pressure. It also may result from several heart, neurologic, psychiatric, metabolic and lung disorders. And it may be a side effect of some medicines.
- those occurring with exercise
- those associated with palpitations or irregularities of the heart
- those associated with family history of recurrent syncope or sudden death
What is neurally mediated syncope?
Neurally mediated syncope (NMS) is called also neurocardiogenic, vasovagal, vasodepressor or reflex mediated syncope. It's a benign (and the most frequent) cause of fainting. However, life-threatening conditions may also manifest as syncope. NMS is more common in children and young adults, although it can occur at any age. NMS happens because blood pressure drops, reducing circulation to the brain and causing loss of consciousness. Typical NMS occurs while standing and is often preceded by a sensation of warmth, nausea, lightheadedness and visual "grayout." If the syncope is prolonged, it can trigger a seizure. Placing the person in a reclining position will restore blood flow and consciousness and end the seizure.
The majority of children and young adults with syncope have no structural heart disease or significant arrhythmia (abnormal heart rhythm). So, extensive medical work-up is rarely needed. A careful physical examination by a physician, including blood pressure and heart rate measured lying and standing, is generally the only evaluation required.
This content was last reviewed on 10/23/2014.