Vasovagal Syncope (Reflex Syncope)
SYNCOPE is a medical term for a blackout that is caused by a sudden lack of blood supply to the brain. This is very common, and occurs in roughly half of all individuals during their lives. There are many causes of Syncope, but the most common by far is 'Vasovagal Syncope' (also known as Reflex Syncope). This is also known as the 'common faint'. Fainting may be simple, with a typical warning, going pale with a gentle collapse to the ground, a brief period of unconsciousness, and a prompt recovery. However, fainting may also be complex. There may be no warning, there may be jerking of the limbs and even incontinence, (accidental wetting), and some people may take quite a while to come around. To a patient, it may be very traumatic, and can be triggered by having blood drawn, or seeing an accident on the street; you turn pale and may become sweaty or nauseous; sounds appear to come from a distance, the world goes dark, and you fall down, unconscious. Complex fainting may appear just like a "seizure" or "fit". However, this can occur when there is a sudden fall in blood flow to the brain, it does not have to be due to epilepsy. Blackouts due to epilepsy occur when brain cells suddenly activate chaotically, but usually the blood flow remains normal. Furthermore, while Syncope affects 50% of people, epilepsy affects about 1%. It is very important to make sure that Syncope and epilepsy are distinguished from each other. A blackout is too often assumed to be due to epilepsy.
In VASOVAGAL SYNCOPE, either simple or complex, there is sudden triggering of a brain reflex. The nerves involved are part of the nervous system that behaves automatically. When we raise our arm or lift our leg, we do this voluntarily, but the automatic nervous system acts without our efforts. The correct name for this automatic behaviour is an "autonomic reflex". In Vasovagal Syncope, the heart rate drops or may even stop for several seconds. (bradycardia) and the blood pressure drops sharply (hypotension). This reflex mechanism is present in all of us, but in a more exaggerated form in some individuals. In effect, the reflex has shut down the body's blood circulation. When this happens insufficient oxygenated blood is pumped to the brain leading to dizziness and fainting. This odd reflex can be triggered by many different stimuli. Seeing blood is a common one, but simply standing immobile may also trigger a Syncope. Fainting can also be triggered in situations that make people anxious, stressed or emotional. Being in a overly warm environment, not having eaten or not having drunk sufficient liquids are all factors that increase the chances of setting the reflex in motion. Some patients do not take enough salt in their diet.
What are the symptoms
Symptoms can vary from patient to patient and from one faint to another. The most common symptoms are light-headedness, dizziness, and nausea. Accompanied with these symptoms may also be feelings of being hot, clammy or sweaty and sometimes experiences of visual and hearing disturbances. Often individuals become extremely pale looking. These symptoms are known a "pre-syncope" and may or may not be followed by a complete blackout. Some people get very little, or no warning symptoms prior to loss of consciousness. A tendency to faint can run in families.
Other names for Vasovagal Syncope
- Emotional Fainting
- Reflex Syncope
- Common Benign Fainting
- Neurocardiogenic Syncope
- Neurally Mediated Syncope
- Malignant Vasovagal Syncope
- More detailed information is available:
- What should you do?
- Measures to help you prevent episodes.
- What can be done during a Vasovagal Syncope (Reflex Syncope)?
