Reflex (Neurally Mediated) Syncope

What is syncope?

Syncope is a faint or short loss of consciousness, causing collapse with a natural recovery. Other terms used to describe syncope include ‘blackout’ or ‘drop attack’.

Syncope may be caused by a number of things such as a drop in blood pressure, change in heart rhythm or breathing too quickly (known as hyperventilation).

Reflex syncope

Reflex syncope is also known as ‘neurally mediated’ syncope because it is the result of changes in the nervous system causing a sudden drop in your blood pressure and heart rate.

This often happens when someone is standing up but can happen when they are sitting down. It rarely happens when lying down.

These faints are more likely to happen in certain situations, such as when eating a large meal in a warm room, during long haul flights or after standing for a long time. They may also be triggered by specific actions such as coughing or passing urine.

When people collapse in this way, it may be sudden or start with warning symptoms. Examples of these symptoms include tiredness, weakness, feeling sick, sweating, loss of colour vision, tummy discomfort, headache, pins-and-needles, light-headedness or spinning sensation. These symptoms may last for seconds or minutes. They can be referred to as ‘presyncope’ or ‘prodrome’. Older people may not have these warning symptoms.

After someone collapses, they will usually lie very still. Sometimes they will start to shake. The shaking is due to less oxygen getting to the person’s brain and may be mistaken for epilepsy.

As the person starts to become more aware they may feel sick, clammy, light-headed or tired. They may also complain of a headache and feel clammy to touch. Some people may not be able to stand up for several minutes. Full recovery can take up to a few hours.

Simple fainting (vasovagal syncope)

This is a form of reflex syncope and the most common cause of collapse. It happens most often in young adults. It is not often seen for the first time in older people.

Fainting may be brought on by, for example, standing for a long time, the sight of blood or severe pain and is linked with warning symptoms such as feeling sick (nausea), sweating and loss of skin colour. Injury to the person fainting does not often happen.

Treatment of reflex syncope

In most cases, reflex syncope is not treated with medication. To help you manage syncope you should follow the advice below:

1. If you think you are about to collapse, act quickly:
   1. Lie down flat propping your legs up on a chair or against a wall. If you cannot lie down, squatting can be good and is less likely to attract attention. These actions should improve your blood pressure and keep blood flowing to your brain. When you feel better, get up carefully. If your symptoms return or get worse, lie down or squat again.
   2. Simple exercises can help prevent you from collapsing. You can perform clenching exercises (known as physical counter-pressure manoeuvres) that contract large muscle groups, such as your thighs or buttocks.
   3. Drink a glass of water (200ml) quickly. This will also increase blood pressure and reduce the risk of fainting.
2. Try to avoid situations that are likely to cause you to collapse. These situations may include; standing in a queue, taking a long hot bath, eating a large carbohydrate-rich meal in a warm room or not drinking enough fluid while in a hot setting.
3. Keep hydrated. You will know if you are drinking enough if you pass clear, pale coloured urine.
4. Avoid alcohol.
5. Wear support stockings and tights during the day. Your GP can provide you with more information about these.
6. If you do not have high blood pressure, we will measure how much sodium (salt) you pass during a 24 hour urine sample. If this test shows that you are not eating enough salt, we will advise you to eat more.

Medication

In certain situations, medication can be used to treat reflex syncope. The medications most often used include fludrocortisone and midodrine.

Pacemaker

There are rare occasions when a patient will need to have a permanent pacemaker fitted.

If a pacemaker is needed, it will be discussed with you during a clinic appointment and further information given. You will also have the opportunity to ask any questions you may have.

Contact information

If you have any questions or queries, please do not hesitate to contact:

Syncope Clinic

Gloucestershire Royal Hospital

Tel: 0300 422 5673

Monday to Friday, 9:00 am to 4:30 pm