Introduction

Fainting spell, “blacking out,” or syncope is defined as a sudden, brief loss of consciousness followed by the return to full wakefulness. This loss of consciousness may be accompanied by loss of muscle tone that can result in falling or slumping over.

Fainting is relatively common in adolescence, especially in the ages between 15 to 19 years old. Although syncope can be non-dangerous and mostly occurs in a normal individual, in some circumstances it can cause potentially serious problem related to the heart or has to differentiated from a seizure.

What causes fainting?

It happens in one of the following conditions:

• Vasovagal syncope (Neurally mediated syncope 50%).
• Postural hypotension (low blood pressure secondary to body position) (20%).
• Cardiac syncope (structural or rhythm problems of the heart).
• Anemia (low number of red blood cells).
• Dehydration (lack of body fluid).
• Hypoglycemia (low blood glucose level).
• Others: like simple fainting attacks due to anxiety, fear, intense emotional stress, hunger, use of alcohol or drugs in patients with no heart or neurological problems.

The above conditions cause:

• Inadequate blood pumped out from the heart.
• Inadequate tone of blood vessel to maintain the blood pressure.
• Low blood volume.
• Combination of the above

These lead to decreased blood flow to the brain which may cause a fainting attack.

Vasovagal syncope (Neurally mediated)

This is the most common type of fainting spell especially in children and young adults. It typically occurs while standing motionless for long periods of time especially in hot conditions and is preceded by sensation of warmth, nausea, lightheadedness and visual grey out. Pain is a common cause of vasovagal syncope. Other noxious stimuli can do the same thing, including situational stressors. Some people faint when they hear bad news. It happens due to transient unbalanced innervations of the heart, blood vessels and chemical substances which lead to loss of control on heart and the blood vessel functions causing low blood pressure and fainting attacks.

Postural hypotension (low blood pressure secondary to body position).

Blood vessel tone which is controlled by an automatic body mechanism is very important to overcome the effect of gravity to maintain a normal blood pressure. When the mechanism is impaired, it can cause reduction of blood flow to the brain and cause the child to faint. This is referred to postural hypotension. It presents particularly when the child moves too quickly to a standing position from a sitting or lying position.

Heart or blood vessel problems

Structural problems of the heart such as narrow heart valves and thickenedn heart muscles can disturb the normal blood flow to and out of the heart. WAlso weakened heart muscles due to viral or bacterial infections These conditions can also affect the blood flow to the body and cause fainting.

Arrhythmias (heart rhythm abnormalities)

The blood flow to the body especially to the brain can be affected by the heart rate and rhythm especially if the heart beats too fast or too slowly or irregularly.

Anemia (low red blood cell count)

It can occur acutely from bleeding or with a more gradual onset due to various reasons, and can cause fainting attacks as there are insufficient red blood cells to deliver oxygen to the brain.

Dehydration or lack of water in the body

This can be caused by excessive loss of water from vomiting, diarrhea, sweating, or by inadequate fluid intake and it causes inadequate blood volume.

Hypoglycemia (low blood sugar)

Fasting long hours, taking in too little food and fluids, severe vomiting or diarrhea, excessive exercise can cause low blood sugar and can lead to fainting too.

Hyperventilation

Some people breathe too quickly when anxious or panicked. Taking in too much oxygen and getting rid of too much carbon dioxide from the body can lead to fainting spells.

Emotional-related (conversion disorders)

This is commonly found in adolescence girls.Typically, these girls are consciously or subconsciously have these events to avoid any unpleasant emotional situations. During these fainting spells, the eyes may be tightly closed with a lid flutter. This fainting spells may occur many times per day with no physical injury.

Unusual conditions

There are unusual conditions that can cause fainting spells e.g. during and after micturition, pain in the nerve of the mouth or throat due to inflammation (glossopharyngeal neuralgia), attacks of intense coughing, excessive stretching out of neck or arms.

What are the signs and symptoms of fainting?

When fainted, the patient is unaware that he or she became unconscious and fallen to the ground. It is only afterward that they notice themselves as to what has happened. There may be symptoms or signs before the fainting occur.

Some signs and symptoms of fainting are :

Lightheadedness, nausea, sweats, or weakness. There may be a feeling of dizziness or vertigo (with the room spinning), vision may fade or blur, and there may be muffled hearing and tingling sensations in the body.

There may be chest discomfort, shortness of breath and palpitations (fast heart rate) before the fainting attack if the fainting is due to a heart problem.

The child may have some confusion after waking up but it should resolve within a few seconds. After a fainting spell, there should be a quick return to normal mental function, though there may be other signs and symptoms depending upon the underlying cause of the fainting spell.

How to differentiate between seizures and syncope?

Witnessing syncope in a child can be a very traumatic experience to a caregiver. It is difficult to differentiate between syncope and seizures especially when abnormal movements are present.

Syncope	Seizures
Abnormal jerking movements begin once the child fall on the ground	Abnormal jerking movements begin even when the child in standing position
The loss of consciousness is usually less than 2 minutes	The loss of consciousness is usually more than 5 minutes
There is hardly loss of bladder or bowel control	There is usually loss of bladder or bowel control
Post incidence, the child is commonly feel tired and but there is hardly any confusion to the surrounding	Post incidence, the child always has confusion to the surrounding
There is no tongue bitting	There is always tongue bitting
Eyes open often wide and deviated	Eyes open often wide and deviated
Normal growth development	May have associated abnormal growth development

Table 1.Differences between seizures and syncope

How is fainting (syncope) diagnosed?

History

The history is the key point to find the cause of the fainting. The description of how the patient felt and what bystanders or family members witnessed will give clues to the diagnosis.

Age 6 years or less	Age 7-18 years
Less common	More common
Usually vasovagal syncope Breath-holding spells – particularly age 6 months to 2 years. There is a prolonged silent cry causing temporary abnormal body nerve response followed by the child turning blue and faint. Extreme pain or emotional trigger such as blood taking or getting hair cut.	Usually vasovagal syncope Prolonged standing Pain example blood taking Fasting Lack of sleep Coughing or neck stretching Micturation, defecation Standing quickly, arising from squat Certain medication
	Emotional-related syncope
Heart-related syncope	Heart-related syncope (least common)

 

Table 2.Common causes of syncope in children

Signs

By physical examinations there will be a clue to identify the cause of faint such as pallor, low blood pressure, abnormal heart rhythm or others signs related to the heart or the brain.

Investigations

Most children who faint are not referred to a doctor if there is no recurrence and if the fainting spell is likely to be a vasovagal one. There are a few basic investigations that the doctor needs, to evaluate the fainting patient. This includes an electrocardiogram to look for rhythm heart abnormality. If it is abnormal, a 24-48 hours heart rhythm monitoring is required. The monitoring may also be done if the fainting spells are recurrent over a short period of time.

The blood glucose level at the time of the incident is ideal to check to make sure the patient is not hypoglycemia. Sometime other blood investigations are also necessary such as full blood count and electrolyte depending on the condition of patient.

A tilt-table test can be used to uncover a diagnosis of postural hypotension, if the story is not clear.

Computerized tomography (CT scan) or magnetic resonance imaging (MRI) of brain is rarely required unless the symptoms and signs suggestive of brain problem such as brain tumour.

Often these tests are normal and a presumptive diagnosis is made of a non life-threatening event. It may be reasonable in some cases to take a watchful waiting approach and not proceed with any further evaluation.

What is the treatment for syncope?

Fainting, due to vasovagal causes, is common in children especially in teenagers . If the child faints for a short while and he/she returns to normal function with no evidence of injury, it is appropriate not to bring the child to seek medical attention if it is the first episode. Medical evaluation is necessary in other situations. The fainting spell also has to be differentiated from a seizure.

Further treatment will be done based upon the evaluation.

What to do if someone faint at home?

• Lay the child flat on his/her back. Elevate the legs to help blood flow back to the heart and go to the brain.
• Loosen any tight clothing.
• If fully awake, alert and orientated, give the child a drink especially if she or he has not eaten or drunk so far. If the child is half awake or look a bit confused stay with him or her until fully recovered.

When to call for medical help?

• If the child shows no signs of response on trying to awaken him/her up.
• If the child turns blue in colour especially if involves the face and lips.
• Irregular heart rate either too slow or too fast.
• Complain of breathing difficulty.
• Complain of chest pain.
• Continue to be confused.
• Attains any injury to the body.

Can fainting be prevented?

Depending upon the cause, there may be opportunities to prevent fainting spells. For example, children who have had a vasovagal cause may be aware of the warning signs and be able to sit or lie down before passing out and avert the fainting and adequate fluid intake may be enough to prevent dehydration as the cause for syncope. Squatting is also effective especially if the teenager is embarrassed to lie down in a public situation.

Avoid triggering factors. Eat properly to avoid hunger or low blood sugar especially if the child is a diabetic. Drink adequately to prevent dehydration or low blood volume. Avoid excessive fatigue, alcohol or too warm environment. Try to avoid breathing too quickly when anxious, fear or panicked. Stand up slowly from sitting or lying down position to avoid postural hypotension.

Avoid having sharp objects or furniture lying around in the house especially if the child is known to have frequent fainting attacks at home.

REFERENCES

1. Fauci, Anthony S., et al. Harrison’s Principles of Internal Medicine. 17th ed. United States: McGraw-Hill Professional, 2008.
2. David J. Driscoll et al.Syncope in Children and Adolescents. JACC Vol.29, No.5 April 1997; 1039-45.
3. David A. Lewis, MD, and Anwer Dhala, MD. Syncope in the pediatric patients. The cardiologist’s perspective. Pediatric Clinics of North America Vol.46, No 2. April 1999.
4. John J. Seger, MD. Syncope Evaluation and Management. Texas Heart Institute Journal, Volume 32, Number 2, 2005.
5. http://www.medicinenet.com/fainting/article.htm

 

Last Reviewed	:	30 September 2013
Writer	:	Dr. Amin bin Itam