Neurocardiogenic syncope (patient information)

Overview

Neurocardiogenic syncope is also known known as vasovagal syncope, reflex syncope, and neurally mediated syncope. It refers to a fainting spell that usually occurs in response to a specific trigger. The syncope, or fainting generally occurs due to a momentary loss of blood flow to the brain, which deprives the brain of oxygen. The fainting spell is involuntary, and there is a rapid recovery afterwards. Episodes of dizziness or lighteheadedness without losing consciousness is called pre-syncope. Injuries can occur as a risk of syncope or fainting, and syncope can signal an impending cardiac arrest. It is important to distinguish neurocardiogenic syncope from other causes of fainting or loss of consciousness, such as low blood sugar levels in diabetics, seizure, or heart attack. Neurcardiogenic syncope is essentially a momentary failure of the brain and the cardiovascular system to communicate with each other, causing a fainting spell in response to a particular trigger. Neurocardiogenic syncope is usually benign, however one should see a doctor following a faiting spell especially if it is the first one.

What are the symptoms of neurocardiogenic syncope?

There may be symptoms leading up to the fainting spell, consisting of:

• Nausea
• Sweating
• Lightheadedness
• Tingling or numbness in the arms and legs
• Blurry vision
• Headaches
• Palpitations or "racing heartbeat"
• Pale in apperarance
• Warmth
• Visual "grayout"
• Abdominal discomfort

What causes neurocardiogenic syncope

Neurocardiogenic syncope occurs when the part of the nervous system that regulates heart rate and blood pressure temporarily malfunctions. Usually in response to some sort of trigger such as fear or the sight of blood, the heart rate slows down, and the blood vessels in the legs dilate. This causes blood to pool in the lower region of the body, and therefore a lack of blood and oxygen to the brain which causes fainting. This is similar to what happens when one feels faint after suddenly standing up. When a person faints, gravity causes blood flow to to the brain to be restored and the person gains consciousness. Possible triggers causing neurocardiogenic syncope are as follows;

• Seeing blood or losing blood
• Pain
• Emotional stress or anxiety
• Prolonged standing
• Heat
• Physical exertion
• Defecation or urination
• Standing up suddenly
• Coughing spells

Who is at highest risk

Neurocardiogenic syncope is most common in children and young adults, and commonly people grow out of this condition as they reach adulthood. It also tends to occur in persons who have a family history of fainting spells. It is thought to affect persons who have a genetic predisposition towards poor resistance in the blood vessels of the lower extremities, causing blood to pool away from the brain in response to certain situations.

When to seek urgent medical care

Syncope or fainting in the setting of certain criteria warrant seeking medical care, and may be a sign of a serious disorder.

• If the syncope occurs while exercising
• If it is associated with heart palpitations or irregularities in the heartbeat, or if the person has a known cardiac arrythmia
• If it occurs in an individual with a family history of recurrent syncope or death
• If the syncope is associated with seizure, or following a head injury
• If the syncope occurs without warning signs in someone who may hurt themselves or faint unexpectedly while driving

Diagnosis

The three main ways to identify the cause of syncope is through a thorough medical history. including a family history, a physical exam, and cardiac testing if neccesary. Neurocardiogenic syncope is benign, and the most common cause of fainting, and the majority of children and young adults with syncope have no structural heart disease or significant arrythmia, so an extensive workup is rarely needed. A careful physical examination by the doctor, including blood pressure and heart rate measured while lying and standing is generally the only medical evaluation that is required.

Medical history

A medical history will include questions such as

• Whether this was the first fainting spell
• Other medical conditions in the patient history such as pre-existing heart disease, diabetes, psychiatric illess
• Current medications that the person is on, and medications they may recently have stopped
• Were there were any signs or symptoms noticed before the fainting occured
• What the person was doing when they fainted
• Whether a bystander noticed any movement in the patient while they were unconscious, as this may signify a seizure over a true neurocardiogenic episode
• Did the patient hit their head or hurt themselves during the fainting spell
• Did it occur while exercising (as this can signify a heart defect such as hypertrophic obstructive cardiomyopathy or aortic stenosis)

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