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)

Physical exam

The physician will start by checking the vital signs which include the heart rate and blood pressure. They may check these with the patient both lying and standing to check for orthostatic hypotension. A close examination of the heart to check for murmurs (such as in aortic stenosis), and asking the patient to bear down while listening for abnormal heart sounds (such as in hypertrophic cardiomyopathy) can lead to diagnosing or excluding possible cardiac causes for the syncope. Depending on the history, the doctor may also check for blood in the stool, as blood loss can cause syncope.They may also check for changes in the heart rate while massaging the carotid artery in the neck, as this can give clues to a possible diagnosis.

Testing

If the diagnosis of neurocardiogenic syncope is not certain, further testing may be required. Based on the medical history and the physical examination, the some of the following tests may be required;

• An electrocardiogram - an electrocardiogram or EKG gives a close view of the electrical activity that is passing through the heart. It may be normal even if there is a cardiac reason for the fainting spell, so further testing may be still be needed. It is not a painful or invasive test, and consists of several sticky pads being attached to the body and a reading being taken.
• A holter monitor or an event recorder - these are all heart monitoring devices that measure the elecrical activity of the heart and are worn by the patient at home. A holter monitor is worn from 24-48 hours and measures any changes in the conduction of the heart during a syncopal episode. An event reocrder is smaller and can be worn for up to two months.
• An echocardiogram - an echocardiogram is a non-invasive method using ulrasound to get a picture of the heart in motion. It is non-painful, does not expose the body to any radiation, and can help identify structural abnormalities of the heart such as hypertrophic cardiomyopathy and aortic stenosis.
• A tilt table test - if EKG and other cardiac tests are normal, the person will undergo a tilt test. The doctor will measure the blood pressure and heart rate when the person is lying completely horizontal on the table, and then the table will be rapidly tilted up. Blood pressure and heart rate will be moitored straight after the tilt. A person with neurally mediated syncope will usually faint during this test.
• Exercise testing - for patients who have a history of syncope during exertion, an exercise test may help to determine the exact nature of the syncope by montoring of the blood pressure, heart rate, and rythm during exercise.
• An electroencephalogram - an EEG is used to determine the cause of syncope when a neurological cause such as seizure is suspected. It usually takes an hour and consists of sticky electrodes attached to the head and subsquent monitoring of brain waves to detect for seizure activity.

Treatment options

Treatment prescribed by the physician will depend on the impact the syncope has on the individual. Factors taken into consideration include frequency of the syncope, whether is causes trauma due to lack of prodromal symptoms or whether the attacks could lead to a significantly dangerous situation (for example in a truck driver). Non-pharmacological treatment options are usually employed first. Some of the treatment options that that may be recommended by the physician are;

• A higher salt diet and drinking plenty of fluids to avoid dehydration and to maintain blood volume.
• Being aware of specific triggers and symptoms that occur prior to a syncopal episode,and lying down immediately to restore blood flow to the brain.
• Cessation of certain medications that may be causing the syncope. Examples of such classes of medications are vasodilators, diuretics, tricyclic antidepressants or MAOI medications.
• Counterpressure maneuvers such as leg-crossing and bearing down to prevent vasovagal syncope by increasing venous return.
• Orthostatic training which includes standing upright against a wall twice per day, for varying amounts of time.
• Medications may be of use for certain patients - the types of medications that may be prescribed are beta blockers, midodrine, and serotonin reuptake inhibitors.
• A pacemaker - in certain pateints a pacemaker may be recommended for recurrent reflex syncope. It is used for patients who are over forty, who do not have any prodromal symptoms before the syncope, and who have been shown to have episodes of spontaneous bradycardia or syncope during cardiac monitoring.

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