According to the Heart Rhythm Society, syncope is a common problem that affects one million people in the U.S. every year. About one-third of us will faint at least once during our lifetime.
Syncope is the temporary loss of consciousness and posture, also known as fainting. It occurs when there is insufficient blood flow to the brain. The episode is usually brief (lasting less than a few minutes) and is followed by rapid and complete recovery. Fainting is fairly common, accounting for 6 percent of all emergency room visits and 3 percent of hospital stays.
Syncope is, by definition, both unpredictable and unexpected. The patient may feel faint, dizzy, nauseous, or lightheaded just prior to losing consciousness.
You should seek medical attention after any fainting episode, particularly if you have a history of heart disease or if the fainting spell is followed by one or more of these symptoms:
- Numbness or tingling in any body part.
- Blurred vision.
- Difficulty speaking.
- Loss of movement in arms or legs.
Syncope can generally be categorized as being metabolic, vasomotor, cardiac, or neurological in nature. For our purposes, we will focus on neurological causes for syncope, which are relatively rare.
There are only four neurological conditions that cause syncope, and none are particularly common:
- Vertebrobasilar transient ischemic attacks (TIAs): Blood flow to the vertebrobasilar arteries, located in the back of the neck near the spinal column, is interrupted. The vertebrobasilar arteries supply blood to the consciousness center of the brainstem.
- Subclavian steal syndrome: Involves a blockage in the subclavian artery. During physical exertion when there is an increased demand for blood flow, the subclavian artery cannot keep up, and blood is re-routed from one of the arteries that supplies blood to the brain.
- Normal pressure hydrocephalus: This is an accumulation of excess fluid in the brain, and it typically affects elderly patients.
- Seizure disorders: A seizure is a sudden disruption of the brain’s normal electrical activity accompanied by altered consciousness. There are more than 20 different seizure disorders, the most notable being epilepsy.
Your doctor will conduct a careful physical examination, measuring your blood pressure and heart rate while you are lying down and standing up. In the vast majority of patients with syncope, neurological causes can be ruled out after a thorough physical exam.
In some cases an electrocardiogram (EKG or ECG) may be used to test for abnormal heart rhythms. Additional tests, such as an exercise stress test, Holter monitor (used to record your heart rhythm over a 24-hour period), or an echocardiogram may be needed to rule out other cardiac causes of syncope.
A CT scan or an MRI may be used to further evaluate suspected neurological causes.
Treatment for syncope varies depending upon frequency and whether or not the episodes are a symptom of an underlying disease. Treatment is generally not necessary in patients who have experienced a single episode, and for many people this is the case.
Treatment becomes necessary when:
- Syncope occurs frequently (e.g., it alters the quality of life).
- Fainting episodes are recurrent, occur unpredictably, and put the patient at risk of sustaining trauma (e.g., injuries from falling).
- Fainting occurs in a high-risk setting (e.g., driving, operating machinery, flying, competing in sports).
Often medications to prevent blood pressure from dropping too low are prescribed. However, if the cause of syncope is linked to cardiovascular disease or other disease, your doctor will treat those underlying causes.
National Heart, Lung, and Blood Institute (NHBLI)
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