2010-07-17 / Columnists

Temporary Loss of Consciousness a Result of Syncopal Attacks

Maintaining Your Health on Mackinac
By Yvan Silva, M.D.

Syncope (SIN'ko-pe) is temporary loss of consciousness and posture, described as "fainting" or "passing out." Syncopal attacks are usually transient and related to temporary insufficiency of blood flow to the brain. It occurs when the blood pressure drops too low (hypotension) for the heart to pump a normal supply of oxygen to the brain. About 3% of the population has one or more syncopal attacks in a lifetime. They account for about 3% of all emergency room visits and also 6% of all hospital admissions.

It may be caused by emotional stress, pain, pooling of blood in the legs owing to sudden changes in body position, overheating, dehydration, heavy sweating, or exhaustion. Syncope may occur during violent coughing spells (especially in men) because of rapid changes in blood pressure. It also may result from several heart, neurologic, psychiatric, metabolic, and lung disorders. And it may be a side effect of some medications.

Some forms of syncope may suggest a serious disorder, such as those occurring with exercise, those associated with palpitations or irregularities of the heart, or those associated with a family history of recurrent syncope or sudden death.

Most often there is a feeling of dizziness accompanied by falling, or the urge to lie down before falling. There may be a feeling of unusual heat or cold, or shaking or chills. Recovery is spontaneous and occurs soon after the episode. The most common cause is a temporary decrease in blood flow to the brain. In otherwise healthy individuals, lying down or getting into a sitting position and bringing the head down between the knees will promote recovery from the episode. Injuries from falling can, of course, be serious, and repeated episodes of fainting require medical attention to determine the underlying disorder. Indeed, fainting episodes may point to a serious health disorder.

A common cause of fainting is physical exhaustion or extreme heat and dehydration. Loss of body salt in extremely hot environments, along with loss of body water, is known to cause fainting. Dehydration resulting from extreme physical exercise or long work hours, lack of sleep, and severe stress can cause fainting. Blood loss, anemia, and drops in blood pressure owing to changes in position from lying to sitting up or standing may produce episodes of fainting.

Syncope, when the cause is not appreciable, can pose a challenge to doctor and patient in regard to diagnosis and treatment. Symptoms can result from a benign condition and pose almost no threat to health. On the other hand, syncope, when it is a hallmark of a serious underlying condition, can pose an imminent threat to life.

People who have a heart condition that is causing syncope are at greater risk for dying within one year after an episode than people who faint owing to non-cardiac causes; therefore, a cardiac cause should be considered in older patients, patients with comorbid conditions of hypertension, diabetes, patients on multiple medications, and those with known heart failure, rhythm abnormalities, and abnormalities observed on electrocardiograms.

Common symptoms observed prior to syncope are a feeling of warmth, nausea, lightheadedness, dizziness, and sweaty palms. Sudden temporary loss of vision with perception of white light or blackouts can also occur.

A detailed history of the event or events and symptoms and signs of occurrences just before and after is crucial. A detailed physical examination should follow. Further cardiac testing with an electrocardiogram can detect certain abnormalities. An ultrasound examination of the heart, an echocardiogram, detects abnormalities of the muscle and heart valves, and in some cases, a 24-hour recording of heart rhythm with a Holter monitor may be indicated. Further heart testing is undertaken when the degree of the heart disease is discovered.

Most often syncope is a temporary condition, one that resolves itself quite quickly with spontaneous recovery. When no serious condition is discovered, the remedy is to avoid circumstances under which episodes occur. When required, comprehensive testing to identify the cause is crucial, because if untreated, the cause may be life-threatening.

Dr. Silva is a professor of surgery at Wayne State University and a resident of Woodbluff on Mackinac Island.

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