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Reye's Syndrome

An acute childhood illness, Reye's syndrome causes fatty infiltration of the liver with concurrent hyperammonemia, encephalopathy, and increased intracranial pressure (ICP). In addition, fatty infiltration of the kidneys, brain, and myocardium may occur.

Reye's syndrome affects children from infancy to adolescence and occurs equally in boys and girls. It affects Whites over age 1 more often than Blacks.

The prognosis depends on the severity of central nervous system depression. Previously, mortality was as high as 90%. Today, ICP monitoring and, consequently, early treatment of increased ICP, along with other treatment measures, have cut mortality to about 20%. Death is usually a result of cerebral edema or respiratory arrest. Comatose patients who survive may have residual brain damage.

Causes

Reye's syndrome tends to occur in previously healthy children about a week after common viral infections such as influenza or chickenpox. It can also develop after an ordinary upper respiratory infection such as a cold. The precise reason is unknown, but using aspirin to treat a viral illness or infection may trigger the condition in children.

Reye's syndrome may be a metabolic condition - one without symptoms (asymptomatic) - that's unmasked by viral illnesses. Reye's syndrome occurs most commonly in children between the ages of 4 and 12.

Signs and symptoms

The severity of the child's signs and symptoms varies with the degree of encephalopathy and cerebral edema. In any case, Reye's syndrome develops in five stages.

After the initial viral infection, a brief recovery period follows when the child doesn't seem seriously ill. A few days later, he develops intractable vomiting, lethargy, rapidly changing mental status (mild to severe agitation, confusion, irritability, delirium), hyperactive reflexes, and rising blood pressure, respiratory rate, and pulse rate.

Reye's syndrome often progresses to coma. As the coma deepens, seizures develop, followed by decreased tendon reflexes and, frequently, respiratory failure.

Increased ICP, a serious complication, results from cerebral edema. Such edema may develop as a result of acidosis, increased cerebral metabolic rate, and an impaired auto regulatory mechanism.

Diagnosis

Reye's syndrome may be suspected in a child who begins vomiting three to six days after a viral illness, followed by an alteration in consciousness. Diagnosis involves blood tests to determine the levels of certain liver enzymes, which are highly elevated in Reye's syndrome. Other blood changes may occur as well, including an increase in the level of ammonia and amino acids, a drop in blood sugar, and an increase in clotting time. A liver biopsy may also be done after clotting abnormalities are corrected with vitamin K or blood products. A lumbar puncture (spinal tap) may be needed to rule out other possible causes, including meningitis or encephalitis.

Treatment

Intensive, supportive care is needed, although specific treatment measures have not been determined.

Intravenous fluids to provide electrolytes and glucose are given. Steroids are given to reduce swelling in the brain. Intensive monitoring of the pressure within the brain, blood gases, and blood pH is required. Support for breathing ( respiratory system) during a deep coma using a mechanical ventilator may be needed.

Prevention

Aspirin and other salicylate drugs should never be used in the treatment of chickenpox, influenza, and other viral diseases. In general, aspirin should not be used for children or teenagers except on the advice of a doctor for certain conditions.

In addition, other over-the-counter medications such as Pepto-Bismol and compounds containing oil of wintergreen also contain salycilates, and should not be given to children with colds or fever.