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. It’s most common in patients ages 4 to 12, with a peak incidence at age 6.
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
Incidence of Reye’s syndrome usually rises during influenza outbreaks and is linked to aspirin use. It almost always follows within 1 to 3 days of an acute viral infection, such as an upper respiratory tract infection, type B influenza, or varicella (chickenpox).
With Reye’s syndrome, damaged hepatic mitochondria disrupt the urea cycle, which normally changes ammonia to urea for its excretion from the body. This results in hyperammonemia, hypoglycemia, and an increase in serum short-chain fatty acids, leading to encephalopathy. Simultaneously, fatty infiltration is found in renal tubular cells, neuronal tissue, and muscle tissue, including the heart.
Signs and symptoms
Reye’s syndrome develops in five stages, but the severity of the child’s signs and symptoms varies with the degree of encephalopathy
and cerebral edema. Infants may have atypical presentation.
and cerebral edema. Infants may have atypical presentation.
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 may progress to coma. As the coma deepens, seizures develop, followed by decreased tendon reflexes and, commonly, respiratory failure.
Increased ICP, a serious complication, results from cerebral edema. Such edema may develop as a result of acidosis, increased cerebral metabolic rate, or an impaired autoregulatory mechanism.
