Reye’s syndrome in Children

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.

Incidence
Reye’s syndrome affects children. It’s most common in patients ages 4 to 12, with a peak incidence at age 6.

Pathophysiology

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.
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.

Diagnosis

• Early diagnosis and treatment improves chances of recovery. A history of a recent viral disorder with typical signs and symptoms strongly suggests Reye’s syndrome. An increased serum ammonia level, abnormal clotting studies, and hepatic dysfunction confirm it.
• Testing the serum salicylate level rules out aspirin overdose. Absence of jaundice, despite increased liver transaminase levels, rules out acute hepatic failure and hepatic encephalopathy.
• Abnormal test results may include the following:
• Liver-function studies show aspartate aminotransferase and alanine aminotransferase levels elevated to twice normal; bilirubin level is usually normal.
• Liver biopsy reveals fatty droplets uniformly distributed throughout cells.
• Cerebrospinal fluid (CSF) analysis reveals a white blood cell count of less than 10; with coma, CSF pressure increases.
• Coagulation studies result in prolonged prothrombin and partial thromboplastin times.
• Blood values show elevated serum ammonia levels; normal or, in 15% of cases, low serum glucose levels; and increased serum fatty acid and lactate levels.

Treatment

Reye's syndrome is usually treated in the hospital. Severe cases may be treated in the intensive care unit. It is important to closely monitor the child's blood pressure and other vital signs. Specific treatment may include:

• Intravenous fluids. Glucose and an electrolyte solution may be given through an intravenous (IV) line.
• Diuretics. These medications may be used to decrease intracranial pressure and increase fluid loss through urination.
• Medications to prevent bleeding. Bleeding due to liver abnormalities may require treatment with vitamin K, plasma and platelets.

In Serious cases if the child has trouble breathing, he or she may need assistance from a breathing machine (ventilator).

Prognosis

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.