Reye’s syndrome describes an acute and often fatal encephalopathy of childhood that is characterized by acute brain swelling associated with hypoglycemia and fatty infiltration and dysfunction of the liver. Reye’s syndrome may follow a variety of common viral infections.
Etiology and Pathogenesis.
Reye’s syndrome has been reported after infections with influenza B, varicella, adenovirus type 3, coxsackievirus A and B, reovirus, echovirus, herpes simplex, and parainfluenza. Viral infection is suggested as the initiating factor by recovery of virus from a few patients, by the frequency of varicella as the prodromal illness in sporadic cases, and by the reported increased incidence concurrently with out- breaks of influenza B infection in two epidemiologic studies. The pathogenic relationship between virus infection and the encephalopathy and hepatic injury is unknown.
It is possible that the encephalopathy is secondary to metabolic effects of the hepatic lesion. The combination of hypoglycemia and ammonia retention, together with other abnormalities of intermediary metabolism, may be sufficient to produce the coma and cerebral edema which occur. The early occurrence of mitochondrial abnormali ties in liver suggests that induction of a partially reversible mitochondrial injury may be instrumental in the evolution of Reye’s syndrome. It is not known whether similar changes in brain mitochondria occur concomitantly.
Pathology of Reye’s syndrome.
Marked cerebral edema occurs, with or without anoxic neuronal changes and neuronal degen- eration, but with no cellular infiltration or demyelination. The liver is swollen and orange to pale yellow. Fatty infiltration occurs initially as diffuse small vacuoles in the periportal areas, and spreads to cause masSive involvement in fatal cases. Electron microscopic examination of liver biopsy specimens shows swollen pleomorphic mitochondria and small droplets of triglycerides in hepatocytes. Fat deposition also occurs in the renal tubules and in the myocardium.
Reye’s Syndrome Diagnosis.
The diagnosis of Reye’s syndrome is suggested by the clinical manifestations described above. Biopsy or autopsy demonstration of fatty infiltra- tion of the liver can be considered as a confirmatory ab- normality.
Reye’s Syndrome Treatment.
Treatment is empirical. Hypoglycemia, acidosis, and electrolyte disturbances should be cor- rected. Enemas, neomycin and low protein intake as employed in hepatic encephalopathy are commonly used. Peritoneal dialysis and exchange transfusions have been used to correct refractory metabolic abnormalities and to correct clotting factor deficiencies. Corticosteroids, mannitol, and hyperventilation may be used to reduce intracranial pressure.