[Reye's syndrome. A current entity which remains enigmatic]

Reye's syndrome (RS) has been defined by the CDC as an acute non-inflammatory encephalopathy and hepatopathy, with no reasonable explanation for the cerebral and hepatic abnormalities. The diagnosis of RS is made by a constellation of clinical and laboratory features, none of which are pathognomonic. The demonstration of a fatty infiltration on liver biopsy is not really specific. On the other hand, the mitochondrial ultrastructural abnormalities appear to be characteristic of RS. Cerebral edema with intracranial hypertension represents the most immediate threat to life, the cause of the encephalopathy being unknown. The treatment of RS consists in perfusion of hypertonic glucose solution and management of intracranial hypertension. Grade I RS should be recognized early and treated with intravenous glucose. A number of metabolic disorders may yield a clinical picture resembling RS. These include disturbances of organic acid metabolism, urea cycle defects, and disorders of carbohydrate metabolism. The pathogenesis of RS is a mitochondrial insult induced by different viruses, drugs, exogenous toxins, and genetic factors. In the USA, pilot studies showed that a majority of RS cases may be attributable to salicylate use. In France, RS remains unfrequent although no precise epidemiological data are available. An epidemiological study appears therefore necessary for a better understanding of this mysterious syndrome. There is a need for a biological marker of the mitochondrial injury.