Classification of infantile seizures: implications for identification and treatment of inborn errors of metabolism.

Metabolic disorders constitute an important cause of neurologic disease, including infantile epilepsy. The inability to characterize seizures and epilepsy syndromes precisely in infants impedes the recognition of features suggestive of specific underlying metabolic and neurodegenerative etiologies. Classification systems using simple descriptions of ictal behaviors can be reliably applied and may aid in the recognition of these disorders. Myoclonic seizures in infancy in particular suggest an inborn error of metabolism. In addition, certain epileptic syndromes are known to be associated with metabolic disorders, including some forms of neonatal seizures, West's syndrome, early myoclonic encephalopathy, and early infantile epileptic encephalopathy. Occasionally, there are distinctive electroencephalographic patterns that may suggest a specific metabolic disease. Earlier recognition of metabolic disorders may be accomplished by careful study of clinical and electrographic characteristics. There are important treatment considerations associated with these disorders.