Intractable seizures, developmental delay, and the ketogenic diet.

Glucose transporter type 1 (GLUT1) deficiency syndrome is a rare, treatable cause of developmental delay and seizures. It must be considered in the differential diagnosis of infants with intractable seizures. The finding of a low glucose level in the cerebrospinal fluid with normal level in the blood in the absence of pleocytosis or other cerebrospinal fluid abnormalities identifies the condition. Genetic analysis for confirmation is available. Treatment with antiepileptic medications often is unsuccessful, and the ketogenic diet is the favored treatment for seizure control. Early identification and initiation of treatment may prevent or lessen the severity of developmental delay.