Seizures and epilepsy in hypoglycaemia caused by inborn errors of metabolism

© 2014 Mac Keith Press. Aim: The aim of the study was to characterize seizures and epilepsy related to hypoglycaemia. Method: We analyzed the files of 170 consecutive patients referred for hypoglycaemia (onset 1h to 4y) caused by inborn errors of metabolism (glycogen storage disease type I, fatty acid β-oxidation disorders, and hyperinsulinism). Results: Ninety patients (42 males and 48 females; 38 neonates and 52 infants/children) had brief hypoglycaemic seizures (68%) or status epilepticus (32%). Status epilepticus occurred earlier (mean 1.4d) than brief neonatal seizures (4.3d, p=0.02). Recurrent status epilepticus followed initial status epilepticus and was often triggered by fever. Epilepsy developed in 21 patients. In 18 patients, epilepsy followed hypoglycaemic status epilepticus and began with shorter delay when associated with grey matter lesions (1.9mo, standard error of the mean [SEM] 1mo) than with white matter damage (3.3y [SEM 1y], p=0.003). Three patients with hyperinsulinism developed idiopathic epilepsy following brief neonatal seizures. Interpretation: Brief neonatal hyperinsulinaemic hypoglycaemic seizures have characteristics of idiopathic neonatal seizures. Neonatal status epilepticus should be prevented by the systematic measurement of glucose blood level. Recurrent seizures never consist of status epilepticus when following brief initial seizures. Epilepsy is symptomatic of brain damage with shorter delay in the case of grey rather than white matter lesions, except in a few idiopathic cases in which epilepsy and hyperinsulinism may share a common genetic background. What this paper adds: First hypoglycaemic status epilepticus caused by inborn error of metabolism predisposes to recurrent status epilepticus, often in a febrile context. Symptomatic epilepsy only follows status epilepticus. Time lag to onset of epilepsy depends on topography of brain lesions. Hyperinsulinism and idiopathic epilepsy may share a genetic background.