Epilepsy and inborn errors of metabolism

Introduction. Epilepsy is a common manifestation in inborn errors of metabolism, with varying degrees of severity and response to treatment. Objective. To determine its incidence and characteristics in metabolic diseases. Material and methods. A retrospective review of neuropaediatric and metabolic databases was performed. Data on the type of epilepsy, age of onset and refractoriness were collected. Results. Two cases out of three (66%) with molybdenum cofactor deficiency and neonatal epileptic encephalopathy; three with vitamin-sensitive epilepsies: pyridoxamine sulphate oxidase deficiency, antichitin and biotinidase deficiency, early onset and good seizure control with biotin; one with homocystinuria, with late onset and polytherapy; one with Menkes disease difficult to control; two with GLUT-1 deficiencies with absent and generalized discharges in the electroencephalogram; five (33%) peroxisomes in monotherapy, except for a suspected peroxisome biogenesis deficiency; 13 (34%) lysosomal deficiencies; a glycosylation disorder, with infantile and refractory spasms; seven (8.5%) organic aminoacidopathies and acidurias, one with infantile spasms (propionic acidemia), three with nonketotic hyperglycinemia with neonatal epileptic encephalopathy, one with monotherapy (leukinosis) and two (3.3%) with unscreened hyperphenylalaninemia; and five (20%) mitochondrial, most of which had oxidative phosphorylation deficiencies. Conclusions. The diagnosis of metabolic epilepsy requires a high level of suspicion in unscreened diseases. The semiology of the seizures and the electrocardiogram data are not characteristic, but some clinical data may provide guidance, such as early onset and refractoriness, neuroimaging and some biochemical markers. Although genetic studies are increasingly cost-effective in epilepsy, we must continue to search for earlier biomarkers and test targeted therapeutic trials.