Most of the metabolic disorders can lead to neurologic disease, including neonatal epileptic encephalopathy. Sometimes, neonatal seizures may be the first sign of inborn errors of metabolism, a fact that makes them much more difficult to diagnose. Thus, a high index of suspicion is required. Distinctively, however, epilepsy secondary to inborn errors of metabolism is usually associated with other neurologic symptoms, such as microcephaly, hypotonia, or hypertonia. After exclusion of acquired causes such as structural or infectious causes, inborn errors of metabolism should always be considered in the differential diagnosis. Among the most common metabolic causes are disorders of neurotransmitter metabolism, disorders of energy production, and synthetic or catabolic disorders associated with brain malformation, dysfunction and degeneration. In most cases, epilepsy secondary to inherited metabolic disorders is characterized by polymorphic clinical and electroencephalographic features, such that they are difficult to classify into precise epileptic syndromes. However, specific types of seizures, such as myoclonic seizures, or distinctive electroencephalographic patterns, such as suppression burst patterns, epileptic syndrome or early myoclonic encephalopathy, may suggest a specific metabolic disease. Timely diagnosis and early treatment may improve the prognosis of these disorders. An early diagnosis of inborn errors of metabolism is crucial from the point of view of a favorable long-term outcome, because some of them can be treated effectively with dietary restriction or supplementation. In addition, all are inherited disorders that may recur in future pregnancies, and therefore their diagnosis allows for appropriate genetic counseling. The treatment of epileptic encephalopathies due to inborn errors of metabolism generally relies on the use of one or more anticonvulsant medications along with evaluation and management of any underlying etiology. Certain rare vitamin-responsive inborn errors of metabolism, for example, may present as neonatal encephalopathy with anticonvulsant-resistant seizures. Therefore, the clinicians caring for newborns with epileptic encephalopathy should consider these particular disorders early in the hospital course. In this review, the importance of considering inborn errors of metabolism in the differential diagnosis of epileptic encephalopathies is emphasized, and an overview of the diagnoses and treatments of inborn errors of metabolism most commonly associated with neonatal epileptic encephalopathy is given.

Keywords: epileptik ensefalopati, kalıtsal metabolizma hastalıkları, börst süpresyon patterni, pridoksin, piridoksal fosfat, folinik asit, nörotransmitterler, yenidoğan, süt çocuğu.