-Inborn metabolic errors (IME) and cortical developmental malformations are uncommon etiologies of neonatal seizures, however they may represent treatable causes of refractory epilepsy and for this reason must be considered as possible etiological factors. This case report aims to demonstrate the importance of neuroimaging studies in one patient with neonatal seizures, even when there are clues pointing to a metabolic disorder. Case report: A previously healthy 14 day-old child started presenting reiterated focal motor seizures (FMS) which evolved to status epilepticus. Exams showed high serum levels of ammonia and no other abnormalities. A metabolic investigation was conducted with normal results. During follow-up, the patient presented developmental delay and left side hemiparesia. Seizures remained controlled with anti-epileptic drugs for four months, followed by relapse with repetitive FMS on the left side. Temporary improvement was obtained with anti-epileptic drug adjustment. At the age of 6 months, during a new episode of status epilepticus, high ammonia levels were detected. Other metabolic exams remained normal. The child was referred to a video-electroencephalographic monitoring and continuous epileptiform discharges were recorded over the right parasagittal and midline regions, with predominance over the posterior quadrant. A new neuroimaging study was performed and displayed a malformation of cortical development. Our case illustrates that because newborns are prone to present metabolic disarrangement, an unbalance such as hyperammonemia may be a consequence of acute events and conduct to a misdiagnosis of IME.KEY WORDS: metabolic disorder, cortical dysplasia, neonatal seizures.Crises neonatais: a sobreposição entre o diagnóstico das doenças metabólicas e as anormalidades Crises neonatais: a sobreposição entre o diagnóstico das doenças metabólicas e as anormalidades Crises neonatais: a sobreposição entre o diagnóstico das doenças metabólicas e as anormalidades Crises neonatais: a sobreposição entre o diagnóstico das doenças metabólicas e as anormalidades Crises neonatais: a sobreposição entre o diagnóstico das doenças metabólicas e as anormalidades estruturais. Relato de caso estruturais. Relato de caso estruturais. Relato de caso estruturais. Relato de caso estruturais. Relato de caso RESUMO -Erros inatos do metabolismo (EIM) e distúrbios do desenvolvimento cortical são causas pouco comuns de crises neonatais, entretanto eles podem representar causas tratáveis de epilepsia refratária e, por esta razão, devem ser consideradas como possíveis fatores etiológicos. Este relato de caso tem como objetivo demonstrar a importância dos estudos de neuroimagem em um paciente com crises neonatais, mesmo quando as pistas diagnósticas são sugestivas de uma doença metabólica. Relato do caso: Uma criança , previamente hígida, de 14 dias de vida começou a apresentar crises focais motoras (CFM) reiteradas que evoluíram para estado de mal. Os exames demonstraram altos níveis séricos de amônia e nenhuma outra a...