Introduction. Leucinosis is a severe neonatal metabolic disease. It is the consequence of the genetically determined enzyme deficiency of the complex formed by decarboxylase-dihydrolipoyl transacylase and dihydrolipoyl dehydrogenase, and of the subsequent accumulation of precursor metabolites, long branched-chain amino acids and their alpha ketoacids. They are powerful neurotoxins, responsible for the swift onset of oedema and diffuse cerebral demyelination. Delays in its diagnosis usually result in severe psychomotor sequelae or even death.
Case report. We report the case of a newborn female patient with severe neonatal encephalopathy, epileptic seizures and an electroencephalogram (EEG) with certain special characteristics that guided the diagnosis towards that of possible leucinosis. Early diagnosis makes it possible to establish specific treatment and achieve a favourable patient outcome.
Conclusions. An EEG in patients with suspected neonatal encephalopathy offers highly cost-effective functional information at a low cost, especially because it promotes early diagnoses and treatments. In cases of leucinosis, EEG presents peculiar signs that are easily recognisable in early periods in most patients, as occurred in the case reported here. We believe EEG should be included in screening for neonatal encephalopathies because it is a valuable, innocuous and generally accessible diagnostic technique. It is especially helpful in treatable metabolic diseases, such as leucinosis.