ContribuiÇÃo da SeQÜÊnCia difuSÃo da Mr no diagnÓStiCo e aCoMpanhaMento da enCefalopatia por doenÇa da urina eMMaple syrup urine disease (MSUD) or leucinosis is caused by a deficiency of the catalytic components of the α-ketoacid-dehydrogenase complex, which is responsible for the catabolism of branched-chain amino acids (leucine, isoleucine, and valine) 1,2 . It is an inherited genetic disease with an autosomal recessive pattern affecting approximately 1 out of 120,000-500,000 infants worldwide 3,4 . Diagnosis is made clinically based on the peculiar maple syrup odor or sugar burnt of the urine, encephalopathy, increased levels of branched-chain amino acids in the plasma and urine, and the presence of α-hydroxyacid and branched-chain α-ketoacids in urine. The presence of plasma L-alloisoleucine and urinary α-hydroxyisovalerate are pathognomonic for MSUD 2 . According to the literature, five forms of MSUD have been described: classic, intermediate, intermittent, thiamine-responsive, and dihydrolipoyl dehydrogenase-deficient. The commonest and severest form of the disease is the classic type, which is characterized by a neonatal onset of encephalopathy 2 . Magnetic resonance imaging (MRI) studies in the acute phase of classic MSUD are characterized by diffuse edema corresponding to both myelinated and unmyelinated areas of the brain [3][4][5][6] . The purpose of this case report is to show conventional MRI and diffusion-weighted imaging (DWI) findings of the different evolutionary phases in MSUD of a newborn that evolved with brain white matter lesions.
CaSeA full-term male infant born from an uneventful pregnancy and delivery, with a birth weight of 3.245g and Apgar scores of 9/10 (at 1 and 5 min, respectively), was hospitalized because of sucking difficulties, weak cry, and lethargy. At 10 days of life, the baby had episodes of seizures, bradycardia, and apnea, leading to coma. Biochemical examinations showed hypoglycemia and metabolic ketoacidosis. Brain MRI at 10 days of life showed hypersignal lesions on DWI and corresponding hyposignals on ADC maps throughout the white matter of the brainstem, cerebella and internal capsules (Fig 1).At 20 days of life the clinical condition of the baby became critical and maple syrup odor or sugar burnt was noted in the urine. A repeat MRI at this time showed increasing myelinating white matter lesions and new hypersignal lesions on T2-weighted sequences and hyposignal on the diffusion-weighted images located in the unmyelinated white matter of the frontal, parietal and temporal lobes (Fig 2).At 25 At 8 months of age, a follow-up MRI was performed that showed persisting white matter lesions in the frontal, parietal and temporal lobes with associated hypersignal on DWI and hy-
