Intermediate maple syrup urine disease: neuroimaging observations in 3 patients from South India.

Maple syrup urine disease is a disorder of branched-chain keto acid metabolism. Three children were diagnosed with the intermediate form of maple syrup urine disease during routine evaluation of mental retardation. Clinical features were characterized by mental retardation, seizures, autistic features, and movement disorder in the form of dystonia. High-performance liquid chromatography of the urine and serum revealed elevated levels of branched-chain amino acids, suggesting a diagnosis of maple syrup urine disease. Magnetic resonance imaging showed diffuse hyperintense signals in the white matter along with involvement of the thalami and globus pallidus. Magnetic resonance imaging in the intermediate form showed myelination in the posterior limb of the internal capsule, in contrast to the classic form of the disease. Knowledge about the neuroimaging findings of this rare disease will help to narrow down the differential diagnosis when evaluating children with unexplained mental retardation and seizures.