Background: The acute phase of the neonatal classical form of maple syrup urine disease (MSUD) is usually associated with generalized brain edema.
Methods and results: The authors present the case of a newborn infant in the acute stage of the classical form of MSUD in whom a remarkable decrease in the water apparent diffusion coefficient (ADC) in advanced myelinating white matter areas was associated with an increase in the T2 signal. This diffusion magnetic resonance imaging (MRI) pattern appears to be compatible with a rare kind of cytotoxic edema, the so-called intramyelinic edema. At the same time, an increase in the ADC was seen in unmyelinated areas together with an increase in the T2 signal, a sign of a coexistent vasogenic-interstitial edema.
Conclusions: ADC measurements in MSUD provide more specific information than conventional MRI about the pathophysiology of white matter changes.