Nonketotic hyperglycinemia: Diffusion magnetic resonance Imaging findings

We report about a boy with nonketotic hyperglycinemia who was studied at 15 days of life with a follow-up examination at age 6 months. Magnetic resonance (MR) imaging revealed progressive atrophy, callosal thinning, and delayed myelination. Glycine peaks were shown by proton MR spectroscopy at 3.56 ppm with a long echo time (TE, 135 milliseconds; TR, 1500 milliseconds). Echo-planar diffusion MR imaging (TR, 5700 milliseconds; TE, 139 milliseconds) at 15 days of life revealed high-signal lesions in the pyramidal tracts, middle cerebellar pedicles, and dentate nuclei on b = 1000 s/mm(2) images associated with low apparent diffusion coefficient (ADC) values. By age 6 months, the lesions became more prominent on b = 1000 s/mm(2) images with lower ADC values. Diffusion MR imaging findings likely reflected the histopathologic changes of the disease which consisted of spongiosis of the myelinated brain tissue due to myelin vacuolation.