MRI findings in an adolescent with type I citrullinaemia.

Citrullinaemia is a rare inborn error of urea cycle metabolism. We describe the MRI findings in a 16-year-old boy with type I citrullinaemia during an episode of acute hyperammonaemic encephalopathy and compare them to his previous follow-up MRI studies. MRI revealed bilateral high signal intensity in the cingulate, perirolandic, parietal and temporoinsular cortex, the subcortical white matter and left thalamus. Diffusion-weighted imaging showed high signal intensity and low apparent diffusion coefficient values in the frontoparietal lobes. To our knowledge, MRI findings in an adolescent with type I citrullinaemia have not been previously reported. Since our patient's neuroradiological findings showed greater similarity to type II citrullinaemia, we think his brain injury during this acute episode was probably age-related and independent of the type of citrullinaemia.