Male, 2 years old, with altered mental status. Diffuse gyral swelling is suspected given the lack of visualization of fluid in any of the cerebral sulci. On T2 weighted images, there appears to be a diffuse symmetric pattern of hyperintensity involving the cerebral cortex and the immediate subcortical tissues. Areas of more pronounced abnormal signal are suspected within the bilateral insulae and the hippocampi. On diffusion weighted imaging, there is a striking pattern of diffuse white matter hyperintensity with corresponding low signal on the ADC maps involving the cerebral white matter bilaterally and symmetrically, including the corpus callosum. On the top several slices through the brain, similar imaging characteristics may affect the cortex, but at lower levels, it is primarily found in the white matter.The basal ganglia and thalami may also be somewhat T2 hyperintense, but given the extensive background abnormality, these findings are not definitive. T2 hyperintensity seems to involve the midbrain and to a lesser degree the pons. The cerebellum does not appear to be as severely affected as the supratentorial brain, but it too shows some abnormal diffuse T2 signal. On post contrast imaging, there is prominence of the sulcal vasculature which could reflect slow flow or compression effect from edema. No discrete pathologic parenchymal enhancement is detected.No evidence of intracranial hemorrhage is seen. No abnormal extra axial fluid collections are present. The ventricular system is essentially normal in morphology and perhaps slightly smaller than what is typically seen.Pansinusitis inflammation is seen.
A pattern of extensive T2 signal abnormality is seen involving the bilateral cerebral cortex and immediate subcortical white matter, the insulae and hippocampi. Less convincing is the possibility of involvement of the basal ganglia and thalami. The midbrain is suspected to be affected, with less severe findings noted in the pons and posterior fossa. A fairly striking pattern of restricted diffusion is also demonstrated involving primarily the supratentorial white matter with questionable cortical involvement in the superior most brain.The differential diagnosis for these findings would include hypoglycemic injury, though the findings as present here are not entirely typical of those reported in either the pediatric or adult populations. Additionally, injury related to hyperammonemia or some other abnormality of the urea cycle should be considered. Hypoxic-ischemic injury can be considered, though again the imaging features are not entirely typical. If these possibilities are disproved, consideration might be given to other inborn errors of metabolism.