Purpose or Case Report: The goals of this educational exhibit are to: 1. Explain the basis for the cause of diffusion restriction on brain MRI in children. 2. Discuss the broad differential diagnosis for diffusion restriction in pediatric emergency neuroradiology. 3. Emphasize causes of diffusion restriction unrelated to vascular occlusive disease in the brain. 4. Describe patterns of diffusion restriction commonly encountered in post-ictal states and posterior reversible encephalopathy syndrome.
Methods & Materials: This is an educational exhibit depicting the contrast of differential considerations for non-stroke-induced diffusion restriction in the pediatric brain. Typical signal abnormalities exhibited in post-ictal states and posterior reversible encephalopathy sydrome are emphasized.
Results: Diffusion restriction in disorders of impaired cerebrovascular autoregulation do not exhibit a typical vascular territory distribution. Post-ictal diffusion restriction is commonly seen within the splenium of the corpus callosum, cortical grey matter, subcortical white matter, and mesial temporal lobes. In posterior reversible encephalopathy syndrome, common sites of signal abnormality include the parieto-occipital, superior frontal, and watershed white matter. Hyperintense signal on diffusion weighted images in PRES may be associated with increased or decreased apparent diffusion coefficient values reflecting that the edematous change may be due to vasogenic or cytotoxic edema.
Conclusions: Diffusion restriction in the encephalopathic child can have a myriad of causes. Understanding patterns of diffusion restriction unrelated to stroke is important to guiding appropriate therapy. Posterior reversible encephalopathy syndrome is a partial misnomer, as findings may manifest in additional parts of the brain.