Figure 8.

Images mimicking hypoxic–ischaemic encephalopathy are seen in a 13-year-old child who experienced seizures caused by familial hemiplegic migraine 1 day previously. Extensive left hemispheric cortical oedema is seen on the fluid-attenuated inversion–recovery image (a), and on the diffusion-weighted image (b).The apparent diffusion coefficient map demonstrates restricted diffusion in the cortex, confirming the presence of cytotoxic oedema and not vasogenic oedema (c). The MRI findings mimic hemispheric hypoxic–ischaemic injury, which could arise from several causes such as the presence of a high-grade internal carotid artery stenosis or occlusion with a foetal-origin posterior cerebral artery and no physiological anterior communicating artery. All the left hemispheric abnormality resolved on follow-up MRI (not shown).