Presentation
Admitted to the intensive care unit following near-drowning and prolonged resuscitation.
Patient Data
Evidence of the white cerebellum sign. The cerebellar hemispheres are hyperattenuating relative to the supratentorial structures, which are hypoattenuating, probably due to edema.
There are bilateral symmetrical subcortical and deep white matter restricted diffusion ("reversal sign") consistent with cytotoxic edema. Bilateral and symmetrical hippocampal restricted diffusion related to status epilepticus is also shown.
The absence of hemorrhagic lesions is noted.
Widespread symmetrical basal ganglia, thalamic, substantia nigra and periaqueductal grey restricted diffusion related to ischemia.
Apparent resolution of the subcortical and deep white matter restricted diffusion previously identified, consistent on pseudo-normalization.
Resolution of symmetrical hippocampal restricted diffusion related to status epilepticus previously described.
Case Discussion
Hypoxic-ischemic encephalopathy (HIE) is usually the result of a global injury to the brain and frequently involves the grey matter.
The white matter injury with relative sparing of the grey matter is termed "reversal sign" and is an indicator of the condition called delayed post anoxic leukoencephalopathy.
Myelinated white matter is thought to be more resistant to ischemic insults. Consequently, the involvement of subcortical and deep white matter is more common in young children, where myelination has not yet been completed. In such cases, post-anoxic encephalopathy can occur as early as two days later, after the insult.
Even though it carries a good prognosis in the adult population, young children have shown worse outcomes.
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