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Findings: Areas of hypodensity are seen within the putamina bilaterally as well as the heads of the caudate nuclei bilaterally on a CT scan of the head performed without contrast.
Diagnosis: Anoxic brain injury.
Discussion: Hypoxic-ischemic encephalopathy results from global perfusion or oxygenation abnormality. Causes include carbon monoxide inhalation, severe prolonged hypotension, cardiac arrest with successful resuscitation, and profound neonatal asphyxia. Hypoxic-ischemic encephalopathy can result in "watershed" infarcts or generalized cortical (pseudolaminar) necrosis. The most common area for a watershed infarct is at the confluence between the anterior, middle and posterior cerebral artery territory. However, the basal ganglia can also be involved. The third, fifth, and sixth cortical layers are affected in generalized cortical laminar necrosis, and the caudate nucleus as well as the putamen are also often involved as in this case.
On CT, an area of low density can be seen in the regions between major vascular territories in hypoxic-ischemic encephalopathy. Also, regions of hypodensity can be seen in the basal ganglia as well as the parasagittal areas. On MR, regions of hyperintensity on T2 weighted images can also be seen in the before mentioned areas. Also, marked enhancement can be present. In addition, areas of hemorrhage may be seen.
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