How does the gestational time frame affect histologic findings in hypoxic-ischemic encephalopathy (HIE)?

Updated: Jul 18, 2018
  • Author: Santina A Zanelli, MD; Chief Editor: Dharmendra J Nimavat, MD, FAAP  more...
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Answer

The impressive array of neuropathologic findings that can result from a hypoxic-ischemic event can be primarily explained by the gestational time frame in which the event occurs. Prior to 20 weeks' gestation, fetal macrophages are capable of removing necrotic debris via phagocytosis, resulting in a smooth cavity without a gliotic response. Examples of lesions that can result from hypoxic-ischemic events in the second trimester include hydranencephaly, porencephaly, and schizencephaly.

After 20 weeks' gestation, hypoxic-ischemic insults result in astrocyte activation with subsequent gliosis. Subependymal germinal matrix hemorrhage is most common in premature infants, with hemorrhage involving the germinal matrix, lateral ventricles, and/or the adjacent parenchyma. In the full-term infant, hypoxic-ischemic events primarily result in lesions of the cerebral cortex, basal ganglia, thalamus, brain stem, or cerebellum. The location and severity of the lesions correlate with clinical symptoms, such as disturbances of consciousness, seizures, hypotonia, oculomotor-vestibular abnormalities, and feeding difficulties. The major neuropathologic patterns of injury in hypoxic-ischemic encephalopathy are listed below. More than one pattern can be present.


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