| Immature infant brain
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Etiology
•Immature infant brains are seen as a result of spontaneous
or therapeutic abortions and premature births.
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Pathogenesis
•See Etiology,
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Epidemiology
•Spontaneous abortions and premature births are seen
in patients with little prenatal care and those with
placental infections.
•Therapeutic abortions are done
for abnormal fetuses and intrauterine deaths often.
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General Gross Description
•Premature and very young fetuses have few convolutions.
The primary sulci are the calcarine, parietal-occipital,
and central sulci. They appear by about gestational
age 20 weeks.
•After that particularly after 25 weeks
gestation secondary convolutions are formed. The pre
and post central, superior temporal, and frontal gyri
•After 28 weeks there is a more brain specific formation
of the secondary and tertiary convolutions. The premature
brain does not have any myelin except in the tegmentum
of the brainstem.
•Myelination of the corticospinal
tracts is seen at about 39 weeks gestation. The entire
premature and term infant brain appears white.
•Examples:
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General Microscopic Description
•Microscopically immature brain shows a cortex made up
of small nuclei without cytoplasm or processes until
39 weeks gestation. The immature brain also has a very
cellular germinal plate about the ventricles. The
ventricles are the remnant of the neural canal. The germinal
plate is made up of small nuclei without cytoplasm
which represent neuroblasts and glioblasts which will
migrate to the cortex, white matter and basal ganglia.
Often premature infants develop a germinal plate
hemorrhage.
•Examples:
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Clinical Correlation
•Because of immature lungs the brain is very susceptible
to hypoxia, hyperoxia, and hypotension which can cause
germinal plate hemorrhage, periventricular
leukomalacia and periventriclar leukomalacia complex.
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References
• Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp. 206.
• Greenfield's Neuropathology, 6th ed. Graham DI, Lantos PL (ed), New York: Arnold, 1997, pp. 558-560.
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| Immature infant brain
| | Synopsis by: Dr. MLGrunnet (TX1110M00100)[481]
| |