An infant was born at 36 weeks' gestation to a 22-year-old primigravida. A fetal screening ultrasound study at 18 weeks
showed a single large cerebral ventricle and fused thalami. On physical examination at birth, the infant was small for
gestational age and had multiple anomalies, including postaxial polydactyly of hands and feet, cyclopia, microcephaly, cleft
lip and palate, and rocker-bottom feet. The infant died 1 hour after birth. Which of the following CNS abnormalities best
explains these findings?
A. Anencephaly B. Arnold-Chiari II malformation C. Dandy-Walker malformation D. Holoprosencephaly E. Periventricular leukomalacia F. Subdural hematoma
Holoprosencephaly-(d) holoprosencephaly is a midline defect in which there is absent (alobar) or partial (semilobar) cerebral hemispheric
development. it can occur in trisomy 13, as in this case, with other midline defects. it also may be seen in cases of
maternal diabetes mellitus. anencephaly is the absence of a fetal cranial vault, which leads to absence of most of the
brain. arnold-chiari ii malformation results in a small posterior fossa, a misshapen midline cerebellum with downward
displacement of the vermis, and tenting of the tectal plate. dandy-walker malformation is characterized by aplasia or
hypoplasia of the cerebellar vermis, cystic enlargement of the fourth ventricle, and hydrocephalus. periventricular
leukomalacia is a form of perinatal injury that is caused by hypoxic-ischemic events or infections. a subdural hematoma
results from trauma.
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