Page 59 - SONO 260 The Fetal Head and Brain
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ARNOLD-CHIARI II MALFORMATION AND SPINA BIFIDA
As a result of the cerebellum being displaced inferiorly, the cisterna magna is completely obliterated.
A posterior fossa abnormality such as Chiari II malformation should be suspected if the cisterna magna is not visualized.
The lateral ventricles will also be distorted in shape.
The frontal horns will be small and slitlike, while the occipital horns will be enlarged, a condition known as colpocephaly.
