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Banana sign

Dr Maulik S Patel and Dr Frank Gaillard et al.

The "banana sign", is one of the many a notable fruit inspired signs. It is seen on axial imaging through the posterior fossa of fetus as a sign of a Chiari II malformation. It describes the way the cerebellum is wrapped tightly around the brain stem as a result of spinal cord tethering and downward migration of posterior fossa content. The cisterns magna gets obliterated. The shape of the cerebellum has appearance of a banana

It is also seen in the majority of fetuses with spina bifida, but disappears after 24 weeks. It is only rarely seen in a normal fetus. There is very frequent concurrent hydrocephalus.

Associated signs

The same condition also give the lemon sign.

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