Are there secondary intracranial signs of open spina bifida on Ultrasound?
Most cases of open spina bifida are associated with posterior fossa abnormalities (Chiari II malformations) in utero due to downward traction of the spinal cord. This includes downward-curved “C shaped” herniation of the cerebellum (the “banana” sign), effacement of the cisterna magna, flattening of the bilateral frontoparietal bones (the “lemon” sign), and ventriculomegaly ( Figure 59-6 ). The “banana” sign is seen in more than 90% of cases, and the “lemon” sign in up to 98% of cases of open neural tube defects.
