A sonographic sign which predicts which fetuses with hydrocephalus have an associated neural tube defect.

Abstract

We report a sonographic sign which reliably distinguishes those hydrocephalic fetal heads associated with a neural tube defect from those which are not, particularly in the second trimester. This sign involves a "pointed" deformity of the frontal aspect of the skull in fetuses with hydrocephalus, indicating the presence of a neural tube defect. A retrospective review of 36 cases of hydrocephalus demonstrates that this sign is particularly helpful in the second trimester, where it was present in all the fetuses with hydrocephalus and neural tube defect. It was less reliable in the third trimester; however, this sign was not present in any of the fetuses with hydrocephalus who did not have a neural tube defect. Angulation or pointing of the fetal frontal bone when hydrocephalus is present, particularly in the second trimester, seems to be a reliable predictor of an associated neural tube defect and mandates a careful search for this defect.

Supratentorial Abnormalities in the Chiari II Malformation, III

“…The abnormalities that have received the most attention in the sonographic literature are the so-called lemon sign (inward scalloping of the frontal bones) and ventriculomegaly. However, the lemon sign is frequently not present in later pregnancies 3 and can be seen in healthy fetuses and in other conditions. 15 Ventriculomegaly may be absent, particularly before 24 weeks, and is associated with many conditions other than MMC.…”

“…The detection rates accelerated when the focus of diagnosis shifted from observation of the spina bifida abnormality to the cranial findings associated with the Chiari II malformation. [1][2][3][4][5][6][7][8] The Chiari II malformation is, for all intents and purposes, found exclusively in fetuses with MMC. Therefore, identification of features of the Chiari II malformation virtually ensures that spina bifida will be discovered if assiduously sought.…”

“…Although the principal features of the Chiari II malformation relate to the hindbrain, many supratentorial abnormalities have been described. [5][6][7][8] These features include callosal dysgenesis, an abnormal third ventricle, enlarged interthalamic adhesions, a "beaked" tectum, heterotopias, skull deformities (the so-called lemon sign 3 ), colpocephaly, and other causes of ventriculomegaly.…”

Spina bifida

“…It is less reliable after 24 weeks, when present in only 30–50% of cases (Table 3) 75–78. The banana sign refers to the shape of the cerebellum (Figure 4G, H) and is thought to be due to tethering of the spine with downward traction on the cerebellum (the Chiari II malformation).…”

Supratentorial Abnormalities in the Chiari II Malformation, I

“…The greatest improvements occurred when the focus of diagnosis shifted from observation of the spina bifida abnormality to the cranial findings associated with the Chiari II malformation. [1][2][3][4][5][6][7][8] The Chiari II malformation is, for all intents and purposes, found exclusively in fetuses with myelomeningocele. Therefore, identification of features of the Chiari II malformation virtually ensures that spina bifida will be discovered if assiduously sought.…”