INTRAVENTRICULAR FUSED FORNICES - A SPECIFIC SIGN OF FETAL LOBAR HOLOPROSENCEPHALY

Labor holoprosencephaly can be recognized in utero with sonography. Ho wever, a specific diagnosis is difficult and thus far has relied upon a qualitative evaluation of the morphology of the cerebral ventricles. In infants with this condition, magnetic resonance imaging demonstrat es at times an abnormal appearance of the fornices, which are rudiment ary and fused into a single fascicle running within the third ventricl e. In a 30-weeks' fetus affected by lobar holoprosencephaly, this find ing could be well demonstrated by sonography and was confirmed after b irth by both transfontanellar ultrasound and magnetic resonance imagin g. It is proposed that the antenatal demonstration of an echogenic lin ear structure running within the third ventricle is a specific sign of lobar holoprosencephaly, and can assist this difficult diagnosis.