[Total agenesis of the corpus callosum: ultrasonographic appearances. In two cases].

Transfontanellar ultrasonography in two neonates demonstrated total agenesis of the corpus callosum: this was confirmed by computed tomography in one case, this not being necessary in the other infant. Diagnostic signs on pneumoencephalography and computed tomography are described, and those observed on supplementary ultrasonography are outlined: absence of the corpus callosum normally observed on ultrasonography, and the radial disposition, in a sagittal section, of the sulci of the internal surface of the cerebral hemispheres, which appears to be specific to this type of malformation. A frontal section shows a very typical "bull's head" deformity of the ventricular system.