Sonographic appearance of callosal agenesis: correlation with radiologic and pathologic findings.

Sonographic features are described in six infants in whom total or partial agenesis of the corpus callosum was confirmed by either computed tomographic or pathologic examination. The six patients demonstrated a range of abnormalities involving the neuraxis as well as other systems, notably cardiovascular, gastrointestinal, and genitourinary. Chromosomal abnormalities were present in two patients. The sonographic features of callosal agenesis seen in these patients included: lack of characteristic acoustic interfaces to define the corpus callosum on both coronal and sagittal sonograms; increased separation and parallelism of the bodies of the lateral ventricles; loss of the characteristic convexity of the medial border of the anterior horns of the lateral ventricles; variable prominence of the occipital horns of the lateral ventricles; variable degree of superior extension of the third ventricle; alteration or absence of the cavum septi pellucidi; and radial arrangement of cerebral sulci about the prominent third ventricle. Cases of partial agenesis may show the dysplastic features found in complete agenesis. However, only some of the callosal echoes are present. The sonographic features of partial agenesis in one infant had not been described before.