A 28-year-old woman, gravida 1, para 0, was referred to our fetal diagnosis unit at 28(+2) gestational weeks because no fetal movements were detected. On 2-D ultrasonography, the cephalic axial view showed multiple hypoechoic spaces in the fetal brain, both cerebral cortex and occipital lobe showed bilateral defects, and the septum pellucidum was absent. Multiple irregularly shaped cystic lesions connected with subarachnoid spaces were observed by three-dimensional ultrasonography in surface rendering mode. Septo-optic dysplasia with dysgenesis of corpus callosum was confirmed by prenatal magnetic resonance imaging (MRI). The fetus was complicated with cleft schizencephaly involving bilateral frontal, parietal and occipital lobes, which can often lead to learning disability, epilepsy and cerebral palsy after birth. The flaccid mobility of all four extremities of the fetus, demonstrated prenatally by real-time ultrasound and functional MRI, forecast the risk of postnatal spastic quadriplegia.