Cyst of the Cavum Septi Pellucidi

A 6½-year-old girl had a large cyst of the cavum septi pellucidi associated with other anomalies of neural tube development, including a lumbosacral meningomyelocele, aqueductal stenosis, and a partial defect of the splenium of the corpus callosum. Hydrocephalus was the main clinical problem; ventriculoatrial shunting provided relief, to the extent that intellectual development was satisfactory The anatomical evidence suggests pathogenetic methanisms both early and late in intrauterine life, with an intervening period of normal development. Although the mother was exposed to several viruses during pregnancy, the significance of this is uncertain, and the cause of the developmental abnormalities remains unknown.