Ontogeny and Physiology of the cavum septum pellucidum in premature infants

We report the natural history of the closure of the cavum septum pellucidum in 47 premature infants. In this study, a cavum septum pellucidum was present in all patients at 25 to 26 weeks' postconceptual age, in keeping with previous reports. The data from this study suggest that premature delivery does not change the natural history of the normal closure of the cavum septum pellucidum in most infants by 36 to 40 weeks' postconceptual age. Although not statistically significant, there is a suggestion from these data that higher grades of intraventricular hemorrhage are more frequently associated with loss (early closure) of the cavum septum pellucidum. One particularly illustrative case with a grade 4 intraventricular hemorrhage and subsequent hydrocephalus suggests that increases in pressure and volume in the lateral ventricles can cause the laminae of the septum pellucidum to approximate and appear to fuse earlier than expected. However, the fact that the cavum septum pellucidum reappeared in this case after ventricular pressure was decreased (postventricular shunt) suggests that approximation is not the sole factor in definitive fusion of the laminae of the septum pellucidum.