Relationship between brain volume and size of dural venous sinuses in human fetuses and adults

A quantitative study of 50 human fetuses, ranging in size from 64 to 259 mm crown-rump length (CRL), and 12 adult cadavers was carried out. After removal of each brain from the cranial cavity and measurement of its volume (BV), the cross-sectional area (CSA) of the transverse (TS) and sigmoid (SS) dural venous sinuses were measured; the measurements were taken at the same anatomical point in all fetuses and adults. For each fetus and adult, indices CSA . TS/BV and CSA . SS/BV were calculated. The results of the statistical analysis showed that the mean CSA TS/BV . and CSA . SS/BV indices in fetuses were significantly greater than those of the adults, i.e., relative to the size of the brain, the dural venous sinuses in fetuses were greater than in adults. Furthermore, a significant negative correlation was found between the CSA . SS/BV index and the CRL of the fetuses; this means that as the brain and sinuses grow during fetal development, the growth rate of the sinuses decreases. By implication, the rate of growth of the arterial blood supply decreases proportionately. A similar, progressive decrease in the growth rate of the brain takes place during fetal life.