Acquired hydrocephalus, which develops at the time of birth or later. It can be caused by infections such as meningitis, bleeding, injury, or a tumour.
In infants, hydrocephalus without an obvious extrinsic cause is usually referred to as congenital hydrocephalus, since it is often present at birth. When hydrocephalus occurs as a complication of another condition such as hemorrhage, infection or neoplasm, it is usually called acquired or secondary hydrocephalus. However, forces such as hemorrhage and infection can act prenatally and also cause “congenital” hydrocephalus. Moreover, some genetic forms of hydrocephalus are not evident at birth, but develop over time. Therefore, Tully and Dobyns prefer to distinguish between acquired (extrinsic) and developmental (intrinsic) forms of hydrocephalus 1).