What Is It? Hydrocephalus, also known as "water on the brain,"
is a condition in which there is extra cerebrospinal fluid
around the brain and spinal cord. Cerebrospinal fluid acts as a
cushion for the brain and spinal cord, supplies nutrients, and
takes away waste products. Hydrocephalus can be present at birth
(congenital) or can develop later (acquired). Hydrocephalus can
be classified according to its cause: Another type of
hydrocephalus, called normal pressure hydrocephalus is an
acquired type of communicating hydrocephalus in which the
ventricles are enlarged but not under high pressure. Normal
pressure hydrocephalus is seen in older adults. It may be the
result of injury or illness, but in the majority of cases the
cause is unknown. Premature infants born before 34 weeks or
weighing less than 4 pounds have a higher risk of blood vessels
bleeding in the brain. Severe bleeding can lead to acquired
hydrocephalus, communicating or non-communicating, depending on
the site and extent of the bleeding. The mos