Webster's New World Medical Dictionary

hydro-
Prefix meaning related to water.
hydrocele
Accumulation of fluid in the coat
around the testis. Small hydroceles tend to disap-
pear by 1 year of age. Larger hydroceles may persist
and warrant surgery.
hydrocephalus
An abnormal buildup of cere-
brospinal fluid (CSF) in the ventricles and/or sub-
arachnoid space of the brain. The fluid often
increases intracranial pressure, which can com-
press and damage the brain. Hydrocephalus can
arise before birth or at any time afterward. Causes
can include birth defects (particularly spina bifida),
hemorrhage into the brain, infection, meningitis,
tumor, and head injury. Symptoms depend on the
person’s age. In infants, the most obvious sign is
usually an abnormally large head; other symptoms
may include vomiting, sleepiness, irritability, an
inability to look upward, and seizures. In older chil-
dren and adults, there is no head enlargement from
hydrocephalus, but symptoms may include
headache, nausea, vomiting, and sometimes blurred
vision. Patients may have problems with balance,
delayed development in walking or talking, and
poor coordination. Irritability, fatigue, seizures, and
personality changes (such as an inability to concen-
trate or remember things) may also develop.
Drowsiness and double vision are common symp-
toms as hydrocephalus progresses. Treatment
involves insertion of a shunt to let the excess fluid
exit and be reabsorbed into the bloodstream,
thereby relieving the pressure on the brain. The out-
look with hydrocephalus depends on the cause and
on the timing of the diagnosis and treatment. Also
known as water on the brain and hydrocephaly. See
also 
hydrocephalus, acquired; hydrocephalus,
congenital.
hydrocephalus, acquired
Hydrocephalus that
is due to a postnatal cause, something that hap-
pened sometime after birth. See also 
hydro-
cephalus.