Definition of Hydrocephaly
Hydrocephaly: Also known as hydrocephalus, this is an
abnormal buildup
of cerebrospinal fluid (CSF) in the ventricles of the brain. The
fluid is often under increased pressure and can compress and
damage the brain.
Hydrocephalus can arise before birth or any time afterward. It may
be due to many causes including a birth defect, hemorrhage into the
brain, infection, meningitis, tumor, or head injury. Most forms of
hydrocephalus are the result of obstructed CSF flow in the
ventricular system. With birth defects, physical obstruction of CSF
flow in the ventricular system is usually the cause of the
hydrocephalus. Hydrocephalus is a common companion of spina
bifida (meningomyelocele).
What is termed "hydrocephalus ex-vacuo" occurs when there is
damage to the brain caused by stroke or injury, and there may be an
actual shrinkage of brain substance. "Hydrocephalus ex-vacuo" is
essentially only hydrocephalus by default; the CSF pressure itself is
normal.
Normal pressure hydrocephalus (NPH) can also occur due to a
gradual blockage of the CSF drainage pathways in the brain. Although
the ventricles enlarge, the pressure of the CSF remains within normal
range. NPH is characterized by memory loss (dementia), gait disorder,
urinary incontinence and a general slowing of activity.
In old age or persons with Alzheimer's disease, the entire brain
may shrink and the CSF fills up the space created by the shrinkage.
This is not due to hydrocephalus.
The diagnostic signs and symptoms of hydrocephalus depend upon the
age of the person:
- In infants the most obvious sign of hydrocephalus is
usually an abnormally large head. (That is one reason a baby's head
should be measured at every well-baby visit). Symptoms of
hydrocephalus in an infant may include vomiting, sleepiness,
irritability, an inability to look upwards, and seizures.
- In older children and adults there is no head enlargement
from hydrocephalus, but symptoms may include headache, nausea,
vomiting and, sometimes, blurred vision. There may be problems with
balance, delayed development in walking or talking, and poor
coordination.
Irritability, fatigue, seizures, and personality changes such as an
inability to concentrate or remember things may also develop.
Drowsiness and double vision are common symptoms as hydrocephalus
progresses.
Treatment of hydrocephalus involves the insertion of a shunt to
let the excess
fluid exit and relieve the pressure on the brain. The shunt is a
flexible, plastic tube with a oneway valve. The shunt is inserted
into the ventricular system of the brain to divert the flow of CSF
into another area of the body, where the CSF can drain and be
absorbed into the bloodstream.
The prognosis (outlook) with hydrocephalus depends the cause and
the timing of the diagnosis and treatment. Many children treated for
hydrocephalus are able to lead normal lives with few, if any,
limitations. In some cases, cognitive impairments in language and
non-language functions may occur. Problems with shunts such as
infection or malfunction require revision of the shunt.
Hydrocephalus is sometimes called "water on the brain." The word
"hydrocephalus" in Greek literally means "watery head."
Last Editorial Review: 3/26/1998 2:25:00 PM
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