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Hydrocephalus is a condition where there is an excessive build-up of cerebrospinal fluid (CSF) within the cavities (ventricles) of the brain. CSF is clear fluid, which is made by tissue inside the ventricles within the brain. CSF normally flows from the upper ventricles to the lower ventricles where there are openings. These openings allow the CSF to circulate around the brain, where it is reabsorbed. There is normally a balance between the amount of CSF fluid made and the rate of absorption. Hydrocephalus occurs when CSF is not reabsorbed as fast as it is produced or if there is blockage along the path where CSF fluid flows.
The Ventriculo-Peritoneal (VP) shunt is small tubing
that is placed inside the brain’s ventricle and tunneled underneath the skin to
the peritoneum. The peritoneum is a
membrane that lines and protects the abdominal cavity and its contents. The purpose of the VP shunt is to reduce the
amount of cerebral spinal fluid (CSF) in the brain by draining it into the
abdominal (peritoneal) space. The shunt
tubing does not come into direct contact with the stomach or other organs. The peritoneum is the usual, safe site to
place the end of the ventricular shunt.
However, certain circumstances may require placing the end of the shunt
tubing into a blood vessel leading to the heart (Ventriclo-Vascular or Atrial,
VA) or into the pleural space of the chest (Ventriculo-Pleural, VP).
Many types of shunts are
available. Your child’s neurosurgeon
will decide which VP shunt is best for your child. Each varies slightly but generally has four
parts:
1.
A tube called the ventricular catheter (the proximal end –
nearest the point of attachment) is placed into the ventricle. It has small holes at the end so
cerebrospinal fluid (CSF) from the ventricle can flow into the tube.
2.
The reservoir or pump is used to test the shunt and get fluid
with a needle if ever needed. It can be
felt as a small bubble, about the size of dime, under the scalp. The reservoir and valve are close to each
other.
3.
The valve is a small device near the reservoir or pump. It controls the flow of CSF within a certain
pressure range. It may also prevent
excessive amounts of CSF drainage (siphoning) when the child is sitting or standing
(anti-siphon device).
4.
The distal tubing is the tube coming from the valve down to the
abdomen (or heart or pleural space in some cases). It is much longer than the ventricular
catheter tube. It is tunneled under
VP Shunts (Cont)
the skin of the scalp, neck,
chest, and into the peritoneal cavity.
The tubing is long, allowing it to slowly uncoil as the child grows to
normal adult height.
Your child will need to go
to the operating room and be put to sleep with general anesthesia to have the
shunt placed or revised. Your child may
be admitted to the hospital a few hours before the surgery to receive IV
(Intravenous) antibiotics.
Usually, two incisions are
made. One small incision is made in the
abdomen and a larger curved incision is made in the scalp. Older children may need an additional small
incision on the neck. This is to assist
with tunneling of the shunt tubing. The
proximal end of the shunt is placed into the ventricle while the distal end of
the shunt is tunneled under the skin of the scalp, neck, chest, and finally
into the peritoneum. Once the shunt is
placed, the incision areas are stitched or stapled closed. As first, the shunt track will be visible
under the skin. As your child grows, the
shunt will be less visible.
For the most part, shunts function well. However, there are complications that can occur. A blockage or obstruction of the shunt is the most common complication of the system. Obstruction may occur at any point along the path of the shunt. The opening at the ventricular end may become plugged with brain, choroid plexus tissue, or blood. The peritoneal end may also become blocked by scar tissue. An obstructed shunt causes an increased volume of CSF in the ventricular system of the brain. This can lead to the same symptoms as those listed below for hydrocephalus. The shunt can be repaired (shunt revision) in surgery lasting about 1 – 2 hours.
*Enlargement
of the baby’s head *Head
enlargement *Vomiting
*Fontanel
is full and tense when *Vomiting *Vision
problems
the infant is upright and quiet *Headache *Irritability and/or
tiredness
*Vomiting *A
loss of previous abilities *Loss
of coordination or balance
*Irritability (sensory or motor function) *Difficulty in waking up or
staying
*Sleepiness *Seizures awake
*Downward
deviation of the eyes *Seizures
*Seizures *Decline in school performance.
A shunt infection can also cause the shunt not to
work properly and cause CSF to backup, leading to enlarged ventricles. Signs and symptoms of shunt infection also
relate to signs of shunt malfunction. In
addition, other signs and symptoms related to shunt infection include:
a. Fever.
b. Redness, tenderness, skin
breakdown, or fluid collection noted at the shunt on the scalp or anywhere
along the shunt tract.
c. Drainage at the incisional
areas related to the shunt.
d. Abdominal pain, tenderness,
or refusing to eat or drink.
VP Shunts (Cont)
A malfunction and/or infected shunt can be a serious
problem and sometimes is life threatening.
In these cases, the child is very ill and surgery is done rapidly. In most cases the symptoms appear gradually. They may not become serious until the
ventricles are under pressure. In some
cases, the shunt can be “fixed” several days after finding the problem.
If you think that your child is developing
signs/symptoms of shunt malfunction (obstruction) and/or infection, call your
child’s neurosurgeon’s office for advice.
Complications can occur with CSF shunting
systems. However, it is an effective
method in controlling increased intracranial pressure and a common method of
treatment for hydrocephalus. Due to
possible complications with shunt systems, your child will need to be followed
yearly by his or her neurosurgeon. This
is to assure the proper function of the shunt and the continued control of
hydrocephalus.
Prepared
by:
Janet Freeman, RN, MS, CPNP
Jennifer Diabato, RN, MS, CPNP
Certified Pediatric Nurse Practitioners,
Neurosurgery
The Children’s Hospital,
Denver, Colorado
Revision Date: November 1998
Approved: Patient/Family Education Committee
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