MATIC BRAIN INJURY(TBI), meningitis, subarachnoid
hemmorage, and brain tumors. Untreated or
uncontrolled hydrocephaly places pressure on the
structures of the brain and can displace brain tis-
sue, causing permanent damage to the brain. In
an infant whose cranium has not yet fused,
hydrocephaly may cause the head to enlarge as
the pressure of the excessive fluid pushes the
bones outward.
Hydrocephaly occurs when the brain’s ventri-
cles produce too much CEREBROSPINAL FLUID or
there is an obstruction that blocks the flow of the
fluid through the ventricles and spinal canal.
Diagnostic prenatal ULTRASOUND often detects
hydrocephaly in an unborn child. After birth or in
adults, MAGNETIC RESONANCE IMAGING(MRI) or COM-
PUTED TOMOGRAPHY(CT) SCANcan identify hydro-
cephaly, which most commonly occurs as a
complication of INFECTIONor blunt trauma (closed
injury) to the brain. Symptoms are difficult to dis-
tinguish from those of the underlying condition,
though may include severe HEADACHE, NAUSEA, and
VOMITING.
Treatment for hydrocephaly is usually surgery
to place a shunt in the brain ventricle to drain the
excessive cerebrospinal fluid. The shunt is a small,
rigid catheter that attaches to a one-way valve (to
prevent cerebrospinal fluid from flowing back into
the brain). The valve in turn attaches to a long,
thin, flexible catheter that the surgeon channels
beneath the SKINto drain into the peritoneal cav-
ity. The body then absorbs the fluid. Treatment
also targets any underlying causes for the hydro-
cephaly. Usually the shunt is a permanent therapy,
though may require periodic replacement. The
risks of shunting are postoperative infection and
deterioration of the shunt, valve, or catheter.
See also BIRTH DEFECTS; BRAIN TUMOR; SPINA BIFIDA.hydrocephaly 257