Complications of shunts implanted for hydrocephalus typically
result from mechanical malfunction of the shunt or to infection.20 Mechanical
failure is more likely during the first year after shunt placement,
and primarily results from obstruction at the ventricular site,
due to broken tubing or migration of all or a portion of the shunt.
Shunt infection is often caused by skin flora, such as staphylococcus epidermidis,
followed less frequently by infections with Staphylococcus
aureus, enteric bacteria, and Streptococcus species.20 This
may occur at the time of surgery or in the postoperative period due
to breakdown of the overlying skin. The incidence of shunt infection
is highest during the month after initial placement and in patients
requiring multiple revisions, and ranges from 5% to 15%.21 Infection
must be considered in any child with a mechanical shunt who develops
a persistent fever. Shunt infections can present with few or no
symptoms; in some cases, symptoms develop only when subsequent obstruction
occurs, leading to increased intracranial pressure. Ventriculoperitoneal shunts
may also present with symptoms of peritonitis, including fever,
abdominal pain, and anorexia. Ventriculoatrial infections can also
present with fever and bacteremia. Diagnostic evaluation includes
plain radiographs of the skull, neck, chest, and abdomen (shunt
series) to look for mechanical breaks, kinks, and disconnections
in the shunt, and a cranial computed tomography (CT) scan to evaluate
for signs of increased ventricular size, blood culture and cerebrospinal
fluid (CSF) analysis, preferably through direct aspiration of the
shunt. Antibiotic therapy is guided by the results of the CSF analysis.
In most cases, the shunt must then be removed; if the underlying
hydrocephalus remains an issue, another drainage procedure would
be indicated with replacement of the shunt once the CSF is sterile.