Pediatric emergency medicine trisk 4646 4646
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CSF shunt placement is the most common neurosurgical procedure performed in
children. More than 4,400 CSF shunts were placed in 2003; CSF shunt–related
problems accounted for almost 15,000 hospital admissions and almost $300
million in charges for shunt malfunctions. CSF shunts are placed to divert CSF
from the brain to another area of the body, most commonly the peritoneal cavity.
The clinician evaluating a child with a CSF shunt should be aware of associated
complications such as infection, obstruction, and overdrainage, because certain
complications can be disastrous if unrecognized and untreated. However, children
with CSF shunts may often exhibit symptoms of their chronic illnesses that are
unrelated to shunt malfunction.
Pathophysiology
CSF is an ultrafiltrate of plasma produced at a rate of 500 mL/day in a 70-kg
adult and proportionally less in children and infants. The fluid is mainly produced
by the choroid plexus and various extrachoroidal sites within the brain. CSF
travels from the lateral ventricles into the third ventricle through the foramen of
Monro and then again through the aqueduct of Sylvius to the fourth ventricle. The
CSF then enters the subarachnoid space via the foramina of Luschka and
Magendie and travels through the brain and spinal canal. CSF is reabsorbed and
enters the venous system through the “one-way valves” of arachnoid villi that
penetrate the dura.
Hydrocephalus can result from oversecretion, impaired absorption, or blockage
of CSF pathways. Oversecretion can occur in some choroid plexus tumors.
Impaired absorption can occur as a result of increased CSF protein, often a result
of perinatal hemorrhage or meningitis or less commonly etiologies such as
subarachnoid hemorrhage, or Guillain–Barré syndrome. Severe congestive heart
failure or any other condition that raises venous pressure may impair CSF
absorption as well. Impaired absorption is the cause of communicating
hydrocephalus, in which flow from the lateral ventricles to the foramina of
Luschka and Magendie is not obstructed. Blockage of CSF pathways , or
obstructive hydrocephalus, is the most common cause of hydrocephalus in
children. This is often located at the narrow aqueduct of Sylvius proximal to the
fourth ventricle and is referred to commonly as aqueductal stenosis. Conditions
that can cause obstruction are intraventricular bleeding or scarring, tumors, or
congenital malformations. Dandy–Walker cysts cause obstruction of the foramina
of Luschka and Magendie and therefore may result in enlargement of all four
ventricles.
Equipment
