Pediatric emergency medicine trisk 4649 4649
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is usually obstructed by choroid plexus, but floating debris or hypercellular CSF
can result in the same obstruction; the distal catheter can be obstructed by the
surrounding omentum or can be kinked or coiled. Both proximal and distal
portions can be occluded by the products of infection or by migration of the
catheter tip into the brain parenchyma or intra-abdominal structures. Poor
absorption of excess fluid in the peritoneum due to decreased surface area can
create the appearance of luminal obstruction, particularly in neonates. In addition,
as the child grows, the tension on the shunt system can lead to disconnection of
the distal tubing.
Up to 60% of patients with CSF shunts experience a shunt malfunction in their
lifetime, most commonly within the first 6 months of initial shunt placement.
Parental history is paramount in deciding whether a child is experiencing
symptoms of shunt malfunction. The parent often notices that the child “just isn’t
acting right” or is less active or thinking less clearly than usual. The statement,
“This is exactly how he acted the last time his shunt was obstructed,” is
suggestive of another malfunction, regardless of the presence or absence of the
symptoms listed in the following section.
Common signs and symptoms of mechanical shunt failure include headache,
visual disturbances, vomiting, lethargy, and irritability ( Table 135.2 ). The astute
parent or clinician may note mild ataxia, increased head circumference or bulging
fontanel in an infant, swelling at the reservoir site, poor cognition, or abnormal
behaviors. A classic sign is “sunsetting eyes,” which is really an upgaze paresis
and eyelid retraction associated with Parinaud syndrome from pressure on the
quadrigeminal plate by a dilated suprapineal recess in direct communication with
the third ventricle. Increased tone, hyperreflexia, or Babinski reflex represents
stretching and disruption of the corticospinal fibers originating from the motor
cortex and can suggest shunt malfunction in a patient with a previously normal
examination, although these symptoms are rarely present in a child without a
severe alteration of consciousness. Patients with Cushing triad (hypertension,
bradycardia, and abnormal respiratory pattern) require immediate maneuvers to
decrease ICP and guide them quickly toward operative repair of the shunt.
Seizures are uncommon as the sole manifestation of CSF shunt malfunction.
However, seizures can occur in children who have predisposing brain lesions, and
many patients with CSF shunts have epilepsy. Shunt infection must be considered
in the child with symptoms of shunt malfunction, especially if the child has a
history of recent shunt revision. Ronan et al. reported that more than one-third of
patients with shunt infection presented with symptoms of malfunction.
