Shunt Dysfunction and Infection
Infection
  Skin breakdown over hardware
Mechanical failure
  Undershunting
  Separation of shunt components, fractures, migration of hardware
  Overshunting
  Subdural hematoma

These account for majority of shunt problems

Undershunting
Etiology
Blockage within system
Choroid plexus
Glial adhesions
Build-up of proteinaceous accretions, blood, cells (inflammatory or tumor)
Ventricular end most common site

Disconnection, kinking, or breakage of system
With age, silicone elastomers calcify, break down, & become more rigid & fragile which may promote subcutaneous attachments
Barium impregnation may accelerate process
Tube fracture often occurs near clavicle, likely due to ↑ motion there

Evaluation
History
 Symptoms of active hydrocephalus
 Reason for initial insertion of shunt
 Date & reason of last revision
 Type of hardware
Physical
 Signs of active hydrocephalus
 For children, plot head circumference on graph of normal curves
 Before sutures close, head circumferences crossing growth curves
 Swelling along shunt tubing from CSF dissecting along shunt tract
 Ability of shunt reservoir to pump & refill
  May exacerbate obstruction, esp if shunt is occluded by ependyma due to overshunting initially
In children presenting only w/ N/V, esp those w/ cerebral palsy & feeding G-tubes, R/O GE reflux

Shunt Tap
To obtain CSF specimen
To evaluate shunt function
As temporizing measure to allow function of distally occluded shunt
To inject medication
For catheters placed within tumor cyst (not a true shunt)

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