Mechanical Failure: improper functioning of the shunt
1. obstruction of a component of the shunt by blood or cellular debris, intraabdominal adhesions, ingrowth of portions of the choroid plexus or the ependymal surface of the ventricle into the inlet holes of the proximal catheter, etc
2. fracture or disconnection of the shunt components
3. migration of the shunt from the location it was originally placed
Functional Failure: excessive or inadequate flow of CSF through an otherwise well functioning shunt
4. development of extraaxial fluid collections (between dura and cortical surface of the brain) from the collapse of the ventricular system and brain if drainage of CSF occurs too rapidly
5. development of slit ventricle syndrome, small slitlike ventricles, which can present with symptoms consistent with increased ICP ie headaches, nausea, vomiting
6. abnormal accumulation of CSF at distal catheter ie CSF ascites secondary to CSF malabsorption
Infection
7. shunt infection
8. intraabdominal infection from perforation of abdominal viscus or infected CSF ascites
Source
Lee, P and DiPatri, A. "Evaluation of Suspected Cerebrospinal Fluid Shunt Complications in Children" Clinical Pediatric Emergency Medicine. 2008.