• Blocked shunt tube - Shunt tube is seen in situ the ventricles, but ventricles are still dilated.
• Shunt-tube migration - Migration of shunt tube may be extracranial or intracranial (It occurs due to motion of patient's head).
• Subdural hematoma - These may occur when large ventricles are shunted - due to decrease in ventricular size, subarachnoid spaces increase, stretching the vein which tear, resulting subdural hematomas.
• Slit ventricle syndrome - Also called shunt dependency syndrome. It is seen due to inability of the ventricles to re-expand after shunting due to lack of compliance or adhesions.
• Isolated fourth ventricle - This occurs when there are exudates at aqueduct & fourth ventricular outlet or aqueductal stenosis. Following shunting, there is dilation of fourth ventricle due to the aqueductal stenosis. Hence, the fourth ventricle does not get decompressed.
• Infection - Following shunting, there may be infection along the shunt tract leading to ventriculitis, which is seen as an enhancement along the ventricular wall.

Congenital Hydrocephalus with shunt :

Definition of various terminologies used :

• Arrested hydrocephalus - This is a condition, in which the ventricular system is not actively dilating. A more appropriate term is compensated hydrocephalus.
• Active hydrocephalus - Active hydrocephalus is marked by an increase of ventricular volume. The activity is recognized by pronounced clinical symptoms and by progression in follow up CT studies.
• Hydrocephalus ex vacuo - With shrinkage of brain due to atrophy, ventricular system & sulcal spaces increase in size resulting in ex vacuo dilation.

Exvacuo dilation of ventricle :

• Colpocephaly - When occipital horn dilatation is more pronounced than the rest of the ventricular system, it is termed as colpocephaly. Probably, occipital white matter is most vulnerable to damage & hence ventricles get space to increase. It may also be related to stronger growth of the occipital calvaria.