Acquired Hydrocephalus

This occurs after birth and causes will include: 

Brain Haemorrhage:
 Other forms of brain haemorrhage, including those occurring in adults (“stroke”), can result in this type of post-haemorrhagic hydrocephalus. 

Tumours of the brain cause compression and swelling of surrounding tissues, resulting in poor drainage of CSF. In the treatment of brain tumours, it is often necessary to control hydrocephalus, which might only be temporary. 
(Brain haemorrhage and tumours may also occur congenitally). 

Meningitis:
 This is an infection of the membranes covering the brain. The inflammation and debris from this infection block the drainage pathways resulting in hydrocephalus. 
Meningitis can occur at any age, but it is more common in children. The incidence of one form, haemophilus meningitis, has been drastically reduced by HIB vaccine. 

Prematurity:
 Babies born prematurely are at risk of developing hydrocephalus. The brain of a baby born early is far more vulnerable than one which goes to full term, since it is still developing. The area which lies just beneath the lining of the ventricles in the brain is particularly important – because of the activity in this area it has a plentiful blood supply. Its blood vessels are very fragile and can easily burst if the baby suffers too large a swing in blood pressure or becomes severely ill from other causes. 
If these complications do occur, then the baby is at risk of developing a haemorrhage from rupture of the fragile vessels. This can lead to a blood clot developing, which in some cases is big enough to break through the wall of the ventricle. Should the clot block the flow of CSF, the baby will develop hydrocephalus. The blockage may be temporary or permanent. Even if a blood clot does not develop, the blood cells from the haemorrhage can cause blockage. 

Normal Pressure Hydrocephalus:
 Seen in older adults and characterised by dementia, decreased mobility and urinary incontinence.