Hydrocephalus from birth
Hydrocephalus present at birth (congenital hydrocephalus) can be caused by certain health conditions, such as spina bifida.
It can also develop in babies born prematurely, before week 37 of the pregnancy.
Some premature babies have bleeding in the brain, which can block the flow of CSF and cause hydrocephalus.
Other possible causes of congenital hydrocephalus include:
- a mutation of the X chromosome – this is known as X-linked hydrocephalus
- rare genetic disorders – such as Dandy Walker malformation
- arachnoid cysts – fluid-filled sacs located between the brain or spinal cord and the arachnoid membrane
In many cases of congenital hydrocephalus the cause is unknown.
Hydrocephalus that develops in children and adults
Hydrocephalus that develops in children and adults (acquired hydrocephalus) is usually the result of an injury or illness.
Possible causes of acquired hydrocephalus include:
- bleeding inside the brain – for example, if blood leaks over the surface of the brain (subarachnoid haemorrhage)
- blood clots in the brain (venous thrombosis)
- meningitis – an infection of the membranes surrounding the brain and spinal cord
- brain tumours
- head injury
Some people are born with narrowed passageways in their brain that restrict the flow of cerebrospinal fluid, but do not cause any symptoms until years later.
Hydrocephalus in older people
Older people can sometimes develop normal pressure hydrocephalus (NPH) after a brain injury, bleeding in the brain or an infection. But it's often not clear why NPH happens.