Hydrocephalus factsheet


Hydrocephalus is a condition that happens when too much cerebrospinal fluid (CSF) collects in the brain. CSF is a clear fluid that surrounds the brain and spinal cord to give protection, nutrients and remove waste. Too much fluid causes pressure to build and damage the brain. In babies, the pressure and fluid build-up can increase their head size. This is because the bones that make up their skull have not fused together.

Hydrocephalus can happen after: 

If a child is born with hydrocephalus, it is called congenital hydrocephalus. This can be caused by genetics, or brain development problems including:

  • spina bifida or neural tube defects - when the spinal cord is exposed at birth and does not have enough CSF
  • chiari malformations - defects at the base of the brain where the spinal column joins the skull
  • craniosynostosis - when the bones in the skull fuse together before the brain has stopped growing

 Signs and symptoms

The most common symptoms of hydrocephalus are:

For babies, hydrocephalus can also cause:

  • increased head size
  • bulging or firm fontanelle - the soft spot on a baby’s head
  • poor feeding
  • drowsiness or sleepiness
  • eyes turning inwards.

For older children and teenagers, hydrocephalus can also cause:

  • blurred or double vision
  • problems concentrating
  • coordination issues
  • confusion
  • incontinence.


If your child is showing symptoms of hydrocephalus, their doctor will order scans and tests that can check the levels of CSF around the brain.

These can include:

  • ultrasound – during pregnancy and on babies whose fontanelle has not closed
  • CT Scan
  • MRI
  • lumbar puncture - a procedure where CSF is taken from the lower spine and the pressure is checked.


The pressure on the brain can be relieved by inserting a ventricular peritoneal (VP) shunt.

The shunt is a long, thin piece of tubing under the skin. It has a one-way valve that takes the fluid from the brain and drains it and into the abdomen. The shunt sits inside body, but the outline of the tube can be seen down the side of the neck and below the ear. The shunt will normally have a long coil of tubing in the abdomen. This allows it to grow with your child as they get bigger.

A shunt will not cure hydrocephalus, but it will relieve pressure and help the head and brain to grow normally.


Hydrocephalus and learning development

Children with hydrocephalus may be slower to learn some skills or may have learning difficulties as they get older. This is different for every child with hydrocephalus.

If your child is showing signs of slower development or learning difficulties, it is important to take early action on therapy and supports. Speak to your child’s treatment team about early intervention services for learning and development.

Hydrocephalus and eyesight

Hydrocephalus can cause issues with eyesight, including:

  • nystagmus - involuntary rapid movements of the eyes
  • optic atrophy - degeneration of the optic nerve
  • squinting or becoming cross-eyed
  • reduced eyesight.

Regular eye tests are good to check eye health and the pressure in your child’s head.

Hydrocephalus and seizures

Children with hydrocephalus have a higher risk of seizures and fits. Some children may need to take medication if they are having seizure regularly.

Seizures can also happen if the VP shunt becomes infected.

Shunt problems

A shunt won’t work properly if the tubing is:

  • blocked
  • kinked
  • disconnected.

A damaged valve will also stop the shunt from working properly.

The following are warning signs that the shunt is not working properly.


  • rapid head growth (in babies)
  • full, bulging, or tense fontanelle, present until the skull closes at about 18 months of age
  • swelling and/or pain along the shunt, especially at the side of the neck
  • unusual irritability
  • nausea and vomiting
  • crossed eyes or eyes that focus downwards, also called sun-setting eyes
  • periods when the baby stops breathing
  • excessive drowsiness
  • difficulty drinking, swallowing and crying.


  • headache
  • visual disturbance like blurred vision
  • drowsiness
  • loss or decrease of consciousness
  • lethargy.

Less common signs can include:

  • difficulty in walking and changes in mobility
  • memory problems or significant change in intellect
  • decline in reaching developmental milestones
  • new seizures or worsening or increased frequency of existing seizures
  • back pain or worsening scoliosis
  • changes in bowel or bladder functioning
  • changes in hearing.

Your child will have regular appointments with their treatment team to check their hydrocephalus and make sure there is no shunt dysfunction.

Shunt infection

Shunt infection can happen at any stage but is more common just after a new shunt has been inserted or after it has been changed.

Signs of infection include:

  • fever
  • neck stiffness
  • redness
  • leakage from the shunt wound area or tenderness along the tract
  • abdominal pain.

A shunt malfunction and/or infection is life-threatening. Call triple zero (000) or go to your nearest emergency department if your child shows symptoms.


Last updated Monday 29th January 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024