Adoptive Families Association of BC
AFABC Special Needs Database

Hydrocephalus comes from the Greek "hydro" (that means water) and "cephalus" (that means head). Hydrocephalus is an abnormal accumulation of cerebrospinal fluid (CSF), within cavities called ventricles, inside the brain.

CSF is formed in a region of the brain known as the choroids plexus. CSF usually circulates through the ventricles of the brain, and also flows around the outside of the brain and through the spinal canal.

When the circulation or absorption of this fluid is blocked, or excessive fluid is produced, the volume of fluid in the brain becomes higher than normal. The accumulation of fluid puts pressure on the brain, forcing it against the skull and damaging or destroying the tissues.

There are three types of hydrocephalus:

  • Obstructive: this form, also called non-communicating hydrocephalus, occurs when a blockage in a ventricle restricts the flow of CSF.
  • Non-obstructive: this form, also called communicating hydrocephalus, occurs when CSF is not absorbed properly into the bloodstream.
  • Normal Pressure: this form occurs in old age as a result of a gradual blockage and build up of CSF.

Hydrocephalus is also classified as:

  • Congenital if hydrocephalus is present before birth.
  • Acquired if hydrocephalus develops after birth, usually as a result of trauma to the brain such as infection, head injury, meningitis, or tumors.

Scientists believe congenital hydrocephalus is a result of both environmental and genetic factors. Acquired hydrocephalus is a result of head trauma.

Aqueductal Obstruction (Stenosis): the most common cause of congenital hydrocephalus is obstruction of the cerebral aqueduct - the long, narrow passageway between the third and fourth ventricle. Aqueductal obstruction may result from narrowing or blockage of the aqueduct, or may be caused by infection, hemorrhage, or a tumor. Fluid accumulates upstream from the obstruction, producing hydrocephalus.

Spina Bifida: it is an open "neural tube defect" wherein the spinal cord is exposed at birth and is often lacking cerebrospinal fluid.

Intraventricular hemorrhage: is an acquired form of hydrocephalus and most frequently affects premature newborns. It occurs when small blood vessels lying alongside the ventricles rupture.

Meningitis: is an inflammation of the membranes of the brain and spinal cord. It may caused by bacterial infections or, less frequently, viral infections, which can scar the delicate membranes that line CSF pathway.

A head injury: can damage brain tissues, nerves, or blood vessels. Blood from these ruptured vessels may enter the CSF pathway. Because this blood causes inflammation, there may be scarring of the meninges, or blood cells may block the CSF absorptive sites. When this occurs, the CSF flow becomes restricted and hydrocephalus develops.

Tumors: in children, brain tumors most commonly occur in the back of the brain. As a tumor grows, it may fill or compress the fourth ventricle, blocking the flow of spinal fluid.

Symptoms vary depending on the cause of the obstruction to CSF circulation, the age at which the problem develops, and the extent of damage to brain tissue caused by the swelling.

Early symptoms in infants/toddlers:

  • Enlargement of the head (increase head circumference)
  • Bulging fontanels (soft spots of the head) with or without enlargement of the size
  • Sutures-separated
  • Vomiting
  • Irritability, lethargy
  • Downward displacement of eyes
  • Seizures
  • High-pitched crying

Symptoms in children/adults:

  • Headache
  • Nausea/vomiting
  • Vision problems
  • Fever
  • Irritability/lethargy
  • Loss of coordination
  • Seizures
  • Decline in work performance
  • Personality changes

The most common method of treatment of hydrocephalus is surgical placement of a shunt. A shunt is a flexible tube placed into the ventricular system that diverts the flow of CSF into another region of the body where it can be absorbed, such as the peritoneal (abdominal) cavity or the right atrium of the heart. The shunt tube is about 1/8 inch in diameter and is made of a soft and pliable plastic that is well tolerated by our body tissues. Follow-up examinations continue throughout the child's life to evaluate the child's developmental level and to treat any intellectual, neurologic, or physical impairments.


  • Shunt dysfunction (kinking, obstruction, separation of tubing, or similar problems)
  • Infection of the area to which CSF is shunted
  • Encephalitis
  • Meningitis
  • Neurologic damage (decrease in movement, sensation, function)
  • Intellectual impairment
  • Physical disabilities

This resource is by no means intended as a substitute for a doctor's advice or diagnosis. Any concerns you may have with regard to your child's health and development should be discussed with a professional in an appropriate field.