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hydrocephalus in children Alternative Names
water on the brain
Definition
Hydrocephalus is a condition involving the abnormal accumulation of cerebrospinal fluid in and around the brain.
What is going on in the body?
The brain and spinal cord are collectively known as the central nervous system (CNS). A fluid called cerebrospinal fluid (CSF) surrounds the CNS. The CSF protects and nourishes the brain. This watery fluid is produced by a group of cells called the choroid plexus located in the ventricles near the centre of the brain. The ventricles are a series of chambers inside the brain that contain and help circulate CSF.
Normally, the CSF flows through the ventricles in the brain. It is then reabsorbed into the bloodstream through the membranes that line the skull and spinal canal. Any blockage to the normal flow of CSF can result in increased pressure inside the skull.
This condition has two categories: obstructive and nonobstructive. Obstructive, also known as noncommunicating, hydrocephalus occurs when the circulation of CSF in the brain is blocked. Non-obstructive, or communicating, hydrocephalus occurs when something interferes with the reabsorption of CSF into the bloodstream.
What are the signs and symptoms of the condition?
The signs and symptoms of this condition vary depending on several factors. These include the age at which it occurs, as well as the duration and rate of increase of pressure inside the head.
If something blocks the flow of CSF in the foetus, the head size can increase to the point where caesarean delivery is necessary.
If this condition occurs in the first one or two years of life, the infant's head will enlarge more rapidly than normal. The "soft spot" on top of the head will bulge and feel tense. Scalp veins will be dilated. The eyes may look downward. The infant may also suffer from stiffness in the arms and legs due to muscle spasms.
In the older child, the symptoms of this condition may not be as obvious. Because the bones of the skull have fused together, the head does not enlarge. The child may be irritable and tired all the time. He or she may have a poor appetite and may vomit. Headache is usually present in a child old enough to complain of it. A gradually worsening form of this condition may cause a gradual decline in school performance and a personality change. This set of symptoms is due to an increase in the pressure inside the skull and is not specific for hydrocephalus.
What are the causes and risks of the condition?
Obstructive hydrocephalus can be caused by: - viral infections of the brain of a foetus
- meningitis, an infection of the membranes surrounding the brain
- bleeding inside the brain of a premature infant
- cysts, which are fluid-filled masses
- tumours that block the flow of CSF within the brain
- an inherited abnormality of the brain present at birth that blocks the flow of CSF
- meningomyelocele This is a severe form of spina bifida in which the spinal cord protrudes outside the body.
Nonobstructive hydrocephalus can be caused by: - bleeding over the surface of the brain, which can clog the membranes that reabsorb CSF
- meningitis
- leukaemia, a type of blood cancer, that involves the brain
Premature infants are at increased risk for developing this condition. This is because premature babies are more likely to develop bleeding inside or around the brain. The blood can block the membranes that reabsorb CSF, causing hydrocephalus. This risk rises with the degree of prematurity.
The primary risk of this condition is permanent brain damage. This may cause a decreased IQ, learning and behaviour problems, vision problems or other abnormalities.
What can be done to prevent the condition?
Intensive care of premature infants may help prevent some cases due to bleeding in the brain. Taking folic acid supplements before and during pregnancy can reduce the child's risk of developing a meningomyelocele. folic acid intake by the mothers is especially important during the first three months of pregnancy. This is when the central nervous system is forming. Women who may become pregnant are also advised to make sure their routine vaccinations are up to date. This can help prevent certain infections of the foetus during pregnancy. Some of these infections may cause hydrocephalus in the child before or at birth.
How is the condition diagnosed?
A doctor will ask about a family history of prematurity, meningitis or meningomyelocele. A family history of brain malformations or brain tumours can mean a child is at risk for the condition. Physical signs, such as an enlarged head or enlarged scalp veins, also can signal suggest this condition. A final diagnosis requires imaging of the CNS. Various x-ray tests may be used in different settings, such as computed tomography (CT) and magnetic resonance imaging (MRI) of the brain. These x-ray tests can also help determine the cause of this condition.
What are the long-term effects of the condition?
Children with this condition are at risk for brain damage. IQ is generally lower than average. Behaviour, memory, and learning problems may occur. Vision problems such as crossed eyes and poor eyesight are common.
What are the risks to others?
This condition is not contagious and poses no risk to others. In some cases, this condition may be caused by an infection, such as meningitis, which may be contagious.
What are the treatments for the condition?
If a tumour or cyst is causing the obstruction, surgery to remove it may cure this condition.
Most cases of this condition require the insertion of tube, called a shunt, to go around the blockage. This allows CSF to flow freely, relieving the pressure inside the brain. Shunts are usually made of special plastic materials. One end of the shunt is placed under the scalp. It is inserted into one of the ventricles in the brain through a hole drilled into the skull. The other end of the shunt is tunnelled under the skin. It is usually threaded down into the heart or abdomen. The shunts have a one-way valve that only allows fluid to flow away from the brain. Some shunts have a chamber placed under the scalp. This allows the shunt to be pumped. Occasionally, shunt tubing needs to be replaced with longer tubing as the child grows.
Managing this condition is a complicated process, requiring the input of a number of specialists. It should be carried out at large medical centres familiar with the treatment of children with hydrocephalus.
What are the side effects of the treatments?
Any surgery carries a risk of bleeding and reactions to any analgesics used. The major complication of shunts, however, is infection. A shunt must be removed if it becomes infected. The infection is treated with antibiotics, such as cefotaxime or ceftriaxone, and a new shunt is inserted. Over time, shunts can become blocked and may need to be replaced.
How is the condition monitored?
Children with hydrocephalus need ongoing, long-term monitoring. Signs of shunt infection or increased pressure inside the skull are watched for. The child's physical and mental development, learning ability, vision and behaviour also need to be monitored.
Author: John Wegmann, MD
Reviewer: HealthAnswers Australia Medical Review Panel
Editor: Dr David Taylor, Chief Medical Officer HealthAnswers Australia
Last Updated: 1/10/2001
Contributors
Potential conflict of interest information for reviewers available on request |
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