Medical Information on Hydrocephalus
by Dr Andrew Blaikie for VI Scotland
This document is written with the minimum use of medical terms and jargon. It is impossible to avoid all medical terms but where we have used them we have attempted to explain them as clearly as we can. Although the information is intended to describe most aspects of the condition each child is different and there will always be exceptions to the rule. As far as we can determine these pages are true and accurate and have been written in good faith.
What this Information is not for?
This document is not a substitute for a consultation with a Health Professional and should not be used as a means of diagnosing a condition.
We hope the information will help you to:
- Have a better understanding of the condition
- Know what tests and treatments are normally available
- Know when to seek professional advice
- Be able to discuss the condition in a more informed way
- Make the most of consultations with carers, teachers and health professionals
- Be reassured and more able to cope
Due to staffing limitations we are not able to offer telephone or email advice to parents of children.
What we see is made in the brain from signals given to it by the eyes. What we see is in fact made in the brain. The brain makes sight from signals given to it by the eyes.
What is the normal structure of the eye?
The eye is made of three parts.
- A light focussing bit at the front (cornea and lens).
- A light sensitive film at the back of the eye (retina).
- A large collection of communication wires to the brain (optic nerve).
A curved window called the cornea first focuses the light. The light then passes through a hole called the pupil. A circle of muscle called the iris surrounds the pupil. The iris is the coloured part of the eye. The light is then focused onto the back of the eye by a lens. Tiny light sensitive patches (photoreceptors) cover the back of the eye. These photoreceptors collect information about the visual world. The covering of photoreceptors at the back of the eye forms a thin film known as the retina. Each photoreceptor sends its signals down very fine wires to the brain. The wires joining each eye to the brain are called the optic nerves. The information then travels to many different special 'vision' parts of the brain. All parts of the brain and eye need to be present and working for us to see normally.
The brain is surrounded by special water called cerebrospinal fluid (CSF). The CSF is made in a part of the brain called the choroid plexus. From there it flows in and around the brain through pipes and water tanks called aqueducts and ventricles. It drains and exits out of the brain through bits called the arachnoid villi. If a pipe (aqueduct) becomes blocked the water pressure behind it builds up. If the drain becomes blocked (arachnoid villi) and the water cannot flow out the pressure will also rise. Hydrocephalus is a condition where this happens. This leads to high pressure in the head.
If the flow of CSF becomes blocked at the aqueducts or ventricles then the Hydrocephalus is called 'Non-Communicating'. If the CSF flows through all the aqueducts and ventricles but then cannot drain and exit out of the brain at the arachnoid villi then the Hydrocephalus is called 'Communicating'.
Why might a child develop Hydrocephalus?
Sometimes a child is born with Hydrocephalus. This is called 'Congenital Hydrocephalus'. Many children develop Hydrocephalus after they are born. This is called 'Acquired Hydrocephalus'.
There are many different causes of Hydrocephalus. These include:
- Being born with blocked 'pipes' (aqueductal stenosis)
- Brain Cysts
- Infection of the baby while still in the womb (intrauterine infection)
- Infection after being born (meningitis)
- Bleeding into the water spaces (intraventricular haemorrhage)
- Brain Tumours which block the flow of water
The aqueducts are the pipes in which the CSF flows through the brain. Stenosis is a medical word for 'narrowing'. If the aqueducts are narrow then the flow of CSF will be slow. This will lead to raised CSF pressure in the head (Hydrocephalus). Some children can be born with aqueductal stenosis.
Very rarely babies can be born with round, swollen, fluid-filled spaces in the brain. They are called cysts. These cysts can press on the aqueducts and stop CSF flowing. This will lead to raised CSF pressure in the head (Hydrocephalus).
The womb is also known as the uterus. The uterus is a strong sac of muscle in which the unborn baby grows. 'Intra' is a medical word for 'within'. Intrauterine Infection is when an unborn child, still within the womb develops an infection from a germ. The baby may 'catch' the germ from the mother's blood or birth canal. There are many different types of germ that may cause intrauterine infection. The infection may cause inflammation in the baby's brain. As the inflammation heals it may cause scarring. The scarring can damage both the aqueducts and arachnoid villi where the CSF drains and exits out of the brain. This may lead to raised CSF pressure in the head (Hydrocephalus).
Infection after being born (meningitis)
A protective coating called the meninges covers the brain. Meningitis is when a germ infects this protective coating. The infection may cause inflammation in the baby's brain. As the inflammation heals it may cause scarring. The scarring can damage both the aqueducts and arachnoid villi where the CSF drains and exits out of the brain. This may lead to raised CSF pressure in the head (Hydrocephalus).
Bleeding into the water spaces (intraventricular haemorrhage)
A medical word for the reservoirs and water spaces in the brain is 'ventricle'. A medical word for bleeding is haemorrhage. Bleeding into the water spaces of a baby's brain is called intraventricular haemorrhage (intra means within). This is a very rare condition in babies born near to their due date. It is more common in babies born before their due date (premature). The bleeding causes inflammation. As the inflammation heals it may cause scarring. The scarring can damage the arachnoid villi where the CSF drains and exits out of the brain. This may lead to raised CSF pressure in the head (Hydrocephalus).
A tumour is a condition where a part of the body grows more than it would normally. A brain tumour is a growth of one part of the brain. Most brain tumours are benign. Benign means that bits of the tumour will not normally break off and spread to other parts of the body. They may, with time however grow and get bigger. A growing brain tumour may press and squeeze an aqueduct until it is so narrow that no more CSF can flow. The aqueduct is then blocked and the CSF pressure in the head may rise (Hydrocephalus).
What symptoms might a child with Hydrocephalus complain of?
The symptoms and signs that a child with Hydrocephalus might complain of can vary. High pressure in the head can often cause headaches. A child might also feel sick and tired. Hydrocephalus may also cause blurred vision, squint and nystagmus.
If Hydrocephalus is suspected then the pressure of CSF can be measured. A small needle is placed into the fluid around the brain. It is connected to a gauge that measures the pressure. A scan of the head is often also done. This will show if there is any obvious cause for the raised pressure.
How is Hydrocephalus treated?
With most children a drain can be placed that overcomes the blockage. This can help reduce the pressure and improve some of the symptoms. The drains can sometimes become blocked and need to be fixed or replaced.
Different children will be affected in different ways by hydrocephalus. Many children with hydrocephalus will not have any visual impairment. Others may develop several different conditions of the eyes and vision. These might include:
- Cerebral Visual Impairment (CVI)
- Visual Field Loss
- Optic Atrophy
What is Cerebral Visual Impairment?
Cerebral Visual Impairment (CVI also sometimes known as cortical visual impairment) is a condition where some of the special 'vision' parts of the brain are damaged and not working properly. 'Cerebral' is another word for the brain. This causes reduced vision, even though the eyes are normal. In most cases, once the damage has happened it does not get worse. As the child grows the vision may slowly improve.
What is Visual Field Loss?
If certain parts of the brain are damaged with other bits not affected there may be loss of only one half or quarter of the visual world. This is called visual field loss. Different patterns of visual field loss can occur.
The right side of the brain is responsible for seeing the left side of the visual world. The left side of the brain sees the right side of the visual world. If the right side of the brain is damaged the left side of the visual world may not be seen. In the same way the upper part of the back of the brain is responsible for seeing the lower part of the visual world. A child with damage in this area will not see the ground when looking straight ahead. The child may then tend to trip over things.
What is Optic Atrophy?
The optic nerve contains thousands of communication wires from the eye to the brain. The wires may become damaged by high CSF (brain fluid) pressure. Some of the wires will then wear out and disappear. This may cause blurred vision and 'washed' out colour vision.
What is Nystagmus?
Our eyes move quickly when we watch something that is moving quickly. Our eyes are still when we look at something that is still. This is so the eyes can focus sharply on an object. The eye can then give clear signals to the brain to make clear vision. In some children the eyes are always moving to-and-fro even though the object that they are looking at is still. This to-and-fro movement is called Nystagmus. Children do not know that they are doing it. Because the eye is shaking the vision is usually a bit blurred. This is like if a camera moves during a photograph. The photograph is also usually blurred.
What is Squint?
Squint is when a child's eyes do not appear to be looking in the same direction. One eye may be looking too far out (divergent squint) or too far in (convergent squint). Sometimes spectacles or an operation may help the eyes to look straighter.
There are lots of things that can be done to help children with Hydrocephalus see better.
We use our vision to get around, learn new things and to meet other people and make friends. It is important to consider what your child's particular problems with vision might be.
If your child has been prescribed spectacles, contact lenses or a Low Visual Aid (LVA) it is important that they are encouraged to wear and use them. This will help your child see more clearly and help the vision parts of the brain grow and develop.
Problems at school may be due to some of the reading books being hard to see. This often means it takes longer and more effort to do the work. If the size of print is increased and letters and words spaced more widely most children will find schoolwork easier. Good bright lighting and crisp black print on a clean white background will also make things easier. Sometimes placing reading books on a slope, which tilts the print towards the child, will improve reading speed as well.
When reading it can be helpful to read one line at a time through a 'letter box' placed over the page. Placing a piece of blue tack below the line they are reading, at the beginning of the next sentence, can help some children find their way back to the start of the next line more quickly.
A child with Nystagmus, who chooses to use a head turn or to move the head to and fro, to improve vision should not be made to stop doing this. They are trying to see more clearly and are often doing it without knowing it.
Some children may also benefit from using a computer program while reading. The program only shows one word of a sentence at a time. The word is in the middle of the computer screen. This reduces the need for fast eye movements. It can increase reading speed and reduce tiredness. One program is called Ace Reader. There are many others. A demonstration can be downloaded from www.acereader.com.
It is also worth watching carefully to find out what the smallest toys are that a child can see and play with. Then try to only play with toys that are the same size or bigger. If the child has visual field loss try to place toys in the part of the child's vision that is working. Placing one toy on a plain background will often help children see it more readily. Placing lots of toys of different size and colour close together on a patterned background can make them 'invisible' to many children with CVI.
Recognising facial expressions can often be difficult. It is worth trying to find out at what distance facial expressions can be seen and responded to. Then always try to talk and smile from within this distance. This helps a child to learn what facial expressions mean and to copy them. There is a special part of the brain that helps children 'make sense' of faces. Sometimes this part is also damaged. These children may have difficulty responding to smiling even if their vision is clear enough.
Infants and young children need to learn about the world around them. Home visiting teachers, physiotherapists and occupational and speech therapists may all add to the child's care and education. It is important to continue the programmes that they recommend. If the child is involved in family activities vision can improve and new skills can develop.
Even if a child has very poor vision many useful and practical things can be done to improve the ability of the child to get around, interact with other children and learn.
Who wrote these documents?
These pages are the consensus of opinion of many different people. They include parents of visually impaired children, visually impaired children themselves, Community Paediatricians, Ophthalmologists, Educationalists and Psychologists.
The main author and person responsible for their content is Dr Andrew Blaikie who was an Ophthalmology Research Fellow with Visual Impairment Scotland and is a member of the Royal College of Ophthalmologists.