University of Edinburgh
 

Medical Information on Cerebral Palsy

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 to 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.

Medical Information on Cerebral Palsy

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.

What is Cerebral Palsy?

Cerebral Palsy (CP) is a condition that mainly affects movement. It is caused by damage to different parts of the brain. The damage may occur either before birth, at birth or in early childhood. Some children have only a mild form while others are more severely affected. There are three main types of Cerebral Palsy. These include:

Spastic Cerebral Palsy

Children with this type may find their muscles becoming very stiff and weak, especially under effort. This can affect the way they move.

Athetoid Cerebral Palsy

Children with this type of cerebral palsy often lose control of their posture. They may also tend to make unwanted movements.

Ataxic Cerebral Palsy

Children with this type of cerebral palsy usually have problems with balance. They may also have shaky hand movements and irregular speech.

Although cerebral palsy mainly causes difficulty with movement other conditions may also occur. This is because other parts of the brain may also be affected. This can lead to learning difficulties, epilepsy, difficulty with hearing and visual impairment. The visual impairment that occurs in Cerebral Palsy is called Cerebral Visual Impairment (CVI).

What is Cerebral Visual Impairment?

Cerebral Visual Impairment (CVI) is a condition where some of the special 'vision' parts of the brain and its connections are damaged. This causes visual impairment even though the eyes are normal. Often children with CVI actually have good visual acuity but can not 'make sense' of what they see. In most cases, once the damage has happened it does not get worse. As the child grows older the visual difficulties may slowly improve.

How is the diagnosis made?

Many children with Cerebral Palsy will have visual impairment. It is often difficult to tell if a child has problems seeing because of other problems with communication, movement or learning difficulties.

Sometimes it is the parents who notice, by the way their child acts, that vision is impaired. If they discuss this with their Family Doctor an assessment can be arranged. Doctors, teachers and other carers should always consider that a child with cerebral palsy might have some kind of visual impairment. If they suspect a child to have visual impairment an assessment should be organised.

CVI can be diagnosed in a child who has:

  1. Visual Difficulty
  2. Damage to the 'vision' parts of the brain
  3. But apparently normal eyes

A head scan will usually confirm the damage to the brain. There are other special tests that can also be done. These tests measure signals from the 'vision' parts of the brain when a child is shown patterns on a screen. Sticky patches are placed on the back of the head. The sticky patches are attached to wires that lead to a machine. The machine records the electrical signals made by the brain. The record of the signals will help the doctors decide what the matter is. If the signals are reduced in size or slow then CVI is more likely. This test is called a Visual Evoked Potential (VEP).

It is uncommon for children with CP to have these tests done. Often the best way to find out if a child has Cerebral Visual Impairment is by asking questions. An eye doctor can find out from the parents and teachers of the child what kind of problems they seem to be having. The questions are based on the visual difficulties that commonly occur in children with CVI. If the child has difficulties that are typical of the condition then they are very likely to have CVI.

What kind of visual difficulties is a child with CVI likely to have?

Most young children with Cerebral Visual Impairment feel their vision to be 'normal' as they have never known anything else but their own visual world. At first they assume that everyone else has vision the same as their own and do not realise that other people see things differently.

Cerebral Visual Impairment can affect vision in many ways. All or only one of the special 'vision' parts of the brain can be damaged to different degrees. If there has been lots of damage to many parts of the brain the vision can be very poor. However the child may still see movement and bright lights. Complete blindness due to brain damage is rare.

If there has been only a small amount of damage in only one part of the brain the visual problem can be a lot less impairing.

Children with CVI can have problems with:

  • Getting Around
  • Recognising Objects
  • Focusing for near objects
  • Fast eye movements
  • Visual Field Loss

What can be done to help?

There are no medicines or surgical treatments that will fix or improve brain damage. There are however lots of things that can be done to help children with CVI 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 now and in the future. 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 ensure 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.

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. 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. If the child has visual field loss try to place objects in the part of the child's vision that is working.

Cerebral Visual Impairment commonly occurs in children who have difficulty controlling both head and eye movements. Careful positioning of the head to prevent it falling to the side or falling forward can help a lot.

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.

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