University of Edinburgh
 

Medical Information on Craniopharyngioma

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 Craniopharyngioma

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 optic nerves join about half way between the eye and brain, and then split up again. The join is called the optic chiasm. At the join, signals from the 'nose' side of each eye's visual world swap sides and continue travelling along the opposite side from where they started. The two optic nerves then join on to the brain. The brain is split into two halves, right and left. This means all the signals from the visual world on the child's right hand side are now travelling in the left side of the brain. It also means that all the signals from the visual world on the child's left hand side are now travelling in the right half of the brain.

The information then travels to the many different special 'vision' parts of the brain. The main bit of the brain that works vision is at the back of the head. It is called the occipital lobe. The joined up path that signals travel down from retina to optic nerve then optic chiasm then occipital lobe is called the visual pathway. There are two visual pathways, one on the right side of the brain and another on the left. All parts of both visual pathways need to be present and working for us to see normally.

What is a Craniopharyngioma?

A Craniopharyngioma is a benign brain tumour. A tumour is a condition where a part of the body grows more than it would normally. Benign means that bits of the tumour will not normally break off and spread to other parts of the body. It may, with time however grow and get bigger. The part of the brain that is affected is very near to the optic chiasm. The optic chiasm may become damaged by the growth of a Craniopharyngioma. This is why this condition may cause visual impairment. Other parts of the brain may also be damaged leading to many other different types of symptoms.

How might a Craniopharyngioma affect a child's eyes and vision?

A Craniopharyngioma may cause:

  • Visual Field Loss
  • Blurred Vision
  • Nystagmus

Visual Field Loss

The visual field is the medical word for the full area of a child's visual world (what they see). Visual Field Loss may occur if damage occurs to a part of the visual pathway. The visual pathway that signals travel along includes the eye, optic nerve, optic chiasm and the special 'vision' parts of the brain. Damage to the visual pathway may cause blurring or even complete loss of bits of the visual world (visual field).

If damage occurs to the optic chiasm then a special type of visual field loss may occur. The child will lose the outside bits of the visual world on both sides. It is called a Bi-temporal Hemianopia. 'Bi' means both right and left sides. 'Temporal' means the outside bit of vision. 'Hemi' means half and 'anopia' means no vision.

It usually takes younger children longer to notice visual field loss. Older children may notice that something is wrong with their vision sooner. The visual field loss does not usually get better and may slowly get worse.

Blurred Vision

If the visual loss spreads into the central part of vision then the child may complain of blurred vision. Usually both eyes will become affected. Children may often only complain of blurred vision when the vision in their only remaining good eye becomes blurred. Often there can also be reduced colour vision.

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. A Craniopharyngioma may cause Nystagmus.

Children do not know that they are moving their eye like this. 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. Surprisingly children do not complain of the visual world moving. The to-and-fro movements can be up and down, side-to-side or even in a circle. The movements of the eyes can be large or small and fast or slow. If a child develops Nystagmus they should be referred to an eye doctor for an examination and investigations.

What other conditions might a Craniopharyngioma cause?

Craniopharyngiomas are benign tumours. This means they do not normally spread and grow to other parts of the body. They can however slowly grow and become bigger. The tumour can then press and squeeze parts of the brain near the chiasm. This can lead to other conditions and symptoms also developing. These may include:

  • Raised pressure in the head
  • Problems with growth and development
  • Damage to the hypothalamus

Raised pressure in the head

High pressure in the head can often cause headaches. A child might also feel sick and tired.

Problems with growth and development

A Craniopharyngioma may damage a part of the brain called the pituitary gland. The pituitary gland makes important chemicals called hormones. The hormones help the body grow and work correctly. Many different types of symptoms might occur if a Craniopharyngioma damages the pituitary gland. In children this may include slow growth and delayed onset of puberty.

Damage to the hypothalamus

The hypothalamus is another important part of the brain that helps the body control many functions. It is often damage by a Craniopharyngioma. This may lead to problems with sleeping, mood swings, poor concentration and changes in appetite and weight. It may cause a type of diabetes to develop. This may cause a child to be thirsty and pass lots of urine.

How is the diagnosis made?

Children may notice that their vision is blurred or a bit is missing (visual field loss). Parents may notice that their child's eyes develop Nystagmus. Parents may also suspect, by the way their child acts, that their child's vision is impaired. If they discuss their concerns with their Family Doctor an assessment can be arranged.

The School nurse may notice the blurred vision during a vision screening examination. They can organise an examination at the eye clinic. An eye doctor at the clinic can also check for visual field loss. By also asking questions of the parents and teachers of the child the doctor can get a good idea about where and what kind of visual field loss the child may have.

More often a child may present to their family doctor with one of the many different types of symptoms due to damage to the pituitary or hypothalamus. They may also present with headaches and sickness. It can often take three years from the beginning of symptoms until the diagnosis is confirmed.

If a Craniopharyngioma is suspected blood tests and a head scan may help confirm that a Craniopharyngioma is the cause.

What can be done to treat a Craniopharyngioma?

The treatment of this condition requires a 'team' of doctors. The team usually includes a brain surgeon (neurosurgeon), a doctor who treats tumours (oncologist), a children's doctor who specialises in hormones (paediatric endocrinologist) and an eye doctor (ophthalmologist). Any decision on treatment is discussed fully with the child and their parents. Most treatments can have side effects. The benefit to the child must always be weighed against any possible damaging side effects of the treatment.

A neurosurgeon will study the head scans closely. After discussion and explanation with the child and parents the surgeon will perform an operation. The operation aims to remove as much of the tumour as possible. It is often difficult to remove all the tumour. Sometimes other parts of the brain can be damaged during the operation. These include the optic chiasm, pituitary and hypothalamus.

After the operation X-ray treatment (radiotherapy) to the area where the tumour was removed may be needed. An oncologist will organise this. X-rays are normally used to take pictures of patient's lungs and broken bones. When concentrated and focused on to a tumour they can help slow down and stop its growth. Radiotherapy is usually needed because not all of the tumour can usually be removed during the operation. The small bits that remain might grow again. This can lead to further problems. Radiotherapy reduces the chance of the remaining tumour growing again.

After the treatment regular checks at the clinic and scans are needed. This is to makes sure that the child's growth is normal and can help to see if the Craniopharyngioma is starting to grow again. If the child has low levels of hormones they can often be replaced with tablets. A paediatric endocrinologist will decide on this treatment.

An ophthalmologist can offer advice if vision has been affected.

How can parents, family, friends and teachers make a difference?

We use our vision to get around, learn new things and to meet other people and make friends. It is important to be aware of your child's own special problems with vision.

If part of the child's visual world is missing or blurred (visual field loss) try to place objects away from this part. Instead place objects in parts of the visual world where the child's vision is clearer. This may require some experimenting and discussion with the child's teacher and eye doctor.

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 most children will find schoolwork easier. If a Low Visual Aid (LVA) or spectacles have been prescribed then try to encourage their use. This will help the child see more clearly. It will also help the vision parts of the brain to grow and develop.

It is 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.

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

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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