University of Edinburgh
 

Medical Information on Incontinentia Pigmenti

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.

Medical Information on Incontinentia Pigmenti

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 called 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 Incontinentia Pigmenti?

This condition mainly affects the skin, hair and teeth of girls. It is unusual for boys to develop Incontinentia Pigmenti (IP). The first sign of this condition is usually a skin rash, often seen in the first few months of life and sometimes even at birth. The rash changes its appearance over a period of months and years. At first red blisters appear, these then become crusty and turn into raised scabs. The rash tends to appear in lines on the legs, arms and around the chest. Often by the age of 12 months, once the scabs have begun to heal, swirling patterns of dark skin develop. The streaks of darker skin mainly affect the chest. They often appear in areas different from the blisters.

The colour of our skin depends on how much melanin pigment is in it. Pigment is a kind of dye or tint that the body uses to give skin its different shades and colours. Melanin pigment is dark brown and colours skin, hair and eyes.

All the different parts of the body are made up of 'cells'. Cells are tiny factories making materials that the body needs to work and grow. Melanin pigment is normally held within cells. Some cells in the skin spill their melanin pigment into the skin. These cells are said to be 'incontinent' of pigment and cause darker patches on the skin. This is why this condition is called Incontinentia Pigmenti.

By late teens the darker patches usually become lighter and lose pigmentation. The new paler areas of skin can also lose any hair that was there before. Hair loss mainly affects the lower legs. Hair on the head is usually not affected. The stages may overlap and start and end at different ages. Not all children with IP will always develop all the stages of the rash.

The brain and eyes can also be affected by IP. This can lead to:

  • Learning difficulties
  • Developmental delay
  • Problems with mobility
  • Epilepsy
  • Visual impairment

How does IP cause Visual Impairment?

There are several eye conditions that can occur along with IP. They can all cause reduced vision. These conditions include:

  • Cataract
  • Microphthalmia
  • Optic Atrophy
  • Nystagmus
  • Poor blood supply to the Retina
  • Cerebral Visual Impairment
  • Scarring & Detachment of the Retina

What is Cataract?

Cataract is when the normally clear lens of the eye becomes hazy. If the lens is not clear then not all the light can get into the eye and vision is often blurred.

What is Microphthalmia?

When a baby is growing in the womb sometimes not all the parts of the baby grow fully. If an eye (ophthalmia) does not grow to its full size and is smaller (micro) than it should be this is known as Microphthalmia. This can lead to visual loss.

What is Optic Atrophy?

If damage occurs to the brain, retina or optic nerve then some of the wires in the optic nerve wear out and disappear. This is known as Optic Atrophy. By looking into the eye with a special instrument all these wires can be seen 'end on' as they exit the eye and pass to the brain. This is the 'head' of the optic nerve. If none of the wires are damaged then the 'head' of the optic nerve looks yellow and pink. If many wires are missing then the optic nerve looks pale and white. This is the common appearance in children with optic atrophy and visual impairment.

What is Nystagmus?

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.

Poor blood supply to the Retina can develop

The retina needs a good blood and oxygen supply to work. Children with IP can be born with or quickly develop areas of retina with reduced or no blood supply. Often the central part of the retina can be affected (the macula). This can lead to blurred vision.

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 maybe normal and working. 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.

Scarring & Detachment of the Retina

One of the main causes of visual impairment in IP is scarring and detachment of the retina. Retinal detachment is when the thin retinal film peels off from the back of the eye.

Why Does The Retina Scar And Detach?

In children with IP the retina may not have a good blood supply in all areas. Sometimes areas of the retina around the edges have a poor blood supply. This retina can become damaged because it is starved of blood and oxygen. The damage can lead to scarring. The scar tissue can then shorten and pull the retina off the back of the eye. This is called a retinal detachment and causes visual impairment.

Children with IP should be examined regularly by an eye doctor during the first few years of life. The eye doctor looks for early signs of poor blood supply or retinal detachment. Early treatment may help prevent it getting any worse. Treatment usually means applying cold (cryotherapy) or hot (laser) treatment. Even if treatment is given the retina may still detach.

How does Incontinentia Pigmenti affect the way a child sees?

The symptoms that a child might complain of will depend on:

  • The age of the child
  • Which bit of the retina has detached
  • Whether only one eye is affected or both
  • Whether the child has any other conditions that might affect vision

If a child has had poor vision from an early age they are likely to initially feel their vision to be 'normal' as they have never known anything else but their own visual world. They will assume that everyone else has vision the same as their own. They will not realise that other people see things differently.

Children with IP may however develop visual problems around the age of 3, 4 or 5 years. Most of these children will only complain of poor vision when the central bit of the retina detaches in their better eye. This will cause the central area of vision to become very blurred and 'grey'. Children usually notice this because faces and toys will become hard to see. Younger children do not usually notice smaller areas of detached retina, causing blurring, away from central vision. This is especially true if their other eye still sees well.

Even if the retina is unaffected blurred vision can still occur. This is because many other eye conditions can develop that may lead to visual impairment.

IP may also cause brain damage. This often leads to Cerebral Visual Impairment (CVI). 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 maybe normal and working. Often children cannot 'make sense' of what they see. If you would like a VI Scotland document on CVI please let us know.

What is the cause of Incontinentia Pigmenti?

IP is caused by a misprint in a gene on the X sex chromosome.

What are Genes and Chromosomes?

The body has a 'built-in plan' to make sure all the parts of the body grow and work fully and correctly. This plan is written in our genes. Genes are a chemical alphabet held in every cell of the body. If a gene has the chemical alphabet rearranged by accident a misprint will occur. Misprinted genes do not work correctly. This often leads to disease.

Within each tiny cell genes are stored one after the other as long threads. To save space within the cell the threads are folded up tightly into shorter thicker ropes of genes called chromosomes. Almost every cell of the body has exactly the same number and kind of chromosomes. There are 23 different chromosomes. Each chromosome has a copy of itself so that there are 46 in total (23 pairs).

What are sex chromosomes?

One pair of chromosomes are called the sex chromosomes. They are called sex chromosomes because they hold the plan for making an unborn baby grow into a boy or a girl (they determine the sex). There are two types of sex chromosomes called X and Y. The letters just describe the shape of the chromosome when seen in fine detail. If a child has an X and a Y sex chromosome then they will develop into a boy (XY). If the sex chromosomes are both X then the child will develop in the womb into a girl (XX).

Incontinentia Pigmenti is caused by a misprint in a gene on the X chromosome

Children who develop Incontinentia Pigmenti have a misprint in a gene on the X chromosome. Because boys are XY they only have one X chromosome. The effect of the single misprinted gene is unopposed. This means that males with this condition never survive. Girls (XX) however have two copies of the X chromosome. If they happen to have a misprinted copy they will still have a normal 'back up' copy. This means that they survive but are affected by IP. This is called dominant X-linked inheritance.

How is Incontinentia Pigmenti diagnosed?

A doctor may suspect IP if a typical rash develops in a young child. Other typical features of IP can be seen in a child's hair, teeth and eyes. Altogether these signs will help the doctor make a 'clinical' diagnosis, without the need for any tests. If the diagnosis is in doubt a small piece of skin can be examined in fine detail. IP is confirmed if melanin pigment is 'loose' in the skin, having been released from cells.

What can be done to help?

Regular eye examinations in the first few years of life are very important. This can help identify problems before a child might be aware of them. Early treatment may prevent the condition getting worse.

Different surgical operations can help improve vision in children with cataract or retinal detachment. The operations are difficult. They are not always successful.

Spectacles, contact lenses and Low Visual Aids (LVAs) can help children use their remaining vision.

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

There are lots of things that can be done to help a child with IP see better.

Vision helps children 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.

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.

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.

Parents can make a big difference. If spectacles have been prescribed they need to be worn while the child is awake and active.

Children with IP can have difficulty controlling head, eye and body movements. When reading or watching TV careful positioning of the head to prevent it falling to the side or falling forward can help a lot. Some children with IP may see poorly in the some parts of their visual world. Placing objects away from this blurred area can be helpful.

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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