Further information about cerebral palsy

This page follows on from Introduction to Cerebral Palsy and is intended to explore the subject in greater detail, but still using simple language.

If you or someone close to you has cerebral palsy and you require further clarification of any terms used in connection with cerebral palsy – which may or may not be mentioned on this page – please refer to our jargon buster or contact a relevant health professional such as your physiotherapist or consultant.

What is cerebral palsy?

Cerebral palsy is a very diverse and complex condition, which ranges from very mild to severe, with no two people being affected in precisely the same way.

There has never been a simple explanation of what cerebral palsy is. In 1984 P Scrutton wrote, “The almost infinite variety (and the lack of a common language to describe this variety accurately) makes learning about it very difficult indeed.” (1)

Cerebral palsy does not have a clear-cut single cause; it is not a specific condition – unlike Down’s Syndrome for example, which is an identifiable chromosomal disorder.

In cerebral palsy the brain impairment is non-progressive i.e. it does not get worse or improve. However, the effects on the body may become more (or less) obvious as time goes by.

Definitions

Cerebral palsy can be defined as “a persistent (but not unchanging) disorder of movement and posture, as the result of one or more non-progressive abnormalities in the brain, before its growth and development are complete. Other clinical signs may be present as well.” (Cerebral Palsy: Problems and Practice, Griffiths M., Clegg M. (eds). Human Horizons Series ISBN 0-285-65071-8)

“Cerebral palsy refers to a collection of conditions where there is primarily a disorder of voluntary movement and/or co-ordination. It is caused by damage to the developing brain sometime before birth, during birth, or after birth.” (Scope report: Focusing on Cerebral Palsy, by Parkes, J., Donnelly, D. and Hill, N.)

The dysfunction of the motor control part(s) of the brain is present ‘before the brain’s growth and development are complete’. This means the impairment occurred during pregnancy, birth or early childhood – before the brain’s growth and development has reached a certain level of maturity. The following quote explains further how age may influence diagnosis:

“Insults to the brain that occur after eight years of age result in neurological impairments reminiscent of those observed in adults; similar insults prior to three years of age (including during the prenatal period), result in neurological impairments and motor outcomes – such as cerebral palsy – that are characteristic of injury to the immature brain. From three to eight, mixed patterns of neurological impairment are observed. An arbitrary upper age limit of five or six years has been suggested for assigning the diagnosis of cerebral palsy; however, in practice, the determination is typically made on a case by case basis.” (2)

Growing babies and children have to learn to use many other muscles besides those concerned with the co-ordination and movement of arms, legs and trunk. For example, the brain ‘learns’ how to position and focus the eyes, make noises and sounds, chew food, control the muscles used when going to the toilet and those used for breathing. Therefore, there may also be difficulties for some children in these areas of function.

In addition, because other areas of the brain may also have been affected there is a possibility of associated or related difficulties such as sensory or perceptual impairment. Other associated difficulties may include learning difficulties or epilepsy (seizures).

Risk factors associated with cerebral palsy

A risk factor is not a cause; it is a variable which, when present, increases the chance of something occurring – in this case, cerebral palsy. Just because a risk factor is present does not mean cerebral palsy will occur; nor does the absence of a risk factor mean that cerebral palsy will not occur.

In a study in the US (3), a group of investigators found the following factors are associated with an increased risk of cerebral palsy:

• Mother 40 years or older
• Mother under 20 years
• Father under 20 years
• First child or child born fifth or more
• Child one of twins (particularly if one twin died)
• Baby of low birth weight (less than 2.5 lbs)
• Premature birth (less than 37 weeks)

More than one risk factor can be present at the same time (for example, low birth weight and being a twin) and such a combination can further increase the probability of cerebral palsy occurring.

Types of cerebral palsy

Three different parts of the brain working together initiate and control the muscles that affect movement and posture. The part of the brain that is impaired determines how a person with cerebral palsy will be affected. There are three main types of cerebral palsy:

Spastic cerebral palsy (spasticity)

This is caused by impairment in the cerebral cortex of the brain and is the most common form of cerebral palsy. It is characterised by constant increased muscle tone and weakness in the parts of the body affected. This increased muscle tone (hypertonia) creates tightness in the muscles, leading to a decreased range of movement in the joints. The effects may increase with anxiety or increased effort, leading to excessive fatigue.

Athetoid or dystonic, also known as dyskinetic cerebral palsy (athetosis)

This is caused by impairment in the basal ganglia area of the brain. It is characterised by involuntary and uncontrollable muscle tone fluctuations, sometimes involving the whole body. The muscles alternate between being floppy and tense and there will often be difficulty in maintaining posture. The person usually has full range of movement in their joints, but not the stability or co-ordination to control their movements.

Unwanted movements may be small, rapid, irregularly repetitive, random, and jerky, sometimes referred to as choreic movements. The unwanted movements may also be of a long slow, writhing nature. Someone with athetosis will often appear restless and constantly moving, only being still when fully relaxed and sometimes only when asleep.

The movements will often become worse when the person is excited or is attempting to do something.

Speech is nearly always affected to some degree, because of difficulty in controlling the tongue, breathing and vocal chords. Similarly there may be difficulties with eating and, the person may drool (have saliva coming out of their mouth).

Ataxic cerebral palsy (ataxia)

This relatively rare form of cerebral palsy, which affects less than 10% of people with cerebral palsy, is caused by impairment to the cerebellum, which is in the base of the brain.

The cerebellum co-ordinates the actions of groups of muscles and is responsible for, amongst other things, balance. As with athetoid cerebral palsy, all four limbs and the trunk are usually involved.

This impairment can lead to a general poor sensation of balance, unsteadiness and staggering when walking. Tremors may also be present when the person is attempting a task.

It is, however, quite common to have a combination of two or more of the above types and so not fit neatly into any one category. This is usually described as “mixed cerebral palsy”. Examples of this are:

• A child with spastic diplegia will have mostly spastic muscle difficulties, with the legs affected more than other parts of the body. However the child might also have some athetosis and balance problems.
• A child with athetoid quadriplegia might have some ataxia and spasticity present as well.

Cerebral palsy can be categorised further, by referring to the parts of the body affected.

The three main categories are as follows:

• Diplegia is a paralysis affecting symmetrical parts of the body such as arms or legs. In diplegic cerebral palsy, it is often the legs which are more affected that the hands and arms.
• Hemiplegia occurs where one side of the body (including arm and leg) is affected.
• Quadriplegia/Tetraplegia means that all four limbs are involved together with, usually, the trunk and neck.

Occasionally you may come across these categories:

• Monoplegia – used when only one limb is involved.
• Triplegia means that three limbs are affected - usually both legs and one arm.

However, you may find different categories may be used by different professionals.

References

(1) Scrutton D (1984) Management of the Motor Disorders in Cerebral Palsy.

(2) Chugani (1993) Caring for Children with Cerebral Palsy - A Team Approach.

(3) Cummins, S.K. et al. - Journal of Pediatrics 123/2; 230-237, cited in United Cerebral Palsy Research Foundation factsheet “Risk Factors for Cerebral Palsy” (1994)

Scope has published a report entitled Focusing on Cerebral Palsy, by Parkes, J., Donnelly, D. and Hill, N. £3.30 to individuals, £12.50 to organisations (plus 10% p&p). For further information on how to obtain a copy, contact Scope Response.

For more information on Scope

Contact Scope Response for information, advice and support on cerebral palsy and disability issues. Copies of all our factsheets can be downloaded from our website or obtained from Scope Response.

Scope Response hours are:

Monday - Friday 9 am to 5 pm
Closed weekends and Bank Holidays

Scope Response
PO Box 833
Milton Keynes
MK12 5NY

Tel: 0808 800 3333 (freephone Helpline)

Fax: 01908 321051

SMS Text: Type SCOPE plus your message to 80039

Email: response@scope.org.uk

Scope acknowledges the help and support of everyone who has been involved in the production of this information. Although we have taken care to ensure the accuracy of this information, Scope cannot accept responsibility for errors or omissions. We always recommend getting independent advice from a professional before embarking on any process, therapy or medical intervention.

We have information about Scope and cerebral palsy available in some languages on CD-ROM. We also offer a telephone interpreting service to people whose preferred language is not English. Please contact Scope Response for more details of these services.

This information was last reviewed March 2010.

© We are happy for you to make photocopies of any part of this document. However, we would be grateful if you would attach an acknowledgement of the source to any copies.