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Cerebral palsy and communication impairments

Cerebral palsy is one of the most common conditions that affects children. It is particularly prevalent in South Africa. 


What is cerebral palsy?

The  definition is as follows:

‘Cerebral palsy (CP) describes a group of permanent disorders of the development of movement and posture, causing activity limitation, that are attributed to non-progressive disturbances that occurred in the developing fetal or infant brain. The motor disorders of cerebral palsy are often accompanied by disturbances of sensation, perception, cognition, communication, and behavior, by epilepsy, and by secondary musculoskeletal problems’(Rosenbaum et al. 2007).

In simpler terms:

  • CP is a GROUP of different problems (i.e. there is no such thing as one type of CP)

  • and that SOMETHING happens (there are many, many causes and sometimes we can't work out what the cause was)

  • that causes  BRAIN DAMAGE

  • and  the damage occurs to an IMMATURE BRAIN  (one that has not developed fully yet -  under the age of 2 years).

  • The brain damage is PERMANENT  ( the brain damage itself will never go away)

  • but it will NOT PROGRESS  ( the brain damage itself will not get worse or deteriorate).

  • The most obvious problems that the brain damage results in are PHYSICAL (motor) problems (e.g. spasticity, ataxia, dystonia),

  • but these physical problems are usually associated with OTHER PROBLEMS such as epilepsy, sensory problems, cognitive problems, behavioural problems, and communication problems. These associated problems vary in the degree of severity from mild to profound.


Brain damage does not ALWAYS result in cerebral palsy. Brain damage to the young brain often results in CP but we don't usually label a child who has brain damage as having cerebral palsy UNLESS there are clear motor impairments.

The diagnosis of CP  EXCLUDES  genetic conditions or childhood deteriorating conditions that have associated brain injury with motor impairments ( eg Tay Sachs).

How prevalent is cerebral palsy?

Almost all the research on CP has been done in high-income countries. The  estimated prevalence in these countries is 2 to 3 per 1000 live births. We simply have no reliable data that tell us how prevalent CP is in other contexts, such as South Africa. In rural contexts in SA, it is estimated to be as high as 14/1000. In poor areas of Mexico, it has been reported as 4/1000. 

How do we classify cerebral palsy?
1) Classifying CP in terms of the distribution of the motor impairments in the body:


  • Monoplegia means only one limb is affected.

  • Diplegia usually indicates the legs are affected more than the arms; primarily affects the lower body.

  • Hemiplegia indicates the arm and leg on one side of the body are affected.

  • Paraplegia means the lower half of the body, including both legs, is affected.

  • Triplegia indicates three limbs are affected. This could be both arms and a leg, or both legs and an arm. Or, it could refer to one upper and one lower extremity and the face.

  • Double hemiplegia indicates all four limbs are involved, but one side of the body is more affected than the other.

  • Tetraplegia indicates that all four limbs are involved, but three limbs are more affected than the fourth.

  • Quadriplegia means that all four limbs are involved.

There are some problems with this classification system: sometimes it is difficult to tell if the arms are worse than the legs; sometimes, if you test carefully enough, what appears to be a hemi is actually a quad...and give a child to three professionals and you'll probably get three different opinions on the distribution.


2) Classifying CP according to the predominant type of motor impairment:

Spasticity results from an abnormal amount of  increased muscle tone. Tone is the readiness of a muscle to move. Increased tone means that the muscles are in a 'hyper'-ready state, which means that they are contracted, which makes arms and legs stiff or rigid, unable to easily flex or relax.  Reflexes are often exaggerated. The movements of spastic limbs are jerky, ungraded, unsymmetrical, awkward, and sometimes there is no movement whatsoever. 

The arms and legs are often affected. The tongue, mouth, and pharynx can be affected which will have an effect on  speech, eating and swallowing,  and breathing.

The atypical muscle movements often result in associated problems such as contractures, hips being dislocated, scoliosis, and joint deformities.

Spastic Cerebral Palsy is then described in combination with the topography that describes which limbs are affected, such as

  • spastic diplegia,

  • spastic hemiplegia,

  • and spastic quadriplegia.


Ataxic Cerebral Palsy affects the coordination of voluntary movements, and so balance and posture are affected.

People with ataxia often walk with a very wide base or they will fall over. Their walking rhythm can be irregular.

People with ataxia often experience problems with the control of eye movements, and can have problems with visual perception such as perceiving depth. 

Ataxia affects the coordination of fine movements such as pointing, writing, and eye-hand coordination.

Ataxia also affects speech because the coordination of all the movements required for speech is a problem, and speech is really fast and requires a huge amount of coordination.

Feeding and swallowing can be affected by poorly coordinated movements.



One of the main characteristics of extra-pyramidal CP is involuntary movements. These involuntary movements are not the same as voluntary movements (e.g. reaching for a ball; licking one's lips). The involuntary movements can be slow or fast, often repetitive, and sometimes rhythmic. They can be writhing, large, small, jerky, smooth, and can be seen in the body as well as in the mouth.

We also see 'intention tremors' which occur when the person is attempting to carry out planned movements such as reaching for something. 

Stress, poor health, and even thinking about moving, can  worsen the involuntary movements.

It is rare to observe involuntary movements when the person is sleeping.

These involuntary movements interfere with voluntary movements.

Athetoid Cerebral Palsy affects the movements of the arms and legs as well as the feet and hands, whereas dyskinesia affects mainly the trunk so posture is often affected. Athetosis and dyskinesia can be evident in the face and mouth.

Involuntary movements have also been further analysed into various types:

  • Athetosis is characterised by slow, involuntary, convoluted, writhing movements of the fingers, hands, toes, and feet and in some cases, arms, legs, neck and tongue

  • Chorea  is characterised  by jerky involuntary movements affecting especially the shoulders, hips, and face.

  • Choreoathetoid is the occurrence of involuntary movements in a combination of chorea (irregular migrating contractions) and athetosis (twisting and writhing).

  • Dystonia  are involuntary movements accompanied by a sustained posture that is created by markedly abnormal movement


Many children are born with a mixed CP where BOTH the pyramidal and extra-pyramidal tracts are affected.  The most common form of mixed CP involves spasticity and athetosis.



Speech is the production of sounds; language is understanding and expressing ideas using words and sentences. People with CP often experience speech and/or language problems.




When a person presents with impairments of speech production that are a direct result of damage to the neurological system, we refer to the speech as being "dysarthric". 

  • Dysarthria is a broad term that encompasses many different types. The classic definition of dysarthria is a group of speech disorders  (i.e. dysarthria is not one type of problem but a group of different problems) that is caused by neurological damage in the brain and/or the tracts that lead from the brain to the muscles. Depending on the type of neurological damage, the entire speech system is affected to different degrees and in different ways: respiration, voicing, resonance, articulation and prosody (rhythm). 'Anarthria' refers to the complete inability to produce speech due to neurological damage.

  • The speech of children with cerebral palsy is not to be compared to the speech of people who have acquired speech problems associated with neurological damage as adults. Children with CP have not acquired speech, and so the actual acquisition of speech is affected.



Often, the problems with the trunk and spine and the under-development and impaired functioning of the abdominal and spinal muscles results in poor ribcage and lung development. The lungs may be small, and the rib cage can remain high. Sometimes the ribs protrude; sometimes one can see a little pigeon chest; the breast bone can protrude or be sunken in . The workings of the muscles of the trunk, including those between the ribs, the diaphragm, the spinal muscles that hold us upright, and the abdominal muscles that help to control breathing, can be affected. These structural problems, as well as the poor control over the muscles involved in breathing and in special breathing for speech, can result in a number of speech difficulties, such as:

  • not enough breath  or poor control over the forward flow of breath out of the lungs to be able to say a whole word, a whole phrase or a whole sentence

  • not enough breath control to produce speech at all

  • talking on residual air

  • not enough air to produce voicing



The control over the muscles in the larynx and the muscles that hold the larynx in the neck can be affected. Voice of people with CP can be affected such as:

  • Voice can be too soft, too loud, or there can be poor control over loudness

  • Voice can be high pitched, too low pitched, or can fluctuate

  • Voice can sound strained or strangled

  • Sometimes people with CP cannot produce voicing at all

  • Voice can be gurgly or breathy


The muscles of the pharynx and palate  (where the mouth joins the throat) control whether air is to pass through the mouth or the nose when speaking.  The movements of this "velo-pharyngeal" system are  extremely complex, fast, and require huge coordination. This control is very difficult for people with CP, and often their speech sounds hypo- or hyper-nasal. Much of the time, air escapes and rushes through the nose in-between sounds.



The articulation of vowels and consonants depends on the rapid coordinated movement of many muscle groups, especially the tongue, lips, and jaw. These movements are rapid, extremely small, and exceptionally complex. The control over the movements required for the articulation of sounds is affected in most people who have dysarthria. They can have problems such as:

  • Inability or limited ability  to close the lips resulting in poor production of sounds such as /b/, /p/ and /m/

  • Inability or limited ability to raise the tip of the tongue resulting in distorted production of sounds such as /t/, /d/ , /n/, /l/

  • Inability or poor ability to control the tongue  and jaw movements to produce vowels

  • Inability of poor ability to move from one sound to another so the speech sounds slurred


It is estimated that 20% of children with CP experience very severe problems with intelligibility (i.e. how much we can understand a person's speech).  The reason for the poor intelligibility is that the control of the movements required for speech production is  very challenging. In addition, we have not, to date, developed very effective therapy strategies, and it is very difficult to change a physiological problem. We work on two strategies: (1) to help the person to produce the best speech possible, and (2) to compensate for the persistent problems. Some people benefit enormously from AAC (Alternative and/or augmentative communication).



There is tremendous controversy about why so many children with CP experience difficulties with the development of language.  Firstly, we have very, very little research that tells us about language development in children with CP. Secondly, the group of children who are diagnosed as presenting with CP is very mixed - there are so many causes of CP, many different ways in which CP presents, and  many different ways in which children with CP are treated medically.  It makes comparing the children virtually impossible.  So conducting research on the language development of children with CP is so difficult to do. There is no doubt that, for many children with CP, the language areas of the brain are damaged which results in language learning problems.


BUT, complicating things, language development is very, very tightly connected to environmental exposure. Many children with CP come from contexts in which the exposure to communication is extremely limited. Other children with CP  may experience environmental deprivation simply because of their limited opportunities to explore the world. Some children have limited opportunities to learn because they don't get the opportunities to interact with others. Some children do not learn to negotiate, argue, debate, joke and so on simply because they are unable to speak clearly and have few opportunities to develop these skills.


Language is also tightly connected to intellectual development. It is well known that many children with CP, because of the extent of brain damage, present with intellectual disabilities. Although it is very difficult to test the cognition of children with CP, there is research that tells us that about 45% of children with CP are intellectually disabled. Impaired or limited cognitive skill results in difficulties learning language.

It is also really important to remember that children with CP can present with language difficulties that have nothing to do with CP. If, for example, there is a family history of language and/or learning disabilities, then a child with CP may have problems because of a genetic inheritance of a language/learning disorder.


Sometimes, children with CP have hearing losses. The hearing loss may be associated with the same cause of the brain damage, but sometimes the hearing loss has nothing to do with the brain damage. In any event, learning speech and language for children with CP and a hearing loss can be very challenging.




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