Cerebral Palsy and Visual Impairment in Children: Experience of Collaborative Practice in Scotland
Chapter 2 by Heather McLean
A more detailed look at Cerebral Palsy
The following is intended to provide an introduction to cerebral palsy and is written from a Bobath perspective.
Cerebral palsy (CP) is the most common physical disability in childhood. The incidence ranges from 2 to 2.6 per 1000 live births in industrialised countries. (Hagberg, Hagberg, Olow, & van Wendt, 1996)
Definition: Cerebral palsy is defined as a permanent, though not unchanging disorder of posture and movement, due to a non-progressive lesion to the immature brain. (Brett, 1991)
Although this definition describes cerebral palsy, it only provides a brief outline of the disorder, and the impairments that result are only explained in terms of movement. There is much more that needs to be understood about this diagnosis:
- the impairment of movement that the child presents with; and
- the associated impairments that occur concurrently as a result of the brain damage, eg: visual impairment, hearing impairment, learning difficulties and sensory processing impairment
All of these impairments may interfere with the childs ability to move, explore and interact with the environment in terms of play, self-care, dressing, eating and drinking, communication and mobility. The abilities and disabilities of each child (I will use he/his/him when talking about a child as there are more boys than girls affected) will be unique to him, which highlights the need for careful assessment of the childs skills. The complexity of each child will also be unique and emphasises the importance of the need for teamwork, with sharing of knowledge between the child, family/carers and all professionals involved, to gain as clear a picture as possible of the childs needs and wishes in order to direct services appropriately. This comprehensive assessment and ongoing intervention will help to maintain the childs functional skills at as high a level as possible into adulthood. For some children with severe physical impairment this focus may be one of prevention of development of tight muscles with loss of joint movement (contractures), and prevention of development of permanent joint structure and soft tissue structure changes which result in abnormal joint position (deformity). These changes can affect the childs level of ability, both of his mobility and potential to access the environment. It is important to understand the possible future development of these contractures and deformities, which can reduce the functional possibilities for the child. The following descriptions of the types of motor impairments will help to provide a picture of how the children move and the potential for them to develop patterns of movement or changes in their muscles and other soft tissues, which can be detrimental to functional skills. However, it will also help to highlight that it is possible to help the child to learn to move in a more normal way, therefore reducing the risk of development of poor patterns.
Current causes (aetiology) of cerebral palsy
Many children with cerebral palsy present with a number of the above listed impairments. In more recent years there has been an increased survival rate of infants who are born prematurely. The time when the damage occurs in the brain is the key factor. This has an impact on the extent of the brain damage; there are particular times during the development of the foetus when the brain is vulnerable. From clinical experience and a review of the literature there appear to be differences in the presentation of infants who are born prematurely or born at term. These are briefly outlined below as they can present with a recognisable picture that is relevant to their responses to the learning environment.
- In general the childs postural tone is such that it is low around his trunk (proximally) and higher in his limbs (distally).
- The increased incidence of cerebral visual impairment.
- These children often have difficulties being able to self soothe.
- The child often has difficulties learning to filter only the pertinent sensory stimulation from the environment at one time, that is, not to be reacting to every stimulus in the environment, which results in difficulties maintaining attention to a single task.
- Severe brain damage - more likely to be greater global damage to a larger area of the brain. This can result in more of the body being affected by the motor impairment.
- Severe tone problems - disruptive of attention, learning and functional skills.
- Severe visual impairment.
- Severe management problems due to the complex nature of his movement impairment - eating, sleeping, positioning in equipment.
What are the different types of motor impairment seen in the child with cerebral palsy?
A number of classification systems have been designed to group different types of motor impairment. One reason for this is that it is important to understand how the child moves in order to identify the best means of assisting him to develop greater control of his movement. Another reason is to help predict the future difficulties the child may experience due to the movement impairment and again put in place the correct management to minimise deterioration.
In the definition referred to above there is an inherent understanding that posture and movement provide a basis for humans to carry out complex functional skills such as dressing, driving a car, writing, etc. Therefore a disorder of movement will result in impairment of function. The children we are considering in this text also have a visual impairment, so we must consider the added impact of the visual impairment on movement and vice versa.
The following words are used to describe the childs posture and movement. The terms used describe the state of the childs muscle tone, eg: high tone = Hypertonus = spasticity (the most common); low tone = hypotonia; changes in tone between high and low = fluctuating tone = Athetosis.
Postural tone is used to describe the process by which there is an increased activity level in the muscles, which we need to make use of to enable us to stand upright and move our limbs against gravity, to achieve independent movement (Shumway-Cook & Woollacott, 1995). For example, our postural tone will be lower when we are well supported in a comfy chair and relaxing and will be higher if we attempt to walk across a tightrope; to begin with the muscles will have to become more active in order to support us in standing, and then the effort and concentration of the task will cause us to increase the activity in our muscles further, in an attempt to reduce the risk of falling off the tightrope.
Impact of EFFORT: within all of the classifications of the motor impairment it is essential that we consider the impact of the childs own effort on his movement impairment. It is imperative that we consider not only the childs physical effort but the effort of thinking, speaking, breathing, looking and the effort of anticipating a movement. Effort results in an increase in the childs level of postural tone which in turn can reduce possibilities for movement, and therefore reduce the childs functional possibilities - a vicious circle builds.
In all of the following examples a general picture is presented. It is important to point out that each child will present differently, and careful assessment by a paediatrician, physiotherapist, occupational therapist and speech and language therapist is necessary to clearly identify the childs movement patterns, functional abilities and identify areas of concern.
Spasticity (Hypertonia): characteristically the child has stiff muscles, which are weak and have limited range of movement, resulting in limitation of functional abilities. The stiffness can affect all muscles of the body, depending on where the damage has occurred in the brain. Spasticity in the muscles of the lower limbs can cause the legs to be held tightly, turning inwards with the child standing up on his toes. As the child attempts to walk, the legs are pulled together more under the effort of movement, and he will tend to trip over his toes, resulting in instability and loss of balance. Spasticity in the muscles of the eyes can cause the eyes to be pulled in one direction away from the midline position our eyes naturally adopt, although not a common cause of squint. Spasticity in the muscles of the throat and the voice box can cause the child to talk with a very strained voice. Spasticity in the muscles of the shoulders and upper limbs can result in the arms being held bent, with the hands held up towards the shoulders and away from the middle of the childs body. This obviously interferes with the childs ability to bring the hands together in the middle for play and manipulation of objects. The hands themselves can be held tightly fisted, making it difficult for the child to release his hands to be able to reach and grasp a toy. The stiff muscles can also become weak as they are not used and exercised normally, and the child then finds it difficult to sustain a position or continue a sequence of movement for long periods of time.
The child can be seen to put in a considerable amount of effort to achieve a relatively small movement. With this effort the stiff muscles become stiffer and the movement limitation becomes greater. This is called an associated reaction. This can result in the childs balance being further compromised as one side of the body becomes stiffer. The child is pulled to one side and there is less opportunity for the child to make use of this part of his body to make a movement to improve his balance and adjust to changes in position. For example, the child cannot reach out to the side with his arm, as he is pulled to the side and he ends up falling as the arm is pulled in towards the trunk.
Spasticity can be classified further into different degrees of stiffness of the muscles; mild, moderate and severe. The stiffness and limited movement that we characteristically see in the child with spasticity is the result of the brain telling too many muscles to work at once and the muscles working too hard. There is a failure of the brain to "calm down" this activity.
The child with severe spasticity will present with extremely limited movement and his movements can be very predictable as there are little variety of movement patterns available. The childs posture could be described as having too much stability and insufficient mobility to allow movement. This child can appear to be stuck in one position with extremely limited ability to move his body or limbs out of the position. Careful postural management and change of position is required to assist this child in maintaining comfort and maintaining the movement he has to ease daily management. The child with moderate spasticity will present with greater movement possibility than the child with severe spasticity. Greater mobility at the joints allows a greater variety of movement patterns, although the child will still present as having limited variety of movement patterns. For example, he will always reach out in the same way perhaps with the elbow, wrist and hand slightly bent, but the fingers will be able to open more to allow the possibility of grasping an object and maybe even moving it around between his hands.
This is the group of children who are most likely to have a visual impairment, which may take the form of only impaired movement of the eyes, visual field loss, or the more complex picture of cerebral visual impairment.
Athetosis: this child presents with continuous, unwanted movements, which are outwith the childs control. Pure athetosis is rare and a more common picture is seen of a child with a combination of spasticity and athetosis, or hypotonia and athetosis. With this type of cerebral palsy the distribution is usually that the total body is involved (quadriplegia). However some children do present with only one side affected (hemiplegia) although this is extremely rare. Again it is important to highlight that the involuntary movements are influenced by the childs level of effort, both physical and even thinking about or anticipating a movement/action including speech and looking.
There are different types of involuntary movements that can be described, the most common being:
- writhing type movements, sometimes described as mobile spasms;
- spasms that result in an excessive and extreme movement (dystonic spasms).
With both of these types of movement the impact on the childs posture is such that it is extremely difficult for him to maintain any stability in his body. This is particularly clear to see when he attempts to move his limbs, eg: the child may try to reach forward to touch an object, and his hand will fly backwards in the opposite direction to where he wants it to be. This childs movements are very much influenced by the position of his head. For example, the child may lift his head upwards (extension) and his whole body will straighten, including his arms. The child is using unnecessary muscles, that is, cannot isolate individual movements. This clearly has an impact on the childs potential to bring his hands towards his eyes for visual exploration, and it is important to find positions or prepare the child for head movement to increase the potential for the child to experience hand to mouth exploration.
In the child with the dystonic type spasms, the limb can then become stuck in this position for a few seconds before the forward movement of the arm can occur. The child understandably often becomes distressed and frustrated that his efforts to reach out are unsuccessful. Often with these children the spasms can occur very asymmetrically in their body, that is, child turns his eyes to one side and his head is then pulled to that side, with the arm and the leg of the same side stiffly extending and further reducing the childs stability in a position. It is important with this child to observe at what point the position of the eyes influences the rest of the body, and work carefully around that range. For example perhaps if a toy is held only slightly off centre the child will be able to visually locate it and begin to be able to reach for the toy. However if the toy is taken too far to the side to encourage greater tracking or scanning skills then the dystonic pattern will be triggered and the whole posture of the child is disrupted. On the other hand a child who has better peripheral vision than central vision will choose to look to the side to explore his world; on looking in this way the child will become more asymmetrical in his posture, reducing his stability and limiting the development of more normal patterns of movement which are important in preventing the development of contractures and deformities. But the lead with this child may need to be his vision, that is, starting where the child is choosing to look, and using his vision to try and influence his posture towards a position of greater symmetry and stability, which may in turn enhance the possibilities for the use of his arms to reach out. Again, this highlights the need for careful teamwork to identify the childs thresholds, and gradually try to extend these without detriment to his visual development or postural development.
Hypotonia (low tone): characteristically this child has flopp muscles, which also results in difficulties in moving his limbs/body. It is unusual for a child with cerebral palsy to have pure hypotonia. It is more common for hypotonia to occur along with hypertonia in other parts of the body. The childs joints can appear to have excessive movement and can tend to be unstable, as the muscles around the joint are too lax and do not support a stable position of the joint. This child can also lack strength in his muscles, again due to under-use, and as with the child with spasticity he requires to make excessive effort to achieve a movement.
Often this child has a high stimulation threshold and may have a low state of alertness; this child may appear uninterested in his surroundings as it is so difficult for him to gain sufficient activity in his muscles to make a movement, he often needs longer to respond. This child often requires assistance with head control, particularly in upright positions; side-lying may be good for this child as it helps to bring his hands together in the midline, and enables him to see his hands.
Ataxia: the type of movement impairment seen is that the child finds it difficult to control the direction of the movement of his limbs and to grade the movement. This will be seen as the child having difficulty holding a steady posture of the whole body or maintaining steadiness in a limb or of his head. For example, when the child reaches for an object, his arm might appear to be jerky in its movements, which may worsen as the childs hand comes closer to the target (intention tremor). Another example would be that the child has difficulties maintaining his balance when walking, as the movements of the legs are ungraded and jerky. In addition the child may not be able to make use of adjustments to his body, head or arm posture, in order to maintain his balance. For example, the child is not able to produce controlled and co-ordinated movement of his arms away from his body when he is falling over. Instead an excessively large movement may be produced in the wrong direction, which only serves to knock him further off balance. This is because the childs body cannot react quickly enough to demands on his balance as he moves around in the environment, negotiating obstacles or changes in floor surface.
As with hypotonia, it is rare that a child with cerebral palsy would have pure ataxia. There are many syndromes that have ataxia as one of their symptoms. Ataxia associated with cerebral palsy is usually seen in combination with spasticity, athetosis or both. Ataxia is most likely to be caused by damage to a specific part of the brain that is responsible for the co-ordination of movement, the cerebellum, which is situated below the two cerebral hemispheres at the back of the brain.
As a result of the picture described above, many of these children are fearful of movement as they know they can easily lose their balance and fall over. Therefore they tend to move slowly. However, there are also those children who try to compensate for their lack of balance by constantly being on the move, and find it difficult to maintain stillness. These children can have difficulty with precise control of their finger movement, making activities that involve selective hand movements difficult for them, eg; tying laces, writing. They may have a type of uncontrolled movement of the eyes (nystagmus), or they may require to make use of their eyes to fix on an object in the environment to help them to maintain their balance (optical righting). This is seen when the child finds it difficult to bring his eyes down to look in his lower visual field, eg: to untie his shoelaces, or look down towards the table surface when participating in a table-top activity.
Due to the site of the damage that occurs in this type of cerebral palsy, children may present with difficulties appreciating and organising the relationship in distance of one object to another (spatial relationships). For example, they have difficulty in perceiving the relative distances between objects or between themselves and objects, and this also results in misjudging the amount of movement required to reach or avoid an object.
Distribution of tone
In all types of cerebral palsy there can be certain parts of the body affected. The following terms are used to describe the distribution of the motor impairment in the body:
- Diplegia - all four limbs affected but lower limbs more affected than upper limbs.
- Hemiplegia - one side of the body affected, arm and leg may be equally or unequally affected.
- Quadriplegia - all four limbs affected but upper limbs more affected than lower limbs, and the child is not able to use his upper limbs efficiently to support himself when moving from one position to another.
"Prognosis" of cerebral palsy
Although the lesion in the brain is permanent and unchanging, the child does change in his functional abilities due to the influence of sensation and movement on development. There may be changes to the soft tissues of the body, that is, the muscles and tendons, which can lose range of movement and strength. This is particularly seen when the child takes a growth spurt when the bones are growing faster than the muscles and tendons, and the child appears to lose abilities and may seem to deteriorate. There is a danger that a child can develop contractures and deformities due to the nature of the changes in the soft tissues. There are external factors, which also influence change, eg; changing demands on the child like starting school, where more time may be spent in one position, and the nature of the daily routine may require more precise hand function and increased concentration. These both require effort, which will influence the degree of stiffness or involuntary movements in the childs body. There is also some evidence to support the fact that adolescent children can reach a stage of burnou. This can be due to years of effort to maintain physical skills and a combination of increased weight, increased height, difficulty in achieving a full range of movement of muscles and a reaction against frequent therapy. This may be a time in their life when they decide to make different choices about their main means of mobility, for example, to make use of a wheelchair for longer distances rather than continuing with independent walking.
Listening to the children and families
The issues raised above highlight the importance of maintaining ongoing discussion with the young person regarding his wishes, concerns and the areas of skill that he wishes to work on. It is important to emphasise here the importance of listening to families and the young person’s own assessment of his abilities and situation within the various environments of home, school and the community. It is important also to consider that the family may experience a feeling of burnou following years of providing appropriate therapy and support. This again reinforces the need for teamwork.
Impact of cerebral palsy on the childs daily activities (functional skills)
How does the impairment of movement and sensation impact on the childs general development and functional abilities - more specifically on visual skills?
Impairment of movement
As we observe a small baby from the first days of dependence on his parents for care, to the baby reaching out for the first time to hold his bottle, or looking at his parents’ faces and responding with a smile, we can be unaware of the complex process that takes place within the childs brain. In simple terms this is a process of receiving information, organising information and orchestrating the necessary response of moving, looking, touching, smelling, thinking, etc, to then enable the child to reach out and grasp the toy that he is looking at, for example. To help explain this process and understand the impairment of movement seen in the child with cerebral palsy, we will briefly examine how a child with an intact central nervous system develops normal movement and therefore the ability to reach out and grasp a to.
Example of child developing normally (refer to Figure 2.2)
A baby around three months begins to practise reaching for a toy when lying on his back. This happens at this stage because the baby has developed enough control and strength in the muscles around the back and tummy to be able to hold a stable position of lying on his back. The baby has also developed enough control and strength in his shoulders and arms to be able to hold his arms out. The baby even has the ability to stay in this position without falling to the side as he reaches out with his arms. The parent tends to use visually interesting and noisy toys that are easy for the baby to hold, as they know that the baby responds to these most easily. The baby is beginning to look at his own hand movements as he approaches the toy, to assist in successfully grasping it. The baby may even look at his hands and then look at the toy as if trying to work out "How do I get my hands to touch that thing?" The baby is therefore beginning to learn about space and distance both as he moves his arms through space but also as he moves his eyes towards and away from the toy. This is when we see the constant interplay between the sensory system (touch and vision) and motor system (movement of body and its parts including eyes); in simple terms, in this instance, the parts of the brain controlling vision and the sense of touch send information to the parts of the brain controlling movement, resulting in the babs visual and touch exploration driving the desire to reach and grasp and practise this movement until the baby achieves greater control and accuracy. The brain remembers the feeling of this movement (proprioception) so that the next time he reaches for a toy, the activity of reaching is immediately more accurate and this process of refinement continues throughout life.
This act of looking, reaching and touching also helps to promote use of the head and eyes in midline, which is important both for efficient use of the eyes to scan our environment, but also for balance of our whole body as we move around our environment. At the same time, the strength and control of the muscles of the back, tummy and shoulders also helps to maintain the position of the head such that the sensory system and the motor systems are working in harmony. This is the beginning of head control where the child can move his head while still lying on his back. This developing head control in a supported position on the floor is important to gain movement of the eyes independent of the head. Head control is later important for the child developing the ability to hold his head in the middle when sitting/standing and walking, and in providing the correct position for the eyes to take in the visual information.
If we carefully observe the eye movements of a newborn, we would see that each eye can move independently of the other. For example, the left eye may be turned outward and the right eye may be turned upwards. At this stage this is a completely normal occurrence, although it can be disconcerting to the observer! These random eye movements gradually become more organised until the child develops more graded control of the eye movements together in unison (binocular vision) to assist in gaining a clear picture of the toy and the three-dimensional world the baby interacts with.
The baby is also developing the skill of being able to look at a lot of information at one time and to be able to make sense of what is seen, to pick out the relevant information and carry out an action to respond to the busy visual environment. For example, the parent may present several toys and the baby will choose to reach for only one. The parent also plays an important role in orchestrating the environment for the child by choosing toys which interest the baby by varying colours, sounds and textures. The parent will also position toys carefully so the baby can reach them, or may even place the toy into the babs hand if he is becoming frustrated when he does not succeed with his own efforts.
Sensory Systems / Motor Systems
Analysis of Sensory-Motor information
During motor development, vision provides important feedback to the vestibular and proprioceptive systems; consequently motor development is impeded in cases of early blindness. Our results provide evidence that from the first months onwards blindness does indeed affect early motor development. It is an established fact that sensory systems have a wide range of plasticity and, to a certain degree, early intervention may help to compensate for the lack of vision. (Prechtl, Cioni, Einspieler, Bos & Ferrari, 2001)
Example of developing child with cerebral palsy developing
As diagnosis is almost always not made at the time of birth, diagnosis may not be made until the child is over one year. The type of movement impairment the child demonstrates becomes more apparent over time with the childs efforts to move and to co-ordinate movement with looking and doing. We will use an example of an 8 month old child who has stiffness of the muscles affecting his whole body; his left side is more involved than the right (spastic quadriplegia).
The muscles around the tummy and the back are stiff. It is difficult for the muscles to work together efficiently to enable the child to maintain balance when lying on his back on the floor. The muscles around the pelvis and hips could be stiff, causing the childs legs to be bent up slightly at the hips and pulled together with the knees turning inwards. This pattern of movement in the legs interferes with the childs ability to use his legs for balance; the childs legs may be pulled up off the floor resulting in the child balancing on his bottom and pushing his weight upwards towards the trunk and head. As the left side is more involved, the muscles of this side will probably be stiffer and the leg may bend up more, and the whole side of the body may be tight, which will tend to force the childs body over onto that side. This may be seen as the child always rolling over the left side and perhaps predominantly reaching with the right arm as this is the looser arm and the left arm may become caught under his left side as he rolls.
The muscles around the shoulders are likely to be stiff, therefore the child has difficulty reaching his arms away from his body to reach the toy, particularly with the left side which is stiffer. As a result, as this child tries to reach forward, he becomes stiffer on the left side, with the effort of reaching, and may end up falling to the left as that side of the body becomes tighter, pulling the muscles at the side of his body causing him to be pulled over the left side. The lower part of the arm and hand will also be stiff, with the child achieving better opening of the right hand, as this is the side less affected. This stiffness in the arms will limit the distance the child can reach for the toy, and may limit the movement of the individual fingers to explore and move the toy around in his hands. As the child reaches with the right, the left arm and hand will become tighter and the left arm may be pulled in towards the chest, and the opportunity to play with both hands in the middle, which is necessary for greater exploration and manipulation of the toy, is interrupted. This may interfere with the childs development of use of hands in the sitting position.
This tightness on the left also influences the position of the head, also pulling the head down on the left, therefore taking the eyes away from the middle. Equally the child may try very hard to maintain the head and eyes in the middle to see the toy presented, and this also causes the rest of the body to stiffen with effort, again causing him to be unstable on the floor. Clearly a vicious cycle builds:
Child attempts to reach -> childs limbs become stiffer -> head, eyes, body and arms are pulled away from the toy -> child tries harder to reach -> childs limbs become stiffer ? the possibility to look, reach, grasp and explore lessens -> child becomes frustrated!
As this pattern of limited reach develops the potential for the child to practise looking at his hands may diminish. The childs hands are held closer to the chest so the child is forced to bring the head and eyes down to look at his hands. This movement brings the neck into a more bent position, which can influence a more bent position throughout the whole body, for example, in the tummy and the hips, which further reduces the childs stability in this position of lying on the floor. This reduces the opportunity to gain balance skills. As the head is repeatedly taken into this position there is less opportunity for the child to develop head control, and this may result in poor head control when the child is later learning to sit.
Children with severe visual impairment are able to explore their environment and objects/people within it as they have an intact motor system. However the acquisition of movement skills is delayed in these children due to "the poverty of information from the visual system to pass information (feedback) to the proprioceptive and vestibular systems to drive their movements". (Prechtl et al, 2001)
This reference and the example above highlight the close relationship between all areas of skill development, particularly highlighting visual and movement skills. Considering the child with cerebral palsy who has both movement impairment and a visual impairment presents the challenge of a complex inter-relationship of the impairments affecting each other. It is important to consider two aspects of movement here:
- That we do not make the challenge of a movement too great for the child or do not wait too long for the childs own movement. This may cause the child to use excessive effort and actually serve to further reduce his movement potential and increase his frustration. Or we may be making too great a demand on the childs visual skills as he may not be able to see into the range of movement that we are demanding from him. Rather we should start where the child is at, from both the motor and the visual aspect, and gradually build on his potential. By assisting the child to achieve more normal movement patterns, we can assist in the development of visual skills, by providing the movement possibility to encourage the childs motivation for exploration to stimulate visual skills. For example, by making movements of the upper limbs easier to achieve, the child may be able to begin to bring his hands towards his face and eyes to make use of the vision he has to visually explore the object held.
- That we do not make the challenge of movement too limiting so that the child is not encouraged to move away from his stereotypical patterns. This may cause the child to repeat the same movements over and over again and not learn new patterns of movement. This can lead to lack of movement and increasing risk of contractures and deformity. Clearly it is important to work around the childs thresholds of both vision and movement, but there is potential for change and development and we need to grade this carefully. Perhaps the key issue comes up again of teamworking to provide a graded sensory environment and movement experience for the child. This will help to develop his movement potential and may expand his experience of his environment.
The emphasis of impairment may change from one situation to another and even from one moment to another. Therefore an extremely complex picture is presented which demands careful assessment from anyone who interacts with the child. No one professional can have all the answers, and we must, as professionals, place the child and the carers at the centre of our considerations. How can we meet this challenge to address both the movement needs and the visual needs of these children, and consider other additional impairments?
At the time of diagnosis it may also be clear that the child has associated impairments dependent on the site of the lesion, which will impact on his development of functional abilities: seizures/epilepsy, visual impairment, hearing impairment, perceptual problems, learning difficulties, tactile processing and communication.
These impairments may not be clear at the time of diagnosis and may become apparent as the child develops. In either case, all of the above impairments should continue to be assessed for until they are ruled out. In labelling these areas as associated impairments there is concern that they are somehow then considered to be of secondary importance to the motor impairment. Rather we would like to highlight the strong interplay between the sensory and motor system, and the importance of gaining a balance between all areas of impairment to gain the best outcome for the child. This again highlights the importance of teamwork.
The childs limited movements restrict the freedom to explore and interact with the environment. In turn, decreased interactions with the environment limit opportunities to derive sensory experiences from the interaction. (Blanche & Burke, 1991)
Impairment of sensation - sensory processing impairment
Our understanding of how the body learns to carry out movement is progressing with new concepts developing. There is a greater understanding that the sensory systems of the central nervous system have a much larger role than was previously appreciated. This has led therapists to take much greater consideration of the sensory processing impairments of children with cerebral palsy. As a result we must try to combine therapy to address the motor impairment with therapy to address the sensory processing impairment. An example of this may be a child with a classification of moderate spastic diplegia who is having difficulties making progress with his standing and walking. On assessment it appears that not only does the child have a motor impairment due to the presence of spasticity, which causes the child to walk with his hips and knees always slightly bent and walk up on his toes, but the child also has a sensory impairment. This sensory impairment is seen as the child being unable to identify where he is being touched on his lower legs (poor tactile localisation) and being unable to organise the movement of his legs without looking at his legs (poor proprioceptive awareness). So the question must be asked, "can the child feel his legs"? before we even consider how he is moving his legs. In this occasion it would be helpful to start with activities that help the child to gain greater sensory information about the position of his legs, by perhaps tapping his legs, or brushing different textures over his legs, or assisting him to stamp his feet down onto the floor.
What is a sensory processing disorder?
There are many examples of children with cerebral palsy who demonstrate difficulty with processing information received from the sense of touch, from the sense of position of their limbs/body (proprioception) and from their balance sense (vestibular).
A child with cerebral palsy who has difficulty processing information received from the sense of touch may demonstrate a lack of awareness of the part of his body that is most affected by the movement disorder. For example, a child with hemiplegia can seem unaware of an abnormal position of his hand when he is leaning on the back of his hand with his wrist strongly bent towards the forearm, a position that you and I would find uncomfortable after a short period of time. Another example would be when a child with cerebral palsy places his hand into a texture that the other children in the playgroup are happy to explore and feel, eg; wet spaghetti or finger paint, and the child with cerebral palsy immediately becomes distressed, quickly withdraws his hands from the texture, turns his eyes away from looking at the texture or may even begin to gag or vomit. This would be termed hypersensitivity to tactile input. The child may demonstrate several behavioural signs that could be indicative of hypersensitivity:
- avoiding touch, toy, texture;
- child pushes back/pulls away;
- child averts eyes from the activity;
- child develops worried expression;
- increased sucking/swallowing behaviour;
- facial grimace - pulling back (e?retraction) of lips;
- increased saliva production, increased frequency of swallowing;
- gagging which may lead to vomiting;
- autonomic nervous system (ANS) changes - face flushes, breathing rate increases;
- changes in his arousal and attention levels - child can become over-aroused or under-aroused;
What can be done to help when the above signs are observed?
Firstly, it is important to identify the childs level of ability and level of sensitivity to different textures. This helps to identify the childs threshold of tolerance for a texture. This needs to be done sensitively and gradually in order to avoid an extreme reaction from the child. It is important to make use of the childs other senses to help him build his experience of different textures in a positive way.
Preparation - it may help to prepare the childs body for the experience by reducing the level of stiffness in his muscles; children with stiff limbs find it harder to discriminate objects by touch. If they feel more relaxed this can help them to gain greater tactile information as they can then move their limbs/hands/fingers more easily to gain greater information.
Grade the stimulation - when the childs threshold of tolerance has been identified it is important to work around that threshold, starting by making the activity easier and always working towards the threshold. It is necessary to work towards the threshold in order to build the childs confidence to be able to adapt to this situation.
Be inviting in your approach - it is important to allow the child to come to you and to feel he is in control at all times. We must not impose the experience on the child.
Maintain firm pressure with your hands on the child - it is important to think about how you touch and handle the child. If your hands are used lightly against the childs skin this can be worse than being tickled and only serves to produce more unwanted touch experience. Using your hands firmly gives clearer tactile information and also helps to calm the childs sensitivity to touch. Making minimal changes in the position of your hands is also useful.
Start at the least sensitive area and work towards the most sensitive area - many children with cerebral palsy have sensitive palms and it is important to avoid placing textures here first. Rather take the texture onto the back of the childs hands or even onto the back of his forearm and gradually move towards the hand area. As the child adapts to the experience he will probably begin to open his hands and then you can gradually take the texture towards the palm. However, be cautious and be observant for the signs of hypersensitivity outlined above. If they occur then move away from the palms onto the back of the hand. If you work gradually the child will generally begin to adapt each time and you will be able to get the texture more into the palm.
Use firm/hard objects to begin with - objects that are firm are easier for the child to tolerate and again help to calm his sensitive response. You can also use something hard in a softer texture, for instance a plastic Teletubby in some playdough or sand. In this example the childs hands do not have to touch the texture, but he may be able to see the texture or only part of his hand comes into contact with the texture as he is holding the firm object - this grades the amount of tactile experience and helps the child to adapt.
In all of the above it is important to work towards and around the childs threshold of tolerance to help the child to build his tolerance, and therefore help him to gain positive learning experience from a greater variety of tactile experiences.
Yet another example of a tactile processing disorder would be when a child has difficulty identifying which part of his body is being touched (poor tactile discrimination), eg; the child perceives touch to the index finger of the hand as being touch to the whole hand. This can result in difficulties with the childs control of hand movement as it is necessary to feel the parts of your hand to then be able to move the fingers efficiently. For example you may observe the child attempt to poke at an object with all fingers extended and be unable to isolate only the movement of the index finger to be straight. Another example may be when a child is unable to discriminate properties of objects by exploring the object with his hands. In this situation the child is unable to gather sufficient tactile information from the touch receptors in his hands, or is unable to process the information efficiently in the brain to draw conclusions as to, "what am I touching?". This child may therefore make use of his mouth to explore objects as he may have greater discriminatory abilities with his lips and tongue (the lips and tongue have twice as many touch receptors as the hands). Sometimes this can be interpreted by others as a delay in the childs level of development, but in some cases it could be an alternative strategy for the child to overcome the lack of tactile discrimination in his hands.
An example of poor processing of information about body position (proprioception) would be when the child with cerebral palsy, who has not moved his limbs into external space, and is limited in his movement due to the influence of postural tone and patterns, experiences a new movemen. When we change the tone and movement possibilities to enable him to achieve the movement, it may feel foreign to the child and he may not be able to perceive this new position of his limb. What does it feel like to the child? Is it frightening? Is it like moving his limb into the unknown abyss!
What causes the sensory processing impairment?
There may be a few factors which impact on this:
- Negative experiences from early days of life in the neonatal intensive care unit.
For example the child may become sensitive around the mouth and face due to the placement of a feeding
tube down his nose, which is taped to his face.
- Limitations of movement result in the child missing out on opportunities to touch and
feel his environment. For example a child with a classification of moderate spastic quadriplegia may have
hands that have been predominantly held fisted.
- with thumbs held into his palms and have had little experience of taking weight on his
hands which helps to increase the childs awareness of his hands and reduce any sensitivities. This child’s
palms may be extremely sensitive to being touched to the point where the child may find it distressing to
touch certain textures in the environment.
- There may be damage to a specific part of the brain that is responsible for interpreting sensory information from the environment. This experience, that occurs automatically, provides the developing child with information about how his body feels to him. This develops his appreciation of his body as a three-dimensional object with moving parts which are in a specific position and can move in a specific and variety of ways to allow precise control of movement to interact successfully with the environment, eg; to bring two hands together to bang one object against another to create a sound.
Why is it important to consider these issues with a child with cerebral palsy and visual impairment? What can be done to help?
When we are working with children with particularly severe visual impairment, it has been found that it is important to give the children many experiences of their environment through their other senses, perhaps most obviously through the sense of touch or the sense of movement. Therefore we need to be aware that some of the children may actually find it difficult to tolerate sensory information being received in this way, or there may be specific aspects about touch that are difficult for the child to tolerate and may even cause quite distressing hypersensitive responses. It is important therefore to choose carefully which textures the child prefers to play with. Research in the past has found that children with both spasticity and athetosis typically prefer objects which are hard and firm rather than objects that have lots of soft moveable parts like tinsel pom-poms or soft/slimy textures like playdough, wet pasta, finger paint. This is of importance for the child with a visual impairment also as these objects are difficult to distinguish apart from each other. It is also important that we carefully grade the amount, type, location on their body and duration of tactile input, to enable these children to adjust to the experience and begin to process the information and gain a positive experience. It is important that this is an aspect that is carefully assessed in each child with cerebral palsy to ensure the child remains alert and attending to his environment and therefore gaining as much positive experience from the environment as possible.
The child with cerebral palsy and visual impairment presents an extremely complex picture, which is challenging as the nature of the condition being so individual to each child. It is important to consider the close relationship of the motor impairment and the sensory impairments that the children can present and try to gain a balance in addressing these issues in all of our interventions with the children and their families.
This complex picture demands teamwork, ongoing review and identifying the correct team members at the correct time. Perhaps some key points to highlight would be:
- Careful assessment of all areas to understand the childs motor and sensory needs. Providing comprehensive functional visual assessment and assessment of functional motor skills to identify the childs abilities.
- Teamwork - we need to develop effectiveness of teamwork including involving the parents and increasing parent understanding to empower them. This includes early identification.
- Grading the environment both from a motor and a sensory viewpoint. Children cannot be forced into activities; they require their own motivation to learn and explore within an environment that makes learning possible physically, from a sensory aspect and within a functional, meaningful activity.
- Parallel processing - for many children with cerebral palsy they have difficulty combining two or more sensory modalities; identifying whether the child is integrating sound and touch or sound and vision or vision and proprioception can be difficult. We must improve our skills in this area in order to identify the childs thresholds and then pitch our intervention just around/below his threshold in order to promote learning in a graded environment. We must beware of physical burnout, shutdown and the danger of children being labelled as having behaviour problems and not identifying the root cause of those problems from a motor or sensory viewpoint.
Case Study: Jenny
A picture of Jenny as she presented on first meeting - Jenny likes to listen to sounds and has a favourite Monke toy which has a soft body and hard plastic rings which rattle together when shaken. When she hears Monke she will reach her right hand up slightly as if to find him and sometimes she will make a happy vocalisation. She appears to respond to familiar voices (her parents) demonstrating this by smiling and sometimes vocalising back.
She finds it difficult to move any part of her body and even when lying at rest she is disturbed by little pulls at her hips (spasms) that cause her whole body to curl up. This can be distressing for her and will often be accompanied by a pained expression on her face. As a result she is always held in a bundled up position in her parents arms and they find it difficult to find any position that she is happy in other than on her back. When held sitting or lying on her back she can reach out a little with her right arm but as she does so her whole body tends to become stiff either with her legs shooting out straight or her knees pulling towards her tummy. When she reaches with her right arm her left arm becomes stiffer and she is pulled over to her left side as the whole side of her body becomes stiffer. This sometimes pulls her away from the toy, making it difficult for her to achieve success, and this also takes her head and eyes away from a toy that is presented to her.
Jenny does appear to respond to movement of a person across her field of vision, especially when there is light coming from behind the person to enhance their outline. Her response is seen as a general movement of her head in the direction of the person moving. Her eyes will blink when an object is moved rapidly towards her eyes but she does not attempt to turn her head away from the object. When a moving object with no sound provided is presented to her at the side of her head or in front of her head she does not attempt to turn her eyes or head towards the object or to reach for the object. When a spotlight is used to light up her immediate environment, Jenny will blink in response to the light and at times will turn her head to the light. The light appears to help Jenny to maintain her attention to the toys presented and helps her to orient her head in the direction of the toys.
After some time holding and moving a familiar toy in her hand there are times when Jenns eye movements change. Her eyes come down away from the upward and outward position more towards the middle. Small and rapid side-to-side movements can be seen and her eyelids also close down slightly - perhaps she is trying to visually locate the object.
She is generally a contented little girl but has had periods of illness due to fits, and has had problems coping with food in her mouth and processing food through her stomach. A tube was inserted into her tummy to ease her eating difficulties and this has helped to settle her further.
Jenny is frequently placed on her back on the floor and in this position the stiffness in her limbs is clear to see; her arms are pulled in towards her chest with her elbows bent and her hands held tightly fisted. Her legs are always slightly bent with her knees pulled up and together. When lying on her back her head is often turned to her left side and her left eye area then comes into contact with the supporting surface of the pillow. Her head can remain there for several minutes and she can become slightly distressed by this. Relief is seen in her face, and her whole body is seen to relax slightly when her head is repositioned back to the midline or if she is given support over her chest and around her trunk.
Her parents wished for ideas to help her to be able to play more and make more use of her arms and for her to be more comfortable when being positioned in lying or sitting.
How can we help her to move her arms more easily to reach out into her environment? Preparation
Holding her in side-lying with her hips straighter helps her to accommodate to the position of her hips becoming straighter. She is held comfortably against her parent for security and close contact. As her Dad feels that she becomes looser at her hips, he gradually takes her forward onto her tummy bringing her hips into a more straightened position.
Once on her tummy her Dad maintains close contact for comfort and security. He moves his hands only minimally to allow Jenny to adapt to the new position and so she does not have to process too much information at once. His right hand over her bottom helps to maintain her hips straighter, but if he feels she is pulling at her hips he allows this movement and then gradually gives pressure down over her hips to help her gain straighter hips again. If she can be comfortable in this position, the straightness in her spine and the more relaxed posture will provide a better background for her then to make use of her arms.
As can be seen in the photograph her arms are falling loosely over her Dads knee, indicating that they are less stiff and it will therefore be more possible for her to use them to reach out into her environment.
Positioning - the use of a wedge - this brings her head and trunk slightly above her hips so she does not have to work too hard to bring her head forward and her shoulders forward to lead her arm movement to then reach out into the environment. As outlined previously, if she uses too much effort her tone will only further increase and then her arms will become stiffer, making her reach out more difficult. If she continues to use too much effort, the rest of her body will become more stiff and the vicious circle builds. The neck cushion helps her to maintain her head in the midline and enhance the use of any vision she may have.
In side-lying - the use of V’ cushions brings her lower limbs into a more aligned position. This also helps to maintain her in the side-lying position, which is a good position to bring her two hands together in the midline to allow her to feel her hands touching each other, her hand touching the surface or toys placed on the surface.
What environment can we create that will provide her with the motivation to reach out and will meet her movement possibilities?
Jenny had greater movement possibility with her right arm therefore the toys are placed at her right side. In this picture she has just reached up and out to the right.
Jenny prefers hard objects, so here a choice of either hard or soft was given to see if she would be encouraged to move her left arm to her preferred toy. Her head also has turned to the left to find her preferred toy.
The use of the tent creates an environment where she can feel boundaries around her, giving her security when she reaches out.
The use of lighting can help her to orient her visually to the toy, orient her body towards a more symmetrical position, and help her orient her head towards the midline/away from the side she constantly pulls to.
Selecting/creating toys, which meet her specific interests - pick up on what she responds to - firm, sound, bells.
In this picture we can see she has successfully brought her right arm up off the cushion to hi the bells, creating a sound as she sends them flying. Again a hard, firm texture similar to that of her favourite Monke toy was created. This toy is good as she receives the reward of a sound when she touches it, but also her skills are being developed to reach out and explore as the toy hangs silently between hits.
Children with cerebral palsy present a complex picture. Not only do they have a motor impairment but many of the children we now see present with a mixture of sensory impairments of which a visual impairment may be only one. Although the definition of cerebral palsy describes the condition as one of motor impairment, the increasing understanding of how the motor system of the human body is influenced by the sensory systems is making greater demands on our expertise as clinicians to identify the specific nature of the child’s impairment and the impact on functional abilities. This necessitates a greater awareness of teamworking and a need to always consider that compromise may be necessary in order that we make the best therapeutic and educational provision possible for the child.
Thorough assessment by several professionals may be necessary to best identify a plan of intervention for the child and the family, remembering not to overload the child or the family.
Open and honest communication between professionals is also necessary to establish aims of intervention and a common language, which we can work with to maintain excellence of service to the child and the family.
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