This article will give you a structure on which to base a developmental history, review usual milestones, and give an understanding of structured developmental assessment. The aim is that you will be able to identify key warning signals and know the practical relevance to your current practice.
The fundamental difference between paediatric and adult neurology is that children continue to grow and develop. This process continues into young adulthood beyond what is conventionally regarded as the “cut off” for paediatric services.
For many paediatricians, let alone adult physicians, developmental assessment is an area where they express a lack of competence and confidence. Remembering that your own child was walking on their first birthday and could just about put on his own shoes when he started at nursery does not qualify you as a confident assessor of child development!
Basic concepts in child development
Developmental progress is about gaining functional skills which will over time allow a child to become independent of its adult caregivers.
Developmental skills are achieved sequentially following a remarkably consistent pattern, there is however a wide normal range.
Development is considered within four fields in the young child:
1. Gross Motor
2. Vision and Fine Motor
3. Hearing, Speech and Language
4. Social, Emotional and Behavioural
Hearing and vision are grouped with the skills which are most contingent on them. Important consideration must be given to these areas as impairments can have important consequences for other areas of development and early intervention is crucial.
Difficulties within one developmental field can lead to delays in the acquisition of skills in another field. The child with a significant hearing impairment may be late to speak, this limits his play opportunities with other children and consequently his social development.
Development should always be a process of progression, any suggestion of developmental standstill or loss of previously attained skills is a cause of significant concern.
The abnormal persistence of immature aspects of behaviour can also be a cause for concern eg mouthing approach to toys beyond 12 months of age.
Cognitive development
In the school aged child skills become more complex and progress tends to be judged by cognitive rather than physical development. That is not to say that cognition can not and should not be assessed in the younger child. Concepts which can be covered in a routine assessment include object permanence, recognition of self and symbolic thought (see Table 1).
Infancy – a child sees himself as the centre of the world, thought processes relate to immediate experiences.
Preschooler – inanimate objects are alive with feelings and events have a magical nature.
School age – the dominant mode of thought is practical and relates to specific circumstances and experiences.
Mid teens – abstract thought begins to develop with the ability to test hypotheses and manipulate more complex concepts [2].
Important influences on development
Development occurs as a result of an interplay between hereditary factors and the environment. In order for development to occur a child’s basic physical and psychological needs must be met.
A baby will develop motor skills if:
● he has a normal central nervous system
● he has motivation to practice new skills
● he has the opportunity to practice new skills
In case 1 the child lacks the opportunity and motivation to practice new skills [3].
In case 2 the central nervous system may not be normal as illicit drug and alcohol use in pregnancy are both associated with significant effects on the developing foetus.
Parents who misuse substances may expose their children to significant neglect both physically and emotionally, compounding any underlying neurological problem.
The developmental history
The developmental history needs to be taken within the context of a full assessment as described in the previous article in the series.4 Development is highly influenced by the environmental context in which a child exists, the history is your chance to gain an insight into this.
Begin at the beginning. Concerns may have arisen antenatally on the basis of famlly history or screening tests. In the birth history it is important to identify prematurity, which should be corrected for until two years of age when considering development.
A child born at 30 weeks gestation may not smile until 15 weeks of chronological age, corrected for gestation five weeks, and be normal. A sensitive but thorough social and family history is vital.
Developmental milestones
A developmental milestone is an important developmental skill. For each skill there is a normal range of time for a child to develop it within. A median age is the age at which half of children acquire a skill.
A limit age is the age at which a skill should have been achieved, it reflects two standard deviations from the mean. Failure to achieve these warrants more detailed assessment, investigation or intervention.
This concept can be demonstrated with respect to walking unaided:
• 25% by 11 months
• 50% by 12 months
• 75% by 13 months
• 90% by 15 months
• 97.5% by 18 months2
Of those not walking by 18 months some will be normal late walkers. However, 20% will have a significant problem including cerebral palsy, Duchenne muscular dystrophy or global developmental delay.
It is important to have a feel for which milestones are most consistent. Smiling socially by the age of eight weeks is a very consistent milestone and failure to achieve this is a real cause for concern. Crawling is a very inconsistent milestone, it occurs at a widely varying point and some children with normal development never learn to crawl.
It is important to have a few key milestones on which to base your assessment and to know where to go for more detail (see Table 2).
Developmental assessment
You can gain a brief idea of a child’s developmental level by asking a few targeted questions depending on their age and making a careful observation of their behaviour in the clinic room without recourse to more formal assessment.
These questions form the ‘Parent Evaluation of Developmental Status’ (PEDS).
A study using this in children aged 21 to 84 months found it to be as good as most developmental screening tests [1].
A range of formal developmental tests exist which are based on cross sectional observations of many children. They require specialist training to deliver, but can generate useful information.
Those in common use include:
● Bayley II Scales of Infant Development
● Griffiths Abilities of Babies and Young Children
In school age children assessments would tend to be made by educational psychologists using a different range of standardised tools:
● WISC-III UK3 (Wechsler Intelligence Scale for Children)
● BAS II (British Abilities Scales 2nd Edition 1997)
Testing of development is not without pitfalls, points to consider include:
● Testing reflects a single observation and a child who is unwell, tired, hungry or anxious may not perform at their usual level.
● Many tests rely heavily on motor skills and a child with difficulties in this area may under perform.
● Some test components do not stand the test of time, most children’s shoes fasten with Velcro now, tying shoe laces is a lost art! To gain a skill you must have experience of it.
● Some tests in widespread use were designed many years ago and may not reflect current societal norms. Children from some ethnic groups may therefore appear to be disadvantaged because of this.
Performing one of these tests of development gives a horizontal assessment of the child in comparison with other children of the same age at a point. In a child about whom there are concerns, a vertical assessment of their abilities over time will allow you to assess rate of progress and skill acquisition.
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Conclusion
Child development can seem baffling to,those not used to thinking about it. However, like most things in medicine it is straightforward if you familiarise yourself with what is normal and develop a system for trying to identify what is abnormal. Abnormal patterns or delays in development are essential to recognise in order to identify causes and institute appropriate support.
References
1. Glascoe FP. Pediatrics, 1997;99(4):522-8.
2. Illustrated Textbook of Paeditrics 3rd edition. Lissauer and Clayde n 2007.
3. Pocket Essentials of Paediatrics Thalange. Holmes, Beach, Kinaird 2006.
4 Paediatric Neurology: History and Examination. Dr A Maw.
