Investigation of developmental delay.

The diagnostic process Paediatricians will often be asked to see children with learning difficulties. They will present at a variety of ages in a number of different ways and it is easy to feel unsure how extensively to investigate the problem and what advice to give. This article will review the common presentations and suggest a rational approach to investigation. The role of the paediatrician is to help understand the issue of causation, inform the parents of future outlook, deal with any attendant medical problems, and arrange genetic counselling and supportive services. Special investigation plays only a small part in this process. Clinical skills are equally important; a child's appearance, pattern of movement, or mode of presentation may all give important diagnostic clues. Children with learning difficulties present in relatively few well circumscribed ways: hypotonia in the newborn period, recognised developmental delay later in infancy or in the early toddler age group, language delay, arrest of development, or difficulties at school (see below). In each of these groups the history should detail the pregnancy, including any drug ingestion or early threatened abortion. The presence of fetal distress should lead to careful scrutiny of the obstetric notes, though it is now generally accepted that in order to attribute causation to birth asphyxia the presence of hypoxicischaemic encephalopathy must be established. A record of cord or early pH measurements as well as neonatal behaviour are important in this respect as not all early neonatal encephalopathy is due to hypoxicischaemic insult. 1-3 Parents in their own mind often attribute their child's difficulties to the events of labour and it can be helpful for them to be taken through details of the birth. A detailed family history is clearly of value especially if supplemented by perusal of the family photograph album. These together with home video recordings can give a surprisingly clear idea of the evolution of a disorder. Many motor disorders such as the spasticity in cerebral palsy or the extrapyramidal involvement in Rett's syndrome may evolve over a period of time, raising the possibility of a neurodegenerative disorder. Careful scrutiny of the history often reveals that whereas things have changed, skills may not actually have been lost. Presenting symptoms