A LATE WALKER
History
Justin is an 18-month-old boy referred to the community paediatric clinic because he is not yet walking. He is the first child of white British parents, born at 41 weeks’ gestation following an uneventful pregnancy. There was meconium staining of the amniotic fluid but he cried immediately at birth and didn’t need any resuscitation. He has been generally healthy apart from normal coughs and colds, and he had chickenpox 6 months ago. His parents recall that he could roll over at about 4 months, sat up alone at 10 months, crawled from 13 months and was able to ‘bear walk’ on hands and feet and pull himself to standing from around 17 months. He can take a few steps holding on to furniture but cannot walk independently yet. He is able to scribble with a crayon with either hand and can slot pieces into a shape-sorter toy. He uses lots of single words appropriately, understands simple instructions, feeds himself with a spoon and will also feed his teddy bear. The parents have no concerns about his vision or hearing. He attends nursery 3 days per week and is described by the nursery staff as a likeable boy, although they have been concerned that he still doesn’t walk. There is no family history of delayed walking. Justin’s mother is an accountant and his father is an architect and both are in their early 40 s. They are hoping to have another child soon.
Examination
Justin looks well and enjoys interacting with you. He is not dysmorphic. His weight is 10.8 kg (25th centile), height is 80 cm (25th centile) and head circumference is 49 cm (50th centile). Cardiovascular, respiratory and abdominal examinations are normal. His spine and joints appear normal, and there are no unusual birthmarks. Neurological examin ation shows normal cranial nerves and normal posture, tone, power and reflexes in the upper and lower limbs. He does not have any tremor. When he is helped to stand, holding on to the side of a low table, Justin takes a few steps whilst holding on with both hands.
Questions
• What comments can you make about Justin’s developmental history?
• What further assessment is necessary?
• What is the most important investigation to perform?
• What are the most common causes of delayed walking?
Medicine
Justin’s gross motor development is delayed. Although he rolled at the normal age, he was slightly late to sit independently and crawl. The average age for walking is 13 months (range 9–18 months) and failure to walk by 18 months is a developmental warning sign. The rest of his development seems appropriate for his current age, although there is little detail given. Further assessment of his development in fine motor, speech, language, communication and social domains will reveal whether he has isolated delay in walking or he has other areas of delay too. The most important investigation is a blood test for creatine kinase (CK) measurement. This is because boys with Duchenne muscular dystrophy (DMD) will have a very elevated CK and the diagnosis would be strongly suspected if this were found. As Justin’s parents are planning to have another child, they could have appropriate genetic counselling about the risk of another child being affected. DMD is an X-linked recessive condition affecting about 1:4000 births and it usually results in progressive muscle weakness, loss of ambulation and death in the teens or early 20s. Many children with DMD will also have a degree of learning difficulty and may exhibit delay in other areas of development. Delayed walking is a common problem. Ninety-seven per cent of normal children will be walking by 18 months of age, which means 3 per cent will not. Most children not walking by 18 months will be normal, but up to 10 per cent will have an underlying neurological problem and 10 per cent will have developmental delay in other areas. Less than 1 per cent will turn out to have muscular dystrophy.
Causes of delayed walking
Example
Generalized developmental delay Fragile-X syndrome, Down’s syndrome
Neuromuscular cause Cerebral palsy, Duchenne muscular dystrophy
Musculoskeletal Congenital dislocation of the hip
Normal ‘late walker’ The majority of cases
KEY POINTS
• Failure to walk by 18 months is a developmental warning sign.
• Duchenne muscular dystrophy is the most important diagnosis to exclude in boys.
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