Dissociated motor development, defined as marked gross motor delay without any abnormal
neurological signs and contrasting to a normal fine motor-adaptive performance, was
studied prospectively in a consecutive series of 78 children, 48 girls and 30 boys,
aged 7—23 months at first examination. When 17 months of age, 10 of them had become
normalized, and in further three a disability explaining their gross motor delay had
been diagnosed. At an average age of 4.2 years, the remaining 65 late walkers were,
regardless of cause and developmental and neurological findings at final follow-up,
characterized by a number of deviating clinical features as muscular hypotonia (71%),
shuffling (51%) and dissociated or late pattern of learning to sit (79%). In 30 out
of 65 late walkers (46%) a defined clinical condition of probable pathogenetic implication
was found. In 35 out of 65 late walkers (54%), no explaining clinical condition was
found. They have been designed to be idiopathic late walkers. Except for muscular
hypotonia, present in 77%, conventional neurology was normal in this group. Minor
neurological signs such as a positive Foerster sign, defect balance reactions in standing, or asymmetry in prewalking locomotion
were, however, occasionally and temporarily observed. Girls were overrepresented among
idiopathic late walkers, 69 % compared to 43% among the symptomatic late walkers.
Complete normalization was more common in the idiopathic group (66%) than in the symptomatic
group (27%). Early differentiation between the late walkers who were normalized and
those who developed mild mental retardation or neurological handicaps was difficult
but not quite impossible. Heredity for shuffling, a non-revealing pre- and perinatal
history, a developmental pattern of late learning to sit, and shuffling favoured a
normal outcome. Creepers with a dissociated pattern of learning to sit and crawlers
with muscular hypotonia were found to have an increased risk for later handicap.
Child development deviation - motor skill - muscular hypotonia - mental retardation
- cerebral palsy
