Prevalence of motor abnormalities among healthy 5-year-old children

The prevalence of motor examination abnormalities among a general pediatric population is unknown. We determined the frequency of motor abnormalities noted at five years of age during a neurologic examination by a child neurologist. As part of a follow-up study of neonatal jaundice in a population of 106,627 births, we randomly selected 419 five-year-old children as healthy controls, of whom 168 consented. Child neurologists blinded to the children’s history performed standard neurologic examinations to determine the presence of definite or subtle motor abnormalities. Standardized data on motor and cognitive function were also obtained. Among eight (5%) children diagnosed with a definite motor abnormality, the most common finding was corticospinal tract dysfunction (four unilateral, two bilateral). Two children demonstrated hypotonia and hyporeflexia, one of whom also exhibited proximal weakness. An additional 12 (7%) children were noted to have subtle motor findings that were not clearly abnormal, such as subtle incoordination, mild dystonic posturing, tremor, posting, or hyperreflexia. Children with definite or subtle motor findings were more likely to receive an abnormal score on the Motor Performance Checklist (57% vs. 32%, P = 0.02). There was also a trend towards these children having a lower mean verbal IQ compared to children with normal motor examinations (95.3 vs. 102.1, P = 0.07). Motor examination abnormalities in otherwise healthy 5-year-old children may be more common than previously thought. However, the proportion of children with motor examination abnormalities who have an unrecognized neurologic disorder remains unknown.