Mild head injury in preschool children: evidence that it can be associated with a persisting cognitive defect.

This study describes the effect of mild head injury in preschool children on aspects of their cognitive performance in the year after injury and at the age of 6.5 years, with particular reference to the development of reading skills. Mild head injury was defined by diagnosis at a hospital emergency department of a head injury which was not severe enough to need admission for observation. Seventy eight such children were compared with a group of 86 with a minor injury elsewhere. The groups had similar developmental, family, and socioeconomic status. There were no differences in cognitive tests soon after the injury, but at six months and one year children with mild head injury scored less than controls on one test, solving a visual puzzle (visual closure); they were also more likely to have had another mild head injury. At 6.5 years of age they still scored less than controls, reading ability was related to their visual closure score at one year, and they were more likely to have needed help with reading. Mild head injury seems to be able to produce subtle but significant changes which can affect school performance.