Objective: Commentary on the methods available for ascertaining the incidence of inflicted traumatic brain injury (inflicted TBI) and the difficulties involved in defining and measuring this condition in young children.
Design: Review of published and unpublished international data regarding parental shaking of infants compared to studies assessing incidence.
Results: Review of parental report data reveal that the shaking of young children is a surprisingly common act in a wide variety of countries and cultures. While 2.6% of parents of children aged under 2 years in the U.S. report shaking their child as an act of "discipline," survey data from lesser-developed countries on four continents indicate that shaking, as a form of discipline, may be many times more common among infants in their countries and that the consequences, short of hospitalization or death, are inadequately studied. Methodologic challenges to epidemiologic work to develop better estimates are discussed.
Conclusions: These data highlight the challenges faced in ascertaining the epidemiology of inflicted TBI in young children. While there is scientific evidence that the shaking of young children can produce profound destruction of children's brains and lives, these data reveal that there are many other children who are shaken by their caregivers but escape the acute clinical presentation of "shaken baby syndrome" or for whom the injuries are not recognized as due to inflicted TBI. The impact of these private acts must be further studied as there may be other long-lasting and serious intracranial impacts that have not been characterized.