Shaken babies--some have no impact injuries.

One study has questioned the validity of shaking as a mechanism of head injury in children. A prospective, postmortem study investigated 80 deaths from head trauma to identify the roles of shaking and direct impacts. Evidence of shaking was defined as two or more of the following criteria: 1) finger marks and/or rib fractures, 2) subdural and/or subarachnoid hemorrhage, or 3) a history of vigorous shaking. Shaking to the exclusion of other head trauma was defined as the presence of two or more of the above criteria together with the complete absence of scalp or skull injuries. Nine (11.3%) of the 80 study deaths qualified as exclusively shaking injuries by this definition. Thirty (37.5%) of the deaths had direct injuries as well as two of the criteria of shaking; these deaths were classified as combined shaking and blunt trauma. Forty-one (51.3%) of the deaths had impact injuries without having two of the criteria of shaking. We reviewed the extent of ocular injuries in all the cases. We found ocular hemorrhages with increased frequency in cases with two or more of the criteria of shaking compared to cases with only impact mechanism of injury. Retinal hemorrhages continue to show themselves to be a good marker of infants injured by vigorous, intentional shaking. This study likewise confirms the observations of others that most, but not all, shaken babies have impact injuries as well.