History of an abusive head trauma including a lucid interval and a retinal hemorrhage is most likely false.

A lucid interval (LI) is the period of time between regaining consciousness after a short period of unconsciousness, resulting from a head injury and deteriorating after the onset of neurologic signs and symptoms caused by that injury. The incentive for this study was the case of a father who left his 14-week-old infant with the nanny in whose custody the infant had collapsed. The nanny denied involvement in the injury, and the father became a suspect. Of 47 abusive head trauma (AHT) cases, 8 were found to have an LI in the past. The history of the cases were thoroughly analyzed and compared with evidence in the literature. An LI is not compatible with an inertial brain injury. Shaking has either an immediate effect or no effect, which means that an LI occurs only in pure impact or blunt injuries. When "shaking lesions" are found including a retinal hemorrhage while the history mentions an LI, the story most likely is false, regardless of whether the perpetrator confesses. The finding of an LI may change the assessment of an AHT case. Lucid interval is a valuable variable in the diagnostic accuracy of an AHT.