1. Infant Brain Response Against Shaking Vibration Using Finite Element Analysis

The most serious head injury resulting from shaken baby syndrome (infant brain injuries resulting from violent shaking attributed to child abuse) is acute subdural hematoma (ASDH). ASDH in infants has a high mortality rate and results in serious permanent injury. It is difficult gather accurate evidence from third parties since this abuse occurs mainly in the home mainly. As the result, medical practitioners rely on experience and intuition to determine the cause of infant head injuries. Therefore, in this study, we conducted simulation analysis that reproduced the shaking action—using a finite element model of an infant’s head to provide a scientific basis for the determination of shaken baby syndrome. We used a model head of a 6-month-old that was constructed from adult head models and CT scan images of an infant head. The input value was defined as the angular velocity and head displacement obtained from the vibration experiments using a 6-month-old-infant dummy. ASDH is caused by the relative rotational motion between the skull and the brain with a rupture of the bridging veins that connect the skull and brain. Accordingly, we evaluated the relative movement between the skull and brain and measured the stretch ratio of the bridging veins. We then compared this ratio with the threshold, which is the rupture value. As a result, the violent shaking action regarded as shaken baby syndrome abuse results in ASHD when the bridging veins rupture. As the brain movement follows the skull, the bridging veins are stretched greatly depending on the forced skull movement and the brain’s inertia.