The “Shaken Baby” Syndrome; Computational Studies of a New Hypothesis of its Cause

The term “shaken baby syndrome” refers to a unique pattern of non-accidental traumatic injury occurring in children by shaking. Typical injuries include subdural haemorrhage, retinal haemorrhage as well as tears to cortical bridging veins. Infants younger than 6 months are significantly more vulnerable to the shaken baby syndrome than older infants and children, a fact that has been difficult to reconcile with all previous explanations of the phenomenon. The paper explores a new hypothesis for the unique vulnerability of infants (i.e. those younger than about 6 months) to shaking: - the different motions of the brain in skulls with and without the flexibility provided by the fontanelles. The investigation involved the study of two highly simplified finite element models of a skull and brain subjected to shaking, namely, one with a representation of the fontanelle, and one without. The results revealed dangerously enhanced local accelerations and shear strains in the region of the fontanelle. These findings provide a potential mechanism for the special vulnerability of infants to shaking, and suggest some reasons why shaking motions can be much more dangerous than those associated with impact.