Shaken baby syndrome

Shaken Baby Syndrome (SBS) is a well-defined type of intentional injury to young children: severe rotational acceleration of the head, causing serious whiplash-type injuries, broken bones, or haemorrhages. It was first described in the early 1970s by radiologist John Caffey and has since been recognized as a common form of childhood injury and death. By definition, it arises from child abuse in that the shaking required is violent enough that an outside observer would recognize it as violent and abusive.

Prevalence
SBS is believed to affect around 1500 children in the U.S. yearly. Most of these cases are infants under one year of age. The mortality rate may be as high as 30%. There appears to be variability in definitions and reporting, and exact numbers are difficult to come by.

Denialism
There is a large denialism movement directed towards SBS which seems to arise from the legal system. While there is certainly some disagreement in the medical community about mechanisms, definitions, and how to accurately diagnose the syndrome, it is generally agreed that the syndrome exists and kills babies. A 2011 article in the NY Times magazine throws some more scepticism into the mix.