No abstract

Shaken baby syndrome (SBS) is routinely diagnosed on the basis of a classic triad of autopsy findings, namely retinal hemorrhage, subdural hemorrhage, and anoxic encephalopathy. However, ongoing controversy exists regarding the specificity and potential causes of these signs, and hence their reliability as de facto markers of SBS, or of non-accidental head injury, where no external signs of trauma are evident. We investigated the deaths of 35 infants and young children, which fell into two broad groups: those with suspected hyperflexion/extension neck injuries, and those without. At autopsy, the entire cervical spinal column (spinal cord, vertebrae, intervertebral discs, neurovascular structures and adjacent soft tissues) was removed, formalin-fixed, decalcified, dissected, and microscopically evaluated. Of the 12 cases in which hyperflexion/extension was either suspected or confirmed, all had evidence of either bilateral or unilateral hemorrhages within or surrounding the C3, C4, and/or C5 cervical spinal nerve roots. We provide evidence that hyperflexion/extension forces as experienced by shaken and impacted infants and young children lead to injury of the cervical spinal nerve roots that innervate the diaphragm, with resulting asphyxia and hypoxic brain injury. Therefore, we propose that trauma to the third through fifth cervical spinal nerve roots induced by hyperflexion/extension of the neck is the cause of the anoxic encephalopathy of the classic SBS triad, and is therefore not only a more specific indicator of hyperflexion/extension injury than subdural hemorrhage alone, but is the mechanism of injury in these cases.