| Vol. 3, Issue 1, Article 2 |
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Buadu, et al. |
It is estimated that more than 2000 children in the United States die each year as a result of child abuse [1]. Many think that the number is actually higher because many child fatalities that are actually related to abuse are reported as accidents, homicides or sudden infant death syndrome. Nonaccidental head injury (NAHI) is largely restricted to children under three years of age, with the majority occurring during the first year of life [2]. Inflicted head injury is the most common cause of traumatic death in infancy [2, 3]. With inflicted head injury an accurate history is rarely provided at presentation. The history provided may be vague or may vary with time [4]. Physical examination, although useful may provide little insight regarding underlying brain injury. Consequently, the diagnosis and detection of nonaccidental head injury (NAHI) usually comes to rest on radiologic imaging. If radiographic indicators of abuse or neglect are missed, it portends grave consequences for the child who will invariably be returned to a high risk environment. It is therefore crucial for radiologists to be familiar with the imaging findings of NAHI.
The various terminologies applied to inflicted head injury in children reflect the evolution in our understanding of the underlying mechanisms necessary to cause some of the injuries seen. The term "whiplash shaken baby syndrome" was originally coined by Caffey to explain the constellation of findings of subdural and subarachnoid hemorrhages, traction type metaphyseal fractures and retinal hemorrhages in children [5]. Since then terms like shaken baby syndrome, shaken impact syndrome and shaken infant syndrome have all been used in an attempt to explain underlying mechanisms of inflicted head injury infants. Regardless of terminology it is well accepted that most inflicted head injuries in children are of the dynamic type. Dynamic injuries may occur in either direct contact trauma or indirect injury. Contact phenomena result in localized distortion or a fracture of the skull, a focal cortical injury, epidural hematoma or subdural hematoma. In contrast to direct trauma, indirect injuries are independent of skull deformation and entail inertial loading which occurs with sudden acceleration or deceleration of the head [6]. Although a contact may occur with this mechanism, significant life threatening injuries may occur without an impact. Head acceleration or decelerations results in a variety of strain deformations of the skull and its contents. Shear strain deformation, which produces disruption at tissue interfaces is the most important mechanism in the production of intracranial injury. Furthermore the primary injury occurring with these biomechanical forces may result in other pathophysiologic alterations or secondary injury (e.g. edema, swelling, hypoxic ischemia, herniation) and produce additional imaging findings.
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