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Abusive head trauma (AHT) is the most deadly form of physical abuse but can be easy to miss because the neurologic examination can be difficult in young infants, who are at highest risk. A low threshold for neuroimaging (CT or MRI) should be used for infants who present with bruising, vomiting without fever or diarrhea, fussiness or lethargy, or transient loss of consciousness (apparent life-threatening event [ALTE] and brief, resolved, unexplained event [BRUE]), especially those with increased head circumference or anemia.
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Subdural hematoma is the most commonly recognized injury in AHT, but other injuries can include skull fractures, subarachnoid hemorrhage, or parenchymal injury. None of these injuries is seen exclusively with abuse; isolated, linear parietal skull fractures are most commonly accidental and can occur from relatively minor trauma. Abuse should be suspected when significant injury occurs after relatively minor trauma, such as a short fall, or when other abusive injuries are identified.
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Be careful estimating the age of an injury using radiographic findings alone. The dogma that hyperdense “bright” blood is new and that hypodense “dark” blood is old is not reliable. The skull is made up of membranous bones and, unlike most other fractures, skull fractures do not display the normal healing patterns (periosteal reaction and callus formation) typical of endochondral bones.
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