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.
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.
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.
Subdural Hematoma. There is a crescent-shaped, hyperdense collection, indicating a subdural hematoma over the right cerebral hemisphere. In addition, the right side of the brain demonstrates mass effect. (Photo contributor: Cincinnati Children’s Hospital Medical Center.)
Left Subdural Hematoma. There is a thin hyperdense collection that extends along the entire left hemisphere as well as along the tentorium indicating a subdural hematoma. (Photo contributor: Marguerite Caré, MD.)
Abusive Head Trauma. This CT shows right parietal skull fracture, subdural hematoma, and subarachnoid hemorrhage with effacement of the right-sided ventricles. (Photo contributor: Angie L. Miller, MD.)
Subdural Hematoma and Extra-Axial Swelling. This image shows interhemispheric subdural blood (white arrow) and subtle contusions (black arrows) of the frontal lobes. Extracranial soft-tissue swelling (arrowheads) is also present; sometimes this is visible on CT but not on physical examination. (Photo contributor: Marguerite Caré, MD.)
Mixed Density Subdural Hematoma. Mixed density collections can result from multiple episodes of trauma, hyperacute bleeding, the mixing of blood and cerebrospinal fluid, or new bleeding into an established subdural collection. It is not possible in most cases to estimate the age of a subdural collection using the density of the collection on CT alone. (Photo contributor: Angie L. Miller, MD.)