MRI Head Patients with more significant trauma and lower GCS are more likely to have sustained shear injury or ischemia, and MRI may have a higher yield for prognosis in this instance [25,39]. However, because of the time required to arrange and perform the examination and possible need for sedation, MRI can be difficult to accomplish emergently and should not delay evaluation. IV contrast is typically of little use in evaluation of acute trauma. MRA Head MRA can evaluate the intracranial vasculature and can be performed in conjunction with MRI when vascular injury is clinically suspected. However, as with standard MRI, this examination may be difficult to perform emergently. MRA can be performed without contrast using time-of-flight sequences, although IV contrast may be helpful for clarification in some instances, particularly when imaging is limited by tortuosity or flow artifact. Arteriography Cerebral Conventional cerebral angiography remains the definitive diagnostic test for vascular injury and can demonstrate subtle abnormalities that may be occult on either CTA or MRA. However, because of the invasive procedure and need for sedation, conventional angiography should be reserved for problem solving in cases with uncertain noninvasive imaging and high clinical suspicion of vascular injury. Variant 5: Child. Subacute blunt head trauma with cognitive or neurologic signs. The exact definition of subacute injury varies, but subacute head injury is typically defined as occurring between 8 days and 1 month after the initial traumatic event [40,41]. Injury may be caused by secondary processes, such as herniation from worsening parenchymal edema, ischemia, hydrocephalus, and progressive or delayed hemorrhage. During the subacute phase, up to 30% of contusions may cause worsening mass effect with edema from toxic metabolites released into the surrounding tissue and cerebral autoregulation dysfunction [42].
Head Trauma Child PCAs. MRI Head Patients with more significant trauma and lower GCS are more likely to have sustained shear injury or ischemia, and MRI may have a higher yield for prognosis in this instance [25,39]. However, because of the time required to arrange and perform the examination and possible need for sedation, MRI can be difficult to accomplish emergently and should not delay evaluation. IV contrast is typically of little use in evaluation of acute trauma. MRA Head MRA can evaluate the intracranial vasculature and can be performed in conjunction with MRI when vascular injury is clinically suspected. However, as with standard MRI, this examination may be difficult to perform emergently. MRA can be performed without contrast using time-of-flight sequences, although IV contrast may be helpful for clarification in some instances, particularly when imaging is limited by tortuosity or flow artifact. Arteriography Cerebral Conventional cerebral angiography remains the definitive diagnostic test for vascular injury and can demonstrate subtle abnormalities that may be occult on either CTA or MRA. However, because of the invasive procedure and need for sedation, conventional angiography should be reserved for problem solving in cases with uncertain noninvasive imaging and high clinical suspicion of vascular injury. Variant 5: Child. Subacute blunt head trauma with cognitive or neurologic signs. The exact definition of subacute injury varies, but subacute head injury is typically defined as occurring between 8 days and 1 month after the initial traumatic event [40,41]. Injury may be caused by secondary processes, such as herniation from worsening parenchymal edema, ischemia, hydrocephalus, and progressive or delayed hemorrhage. During the subacute phase, up to 30% of contusions may cause worsening mass effect with edema from toxic metabolites released into the surrounding tissue and cerebral autoregulation dysfunction [42].