Snapshot A 35-year-old man is brought the emergency department following a motor vehicle accident in which his car struck a tree at high speeds. His airway, breathing, and circulation is intact and a noncontrast CT scan of the head is unremarkable. He is unconconscious but hemodynamically stabe. An MRI brain demonstrates multifocal T2-hyperintensities in the splenium of the corpus callosum. Introduction Definition a type of traumatic brain injury (TBI) secondary to blunt injury to the brain it is generally found in severe TBI, and is thus considered in patients with a Glasgow coma score < 8 Epidemiology incidence TBI is a leading cause of death and disability in children and young adults Etiology high-speed motor vehicle accidents (most common) Pathogenesis accelerating and decelerating motions that result in shearing forces to the white matter of axons, impairing neuron interconnection microscopic damage to the axons at the junction of the grey and white matter most commonly affected sites are the corpus callosum and the brainstem Presentation Symptoms headache dizziness nausea and vomiting fatigue loss of concousness and coma (in severe cases) Physical exam dysautonomia (e.g., tachycardia, tachypnea, hyperthermia, posturing, and vasoplegia) Imaging Noncontrast head CT indication initial head imaging study in patients with head injury findings small punctate hemorrhages in white matter tracts note that head CT is low yield in detecting diffuse axonal injury MRI brain indication imaging modality of choice in diagnosing diffuse axonal injury Studies Making the diagnosis this is a clinical diagnosis supported by radiographic findings suspect in a patient with rotational or acceleration-deceleration closed head injury Differential Subdural hematoma differentiating factors crescent-shaped hemorrhage seen on CT head without contrast Subarachnoid hemorrhage differentiating factors thunderclap headache hyperdensity in the subarachnoid space on CT head without contrast Epidural hematoma differentiating factors lens-shaped and biconvex hyperdensity that does not cross the suture lines Treatment Management is geared towards preventing secondary injuries and facilitating rehab e.g., preventing hypotension, cerebral edema, hypoxia, and increased intracranial pressure Complications Dysautonomia