An 18-year-old, previously healthy woman in her senior year of college failed to return home from an evening outing. She was reported missing by her roommate and subsequently discovered on the roadside as a restrained passenger in an overnight motor vehicle accident. Initial GCS was 5, and she remained in an unconscious state with preserved sleep/wake cycles (unresponsive wakefulness) until day 31 posttrauma. She regained a consistent degree of alertness with reliable following of commands at 64 days and regained orientation at 106 days. At 1 year, she had persistently impaired left motor control, visual and verbal memory deficits, and slowed processing speed. She was able to return to college on a modified schedule 2 years postinjury and was living independently 3 years postinjury. She was able to run a continuous mile by 5 years postinjury and obtained a job as a writer for a nonprofit.

Head CT and brain MRI at 5 weeks postinjury revealed patchy edema and microhemorrhages in the corpus callosum, basal ganglia and brainstem ( Fig. 62.1 ).

Severe diffuse axonal injury. (A) Head CT reveals patchy hypodensities in the left caudothalamic region ( arrow ), and corpus callosum and fornix ( arrowheads ). (B) Brain MRI, axial SWI, shows multiple bilateral punctate microhemorrhages throughout the subcortical white matter (arrows) and basal ganglia (arrowhead).

Posttraumatic seizures with postictal encephalopathy.

Hypoxic-ischemic brain injury.

Substance abuse.

Cerebral edema can be associated with traumatic brain injury (TBI), hypoxic-ischemic injury, acute inflammatory processes such as viral encephalitis, multiple sclerosis, or acute disseminated encephalomyelitis (ADEM).

Diffuse microhemorrhages can be seen in diffuse axonal injury (DAI), small vessel vasculopathies, and following radiation therapy.

Localized macro- and microhemorrhages may be seen in association with underlying vascular malformations or tumors.