Extradural vs Subdural Hematoma

A 35-year-old man is brought to the emergency department following a motor vehicle accident. He lost consciousness for 2 minutes, then regained consciousness and appeared well. After 4 hours, he develops severe headache, vomiting, and altered mental status. Non-contrast CT head shows a lens-shaped (biconvex) hyperdensity in the epidural space with mass effect. Which investigation should be performed next to assess for ongoing bleeding and guide urgent intervention?

Which of the following is the characteristic CT finding that distinguishes acute epidural hematoma from acute subdural hematoma?

A 68-year-old woman with chronic alcoholism presents with progressive headache and confusion over 3 weeks. MRI brain shows a crescent-shaped hematoma that crosses the midline. Which feature most reliably distinguishes this subdural hematoma from an acute extradural hematoma in terms of vascular source?

A 52-year-old man presents to the emergency department following a fall from a height. CT head shows a crescent-shaped hematoma that does not cross the midline. Which radiological feature best distinguishes this finding from a subdural hematoma?

A 35-year-old man is brought to the emergency department 4 hours after a motor vehicle collision with loss of consciousness. He is now alert but drowsy. CT head shows a lens-shaped hyperdensity in the right frontoparietal region that does not cross the midline, with 8 mm midline shift. What is the most appropriate immediate next step?