In the emergency department after head injury, a patient who had a brief lucid interval but then loses consciousness most classically indicates which complication?

• A. Epidural hematoma
• B. Subdural hematoma
• C. Subarachnoid bleed
• D. Diffuse axonal injury

Answer: (A)

A sudden arterial bleed after head trauma that produces a brief loss of consciousness followed by a lucid interval points to an expanding epidural hematoma. This pattern happens because arterial blood, typically from the middle meningeal artery often injured with a temporal bone fracture, accumulates quickly under the skull. The person may seem fine for a short time after the injury—the lucid interval—but as the hematoma enlarges, intracranial pressure rises and consciousness deteriorates.

Clinically, you’d expect rapid neurologic decline, headache, vomiting, and sometimes a dilated pupil on the affected side as the pressure compresses the third cranial nerve. On CT, an epidural hematoma appears as a lens-shaped (biconvex) collection that is confined by the sutures.

This scenario is less consistent with a subdural hematoma, which is venous in origin, tends to present with a slower onset and a crescent-shaped collection that can cross sutures; a subarachnoid bleed would show blood within the subarachnoid spaces and often presents with a sudden, severe (“thunderclap”) headache; and diffuse axonal injury typically causes immediate coma without a lucid interval. The described sequence is most characteristic of an epidural hematoma.