Regarding epidural haematoma following head injury, the classic 'lucid interval' is caused by:
- A Arterial bleeding from the middle meningeal artery with initial consciousness recovery before haematoma expands to cause herniation ✓
- B Slow venous bleeding from bridging veins allowing time for brain accommodation
- C Edema formation peaking at 24–48 hours causing delayed deterioration
- D Cortical spreading depression following direct brain contusion
Correct answer: A. Arterial bleeding from the middle meningeal artery with initial consciousness recovery before haematoma expands to cause herniation
Explanation
Epidural haematoma is typically caused by rupture of the middle meningeal artery (or its branches) following temporal bone fracture. The arterial bleeding is initially tolerated as the brain accommodates expanding haematoma; the patient may regain consciousness (lucid interval) before haematoma accumulates beyond the compensatory capacity. Herniation then causes rapid neurological deterioration. Subdural haematoma from torn bridging veins (venous) typically has no or shorter lucid interval and more gradual onset.
Reference: Bailey & Love's Short Practice of Surgery, 27th ed.
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Written and medically reviewed by the StethoPrep medical team.