A 35-year-old man is brought to the emergency department after a motor vehicle accident with loss of consciousness. CT head shows a lens-shaped hyperdense collection in the right frontoparietal region that does not cross the midline and stops abruptly at the coronal suture. Which of the following is NOT true regarding extradural hematoma?

Explanation

## Extradural Hematoma: Clinical and Radiological Profile ### Definition and Location **Key Point:** Extradural (epidural) hematoma is a collection of blood between the **skull and the dura mater**. It is typically caused by tearing of the **middle meningeal artery** following high-impact head trauma. ### Comparison of Risk Factors: Extradural vs Subdural | Risk Factor | Extradural | Subdural | | --- | --- | --- | | **Age group** | Young, high-impact trauma | Elderly, minor trauma | | **Brain atrophy** | Not a risk factor | Major risk factor | | **Anticoagulation** | Not a risk factor | Major risk factor | | **Vascular source** | Meningeal artery | Bridging veins | | **Trauma severity** | High-impact required | Low-impact sufficient | | **Presentation** | Acute with lucid interval | Insidious, delayed | ### Why the Correct Answer is Wrong **High-Yield:** Extradural hematomas occur in **young patients with high-impact trauma**, NOT in elderly patients with brain atrophy and anticoagulation. The latter is the classic risk profile for **subdural hematoma**. **Clinical Pearl:** Elderly patients with brain atrophy have fragile bridging veins that tear easily from minor trauma, predisposing them to subdural hematoma. Young patients with intact brains require high-impact trauma to tear the dura and damage the meningeal artery (extradural). ### Radiological Features of Extradural Hematoma 1. **Lens-shaped (biconvex) collection** — conforms to the skull curvature 2. **Does NOT cross the midline** — respects falx cerebri 3. **Stops abruptly at suture lines** — cannot cross the dura attachment 4. **Hyperdense on acute CT** — fresh blood 5. **Usually unilateral** — confined to one side of the skull ### Clinical Presentation: The Lucid Interval **Mnemonic: LUCID INTERVAL in Extradural Hematoma** **L** – **L**oss of consciousness (initial) **U** – **U**nusually recovers consciousness (lucid period) **C** – **C**ontinued bleeding from meningeal artery **I** – **I**ncreasing intracranial pressure **D** – **D**eterioration (second loss of consciousness) This classic pattern occurs in ~30% of extradural hematomas and is a medical emergency. ### Management **Key Point:** Extradural hematoma is a **neurosurgical emergency**. Even small collections can cause rapid deterioration due to ongoing arterial bleeding. Urgent surgical evacuation (burr holes or craniotomy) is indicated to prevent herniation and death. ### Why Each Option is Correct (Except One) 1. **Caused by middle meningeal artery tear** ✓ — The classic mechanism in high-impact head trauma. 2. **Characteristic lucid interval** ✓ — A hallmark feature occurring in ~30% of cases; patient loses consciousness, recovers, then deteriorates. 3. **Common in brain atrophy and anticoagulation** ✗ — This is the risk profile for **subdural** hematoma, NOT extradural. Extradural occurs in young patients with high-impact trauma. 4. **Requires urgent surgical evacuation** ✓ — Extradural hematoma is a neurosurgical emergency due to ongoing arterial bleeding and risk of herniation. [cite:Harrison 21e Ch 445]