A 25-year-old man sustains a road traffic accident. CT head shows a biconvex (lens-shaped) hyperdense collection over the left temporoparietal convexity that does not cross the coronal suture but crosses the midline falx. Which statement best explains these findings?

• A Subdural haematoma, because subdurals are bounded by sutures
• B Extradural haematoma, because the attached dura at sutural margins limits its spread ✓
• C Subarachnoid haemorrhage, because it follows the convexity surface
• D Chronic subdural haematoma, because it is lens shaped and crosses the midline

Explanation

An extradural (epidural) haematoma arises from bleeding between skull and dura, classically from the middle meningeal artery after temporal bone fracture. The dura is tightly adherent at cranial sutures, so the collection is lentiform and cannot cross sutures, though it may cross the midline under the falx where there is no suture barrier. A subdural is crescentic, crosses sutures freely, and is generally prevented from crossing the midline by the falx cerebri.

Reference: Grainger and Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.