Subdural haematoma
Bridging-vein tear → blood between dura and arachnoid (crescent)
Overview
Venous bleeding from torn bridging veins collecting between the dura and arachnoid. Classically in the ELDERLY or alcoholics (brain atrophy stretches the veins), often after trivial trauma, with a fluctuating or insidious course. CT shows a CRESCENT-shaped collection crossing suture lines.
Recognise
- Fluctuating consciousness, confusion, headache, focal signs — often insidious over days–weeks
- Elderly, alcohol-dependent, anticoagulated, or shaken infants
- CT: CRESCENT (concave/sickle) hyperdensity (acute) or hypodensity (chronic), crosses suture lines
Red flags
- Reduced/fluctuating GCS, anticoagulation, large collection with midline shift
Differentials & how to tell them apart
Investigations
CT head: crescentic collection NOT limited by sutures (acute = bright, chronic = dark, ± midline shift); clotting/INR.
Management
Reverse anticoagulation; surgical evacuation (burr-hole/craniotomy) if significant; otherwise observe
- 1CT head; reverse any anticoagulation. Small/asymptomatic → conservative with monitoring.Gate: A crescent (sickle) shape crossing suture lines = subdural; a biconvex (lens) shape limited by sutures = extradural — the shape decides
- 2Significant collection / deterioration → neurosurgical evacuation (burr-hole for chronic, craniotomy for acute).
Key points
Always image the confused or falling elderly/alcoholic patient — chronic SDH is a reversible "dementia" mimic. Bridging veins are venous, hence the slower course than extradural.
Monitor & prognosis
GCS, repeat imaging, neuro obs.
Chronic SDH does well after drainage; acute SDH with shift carries worse prognosis.
Source: NICE NG232 (head injury); neurosurgical guidance