Traumatic Brain Haemorrhage
Overview
Traumatic brain injuries produce haemorrhage in predictable anatomical compartments, each with characteristic clinical presentations and CT imaging features. Rapid pattern recognition on non-contrast CT is a core competency in emergency radiology.
Classification by Anatomical Compartment
- Epidural Haematoma (EDH): Between skull and periosteal dura. Usually arterial (middle meningeal artery). Biconvex (lens-shaped) hyperdensity. Does NOT cross sutures. CAN cross the midline (unlike SDH).
- Subdural Haematoma (SDH): Between dura and arachnoid. Usually venous (bridging veins). Crescent-shaped hyperdensity. CAN cross sutures. Does NOT cross the midline (falx/tentorium).
- Subarachnoid Haemorrhage (SAH): CSF-filled subarachnoid space. Hyperdensity tracking sulci, Sylvian fissures, and basal cisterns.
- Intracerebral Haemorrhage (ICH): Within the parenchyma. Rounded or lobulated hyperdense focus.
CT Density Evolution of SDH
- Acute (0-7 days): Hyperdense (>40 HU) — fresh blood with intact clot proteins.
- Subacute (1-3 weeks): Isodense — can be invisible on CT; look for gyral compression and displaced vessels.
- Chronic (>3 weeks): Hypodense (<30 HU) — liquefied haematoma.
WarningThe Lucid Interval: Classic EDH Hallmark
EDH classically presents with: brief initial loss of consciousness (concussive episode) followed by apparent recovery (the 'lucid interval') and then rapid neurological deterioration as the arterial haematoma expands. This temporal pattern demands emergency CT head.
High Yield Facts
LightbulbFRCR / MD Prep Pearl
In elderly patients on anticoagulants, bilateral chronic SDH can be isodense with brain and nearly invisible. Clues: symmetrical sulcal effacement, inward displacement of cortical veins shown as 'hyperdense cortical ribbon', and bilateral medial displacement of white matter.