Write a short note on Extradural vs Subdural Haematoma.

The Concept

Both are collections of blood inside the skull that compress the brain, but they arise from different bleeding sources in different anatomical planes, and this single difference explains their contrasting patient profile, speed, CT appearance and outcome. Understanding the source makes the comparison easy to reconstruct rather than memorise.

Extradural (epidural) Haematoma

An extradural haematoma is arterial bleeding — classically from the middle meningeal artery, torn by a fracture of the thin temporal bone — that strips the dura off the skull. Because it is arterial and under pressure, it collects rapidly. The classic history is a 'lucid interval': the patient is knocked out, wakes and seems well, then deteriorates as the haematoma expands. On CT it is a biconvex (lens-shaped) collection that does not cross suture lines (the dura is firmly attached there). It is typically seen in younger patients and, evacuated promptly, has a good outcome.

Subdural Haematoma

A subdural haematoma is venous bleeding — from the bridging veins torn as the brain moves within the skull — collecting between the dura and the brain. Being venous and lower-pressure, it may develop acutely or, especially in the elderly, insidiously over weeks (chronic subdural). It is commoner in the elderly, alcoholics and those on anticoagulants (a brain that has shrunk stretches these veins). On CT it is a crescent-shaped collection that follows the brain surface and crosses suture lines.

Comparison & Management

A significant or symptomatic haematoma of either type needs urgent neurosurgical evacuation (craniotomy, or burr-hole drainage for a chronic subdural); small ones may be observed.

Clinical Presentation

Both present with features of a rising intracranial pressure and, often, a lucid interval or fluctuating consciousness — a declining GCS, headache, vomiting, a dilating pupil on the side of the clot (third-nerve compression) and contralateral weakness. The chronic subdural in an elderly patient is a great mimic, presenting insidiously with confusion, drowsiness, headache or a stroke-like deficit weeks after a often-forgotten minor fall, which is why it must be actively considered in that setting.

Management

Management depends on size and effect. A significant or symptomatic haematoma is a neurosurgical emergency requiring evacuation — craniotomy for an acute extradural or acute subdural, and simple burr-hole drainage for a chronic subdural (which is liquefied). Small, asymptomatic collections may be observed with serial imaging. Throughout, the general head-injury principles apply — protect the airway, maintain oxygenation and blood pressure, and control ICP — because preventing secondary injury matters as much as removing the clot.

A Note on Subarachnoid Blood

Traumatic subarachnoid haemorrhage — blood in the CSF over the brain surface — frequently accompanies these haematomas and causes headache, photophobia and neck stiffness; it is usually managed supportively rather than surgically. The essential exam skill remains distinguishing the two surgical haematomas: if it is biconvex and respects sutures, think arterial extradural; if it is crescentic and crosses them, think venous subdural — the shape on CT reads back directly to the anatomy and the source.

The lucid interval is classic of extradural haemorrhage.

• Both compress the brain; the difference is the bleeding source and plane.
• Extradural: arterial (middle meningeal artery, temporal fracture), young, lucid interval, biconvex on CT, does not cross sutures.
• Subdural: venous (bridging veins), elderly/alcoholic/anticoagulated, acute or chronic, crescent-shaped, crosses sutures.
• Significant haematoma → urgent evacuation (craniotomy; burr-hole for chronic subdural).