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Acute epidural and subdural haematoma — when to operate

The decision to operate on a traumatic intracranial haematoma rests on three CT numbers — volume, thickness and midline shift — together with the GCS and the pupils; an epidural haematoma over 30 mL, or a subdural haematoma thicker than 10 mm or with shift over 5 mm, is evacuated whatever the GCS.

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Why it matters in the exam

The neurosurgery exam usually gives a head-injured patient with a CT and numbers, and the question is whether to operate now, observe with a repeat CT, or first reverse anticoagulation. An epidural haematoma is usually arterial, from a torn middle meningeal artery under a temporal bone fracture, looks lens-shaped (biconvex), does not cross sutures, and may present with a lucid interval. An acute subdural haematoma comes from torn bridging veins, is crescent-shaped, crosses sutures and is often accompanied by injury to the brain itself, so its prognosis is worse.

The Brain Trauma Foundation guidance says: epidural over 30 mL — evacuate at any GCS; epidural under 30 mL, less than 15 mm thick, with shift under 5 mm, GCS above 8 and no focal deficit — non-operative care with repeat CT in a neurosurgical centre. Subdural thicker than 10 mm or shift over 5 mm — evacuate at any GCS; a small subdural in a patient with GCS below 9 — operate if the GCS falls by 2 points or more, the pupils become asymmetric or fixed, or ICP exceeds 20 mmHg. A comatose patient with anisocoria and an epidural goes straight to theatre. In a patient on apixaban or warfarin, reversal starts at once, in parallel with preparation for surgery. Decompressive craniectomy also recurs: RESCUEicp showed lower mortality with refractory ICP above 25 mmHg at the cost of more survivors with severe disability, and DECRA showed that early bifrontal craniectomy did not improve outcome.

Key points

Epidural over 30 mL — evacuate at any GCS.
Subdural over 10 mm or shift over 5 mm — evacuate at any GCS.
Epidural: artery, lens, does not cross sutures; subdural: veins, crescent, crosses sutures.
Anticoagulant — immediate reversal in parallel with preparation for surgery.
Craniectomy for refractory ICP: less mortality, more survivors with severe disability.

Summary table

Finding	Source and appearance	Threshold for surgery	Note
Epidural haematoma	Middle meningeal artery; lens-shaped, does not cross sutures	Over 30 mL at any GCS	Small and stable — non-operative with repeat CT
Acute subdural haematoma	Bridging veins; crescent, crosses sutures	Thickness over 10 mm or shift over 5 mm	Associated brain injury common; worse prognosis
Small subdural and GCS below 9	—	GCS drop of 2 or more, pupils, ICP over 20	ICP monitoring
Refractory intracranial pressure	Diffuse swelling	Decompressive craniectomy after failed tiered therapy	RESCUEicp: less mortality, more severe disability
Anticoagulants	Apixaban, rivaroxaban, warfarin	Immediate reversal before or during preparation	Andexanet or PCC; warfarin — PCC and vitamin K

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Sources

Brain Trauma Foundation: Guidelines for the Surgical Management of Traumatic Brain Injury, 2006 — Surgical management of acute epidural and acute subdural hematomas
Brain Trauma Foundation: Guidelines for the Management of Severe Traumatic Brain Injury, 4th edition (2016) — ICP and CPP thresholds, decompressive craniectomy
American College of Surgeons ATLS, 10th edition (2018) — Head trauma

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.