Epidural Hematoma

An epidural (extradural) hematoma is a collection of blood between the inner table of the skull and the dura mater, most often caused by a skull fracture that tears the middle meningeal artery. Classically associated with a brief lucid interval after head trauma, it is a surgical emergency in which timely evacuation can produce excellent recovery because the underlying brain is often relatively undamaged.

Definition

A cranial epidural hematoma is an accumulation of blood in the potential space between the skull and the dura mater, typically arising from traumatic rupture of a meningeal artery (most often the middle meningeal artery) or a dural venous sinus.

Scope

This entry covers the cranial epidural hematoma as a traumatic surgical mass lesion: its anatomy and arterial source, the characteristic clinical course, the lentiform CT appearance, and the principles underlying surgical evacuation. It is a reference overview, not operative or treatment guidance.

Core questions

• What anatomy and vascular source give rise to an epidural hematoma?
• Why does the classic lucid interval occur, and how reliable is it?
• What CT features distinguish an epidural from a subdural hematoma?
• On what basis is surgical evacuation considered?

Key concepts

• Middle meningeal artery rupture
• Lucid interval
• Lentiform (biconvex) CT appearance
• Limitation by cranial suture lines
• Skull fracture association
• Mass effect and herniation
• Surgical evacuation (craniotomy)

Mechanisms

Trauma, frequently a temporal-region impact with skull fracture, tears the middle meningeal artery or, less often, a dural venous sinus. Arterial bleeding strips the dura from the skull and accumulates under pressure; because the dura is firmly attached at suture lines, the haematoma typically remains lentiform (biconvex) and does not cross sutures. The expanding mass raises intracranial pressure and can cause uncal herniation. The classic lucid interval reflects an initial period before the haematoma enlarges enough to produce deterioration, and arterial bleeding explains why decline can be rapid.

Clinical relevance

Epidural hematoma is a prototypical example of a traumatic lesion in which prompt recognition on imaging and timely surgical decompression are associated with good neurological recovery, because the brain beneath is often spared. The entry describes these principles to support critical reading; it is not a basis for individual diagnostic or treatment decisions.

Epidemiology

Epidural hematomas occur in a minority of significant head injuries and are relatively more common in younger patients, in whom the dura is less adherent to the skull; they are frequently associated with an overlying skull fracture in the temporal or temporoparietal region (Greenberg, 2020).

Evidence & guidelines

The Brain Trauma Foundation/AANS surgical management guideline for acute epidural hematomas (Bullock et al., 2006) summarises the volume, thickness, and clinical thresholds discussed for operative decision-making. These are cited to characterise the literature, not as directives.

History

The lucid interval following head injury has been recognised in clinical descriptions of extradural bleeding for over a century, and the entity became a model for the value of early surgical evacuation. The 2006 surgical management guideline consolidated contemporary criteria for operative versus conservative care.

Debates

When can a small epidural hematoma be managed without surgery?

Selected small haematomas in neurologically intact patients may be observed with close monitoring and repeat imaging, but the thresholds of clot volume, thickness, midline shift, and clinical status that justify nonoperative management remain a matter of clinical judgement.

Key figures

• Ross Bullock
• Mark Greenberg
• Graham Teasdale
• Bryan Jennett

Seminal works

• bullock-2006-epidural
• teasdale-jennett-1974

Frequently asked questions

What is the lucid interval in an epidural hematoma?

It is a period after the head injury when the person seems alert and recovered, followed by deterioration as the arterial haematoma enlarges. It is characteristic but not present in every case.

How is an epidural hematoma distinguished from a subdural hematoma on CT?

An epidural hematoma is typically biconvex (lens-shaped) and limited by skull suture lines, whereas a subdural hematoma is crescent-shaped and can spread along the brain surface across sutures.