An extradural haematoma (EDH) (also known as an epidural haematoma) is a collection of blood which forms between the inner surface of the skull and outer layer of dura.
Typically extradural hematomas are seen in young patients who have sustained head trauma, usually with an associated skull fracture.
Unlike subdural haemorrhages, in which a history of head trauma is often difficult to clearly identify, extradural haemorrhage usually are precipitated by a clearly defined blow. A typical presentation is of a young patient involved in a head strike (either during sport or as part of a motor vehicle accident) who may or may not lose consciousness transiently. Following the injury they regain a normal level of consciousness, but usually have an ongoing and often severe headache (due to the stripping of the dura away from the bone). Over then next few hours they gradually loose consciousness.
Due to the long cisternal course of the sixth cranial nerve (abducens nerve (CN VI)), it is often involved as downward herniation begins, usually on the side of the haemorrhage and can, in an emergency, guide exploratory burrholes.
The source of bleeding is typically from a torn meningeal artery, usually middle meningeal artery. An associated skull fracture is present in ~ 80% of cases. As the dura is stripped from the bone, pain is caused. In about 5 - 10% of patients the EDH is posterior fossa. Occasionally an EDH can form due to venous blood, typically a torn sinus with associated fracture.
Young patients being affected is not only a product of the prevalent demographics of patients with head injury, but also relates to the changes which occur in the dura in older patients. Anyone who has performed or assisted in crainotomies on older patients will know how much more tenaciously the dura adheres to the skull.
In almost all cases, extradural haematomas are seen on CT scans of the brain. They are typically bi-convex (or lentiform) in shape, and most frequently beneath the squamous part of the temporal bone. They are hyperdense, somewhat heterogenous, and sharply demarkated. Depending on their size, secondary features of mass effect (e.g. midline shift, subfalcine herniation, uncal herniation) may be present.
When acute bleeding is occurring at the time of CT scanning the non-clotted fresh blood is typically less hyper dense, and a swirl sign may be evident 1.
An extradural haematoma is essentially a sub-periosteal haematoma located on the inside of the scalp, between bone and outer layer of the dura (which is actually the periosteum). As a result it is limited by the sutures, which is helpful in distinguishing these from subdural haematomas (see below). Extradural haemorrhages can however, cross and elevate venous sinuses as long as there is no suture there.
Treatment and prognosis
Prognosis, even with a relatively large haemotoma, is in general quite good, as long as the clot is evacuated in time. A smaller haematoma can be treated conservatively 2, sometimes resulting in calcification of the dura.
Occasionally delayed complications are encountered, usually relating to the injured meningeal vessel. They include:
In large hematomas, there is rarely significant confusion as to the correct diagnosis. In smaller lesions, especially when there is associated parenchymal injury (e.g. cerebral contusions, traumatic subarachnoid blood, concurrent subdural haematoma) the diagnosis can be more challenging.
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- 1. Al-Nakshabandi NA. The swirl sign. Radiology. 2001;218 (2): 433. Radiology (full text) - Pubmed citation
- 2. Sullivan TP, Jarvik JG, Cohen WA. Follow-up of conservatively managed epidural hematomas: implications for timing of repeat CT. AJNR Am J Neuroradiol. 1999;20 (1): 107-13. AJNR Am J Neuroradiol (full text) - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Extradural haemorrhage (EDH)||✗|
|Extra dural haematoma||✗|