Epidural hematoma (EDH) is characterized by a blood collection in the potential space between skull and dura (epidural space).
Etiology and Phatophysiology
Both traumatic and non-traumatic etiologies are discussed. Traumatic head injuries are the most important etiology.
Traumatic head injury
A high-speed head injury produced by a lateral acceleration along the diameter of the skull can produce injury to vessels or brain parenchyma resulting in both a SDH, epidural hematoma or contusion.
Note that one of the differences between SDH (subdural hematoma) and EDH is that in EDH the vessel that is more frequently damaged is the middle meningeal artery: this result in an hemorrhage in the cerebral convexity in the middle cranial fossa.
Occasionally the hemorrhage can occur in both the anterior cranial fossa, if the anterior meningeal artery is damaged, and at the vertex due to a dural arteriovenous fistula.
Non-traumatic acute EDH
- Hemorragic tumors, vascular malformations of the dura, congenital malformations, infections
- Complication of neurosurgical procedures
- Epidural abscess that produce necrosis of the meningeal vessels
70-80% of the EDH are located in the temporoparietal region in the setting of a skull fracture that transverse the course of the middle meningeal artery. Instead, frontal and occipital EDH account for 10% of EDHs.
A damage of a dural sinus or of a confluence of sinuses can produce an hemorrhage in the posterior cranial fossa.
Other pathologies that cause non-traumatic EDH: sickle-cell disease, LES, cardiac open surgery, Paget disease, hemodialysis
As with SDH, EDH can present a lot of different symptoms and signs.
- Lucid interval: in 47% of cases, after the injury there is a period followed by a progressive neurological decline to coma. This presentation is characteristic of a continuous arterial bleeding.
- High ICP in unchecked SDH:
- Ipsilateral dilated pupil due to uncal herniation (compression of the III CN)
- Cushing reflex (hypertension, bradycardia, respiratory depression/irregularity)
- Cortical blindness due to bioccipital dysfunction in the setting of posterior cranial fossa bleeding.
- Spinal EDH: paraparesis, back pain, sensory loss with discernible level, bladder or bowel dysfunction
In the setting of a traumatic brain injury a variety of lesions (fractures, contusions, hemorrages, etc.) could happen. It’s important to recognize and treat those that are life-threatening.
The finding of a mixed density blood clot (isodense and hypodense) suggest a continue bleeding and it’s an indication for surgery.
Air in acute EDH suggest fractures of sinuses or mastoid air cells.
Note that SDH can cross the sutural margins but is limited by dural attachments. Instead, epidural hematomas are limited by sutural margins but can cross dural attachments so it has a lens-shape appearance.
A non-diagnostic head CT can be present in 8% of cases, particularly if there is some conditions:
- Severe anemia that lower the density of the blood clot
- Severe hypotension that cause a minor blood flow
- Too early scanning
- Venous bleeding with slow collection of blood
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Giorgio Saraceno, MS
University of Brescia (Italy)
Antonio D'Ammando, MD
University of Milan (Italy)