Etiology

• Head injury (most common; e.g., due to motor vehicle accidents, falls, assault)

• Traumatic removal of epidural catheter (especially in patients taking on anticoagulation medication)

• Infections

• Coagulopathies

• Dural vascular malformation

• Dural metastases

• Source: middle meningeal artery rupture or tear (a branch of the maxillary artery and the most common source of hemorrhage in EDH)

• Sites of rupture

  • Pterion (most common): the thinnest part of the skull and a site at which the middle meningeal artery lies in close proximity to the skull

  • Skull base (foramen spinosum)

(rare)

• Source

  • Middle meningeal vein rupture or tear

  • Dural venous sinus injury

  • Rupture of a dural vascular malformation

• Sites of rupture [7]

  • Posterior fossa (injury to the transverse sinus, sigmoid sinus, or confluence of venous sinuses)

  • Middle cranial fossa (sphenoparietal sinus injury)

  • Vertex (superior sagittal sinus injury)

• Head trauma (usually severe) → skull fracture → rupture of middle meningeal artery (most common) → hemorrhage into the epidural space, typically in the temporal or temporoparietal region [2][9]

• Venous shunting of blood out from the epidural space and initial asymptomatic compression of the anterior temporal lobe → lucid interval [2][10]

• Continued expansion of EDH → increased intracranial pressure → transtentorial uncal herniation (Monro-Kellie principle) which leads to: [2]

  • Compression of the ipsilateral oculomotor nerve and loss of parasympathetic supply to the pupillary sphincter → ipsilateral dilated pupil (anisocoria)

  • Compression of the brain stem → rapid neurological decline, Cushing triad, and either of the following:

    • Compression of ipsilateral cerebral peduncle (more common) → contralateral hemiparesis

    • Compression of the contralateral cerebral peduncle against the contralateral tentorial edge (less common) → ipsilateral hemiparesis (false localizing sign known as Kernohan syndrome)

• Unrelieved brain stem compression → coma and death