Anatomy
Summary
An epidural hematoma occurs when blood accumulates between the skull and the dura mater, usually caused by an injury to the middle meningeal artery located at the pterion, the skull's weakest junction. Characteristic features include initial loss of consciousness, a lucid interval, and then rapid deterioration of mental status. On a CT scan, these hematomas present as lens-shaped and do not cross suture lines. In contrast, subdural hematoma results from torn bridging veins between the dura and arachnoid mater. These hematomas can be acute or chronic, manifesting as severe mental changes or a gradually worsening headache, respectively. Their crescent-shaped appearance on CT scan distinguishes them, and unlike epidural hematomas, they do cross suture lines.
Moving further into the cerebral layers, a subarachnoid hemorrhage occurs between the arachnoid and pia maters, often due to a ruptured berry aneurysm or arteriovenous malformations (AVMs). They frequently present with a 'thunderclap headache,' accompanied by signs of meningeal irritation. CT scans reveal blood within the sulci of the brain surface. Lastly, a rare but crucial type of cranial hemmorhage is a subgaleal hemorrhage, which happens extracranially between the galea aponeurotica and the skull periosteum, commonly as a complication of vacuum-assisted deliveries.
Lesson Outline
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FAQs
Intracranial hemorrhages are bleeding that occurs inside the skull, while extracranial hemorrhages refers to bleeding that happens outside the skull but within the scalp
An epidural hematoma typically occurs due to a severe skull fracture due to damage to the middle meningeal artery, which courses through the area of the skull known as the pterion. Tearing of this artery can result in accumulation of blood between the dura mater and the skull, and have a characteristic lens-shape on CT.
An wpidural hematoma is typically associated with traumatic injury and occurs between the dura mater and the skull. A Subdural Hematoma, on the other hand, occurs between the dura mater and arachnoid mater. Subdural hematomas often result from tearing of the bridging veins and can present acutely following trauma or chronically, especially in elderly or alcohol-abusing patients.
A subarachnoid hemorrhage is bleeding into the subarachnoid spaceÑthe area between the arachnoid membrane and the pia mater surrounding the brain. This is often due to rupture of a cerebral aneurysm, such as a berry aneurysm. These aneurysms are small, berry-shaped outpouchings of blood vessels with a high tendency to rupture and bleed, leading to a Subarachnoid Hemorrhage.
A Subgaleal Hemorrhage is a type of Extracranial Hemorrhage, occurring in the space between the scalp's galea aponeurotica and periosteum. This type of hemorrhage is most commonly seen in newborns following delivery and can result from minor trauma or a complication of a vacuum-assisted delivery. The bleeding usually resolves on its own, however, if severe, it may lead to shock in the newborn due to blood loss.
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