An intracranial hemorrhage
is a hemorrhage
, or bleeding, within the skull
Intracranial bleeding occurs when a blood vessel
within the skull is ruptured or leaks. It can result from physical trauma
(as occurs in head injury
) or nontraumatic causes (as occurs in hemorrhagic stroke
) such as a ruptured aneurysm
therapy, as well as disorders with blood clotting
can heighten the risk that an intracranial hemorrhage will occur.
Intracranial hemorrhage is a serious medical emergency
because the buildup of blood within the skull can lead to increases in intracranial pressure
, which can crush delicate brain tissue or limit its blood supply. Severe increases in intracranial pressure can cause potentially deadly brain herniation
, in which parts of the brain are squeezed past structures in the skull.
CAT scan (computed axial tomography
) is the definitive tool for accurate diagnosis of an intracranial hemorrhage.
Types of intracranial hemorrhage are roughly grouped into intra-axial and extra-axial. The hemorrhage is considered a focal brain injury
; that is, it occurs in a localized spot rather than causing diffuse damage over a wider area.
Intra-axial hemorrhage is bleeding within the brain itself, or cerebral hemorrhage. This category includes:
Extra-axial hemorrhage, bleeding that occurs within the skull but outside of the brain tissue, falls into three subtypes:
- Epidural hemorrhage which occur between the dura mater (the outermost meninx) and the skull, is caused by trauma. It may result from laceration of an artery, most commonly the middle meningeal artery. This is a very dangerous type of injury because the bleed is from a high-pressure system and deadly increases in intracranial pressure can result rapidly.
- Patients have a loss of consciousness (LOC), then a lucid interval, then sudden deterioration (vomiting, restlessness, LOC)
- Head CT shows lenticular (convex) deformity.
- Subdural hemorrhage results from tearing of the bridging veins in the subdural space between the dura and arachnoid mater.
- Head CT shows crescent-shaped deformity
- Subarachnoid hemorrhage, which occur between the arachnoid and pia meningeal layers, like intraparenchymal hemorrhage, can result either from trauma or from ruptures of aneurysms or arteriovenous malformations. Blood is seen layering into the brain along sulci and fissures, or filling cisterns (most often the suprasellar cistern because of the presence of the vessels of the circle of Willis and their branchpoints within that space). The classic presentation of subarachnoid hemorrhage is the sudden onset of a severe headache (a thunderclap headache). This can be a very dangerous entity, and requires emergent neurosurgical evaluation, and sometimes urgent intervention.
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