Types of Stroke
Hemorrhagic stroke occurs when a blood vessel in the brain ruptures and bleeds into surrounding tissue. The bleeding compresses nearby blood vessels and deprives surrounding tissue of oxygen, causing stroke. Hemorrhagic stroke usually affects a large area of the brain, is severe, and carries a high risk for death.
Intracranial hemorrhages occur when blood vessels located between the brain and the skull rupture. They can result from traumatic brain injury (TBI) or develop spontaneously as the result of a blood vessel defect or weakness such as a bulge in an artery (aneurysm) or arteriovenous malformation (AVM).
Blood vessel defects can be present at birth (congenital; e.g., berry aneurysm, arteriovenous malformation) or acquired (e.g., atherosclerotic aneurysm). Atherosclerotic aneurysm develops when plaque build-up weakens the arterial wall.
Intracranial hemorrhage occurs in the space between the brain and the skull, or cranium. Three membranes-the dura, arachnoid, and pia-surround the brain and spinal cord.
Epidural hematoma (i.e., a collection of blood) develops in the potential space between the outer membrane (dura) and the skull.
Subdural hematoma develops in the potential space between the dura and the middle layer membrane (arachnoid). This condition may become chronic when shrinkage (atrophy) of the brain (often seen in elderly patients) allows the brain to move more freely within the skull. High velocity impact to the skull may cause acute subdural hematoma, which is often fatal.
Subarachnoid hemorrhage develops in the cerebrospinal fluid-filled space between the arachnoid and the inner membrane (pia), which contains major blood vessels. Subarachnoid hemorrhages are usually caused by a ruptured aneurysm or head injury.
Intracerebral hemorrhage occurs in blood vessels located in the cerebrum, brain stem, cerebellum, or spinal cord.