A cerebral hemorrhage destroys a blood vessel in the brain, causing blood to accumulate in the brain tissue and resulting in damage. A cerebral hemorrhage can occur as a result of a blow to the head (trauma) or when a hemorrhage starts due to a deformity in the blood vessels. Hemorrhages without blood vessel deformity also occur. This often goes hand in hand with existing, prolonged high blood pressure, or when proteins accumulate in the blood vessels (cerebral amyloid angiopathy).
The distinction between different types of hemorrhages is made on the basis of:
the space inside the skull where the blood accumulates
the reason why the blood vessel breaks down (the underlying disorder or “etiology”)
Location of the hemorrhage
If we make a distinction based on where the hemorrhage occurs, then there are 4 types:
Intracerebral or intraparenchymal hemorrhages. These hemorrhages are located in the brain tissue.
Subarachnoid hemorrhages. These hemorrhages take place under (“sub”) the spiderweb-like tissue (“arachnoid”) and the brain. That is why they are called subarachnoid hemorrhages.
Subdural hemorrhages. These hemorrhages occur under (“sub”) the meninges (“dura”). Hence the name subdural hemorrhages.
Epidural hemorrhages. These hemorrhages occur on (“epi”) the meninges (“dura”). Hence the name epidural hemorrhages.
Cause of the hemorrhage
The cause of the blood vessel rupture depends on where the hemorrhage occurs. Overlap is also possible, as you can see below.
Hemorrhage from a brain aneurysm causes subarachnoid hemorrhages, but sometimes intracerebral hemorrhages as well.
Vascular malformations in the brain usually cause intracerebral hemorrhages, but sometimes subarachnoid hemorrhages as well.
Traumatic head injury can result in subdural and epidural hemorrhages, but can also cause subarachnoid and intracerebral hemorrhage.