A head injury can tear or rupture blood vessels inside the skull causing contusion, hemorrhage or hematoma. Because all these terms are associated with bleeding, they can be confusing. Here is what they mean.
Contusion generally refers to any type of bruise. A bruise occurs when an injury damages blood vessels under the skin and they leak below the skin surface, usually causing a large purple lump.
A brain contusion (or “cerebral contusion”) is similar except you can’t see the bruise because it’s hidden inside the skull. A contusion differs from a concussion because while a concussion may cause brain injury it does not cause significant bleeding.
Some brain contusions can be minor and will heal on their own without any specific treatment. A severe contusion can be life threatening, however, as blood leaking into the skull cavity exerts pressure on the brain which can cause additional brain damage.
Hemorrhage means bleeding. Any time a blood vessel is broken and bleeding, whether internally or externally, it’s referred to as a hemorrhage. A brain hemorrhage describes broken blood vessels in the brain and may also be called:
- Cerebral hemorrhage
- Intracerebral hemorrhage
- Intra-axial hemorrhage
A brain hemorrhage is often serious because blood collecting inside the skull’s confined space creates pressure on delicate brain tissues potentially causing irreparable brain damage. In cases of brain hemorrhage, doctors will monitor the intracranial pressure and perform surgery to drain the fluid buildup if necessary. (See Types of Brain Surgery for Head Injuries.)
Hematoma describes a collection of blood in the body’s tissues. A bruise or contusion is also a hematoma. In head injuries, internal bleeding is often described based on how deep it is in relation to the three layers of the meninges. The meninges is the membrane surrounding the brain. Its layers from outside to inside are the:
- Dura mater
- Arachnoid mater
- Pia mater
An epidural hematoma is in the space below the skull bone and above the outer layer of the membrane surrounding the brain (the dura mater). The bleeding causing an epidural hematoma is typically associated with a skull fracture. Bleeding is typically from arteries and the onset of symptoms is rapid. In these cases, there is often minimal initial brain injury and chances of recovery are excellent with prompt treatment.
A subdural hematoma is in the space below the outer layer (dura mater) and above the middle layer of the membrane surrounding the brain (the arachnoid mater). It is often caused by violent movement to the head resulting in torn veins passing between these layers. Because there is no visible head injury and veins bleed slower than arteries, symptoms may not appear for a day or a week or more. The seriousness of the injury depends on the amount of bleeding.
A subarachnoid hematoma is in the space below the middle layer (arachnoid mater) and above the lower layer of membrane surrounding the brain. While often associated with a cerebral aneurysm (stroke), a skull fracture can also cause a subarachnoid hematoma. Approximately half of those suffering this type of injury will endure some degree of life-long impairment or chronic headache.
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