An intracranial hematoma occurs when a blood vessel - either an artery or a vein - ruptures between your skull and your brain. Blood then leaks between your brain and your skull. Although head injuries can be minor, an intracranial hematoma is a serious and possibly life-threatening condition often requiring immediate treatment.

Your brain floats within your skull and is surrounded by cerebrospinal fluid, which cushions it from the light bounces of everyday movement. But the fluid may not be able to absorb the force of a sudden blow or a quick stop. In these situations, your brain may slide forcefully against the inner wall of your skull and become bruised.

An intracranial hematoma occurs when a blood vessel - either an artery or a vein - ruptures between your skull and your brain. Blood then leaks between your brain and your skull. The collection of blood (hematoma), possibly clotted, compresses brain tissue.

Treating hematomas usually requires surgery to remove the blood. However, smaller hematomas may not require removal of the blood.

Signs and symptoms

Signs and symptoms of an intracranial hematoma may occur from immediately to several weeks or more after a blow to your head. As time progresses, pressure on your brain increases, producing some or all of the following signs and symptoms:

• Headache

• Nausea

• Vomiting

• Change in level of consciousness

• Pupils of unequal size

• Weakness in limbs on one side of your body

• Headache

• Nausea

• vomiting

As more and more blood flows into the narrow space between your brain and skull, other signs and symptoms may become apparent, such as:

• Progressive lethargy

• Unconsciousness

An intracranial hematoma can be life-threatening. Emergency medical treatment often is necessary.

Causes

Intracranial bleeding (hemorrhage) is caused by an injury to the head, often as a result of automobile or motorcycle accidents or a seemingly trivial event, such as bumping your head. Mild head trauma is more likely to cause a hematoma if you are elderly. There may be no open wound, bruise or other outward sign. If a hematoma results from the injury to your head, it may occur as either a subdural hematoma or an epidural hematoma.

Subdural hematoma
This occurs when blood vessels — usually veins — rupture between your brain and the outermost of three membrane layers that cover your brain (dura mater). The leaking blood forms a hematoma that compresses the brain tissue. If the hematoma keeps growing, a progressive decline in consciousness occurs, possibly resulting in death.

Hematomas with the onset of prominent symptoms occurring within 48 hours (acute hematoma) are often fatal with or without immediate surgery, and death may occur despite prompt medical attention. Hematomas with the onset of symptoms between 48 hours and two weeks (subacute) or onset of symptoms after two weeks (chronic) have less risk, but they also require medical attention as soon as signs and symptoms are apparent, or permanent brain damage may result. The risk is greater for people who use aspirin and anticoagulants daily.

Epidural hematoma
This occurs when a blood vessel — usually an artery — ruptures between the outer surface of the dura mater and the skull. The blood vessel usually is damaged by a skull fracture. Blood then leaks between the dura mater and the skull to form a mass that compresses the brain tissue.

Although only a small percentage of head injuries result in acute hemorrhage outside the dura mater, the risk of dying is substantial unless prompt treatment occurs. Some people with this type of injury may remain conscious, but most become drowsy or comatose from the moment of trauma.

When to seek medical advice

Seek medical advice after any significant blow to the head in which you lose consciousness or experience any of the signs and symptoms listed above. Although symptoms of intracranial hematoma may not be immediately apparent, watch closely for subsequent physical, mental and emotional changes.

In addition, tell a family member or a close friend if you suffer head trauma. Because memory loss often is associated with a blow to the head, a person may forget there ever was a hit to the head until after the diagnosis or treatment. An alerted friend, family member or work colleague may be more likely to recognize the warning signs and arrange for prompt medical attention if aware of your history.