An intracranial hematoma is a collection of blood within the skull. The blood may collect in the brain tissue or underneath the skull, pressing on the brain. It's usually caused by a blood vessel that bursts in the brain. It also may be caused by a head injury due to a car accident or fall.

Some head injuries, such as one that causes only a short period of unconsciousness, can be minor. However, an intracranial hematoma is potentially life-threatening. It usually requires immediate treatment. This might include surgery to remove the blood.

The most common cause of an intracranial hematoma is a head injury. A head injury that causes bleeding within the skull may result from motor vehicle or bicycle accidents, falls, assaults, and sports injuries.

If you're an older adult, even mild head trauma can cause a hematoma. This is especially true if you're taking a blood-thinning medicine or an anti-platelet medicine, such as aspirin.

A head injury can cause an intracranial hematoma even if there's no open wound, bruise or other obvious damage.

What happens in the brain to cause bleeding varies based on the type of hematoma. There are three categories of hematoma — subdural hematoma, epidural hematoma and intracerebral hematoma. An intracerebral hematoma also is known as an intraparenchymal hematoma.

Subdural hematoma

A subdural hematoma occurs when blood vessels burst between the brain and the outermost of three protective layers that cover the brain. This outermost layer is called the dura mater. The leaking blood forms a hematoma that presses on brain tissue. A hematoma that gets bigger can cause gradual loss of consciousness and possibly death.

Subdural hematomas can be:

• Acute. This most dangerous type is generally caused by a bad head injury, and symptoms usually appear immediately.
• Subacute. Symptoms take time to develop, sometimes days or weeks after a head injury.
• Chronic. The result of less severe head injuries, this type of hematoma can cause slow bleeding, and symptoms can take weeks and even months to appear. You might not remember hurting your head. For example, bumping your head while getting into the car can cause bleeding, especially if you're on a blood-thinning medicine.

All three types require medical attention as soon as symptoms appear. Prompt medical care may prevent permanent brain damage.

Epidural hematoma

An epidural hematoma occurs when a blood vessel bursts between the outer surface of the dura mater and the skull. Blood then leaks between the dura mater and the skull to form a mass that presses on brain tissue. The most common cause of an epidural hematoma is a head injury. This type also is called an extradural hematoma.

Some people with an epidural hematoma remain conscious. But most become drowsy or go into a coma from the moment of injury. An epidural hematoma that affects an artery in your brain can be deadly without prompt treatment.

Intracerebral hematoma

An intracerebral hematoma occurs when blood pools in the tissues of the brain. An intracerebral hematoma also is called an intraparenchymal hematoma. There are many causes, including:

• A head injury, which can result in multiple intracerebral hematomas.
• A rupture of a bulging blood vessel, known as an aneurysm.
• Poorly connected arteries and veins from birth.
• High blood pressure.
• Tumors.
• Some diseases can cause sudden leakage of blood into the brain.

Intracranial hematomas can be caused by a head injury. Activities that increase the risk of a bad head injury, such as riding a motorcycle or bicycle without a helmet, also raise the risk of an intracranial hematoma.

The risk of a subdural hematoma increases with age. The risk also is greater for people who:

• Take aspirin or another blood-thinning medicine daily.
• Have alcohol use disorder.

Some conditions also may increase the risk of having an intracerebral hematoma. They include being born with poorly connected arteries and veins, and having a bulging blood vessel in the brain, known as an aneurysm. High blood pressure, tumors and some diseases also increase the risk.

To prevent or minimize a head injury that may cause an intracranial hematoma:

• Wear a helmet and make sure your kids wear helmets. Wear an appropriate and properly fitted helmet when doing any activity that could result in head injury. This includes while playing contact sports, bicycling, motorcycling, skiing, horseback riding, skating, skateboarding and snowboarding.
• Buckle your seat belt and make sure your kids are buckled in. Do so every time you drive or ride in a motor vehicle.
• Protect young children. Always use properly fitted car seats. Pad countertops and edges of tables, block stairways, and attach heavy furniture or appliances to the wall to prevent tipping. Keep children from climbing on objects that aren't safe or steady. Place safety gates on stairs and guards on windows.

Diagnosing an intracranial hematoma can be a challenge because people with a head injury may seem fine at first. Healthcare professionals usually assume that bleeding inside the skull is the cause of a loss of consciousness after a head injury until proved otherwise.

Imaging techniques are the best ways to determine the position and size of a hematoma. These include:

• CT scan. This uses a sophisticated X-ray machine linked to a computer to produce detailed images of your brain. You lie still on a movable table that's guided into what looks like a large doughnut where the images are taken. CT is the most commonly used imaging scan to diagnose intracranial hematomas.
• MRI scan. This is done using magnetic field and radio waves to make computerized images. During an MRI scan, you lie on a movable table that's guided into a tube.
• Angiogram. If there is concern about a possible aneurysm in the brain or other blood vessel issue, an angiogram can provide more information. This test uses X-rays and a special dye to produce pictures of the blood flow in the blood vessels in the brain.

Intracranial hematomas that are small and produce no symptoms don't need to be removed. However, symptoms can appear or worsen days or weeks after the injury. As a result, you might have to be watched for neurological changes, have your intracranial pressure monitored and undergo repeated head CT scans.

If you take blood-thinning medicine, such as warfarin (Jantoven), you may need therapy to reverse the effects of the medicine. This will reduce the risk of further bleeding. Options for reversing blood thinners include giving vitamin K and fresh frozen plasma.

Surgery

Intracranial hematoma treatment often involves surgery. The type of surgery depends on the type of hematoma you have. Options include:

• Surgical drainage. If the blood is in one area and has changed from a solid clot to a liquid, your doctor might create a small hole in your skull and use suction to remove the liquid.
• Removing part of the skull, known as a craniotomy. Large hematomas might require that a section of your skull be opened to remove the blood.

Recovery

Recovery after an intracranial hematoma can take a long time, and you might not recover completely. The greatest recovery happens up to six months after the injury, usually with lesser improvement after that. If you continue to have neurological symptoms after treatment, you might need occupational and physical therapy.

Patience is important for coping with brain injuries. The majority of recovery for adults happens during the first six months. Then you might have smaller, more-gradual improvements for up to two years after the hematoma.

To aid your recovery:

• Get enough sleep at night, and rest in the daytime when you feel tired.
• Ease back into your typical activities when you feel stronger.
• Don't participate in contact and recreational sports until you get your doctor's OK.
• Check with your healthcare team before you begin driving, playing sports, riding a bicycle or operating heavy machinery. Your reaction times likely will have slowed as a result of your brain injury.
• Check with your healthcare team before taking medicine.
• Don't drink alcohol until you've recovered fully. Alcohol may slow recovery, and drinking too much can increase your risk of a second injury.
• Write down things you have trouble recalling.
• Talk with someone you trust before making important decisions.