Intracranial hematomas are accumulations of blood within the brain or between the brain and the skull.
Intracranial hematomas form when a head injury causes blood to accumulate within the brain or between the brain and the skull.
Symptoms may include a persistent headache, drowsiness, confusion, memory changes, paralysis on the opposite side of the body, speech or language impairment, and other symptoms depending on which area of the brain is damaged.
Computed tomography or magnetic resonance imaging is used to detect an intracranial hematoma.
Sometimes surgery is needed to drain blood from a hematoma.
Intracranial hematomas include
Epidural hematomas, which form between the skull and the outer layer (dura mater) of tissue covering the brain (meninges)
Subdural hematomas, which form between the outer layer and the middle layer (arachnoid mater—see Figure: Viewing the Brain)
Intracerebral hematomas, which form within the brain
After injury, bleeding can also occur between the arachnoid mater and the inner layer (pia mater). Bleeding in this area is called subarachnoid hemorrhage. However, because subarachnoid blood usually does not accumulate in one place, it is not considered a hematoma.
For people who are taking aspirin or anticoagulants (which increase the risk of bleeding), particularly older people, the risk of developing a hematoma after even a minor head injury is increased. Intracerebral hematomas and subarachnoid hemorrhages can also result from strokes.
Most epidural and intracerebral hematomas and many subdural hematomas develop rapidly and cause symptoms within minutes. Large hematomas press on the brain and may cause swelling and herniation of the brain. Herniation may cause loss of consciousness, coma, paralysis on one or both sides of the body, breathing difficulties, slowing of the heart, and even death.
Some hematomas, particularly subdural hematomas, may develop slowly and cause gradual confusion and memory loss, especially in older people. These symptoms are similar to those of dementia. People may not remember the head injury.
Diagnosis is usually based on results of computed tomography (CT). Treatment depends on the type and size of the hematoma and how much pressure has built up in the brain.
Pockets of Blood in the Brain
Epidural hematomas are caused by bleeding from an artery or a large vein (venous sinus) located between the skull and the outer layer of tissue covering the brain. Bleeding often occurs when a skull fracture tears the blood vessel.
A severe headache may develop immediately or after several hours. The headache sometimes disappears but returns several hours later, worse than before. Deterioration in consciousness, including increasing confusion, sleepiness, paralysis, collapse, and a deep coma, can quickly follow. Some people lose consciousness after the injury, regain it, and have a period of unimpaired mental function (lucid interval) before consciousness deteriorates again. People may develop paralysis on the side of the body opposite the hematoma, speech or language impairment, or other symptoms, depending on which area of the brain is damaged (see Brain Dysfunction by Location).
Early diagnosis is crucial and is usually based on results of CT. Doctors treat epidural hematomas as soon as they are diagnosed. Prompt treatment is necessary to prevent permanent damage. Usually, one or more holes are drilled in the skull to drain the excess blood. The surgeon also seeks the source of the bleeding and stops the bleeding.
Subdural hematomas are usually caused by bleeding from veins, including the bridging veins, located between the outer and middle layers of tissue covering the brain (meninges). Occasionally, subdural hematomas are caused by bleeding from arteries.
Subdural hematomas may be acute, subacute, or chronic. Rapid bleeding after a severe head injury can cause acute subdural hematomas, with symptoms that develop over minutes or a few hours, or subacute subdural hematomas, with symptoms that develop over several hours or days. Chronic subdural hematomas can develop over weeks, months, or years. By the time symptoms occur, the hematoma may be very large.
Chronic subdural hematomas are more common among people with alcoholism, older people, and people who take anticoagulant drugs (blood thinners). People with alcoholism, who are relatively prone to falls as well as bleeding, may ignore or forget minor to moderately severe head injuries. These injuries can lead to small subdural hematomas that may become chronic. In older people, the brain shrinks slightly, stretching the bridging veins and making them more likely to be torn if an injury, even a minor one, occurs. Also, bleeding tends to continue longer because the shrunken brain exerts less pressure on the bleeding vein, allowing more blood loss from it. Blood that remains after a subdural hematoma is slowly reabsorbed. After the blood is resorbed from a hematoma, the brain may not re-expand as well in older people as in younger people. As a result, a fluid-filled space (hygroma) may be left. The hygroma may refill with blood or enlarge because small vessels tear, causing repeated bleeding.
Symptoms may include a persistent headache, fluctuating drowsiness, confusion, memory changes, paralysis on the side of the body opposite the hematoma, and speech or language impairment. Other symptoms may occur depending on which area of the brain is damaged (see Brain Dysfunction by Location). In infants, a subdural hematoma can cause the head to enlarge (as in hydrocephalus) because the skull is soft and pliable. Therefore, pressure within the skull increases less in infants than it does in older children and adults.
Chronic subdural hematomas are more difficult to diagnose because of the length of time between the injury and the development of symptoms. An older person with gradually developing symptoms, such as memory impairment and drowsiness, may be mistakenly thought to have dementia. CT can detect acute, subacute, and many chronic subdural hematomas. Magnetic resonance imaging (MRI) is particularly accurate for diagnosis of chronic subdural hematomas.
Often, small subdural hematomas in adults do not require treatment because the blood is absorbed on its own. If a subdural hematoma is large and is causing symptoms such as persisting headache, fluctuating drowsiness, confusion, memory changes, and paralysis on the opposite side of the body, doctors usually drain it surgically, sometimes by drilling a small hole in the skull. However, sometimes a larger opening must be made in the skull, for example when bleeding has occurred very recently, when the blood may be too thick to drain through a small hole. During surgery, a drain is usually inserted and left in place for several days, because subdural hematomas can recur. The person is monitored closely for recurrences. In infants, doctors usually drain the hematoma for cosmetic if for no other reasons.
Only about 50% of people who are treated for a large acute subdural hematoma survive. People who are treated for a chronic subdural hematoma usually improve or do not worsen.
Intracerebral hematomas are common after a severe head injury. They are caused by bruising of the brain (a cerebral contusion). People may develop drowsiness, confusion, paralysis on the side of the body opposite the hematoma, speech or language impairment, or other symptoms, depending on which area of the brain is damaged (see Brain Dysfunction by Location). Fluid accumulation in the damaged brain (cerebral edema) is common and accounts for most deaths. CT or MRI can detect intracerebral hematomas.
Because these hematomas are caused by direct damage to the brain, surgery is usually avoided because it usually does not restore brain function. Also, because the hematomas are within the brain tissue, doctors must remove the overlying brain to get at the hematoma, which also contributes to loss of brain function.