Intracranial bleeding refers to the accumulation of blood within the skull due to rupture of a blood vessel.
The brain is covered by three layers of membranes (meninges), which are called (from the innermost layer to the outermost) the pia mater, the arachnoid, and the dura mater. In intracranial bleeding, blood can accumulate in the spaces between these layers. Intracranial bleeding is said to be extra-axial, meaning that the blood collects between the pia and arachnoid (subarachnoid hemorrhage) meninges; between the arachnoid and dura (subdural * ) meninges; or between the dura mater and the skull (epidural * hemorrhage). Intracranial bleeding is said to be “intraaxial” when blood accumulates within the brain substance (intracerebral hemorrhage or ICH) or in the spaces within the brain (ventricles) where the fluid called cerebrospinal fluid * circulates. Bleeding into the brain's ventricular system is called intraventricular hemorrhage. In general, intracranial bleeding refers to bleeding within the brain or the ventricles.
At the base of the brain lies the Circle of Willis, a network of interconnecting arteries * that routes blood to the cerebrum, a vital part of the brain that has such functions as directing the body's movements; processing information from the eyes, ears, nose, and taste buds so that a person can see, hear, smell, and taste; allowing a person to learn and to remember; and helping a person to communicate. The Circle of Willis is formed by the anterior (front), middle, and posterior (rear) cerebral arteries (one on each side of the brain); the anterior communicating artery (between the two anterior cerebral arteries); and the posterior communicating artery (between the middle and posterior cerebral artery on each side). Each of these arteries subdivides into smaller branches that penetrate the brain substance and give rise to end arteries. These end arteries are often the source of bleeding in intracerebral hemorrhage and subarachnoid hemorrhage. Subdural hemorrhage can occur either from a vein *
Each year, about 12 to 15 intracerebral hemorrhages occur per 100,000 people in the United States. Intracerebral hemorrhages account for 13 percent of all strokes. Intracerebral hemorrhage is more common in Asians, Hispanics, and African Americans than in Caucasians. It is also slightly more common in men than in women.
In addition, older people are more likely than younger adults to experience an intracerebral hemorrhage, and the incidence of intracerebral hemorrhage doubles with each decade above the age of 55. This increase occurs primarily because the percentage of people with hypertension (commonly called high blood pressure) increases as the population ages, and hypertension is a risk factor for intracerebral hemorrhage. However, the incidence of intracerebral hemorrhage has declined in the United States since the 1950s.
Risk factors for intracranial bleeding include old age, hypertension, high alcohol intake, membership in high-risk groups (for example, African Americans experience intracerebral hemorrhage 1.4 times as often as Caucasians), male sex, and use of blood thinners. Trauma * , hypertension, and amyloid angiopathy (deposits of abnormal proteins called amyloids formed on the walls of blood vessels in the central nervous system) are the most common causes.
Intracranial bleeding may result from trauma, such as penetrating injuries, including skull fractures in which the fractured bone is pushed inward into the brain, or acceleration-deceleration injuries that result from motor vehicle accidents. Such traumatic hemorrhages can be epidural, subdural, subarachnoid, or intracerebral. Traumatic hemorrhage in children often results from so-called shaken baby syndrome, in which a parent or other stronger individual violently shakes a child, causing the thin-walled blood vessels in the head to rupture.
Many people who experience nontraumatic intracerebral hemorrhage have hypertension. Individuals with high blood pressure are two to six times more likely to have such a hemorrhage, because hypertension weakens the wall of the blood vessel, making it more susceptible to spontaneous rupture. The common areas for a hypertensive hemorrhage are the deeper parts of the brain, which include the basal ganglia, cerebellum * , brain stem * , and ventricles.
Intracranial bleeding can also result from a condition called cerebral amyloid angiopathy. This condition, which is a disease that occurs primarily in older patients, causes abnormal proteins called amyloids (AHmee-loyds) to build up along blood vessel walls, which leads to their rupture. These ruptures primarily occur in the parietal and occipital areas (the upper middle and the back) of the cerebral cortex * and cerebellum.
Intracranial bleeding due to malformations * of the blood vessels, especially in young patients, arises from certain bulges (aneurysms) in blood vessel walls; from a tangle of abnormal veins (cavernous malformations); or from a tangle of abnormal connections between arteries and veins (arteriovenous malformations). When children have intracranial bleeding that is not the result of trauma, the culprit is often an arteriovenous malformation, which is a birth defect. Scientists are not sure exactly what causes it, but a family history of certain medical conditions may make a child more likely to develop an arteriovenous malformation. Such an abnormal connection between an artery and a vein may occur at various locations on the body, but the most frequent location is the head. Treatment for these malformations may include a type of radiation therapy called proton-beam radiation; a nonsurgical technique called embolization that injects material to block blood vessels; or the surgical removal of the abnormal blood vessels.
If the blood becomes excessively thin (coagulopathy) due to certain disorders such as liver failure, or the use of blood thinners (such as anticoagulants or a common stroke medication called tissue plasminogen activator, or t-PA), or a deficiency of blood-clotting elements such as platelets * , intracranial bleeding occurs. Hemorrhage can also occur in a part of the brain that is dying due to blockage of the artery that supplies it (ischemic stroke). An acute rise in blood pressure due to drugs such as cocaine * or to strokes * can also cause intracranial bleeding. Other causes for bleeding into the brain are tumors * and obstruction of the venous outflow of the brain (cerebral sinus thrombosis * ). In premature births * the lining of the ventricles is very thin and immature and can lead to intraventricular bleeding, or to bleeding in an especially fragile part of a newborn's brain called the germinal matrix.
Symptoms and signs of intracranial bleeding develop over minutes to hours and become worse with time. Many patients have headaches, some of which occur when blood irritates the meninges. In subarachnoid hemorrhage, the headache is sudden and intense (thunderclap headache). Vomiting is common, and some but not all patients may also experience nausea before the vomiting. About 10 percent of patients have convulsions * .
Doctors may be able to pinpoint the location of the intracranial bleeding by checking the patient for certain telltale signs, including pupils of unequal size, limb weakness, various vision problems, and neck stiffness. Patients may have different levels of consciousness; they may be alert, in a stupor * , or sometimes even in a coma *
Intracranial bleeding is a medical emergency. If a person has symptoms of intracranial bleeding, someone should immediately call 9-1-1 so that medical professionals can take the patient to the emergency room. There, doctors will diagnose the condition by asking either the patient or relatives (if the patient is in a coma) a series of questions; by conducting a detailed physical and neurological (nervous system) exam; and most importantly, by examining the brain itself. Doctors may conduct this examination with a computed tomography * scan, which can detect blood within the brain and the ventricles or in the subarachnoid, subdural, or epidural space, and can detect any associated fractures in case of trauma. A CT scan also helps the doctor rule out ischemic stroke, which is actually more common than intracranial bleeding.
Once the patient is stabilized, the doctor may order other forms of brain imaging such as a magnetic resonance imaging * scan, CT angiogram * , or catheter * angiogram to look for the cause of bleeding. Such brain scans are especially useful for diagnosing arteriovenous malformations in children.
Laboratory tests to determine the cause of bleeding include blood counts and clotting * tests to detect coagulopathy or infections, a blood chemistry profile to detect liver * or kidney * failure, and toxicology tests to detect alcohol or drug intoxication. The doctor may also order an electrocardiogram to detect heart rhythm abnormalities, and an echocardiogram * to look at the function and structure of the heart and to check for evidence of long-standing hypertension. In some instances, when subarachnoid hemorrhage or brain infection is suspected, the doctor may also order a spinal tap * to look for blood or bacteria * in the cerebrospinal fluid.
Treatment usually begins in the emergency room and continues in the intensive care unit. The treatment team usually consists of the emergency room physician, a neurologist (a nerve specialist), an intensive care specialist, and in some cases, a neurosurgeon.
Medical therapy is aimed at controlling blood pressure, protecting the airway in comatose patients by inserting a breathing tube connected to a ventilator * , treating convulsions, and finally, using medications to decrease brain swelling. In cases of coagulopathy, the patient typically receives vitamin K, fresh frozen plasma, clotting factors, and platelets to restore the normal clotting mechanisms.
In selected cases (such as rapid deterioration due to a superficial hemorrhage in a young patient, or bleeding into the cerebellum, subdural, or epidural hemorrhage), a doctor may recommend surgery to remove the clot. For intraventricular hemorrhage, the patient will undergo a bedside procedure that involves inserting a catheter into the ventricles to drain blood and cerebrospinal fluid. In addition, medical professionals will surgically clip aneurysms or block them with metal coils to prevent another rupture. Both techniques are often used for aneurysms in the Circle of Willis. Patients may need to have a small hole cut in their windpipe (a tracheostomy) to help them breathe, and a feeding tube placed directly into the stomach so they can receive nutrition.
Once patients survive intracranial bleeding, they need a rehabilitation program. For this process, a rehabilitation expert will lead a team of physical and occupational therapists * , speech therapists, and a nutritionist. Patients may go to an inpatient rehabilitation center, a nursing home, or in some cases, to their own home, depending to their level of disability and how likely they are to recover well.
Intracranial bleeding is fatal in some instances, and patients may die even before they can get medical attention. Death usually results from brain herniation or from medical complications such as pneumonia * . In some gravely ill elderly patients, the family members may opt to withdraw life support based on the patient's previously expressed wishes. Overall, about 50 percent of patients die within 30 days of intracranial bleeding, and those who survive have a long road of rehabilitation ahead of them.
One of the best ways for people to prevent intracranial bleeding is to protect themselves from trauma to the head. Children should wear all recommended protective gear when playing sports, which includes wearing a helmet that fits properly and is worn correctly when they ride a bicycle. Everyone should use seat belts when riding in a vehicle. Adults should have their blood pressure checked regularly and take medications to control high blood pressure if their doctor prescribes them.
See also Aneurysm • Hyperlipidemias • Hypertension • Stroke • Trauma
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* subdural (sub-DOO-ral) means under the dura, the outermost of the three meninges that cover the brain.
* epidural (ep-I-DOO-ral) means the part of the spinal canal that lies outside the dura mater, the outermost of the three meninges that cover the brain and spinal cord.
* cerebrospinal fluid (seh-ree-broSPY-nuhl) is the fluid that surrounds the brain and spinal cord.
* artery is a vessel that carries blood away from the heart to tissues in the body.
* vein is a vessel that carries blood to the heart. Veins have greater capacity and thinner walls than arteries and contain valves that prevent blood from flowing backward and away from the heart.
* trauma refers to a wound or injury, whether psychological or physical. Psychological trauma refers to an emotional shock that leads to lasting psychological damage.
* cerebellum (se-re-BEL-um) is the back portion of the brain that is responsible for muscle coordination and balance.
* brain stem is the part of the brain that connects to the spinal cord. The brain stem controls the basic functions of life, such as breathing and blood pressure.
* cerebral cortex (suh-REE-brul KIR-teks) is the part of the brain that controls functions such as conscious thought, listening, and speaking.
* malformation (mal-for-MAYshun) is a structural deformity of a body part.
* premature birth (pre-ma-CHUR) means born too early. In humans, it means being born after a pregnancy term shorter than 37 weeks.
* thrombosis is the formation or development of a blood clot or thrombus.
* strokes are events that occur when a blood vessel bringing oxygen and nutrients to the brain bursts or becomes clogged by a blood clot or other particle. As a result, nerve cells in the affected area of the brain cannot function properly.
* cocaine (ko-KAYN) is a stimulant, a drug that produces a temporary feeling of alertness, energy, and euphoria. * tumors (TOO-morz) usually refer to abnormal growths of body tissue that have no known cause or physiologic purpose. Tumors may or may not be cancerous.
* platelets (PLATE-lets) are tiny disk-shaped particles within the blood that play an important role in clotting.
* convulsions (kon-VUL-shuns), also called seizures, are involuntary muscle contractions caused by electrical discharges within the brain and are usually accompanied by changes in consciousness.
* stupor is a state of sluggishness or impaired consciousness.
* coma (KO-ma) is an unconscious state, like a very deep sleep. A person in a coma cannot be awakened, and cannot move, see, speak, or hear.
* computed tomography (kom-PYOO-ted toe-MAH-gruhfee) or CT, also called computerized axial tomography (CAT), is a technique in which a machine takes many x-rays of the body to create a three-dimensional picture.
* magnetic resonance imaging or MRI uses magnetic waves instead of x-rays to scan the body and produce detailed pictures of the body's structures.
* angiogram (AN-jee-o-gram) is a test in which x-rays are taken as dye is injected into the body, showing the flow of blood through the heart and blood vessels.
* catheter (KAH-thuh-ter) is a small plastic tube placed through a body opening into an organ (such as the bladder) or through the skin directly into a blood vessel. It is used to give fluids to or drain fluids from a person.
* clotting is a process in which blood changes into a jellylike mass that stops the flow of blood.
* liver is a large organ located beneath the ribs on the right side of the body. The liver performs numerous digestive and chemical functions essential for health.
* kidney is one of the pair of organs that filter blood and remove waste products and excess water from the body in the form of urine.
* echocardiogram (eh-ko-KARdee-uh-gram) is a diagnostic test that uses sound waves to produce images of the heart's chambers and valves, and the direction of blood flow through the heart.
* spinal tap also called a lumbar puncture, is a medical procedure in which a needle is used to withdraw a sample of the fluid surrounding the spinal cord and brain. The fluid is then tested, usually to detect signs of infections (like meningitis) or other diseases.
* ventilator (VEN-tuh-lay-ter) is a machine used to support or control a person's breathing.
* physical and occupational therapists are professionals who are trained to treat injured people by means of activities designed to help them recover or relearn specific functions or movements, and restore their abilities to perform the tasks of daily living.
* pneumonia (nu-MO-nyah) is inflammation of the lungs.
* bacteria (bak-TEER-ee-a) are single-celled microorganisms, which typically reproduce by cell division. Some, but not all, types of bacteria can cause disease in humans. Many types can live in the body without causing harm.