[Editor's note: This article is from 2007. Some newer treatments, risk factors, and current statistics may not be included. See further information on BrainWeb]
sections include: how hemorrhagic strokes occur, diagnosis and treatment
A sudden, severe headache—“like a thunderclap”—is a very serious neurological sign. There are several possible reasons for this pain, but by far the most critical is a hemorrhagic stroke. (The other reasons are discussed here.) If the headache is accompanied by nausea, vomiting, a stiff neck, or loss of mental or physical functions, it definitely requires immediate medical attention. Indeed, any possible stroke is an emergency, and swift diagnosis and treatment are essential.
A hemorrhagic stroke is caused by a sudden bleeding, or hemorrhage, into or next to the brain. This problem accounts for about 20 percent of all people admitted to hospitals for strokes. (The rest of these cases are ischemic strokes.) Most hemorrhagic strokes occur in the brain itself and are called intracerebral hemorrhages. Smaller groups of people suffer bleeding into the fluid filled spaces located deep in the brain (intraventricular hemorrhage) or into the small space between the brain and the membranes that cover it (subarachnoid hemorrhage).
Any hemorrhage affecting the brain or its adjacent spaces is a very serious condition. Depending on the location and size of the mass of loose blood (called a hematoma), it may even be life threatening. Many hemorrhages in or close to the brain stop spontaneously within the first hour. But bleeding can continue until the accumulated fluid disrupts vital brain structures or compresses otherwise healthy parts of the brain, and the person dies.
Bleeding into the Brain. In an intracerebral hemorrhage, the rapidly developing mass of blood in the brain usually causes symptoms resembling those of ischemic strokes. These include sudden weakness or numbness in one part or side of the body, difficulties speaking or understanding language, abrupt confusion, and problems seeing in one eye or in half the visual field. A person may be unaware of his or her impairment, which is another form of impairment. Unlike ischemic strokes, however, an intracerebral hemorrhage is more likely to cause a steady worsening of the initial symptoms, as blood continues to accumulate. A person who has had a hemorrhagic stroke is also more likely to have a headache, feel nauseous, or vomit in the minutes after onset.
Which brain functions are impaired and how badly depend mainly on the size and location of the bleeding. A hemorrhage involving the deep structures of one brain hemisphere might result in weakness on the other side of the body, and at times numbness and visual problems on the same side. If the hemorrhage occurs in the brain stem, the person may immediately plunge into a coma, with weakness in both arms and legs and impaired movements of the eyeballs.
In hemorrhages involving the cerebellum, symptoms usually begin abruptly with vomiting and such severe loss of coordination that a person cannot stand or walk. These signs are occasionally accompanied by slurred speech and double vision. The growing mass of blood does not change the symptoms until it starts to compress the adjacent brain stem; that might bring on coma, at which point it is too late for surgeons to drain the hematoma and reverse the damage. That small margin of time between an alert state and an irreversible coma makes it imperative for people with stroke symptoms to get medical help quickly, and for doctors to consider the possibility of a stroke in all people showing sudden vomiting and incoordination. Prompt brain scans can settle the diagnosis and allow doctors to start treatment.
Bleeding Around the Brain. Individuals undergoing either intraventricular or subarachnoid hemorrhage commonly complain about “thunderclap” headaches. Usually they also experience nausea and vomiting, or a stiff neck. In these two conditions most of the blood leaks into a fluid cavity and not directly into the brain (at least initially). People may therefore not notice the problems associated with bleeding into the brain and ischemic strokes. However, not everyone stays awake to describe their symptoms. An abrupt displacement or compression of vital brain structures may lead to sleepiness, loss of consciousness, and coma. Weakness or numbness in one side of the body and impaired vision, speech, or awareness of the disorder also tend to be bad signs; they indicate that important brain tissue is being disrupted.
How Hemorrhagic Strokes Occur
Intracerebral hemorrhages can happen in any of the cerebral lobes or the cerebellum, but they are most likely to occur in the deeper brain structures: the basal ganglia, thalamus, and brain stem. Most commonly the problem arises at weak spots in the walls of small arteries inside the brain, which have been caused by disease. These tiny blood vessels start to leak. Because the actual source of the bleeding is often small, it can take time for the loose blood to build up. That is why the symptoms of an intracerebral hemorrhage often increase over minutes or hours.
Intraventricular hemorrhage occurs when the source of the bleeding is located close to or within the wall surrounding one of the brain ventricles. In these cases, the blood drains into the fluid-filled ventricular system, often sparing healthy brain tissue.
The source of subarachnoid hemorrhage is commonly located on the surface of the brain. In 80 percent of cases, the problem starts with a congenital weak spot on the wall of a major brain artery, most often where the large arteries divide at the base of the brain. This defect grows into a thin-walled pouch bulging out of the artery’s side, shaped something like a berry. Such a condition is called an aneurysm. When the walls of the pouch grow too weak to hold the blood inside, it ruptures. The leaking blood may drain not only into the small space surrounding the brain but occasionally directly into brain tissue. The mass of the growing hematoma may also displace or compress vital brain structures.
As the brain itself is not sensitive to pain, headaches from hemorrhagic strokes are believed to be due to either the stretching of the arterial wall when an aneurysm ruptures, the sudden increase of pressure within the skull, or the stretching of the membranes surrounding the brain.
Hemorrhagic strokes that stop shortly after they begin may not cause the steady progression of symptoms that helps doctors distinguish them from ischemic stroke. But it is very important to identify which type of stroke a person has had. Treatment to declog an artery (the proper response to ischemia) may cause or contribute to another hemorrhage. Separating hemorrhage from brain ischemia requires emergency brain imaging.
Diagnosis and Treatment
Any stroke symptoms require immediate workup in a hospital. The diagnosis of a hemorrhagic stroke is based on the person’s history, a neurological exam, and brain imaging. A computed tomography (CT) scan shows fresh blood in the skull as a white spot on the film.
Sometimes a person’s symptoms and clinical exam point to a subarachnoid hemorrhage, but the CT scan cannot confirm the diagnosis because there is only a small amount of blood in the space between the brain and the surrounding membranes. In this case, the physician usually undertakes a lumbar puncture, or spinal tap, in order to detect any fresh blood cells in the cerebrospinal fluid.
Magnetic resonance imaging (MRI) may also detect fresh bleeding in the brain, but it is even more useful in the search for possible underlying causes. It can detect vascular malformations, tumors, evidence for congophilic amyloid angiopathy, and even aneurysms. A specialized type of ultrasound called transcranial Doppler ultrasonography is another useful tool for spotting larger malformations of blood vessels—it’s often used for follow-up evaluations of people who have had a subarachnoid hemorrhage. The most reliable technique to confirm or rule out the presence of aneurysms and other malformations of the blood vessels is a cerebral angiogram; physicians inject contrast dye into the blood system to make arteries stand out on X-ray films.
People having a hemorrhagic stroke should usually be kept under close observation in the acute phase of the disease and may even require the support of an intensive care unit. Balancing conservative treatment (administering pain and comfort medication, stabilizing vital signs, lowering the pressure inside the head, and so on) against the need for invasive treatment options such as surgery is influenced by a complex variety of factors. Some cases of intracerebral hemorrhage may require removing the blood in order to relieve otherwise healthy brain areas from pressure. In some instances of intraventricular hemorrhage, surgeons may relieve pressure by inserting a small tube into the ventricles to drain the system (a “shunt” operation).
Whether an aneurysm that caused a subarachnoid hemorrhage is treated immediately or after the acute phase depends on the individual’s condition and on the treatment chosen. Options include “clipping” the aneurysm surgically or blocking it with metal coils inserted through a very small tube (catheter) during the angiogram.
Hemorrhagic strokes tend to be more deadly than ischemic strokes. Subarachnoid hemorrhage is the most life-threatening, with an average mortality of 40 percent within the first month after the bleeding. Overall, a person’s prognosis tends to be worse if there is more blood around the brain. But an individual’s chances also depend on the exact location of the hematoma and on how severely he or she has been affected.
These types of strokes may also cause secondary complications for people after the initial bleeding. Impaired circulation or resorption of the cerebrospinal fluid may lead to hydrocephalus; this often requires a shunt operation. One third of people with such strokes have epileptic seizures, which are usually managed with medication. Other direct effects of the hemorrhage on the brain include irregular heartbeat (cardiac arrhythmia), fluid in the lungs, impaired electrolyte balance, and fever.
The most feared acute complication is more bleeding from the original hemorrhage source. Up to 20 percent of people with ruptured aneurysms have this trouble. Another serious complication, particularly in cases after subarachnoid hemorrhage, is the occurrence of spasms in the basal brain arteries. This condition, called vasospasm, usually occurs between the third and fifth day after the hemorrhage. When these arteries narrow, there is a risk of an additional, ischemic stroke.
People who survive a hemorrhagic stroke and the critical period that immediately follows often make a remarkable recovery. As the mass of the hematoma slowly decreases, the actual disruption of brain tissue can turn out to be smaller than what doctors or family members had feared. Early rehabilitation after strokes benefits most people.
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