The term, “stroke,” is used to identify a variety of pathologic intracranial (within the skull) vascular processes. Basically, the many types of stroke can be broken down into two major categories: ischemic and hemorrhagic. Ischemic stroke refers to blockage of an intracranial artery by a thrombus (clot) obstructing the artery, thereby depriving a portion of the brain from blood, oxygen, nutrients, etc. This is the most common type of stroke. Hemorrhagic stroke, or intracerebral hemorrhage, refers to a rupture of an artery (hemorrhage) in the brain resulting in a collection of blood within the brain substance.
Hemorrhage into the head is subdivided by the compartments within the skull where bleeding may occur. The brain itself is floating in cerebrospinal fluid (CSF) encased by membranes called the dura and arachnoid. Hemorrhage is therefore named according to where the blood accumulates. For example,
- Hemorrhage above the dural membrane is called epidural hemorrhage.
- Hemorrhage below the dural membrane, but above the arachnoid membrane, called is subdural hematoma.
- Hemorrhage below the arachnoid membrane into the cerebrospinal fluid is called subarachnoid hemorrhage.
- Hemorrhage into the brain substance is called intracerebral hemorrhage.
Each of the various types of hemorrhage into their respective compartments has its own underlying cause, natural history, treatment and prognosis. The following describes hemorrhage into the brain substance, or intracerebral hemorrhage.
Epidemiology of Intracerebral Hemorrhage
Intracerebral hemorrhage represents approximately 10% to 15% (10-30/100,000 population) of all strokes. About 2 million of the 15 million strokes worldwide are intracerebral hemorrhages. Men are more likely to suffer an intracerebral hemorrhage than women.
Each year, approximately 37,000 to 52,400 people suffer from an intracerebral hemorrhage. The number of intracerebral hemorrhages is expected to increase substantially over the next few decades as the population ages. Major underlying causes for the increase in incidence include more frequent use of anticoagulant medication and age related changes in the brain itself.
There is racial variation in the incidence of bleeding into the brain substance; Asians, Latin American, Mexican American, Native American and African American patients have a greater risk according to epidemiological data. The variation relates to differences in genetics, rates of elevated blood pressure, diabetes, low cholesterol and disease of the small arteries in the brain.
In a recent review, 34% of patients died from their intracerebral bleed 3 months after the event. Another study documented death rates after an intercerebral bleed of 31% at 7 days, 59% at one year, 82% at 10 years and more than 90% at 16 years. Clearly this is a serious and frequently fatal condition.
Recurrent hemorrhages after the first event remain a problem especially when risk factors, especially elevated blood pressure and anticoagulant use, are inadequately addressed; there is a 4% recurrence rate for rebleeding.
Symptoms of Intracerebral Hemorrhage
The symptoms of hemorrhage into the brain depend on where, within the brain, the hemorrhage occurs. Regardless of the site of hemorrhage, headache, nausea, vomiting and altered consciousness may be noted. Hemorrhage into a cerebral lobe will cause immediate dysfunction of that lobe, with symptoms such as difficulty speaking (aphasia), paralysis on one side of the body (hemiplegia), numbness on one side of the body (hemianesthesia) or blindness off to one side (hemianopsia), just to name a few common presentations. Hemorrhage into the base of the brain (brainstem and cerebellum) may cause a different set of symptoms, including double vision, vertigo (dizziness), difficulty with coordinated movements and trouble swallowing. Large hemorrhages may lead to coma. Seizures may be a presenting symptom as well. Suffice it to say that any function of the brain may be involved depending on where the hemorrhage occurs.
Causes of Intracerebral Hemorrhage
A number of medical conditions are associated with a tendency to bleed into the brain.
- Hypertension (elevated blood pressure), perhaps the most prevalent and treatable cause, is stated to be responsible for 60% of the cases. Patients with systolic blood pressures of 160 mm Hg or higher, or diastolic pressures of 110 mm Hg or higher, had more than 5 times the risk of an intracerebral hemorrhage compared to patients with normal blood pressure.
- Cerebral amyloid angiopathy, an age related accumulation of an abnormal protein in blood vessels, is also a major cause of intracerebral hemorrhage in the elderly population, accounting for approximately 20% of patients with intracerebral hemorrhage. This may, on rare occasions, cause multiple intracerebral hemorrhages simultaneously.
In a recent study, CT of the brain demonstrated that 49% of cerebral bleeding occurred deep within the brain substance, 35% in a more superficial lobe and approximately 16% into the base of the brain (brainstem and cerebellum/pons). The location of the hemorrhage helps determine the cause. Hemorrhage into deep brain or brainstem structures is often caused by hypertension, and hemorrhage into a lobe of the brain is often from cerebral amyloid accumulation.
Use of “blood thinners” (medically referred to as anticoagulants) is an underlying cause of cerebral hemorrhage that is increasing in prevalence. Even the use of medications such as aspirin, clopidogrel (Plavix) or aspirin plus dipyridamole (Aggrenox) may contribute to intracerebral hemorrhage or at least to a larger size hemorrhage if one occurs.
A large number of other conditions may be associated with bleeding into the brain, including abnormalities of blood vessels (aneurysm or vascular malformations), clotting of draining veins (cerebral venous sinus thrombosis) and hemorrhage into tumors in the brain (pituitary tumors, malignant primary brain tumors or tumors which spread to the brain from other sites). Use of illicit drugs, including amphetamines and cocaine, as well as others, can cause cerebral hemorrhage, and smoking doubles the risk of hemorrhage into one of the lobes of the brain.
Diagnostic Tests for Intracerebral Hemorrhage
In the appropriate clinical setting, emergency neurodiagnostic imaging of the brain (CT or MRI) is required to emergently assess the possibility of bleeding into the brain substance. Once the location of the hemorrhage is identified by history, exam and neuroimaging, other direct diagnostic tests may be pursued as appropriate.
Complications of Cerebral Hemorrhage
As one might expect, hemorrhage into the brain is a serious brain disorder leading to a number of possible complications, often culminating in death of the patient.
- Enlargement of the size of the hemorrhage is a major concern, as the size of the blood clot may impact survival, or at least the degree of neurological disability if the patient survives. It is well established that enlargement of the blood clot occurs in the first 24 hours after onset in about one-third of patients. One major factor in enlargement of the hemorrhage is the use of anticoagulant medication (Coumadin/warfarin). Fifty-percent of patients admitted with brain hemorrhage while on anticoagulation deteriorate in the first 24 to 48 hours due to additional bleeding, with a high mortality rate of 64% by 6 months. Although blood pressure elevation is suspected as a contributing cause of the enlargement, this remains unproven. Many other factors, some of which are outlined above, may also contribute to continued bleeding, with increased disability and or death.
- Hydrocephalus, the accumulation of spinal fluid in the cavities of the brain (ventricles), may develop, with secondary expansion of the ventricles, elevated pressure inside the skull and progressive neurological deterioration. Blood may obstruct the normal pathways for spinal fluid drainage and require temporary drainage by a tube, which is inserted into the ventricles to relieve pressure and attempt to preserve neurological function. The development of hydrocephalus is a predictor of 30-day mortality.
- Cerebral edema, or fluid collection around the hemorrhage, develops over several hours and contributes to the size of the hemorrhage and secondary brain damage. The brain swelling adjacent to the hemorrhage will increase by 75% in the first 24 hours, with further increase possible into the second and third weeks following the initial hemorrhage. This causes further pressure on brain structures, elevated pressure inside the head and additional neurological injury.
- Convulsions may develop in the course of a cerebral hemorrhage, depending on the site of the hemorrhage, creating further management problems. Eight-percent of patients with intracerebral hemorrhage have clinical seizures within one month of symptom onset, with a higher number having sub-clinical seizures (unnoticeable seizures). Seizures are associated with neurological worsening and poorer outcomes. Treatment with an anticonvulsant may be required to treat or prevent this complication.
Intracerebral hemorrhage frequently results in permanent neurological deficit (i.e., paralysis, loss of speech, loss of vision, incoordination, etc.), and is, therefore, often associated with permanent loss of independence if the patient survives the initial event.
Treatment of Intracerebral Hemorrhage
Treatment of intracerebral hemorrhage is problematic, as many therapeutic approaches to the disorder have not impacted the outcome significantly. Obviously, management of patients’ vital functions is essential for there to be any hope of a favorable outcome. Close management of blood pressure is particularly important. Rapid reversal of any medication used for anticoagulation should be considered, if medically appropriate. Agents recently studied to limit the size of the brain hemorrhage (i.e., blood clotting factor 7) have been shown to limit the volume of the hemorrhage, but have no long-term effect on outcome for most patients. If the bleeding extends into the central cavities of the brain (i.e., the ventricular system) a drainage apparatus may be used to drain fluid, reduce the intracranial pressure and avoid secondary brain damage. Seizures should be treated rapidly with any one of the available intravenous formulations. Hydration and nutrition issues must be addressed as well.
Treatment of hypertension is the most effective way to prevent recurrent primary intracerebral hemorrhage. Avoidance of other risk factors, such as smoking, alcohol and cocaine, will further lower the risk of additional bleeding into the brain.
Prognosis of Intracerebral Hemorrhage
Those factors, which impact long-term outcome, include advanced age, markedly impaired neurological exam, large size of hemorrhage, hemorrhage into the base of the brain structures and hemorrhage into the central fluid filled cavities of the brain (intraventricular hemorrhage). Patients with a Glasgow coma score of 8 (a quick measure of neurological status assessing eye opening, verbal response and best motor function, for which normal is 15), with hemorrhage size of 60 cubic centimeters, have an estimated 30-day mortality rate of 91%. Patients with a hemorrhage volume of 30 cc or more were severely disabled at 30 days. Hemorrhage into the lower brain region (i.e., pons) carries a grave prognosis, with 55% mortality and 24% dependency in survivors. Hemorrhage into other locations may have a much better prognosis for survival and independence.
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