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Causes of Brain Hemorrhage



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A brain hemorrhage, also known as cerebral hemorrhage, is bleeding within the brain due to damaged blood vessels leaking blood into the surrounding tissue. A bleed can occur between the brain and membrane surrounding it, called a subarachnoid hemorrhage, or leak directly into the brain tissue, called an intracerebral hemorrhage. The bleeding results in increased pressure within the brain cavity, which can damage the brain as it swells and pushes against the skull. It also can result in an infarct, an area of dead tissue caused by decreased blood flow and a lack of oxygen.

Brain hemorrhages can be caused by traumatic or nontraumatic events. Traumatic brain injury can be caused by a hard hit to the skull, or an accident that tears the vessels in the head. Head trauma is the top cause of brain bleeding in persons under the age of 50. Nontraumatic brain hemorrhage means that it occurs in the absence of injury. Eighty percent of non-traumatic cerebral hemorrhage patients have a history of hypertension, which is the most common non-traumatic reason for bleeding in the brain. However, hypertension is both preventable and treatable.

Chronically high blood pressure, called hypertension, can weaken blood vessel walls over time. This makes the walls susceptible to aneurysm and rupture. High blood pressure can also cause other changes in the vessels over time. The deposition of lipids within the vessels and hyalinization can lead to a narrowing of the vessels, reducing flow and increasing pressure within the cerebral vessels. This could potentially lead to infracted tissue within the brain. Scarring of the small vessels can also occur due to plasma leakage from the pressure. Aneurysmal dilatation, called Charcot-Bouchard intracerebral microaneurysm, may occur.

Other causes of aneurysms can also facilitate a hemorrhage. These include congenital abnormalities of the blood vessels or connective tissue, polycystic kidney disease, and, circulatory or bleeding disorders. Brain hemorrhages can also be caused by other blood vessel abnormalities, such as amyloid angiopathy, and liver disease or brain tumors.

The symptoms of a hemorrhage in the brain are caused by the effect of the blood loss and increased pressure on the brain tissue and depend on the severity of the hemorrhage and its location. Symptoms include seizures, sudden severe headache, weakness and numbness in the limbs, sudden nausea and vomiting, loss of motor skills and coordination, sudden vision changes, and loss of consciousness.

Some patients fully recover from a hemorrhage, others suffer long-term complications. Approximately half of patients suffering subarachnoid hemorrhages die within minutes, another 25% can be expected to eventually succumb. For intracerebral hemorrhages, approximately 50% of patients can be expected to succumb in the first 30 days, most of whom in the first week.

For more information on the epidemiology and theories behind cerebral hemorrhages, see Medscape.

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