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Monday, November 2, 2009

Brain hemorrhage

Cerebral hemorrhage


A cerebral hemorrhage (or intracerebral hemorrhage, ICH), is a subtype of intracranial hemorrhage that occurs within the brain tissue itself. Intracerebral hemorrhage can be caused by brain trauma, or it can occur spontaneously in hemorrhagic stroke. Non-traumatic intracerebral hemorrhage is a spontaneous bleeding into the brain tissue.[1]

A cerebral hemorrhage is an intra-axial hemorrhage; that is, it occurs within the brain tissue rather than outside of it. The other category of intracranial hemorrhage is extra-axial hemorrhage, such as epidural, subdural, and subarachnoid hematomas, which all occur within the skull but outside of the brain tissue. There are two main kinds of intra-axial hemorrhages: intraparenchymal hemorrhage and intraventricular hemorrhages. As with other types of hemorrhages within the skull, intraparenchymal bleeds are a serious medical emergency because they can increase intracranial pressure. The mortality rate for intraparenchymal bleeds is over 40%

Prevalence

It accounts for 20% of all cases of cerebrovascular disease in the US, behind cerebral thrombosis (40%) and cerebral embolism (30%).[3]

It is two or more times more prevalent in African-American patients.[4]

Causes

Intracerebral bleeds are the second most common cause of stroke, accounting for 30–60% of hospital admissions for stroke.[1] High blood pressure raises the risk of spontaneous intracerebral hemorrhage by two to six times.[1] More common in adults than in children, intraparenchymal bleeds due to trauma are usually due to penetrating head trauma, but can also be due to depressed skull fractures, acceleration-deceleration trauma,[5][6][7] rupture of an aneurysm or arteriovenous malformation (AVM), and bleeding within a tumor. A very small proportion is due to cerebral venous sinus thrombosis.

Risk factors

Risk factors for ICH include:[8]

  • Hypertension
  • Diabetes
  • Menopause
  • Current cigarette smoking
  • Alcoholic drinks (≥2/day)
  • Caffeine

Symptoms

Patients with intraparenchymal bleeds have symptoms that correspond to the functions controlled by the area of the brain that is damaged by the bleed.[9] Other symptoms include those that indicate a rise in intracranial pressure due to a large mass putting pressure on the brain.[9] Intracerebral hemorrhages are often misdiagnosed as Subarachnoid hemorrhages due to the similarity in symptoms and signs.

Diagnosis

Intraparenchymal hemorrhage can be recognized on CT scans because blood appears brighter than other tissue and is separated from the inner table of the skull by brain tissue. The tissue surrounding a bleed is often less dense than the rest of the brain due to edema, and therefore shows up lighter on the CT scan.

Treatment

Treatment depends substantially of the type of ICH. Rapid CT scan and other diagnostic measures are used to choose proper treatment, which may include both medication and surgery.

Medication

  • Giving Factor VIIa within 4 hours limits the bleeding and formation of an hematoma However, it also increases the risk of thromboembolism. [10]
  • Antihypertensives are given to stabilize the mean arterial pressure at below 130 mmHg, but without causing excessive hypotension. [10]
    • Mannitol is effective in acutely reducing raised intracranial pressure.
  • Acetaminophen may be needed to avoid hyperthermia, and to relieve headache.[10]
  • Frozen plasma, vitamin K, protamine, or platelet transfusions are given in case of a coagulopathy.[10]
  • Fosphenytoin or other anticonvulsant is given in case of seizures or lobar hemorrhage.[10]
  • Antacids are given to prevent gastric ulcers, a condition somehow linked with ICH.[10]
  • Corticosteroids, in concert with antihypertensives, reduces swelling. [11]

Surgery

Surgery is required if the hematoma is greater than 3 cm, if there is a structural vascular lesion or lobar hemorrhage in a young patient.[10]

  • A catheter may be passed into the brain vasculature to close off or dilate blood vessels, avoiding rather invasive surgical procedures.[12]
  • Aspiration by stereotactic surgery or endoscopic drainage may be used in basal ganglia hemorrhages, although successful reports are limited.[10]

Other treatment

  • Tracheal intubation is indicated in patients with decreased level of consciousness or other risk of airway obstruction.[10]
  • IV fluids are given to maintain fluid balance, using normotonic rather than hypotonic fluids.[10]

Prognosis

The risk of death from an intraparenchymal bleed in traumatic brain injury is especially high when the injury occurs in the brain stem.[2] Intraparenchymal bleeds within the medulla oblongata are almost always fatal, because they cause damage to cranial nerve X, the vagus nerve, which plays an important role in blood circulation and breathing.[5] This kind of hemorrhage can also occur in the cortex or subcortical areas, usually in the frontal or temporal lobes when due to head injury, and sometimes in the cerebellum.[5][13]

For spontaneous ICH seen on CT scan, the death rate (mortality) is 34–50% by 30 days after the insult.

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