The ensuing hydrocephalus, or fluid buildup in the ventricles of the brain leads to a decreased level of consciousness and coma. Brainstem hemorrhage most commonly occurs in the pons and is associated with cranial nerve palsies, pinpoint (but reactive) pupils, gaze palsies, facial weakness, and coma (if there is damage to the reticular activating system). Causes
Intracerebral bleeds are the second most common cause of stroke, accounting for 10% of hospital admissions for stroke. High blood pressure raises the risks of spontaneous intracerebral hemorrhage by two to six times. More common in adults than in children, intraparenchymal bleeds are usually due to penetrating head trauma, but can also be due to depressed skull fractures. Acceleration-deceleration trauma, rupture of an aneurysm or arteriovenous malformation (AVM), and bleeding within a tumor are additional causes. Amyloid angiopathy is not an uncommon cause of intracerebral hemorrhage in patients over the age of 55. A very small proportion is due to cerebral venous sinus thrombosis.Risk factors for ICH include:
Hypertension (high blood pressure)
Diabetes mellitus
Menopause
Excessive alcohol consumption
Severe migraineHypertension is the strongest risk factor associated with intracerebral hemorrhage and long term control of elevated blood pressure has been shown to reduce the incidence of hemorrhage. Cerebral amyloid angiopathy, a disease characterized by deposition of amyloid beta peptides in the walls of the small blood vessels of the brain, leading to weakened blood vessel walls and an increased risk of bleeding; is also an important risk factor for the development of intracerebral hemorrhage.
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. 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. Larger volumes of hematoma at hospital admission as well as greater expansion of the hematoma on subsequent evaluation (usually occurring within 6 hours of symptom onset) are associated with a worse prognosis. Perihematomal edema, or secondary edema surrounding the hematoma, is associated with secondary brain injury, worsening neurological function and is associated with poor outcomes. Intraventricular hemorrhage, or bleeding into the ventricles of the brain, which may occur in 30-50% of patients, is also associated with long term disability and a poor prognosis. Brain herniation is associated with poor prognoses.For spontaneous intracerebral hemorrhage seen on CT scan, the death rate (mortality) is 34–50% by 30 days after the injury, and half of the deaths occur in the first 2 days. Even though the majority of deaths occur in the first few days after ICH, survivors have a long-term excess mortality rate of 27% compared to the general population. Of those who survive an intracerebral hemorrhage, 12–39% are independent with regard to self-care; others are disabled to varying degrees and require supportive care.