In the United States, intracranial hemorrhage constitutes approximately 13%–15% of acute cerebrovascular disorders. The most common causes of intracranial hemorrhage are bleeding from aneurysms of the arteries that compose the circle of Willis, bleeding from arterioles damaged by hypertension or arteriosclerosis, and trauma. Although intracranial hemorrhage has many causes, the anatomical location of the bleeding greatly influences the clinical picture. By location, hemorrhages can be broadly categorized as intracerebral, intraventricular, or subarachnoid.
Hypertension is the most common cause of nontraumatic intracranial hemorrhage. Cerebral amyloid angiopathy is the most common cause of nontraumatic intracranial hemorrhage in elderly individuals, whereas AVMs are the most common cause in children. Infections resulting from septic emboli, hemorrhagic infarction, brain tumors, coagulopathies, and intrinsic vascular conditions such as moyamoya disease and vasculitis are all associated with intracerebral bleeding.
The pathophysiology of intracerebral bleeding secondary to hypertension appears to be intimal hyperplasia with hyalinosis that results in focal necrosis with pseudoaneurysm formation. When the vessel is exposed to high pressure that cannot be compensated for by the clotting cascade, small leaks lead to massive hemorrhage. Direct pressure to the brain parenchyma by the expanding clot and from cytotoxic perilesional edema results in direct tissue injury. As the clot expands, the ischemia increases and the cytotoxic edema develops further, raising intracranial pressure; if severe enough, this pressure may lead to herniation. Expansion of the hemorrhage into the intraventricular space occurs in 40%–60% of patients worldwide, greatly increasing morbidity and mortality.
In addition to hypertension, a prospective study showed that age, high alcohol intake, African American race, and, oddly, low levels of low-density lipoprotein and triglycerides are associated with increased risk of intracerebral hemorrhage. Most hypertensive hemorrhages occur during routine activity, but some may occur with exertion or intense emotional stress. Symptoms increase gradually over a few minutes to hours. Headache and vomiting occur in about 50% of cases. When intraventricular blood is involved, meningismus with stiff neck and nuchal rigidity occur.
Excerpted from BCSC 2020-2021 series: Section 1 - Update on General Medicine. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.