Defects in brain vessels, notably arteries, include hardening by atherosclerotic plaque, which narrows carotid arteries and can cause stroke; formation of berry aneurysms, which can rupture causing subarachnoid hemorrhage; deposition of amyloid in cerebral vessels, which can bleed; and congenital arteriovenous malformations, which can bleed.
Berry Aneurysms
The circle of Willis consists of large intracranial arteries connected by smaller arteries in a circle at that base of the brain. The weakest link occurs at the branch points where saccular, or "berry," aneurysms, form. Most cases of subarachnoid hemorrhage result from rupture of a berry aneurysm. According to "Harrison's Principles of Internal Medicine," 2 percent of adults, or 4 million people, have intracranial aneurysms and 25,000 to 30,000 cases per year of ruptured brain aneurysms occur in the United States.
Ehlers-Danlos syndrome, an inherited connective tissue disease, can result in berry aneurysms developing in blood vessel walls, according to MayoClinic.com. Other risk factors include cigarette smoking, alcohol abuse and hypertension.
Arteriovenous Malformation
Arteriovenous malformation, congenital connections between arterial and venous systems, consists of tangles of abnormal vessels. According to "Harrison's Principles of Internal Medicine," bleeding from these tangles occurs most often between the ages of 10 and 30, but sometimes up to the late 50s.
Cerebral Amyloid Angiopathy
According to "Harrison's Principles of Internal Medicine," cerebral amyloid angiopathy occurs in elderly patients when amyloid, a protein, sticks to the walls of cerebral arteries. In elderly patients, amyloid deposition in brain vessels most commonly causes hemorrhage into a lobe of the brain.
Carotid Artery Stenosis
Carotid arteries can become clogged by atherosclerotic plaque. According to the American College of Physicians Medical Knowledge Self-Assessment Program, in asymptomatic patients with greater than 60 percent stenosis of a carotid artery, surgical removal of the plaque by an operation called carotid endarterectomy showed a greater benefit for men than for women in reducing the risk of stroke.
References
- "Harrison's Principles of Internal Medicine"; Dennis Kasper, M.D.; 2005
- "American College of Physicians Medical Knowledge Self-Assessment Program 13: Neurology"; Paul Epstein; 2004
- MayoClinic.com: Ehlers-Danlos Complications
