Cerebral amyloid angiopathy
Cerebral amyloid angiopathy (CAA) is a neurological condition characterized by abnormal deposits of a specific protein called amyloid in the arteries that supply the surface of the brain. The cause or causes of these deposits is poorly understood but CAA is commonly associated with Alzheimer's disease.
Definition & Facts
Angiopathy is the term used to describe any condition that affects the body’s blood vessels, but the term is most often used in reference to diseases involving the smaller arteries and capillaries. CAA describes a group of symptoms that are related to the brain and its blood supply.
CAA is the result of the presence of an abnormal buildup of a protein called amyloid in the muscular portion of the arteries that supply the outer portions of brain tissue. It is felt that the presence of amyloid interferes with the elasticity of the arterial wall and that this lack of elasticity may allow platelets and other blood components to accumulate on the inner lining of the artery.
Symptoms & Complaints
When CAA does cause symptoms, these symptoms are always the result of either bleeding into the brain tissue itself (cerebral hemorrhage or “brain bleed”) or to a blood clot forming within an artery (cerebral thrombosis). In either case the symptoms are related to a disturbance in blood flow to the brain, a condition commonly called a stroke.
Symptoms of a cerebral hemorrhage include a sudden severe headache that may be accompanied by an abrupt change in behavior, paralysis, difficulty speaking, and confusion. On the other hand a cerebral thrombosis can produce the same symptoms with the vital exception that cerebral thrombosis practically never causes pain, an exception that is important in the management of an acute event in that the emergency management of the two conditions are radically different.
CAA results from an abnormal accumulation of amyloid protein in the muscular layer of the walls of the arteries that supply the brain. Amyloid deposits are not normally found in the arterial walls nor is it found attached to normally functioning nerve cells.
Most cases seem to occur at random. CAA may develop in response to hypertension and atherosclerosis (“hardening of the arteries”), a condition that can be responsible for cardiovascular disease and stroke.
Certain types of hereditary cerebral hemorrhage with amyloidosis are associated with cerebral amyloid angiopathy and result from genetic mutations that are passed down via autosomal dominant inheritance. The APOE gene is also linked to cerebral amyloid angiopathy.
It is also understood that the presence of risk factors that are known to increase the risk of heart attack or stroke can also play a role in the development of conditions that may be predisposed to by the presence of CAA. It occurs more often among women than among men, and is common among those with Alzheimer's disease and Down syndrome.
Diagnosis & Tests
Diagnosing this condition is difficult and can only definitively after the patient has died during autopsy. Diagnosis of possible or probable CAA is based on the medical history and findings observed in images obtained with computed tomography (CT) scan and/or magnetic resonance imaging (MRI) studies.
Treatment & Therapy
Since there is no available treatment for CAA, treatment is directed toward the disease processes that arise as manifestations of its presence. In that respect the first goal is to discover if the neurologic symptoms are the result of a cerebral thrombosis or a cerebral hemorrhage because the emergency, and long-term treatment, of these conditions is radically different. Treatment for a cerebral thrombosis can include anticoagulants such as aspirin, warfarin, and clopidogrel. Treatment for cerebral hemorrhage includes diuretics and anticonvulsants.
Prevention & Prophylaxis