Cerebral amyloid angiopathy
Cerebral amyloid angiopathy (including cerebral amyloid angiopathy, CAA ) is a disease of the blood vessels of the brain. It comes to the deposition of beta -amyloid in the walls of blood vessels, which can lead to narrowing of the lumen and the formation of microaneurysms. This in turn can break down and lead to intracerebral hemorrhage.
History
Was first described cerebral amyloid angiopathy in the brains of older people in 1938 by W. Scholz. Due to the commonality of the deposition of amyloid, the CAA was originally seen as a hallmark of Alzheimer 's disease. In the 1970s it was shown that in many intracerebral bleeding, which are not due to high blood pressure, such changes in vessel walls play a role.
Classification
The most common form is the beta- amyloid deposition which is observed in up to 80% of Alzheimer's disease cases. There are also various hereditary forms with mutations in the amyloid precursor protein (Dutch type), presenilin, cystatin C mutation ( ACys, Icelandic type ) and hereditary dementia of the British / Danish type.
Pathogenesis
Beta -amyloid is produced by cutting of the amyloid precursor protein (APP) using the enzymes beta- and gamma -secretase. In normal metabolism, these peptides are not generated, it is believed that the amyloid is generated primarily in neurons. In affected individuals, it accumulates in the cerebrospinal fluid and may accumulate in the brain tissue as so-called senile plaques, such as in Alzheimer's dementia, or in the vessel walls, as in the CAA. This amyloid is deposited mainly in the middle layer of the vessel wall ( media ). The presence of the ApoE4 allele is associated with an increased risk for the deposition of amyloid in the vessel walls.
Diagnostics
The presence of cerebral amyloid angiopathy can be definitively secured only by necropsy or by a tissue biopsy of the brain. Histology typically shows hyalinized capillaries with the detection of beta -amyloid in the vessels, often with loss of smooth muscle cells accompanied.
Clinically, the diagnosis is based on the radiological presence of single or multiple lobar hemorrhages on the cortical marrow - limit or micro- bleeding in the brain with no other likely cause. The presence of cerebral amyloid angiopathy is regarded as probable if present in the history of at least two bleeding without other apparent cause. It is estimated that 5-12 % of all intracranial bleeding in patients over 55 years caused by a cerebral amyloid angiopathy.