Ultrastructural features of cerebral amyloid angiopathy.

Ultrastructural studies of the brain in three cases of cerebral amyloid angiopathy demonstrated that the vascular amyloid in this disease is composed of fibrils identical to those in systemic amyloid disease, mixed with a large amount of vesicular debris. Amyloid appears to be derived from circulating protein and is depostied in areas of vascular basement membrane degeneration. The initiating degenerative change is thickening of basement membrane with accumulation of debris. Inflammation, when present, tends to accelerate amyloid deposition locally. Amyloid transport from the vascular wall into the brain parenchyma proceeds by overflow when perivascular astroglial end-feet are disarranged. Structures of perivascular amyloid plaques are similar to the neuritic (senile) plaques in Alzheimer's disease, which were used as control, except that the amyloid core of the plaques in Alzheimer's disease is not related to blood vessels.