Fibrinoid necrosis of small brain arteries and arterioles and miliary aneurysms as causes of hypertensive hemorrhage: a critical reappraisal.

Cerebral hemorrhage in hypertensive patients is still an important source of morbidity and death. Understanding its underlying pathological basis is essential for the development of fact-based attempts to prevent the hemorrhage. Fibrinoid necrosis and miliary aneurysms are associated with and are the probable underlying causative lesions. Unfortunately much misunderstanding and confusion surrounds understanding of both lesions. This review clarifies several points. These include the following: the nature of fibrinoid necrosis and the susceptibility of small brain arteries and arterioles to this lesion even in the so-called benign hypertension; the relationship of fibrinoid necrosis to lipohyalinosis and the reasons for preferring the term fibrinoid; the existence of miliary aneurysms; the distinction between these aneurysms and pseudo-aneurysms or fibrin globes; the importance of, and basis for, recognizing healed miliary aneurysms; the relationship of fibrinoid necrosis to these aneurysms.