Pseudo-aneurysms in relationship to massive cerebral haemorrhage

Abstract

This paper deals with two types of small body which are found within or close to a massive intracerebral haemorrhage. These bodies have, in the past, been confused with true aneurysms (Charcot and Bouchard, 1868), and for many years it was generally accepted that they were causally related to the main haemorrhage. In 1909 Ellis examined many of these structures from 34 brains with cerebral haemorrhage and concluded that they were not dilatations of arteries but were in fact nothing more than perivascular collections of blood clot which had escaped from small vessels by simple rupture of the wall or by a gradual dissection of the layers. Nevertheless, he believed that these blood clots or 'false' aneurysms were formed before the large haemorrhage and did themselves rupture to give rise to it. Although the latter view was not accepted, this denial of the existence of true aneurysms resulted in subsequent workers seeking alternative mechanisms for this type of stroke, the aneurysmal theory of cerebral haemorrhage being almost entirely abandoned for many years. The 'false' aneurysms were also largely forgotten, and only passing reference to them has been made in the literature since that time. They have been described as dissecting aneurysms (Globus and Epstein, 1952), unorganized arteriolar haema-tomata (Adams and Vander Eecken, 1953) and perivascular collections of blood (Russell, 1954). The picture was somewhat complicated by the fact that, following a painstaking histological survey of 10 brains, Green had in 1930 described three true aneurysms, that is, localized dilatations of intra-cerebral arteries. This was the first unquestionable description of such lesions, but its real significance did not become apparent for many years. Blackwood (1963), for example, felt that Green's lesions were identical to those described by Charcot and Bou-chard. It was not until 33 years after Green's discovery that, by using the much more efficient technique of post-mortem angiography, the presence of these true aneurysms was confirmed and their real numbers described (Ross Russell, 1963). It was during the course of a similar study of the incidence 61 of these intracerebral aneurysms in 200 subjects (Cole and Yates, 1967) that the present observations were made on the nature and mode of formation of the small bodies or 'false' aneurysms of the early workers. METHODS Twelve brains showing massive haemorrhage of the classical type were studied. In all cases the haemorrhage had occurred into the lenticulo-striate areas. All the subjects were more than 60 years old, and all were known to suffer from hypertension. (Diastolic blood pressure over 110 mm.Hg and heart weight over 400 g. for a man or 350 g. for a woman.) Ten brains were examined in which intracerebral haemorrhage was not associated with hypertension; in seven cases it followed rupture of an aneurysm of the circle of Willis; three were cases of leukaemia and one of idiopathic thrombocytopenia. The brains were examined in a way similar to that employed by early workers (Charcot and Bouchard, 1868). Portions of brain tissue adjacent to the haemorrhage were immersed in a stream of running water and the vessels were inspected when they had separated from the surrounding parenchyma. Other portions and those which included vascular bodies were fixed and examined histologically. Using this relatively crude technique two types of structure can be identified. FINDINGS