Spontaneous Thrombosis of Cerebral Aneurysms

The natural course of cerebral aneurysms, both those observed in subarachnoid haemorrhage and those discovered by chance, has been subject to much discussion. Our knowledge in this field is still deficient. The results of conservative treatment of subarachnoid haemorrhage caused by a ruptured aneurysm are discouraging. Hunt, Meagher and Barnes (1962), for example, reported a mortality of 93 per cent in conservative treatment compared with 20 per cent with surgical intervention. For this reason it has not been possible to follow-up a large series of conservatively treated patients with repeated cerebral angiographies in order to study the development of non-surgically treated aneurysms. Some information has been given, however, as regards the morphological development. Mount and Taveras (1956) described a series of 16 conservatively treated patients. The aneurysm was visible in all cases at follow-up angiography. Its size was either unchanged or had increased. No spontaneous thrombosis occurred in any of these cases. af Björkesten and Troupp (1962) reported one case of spontaneous thrombosis, however. In this case attempt had been made to repair the aneurysm surgically by the application of a silver clamp. A few months after the operation, however, angiography showed that the condition was unchanged and that the silver clamp was situated behind the aneurysm and with no anatomical contact with it. Further examination five years later revealed total thrombosis of the aneurysm.