Subarachnoid Haemorrhage of Unusual Aetiology

SUBARACHNOID HAEMORRHAGE is not a disease entity, since it can be produced by a variety of pathologic lesions. Indeed, if all cases are considered in which blood appears in the subarachnoid space, Courvillel has shown that more than half are due to external trauma, whereas many others occur in the neonatal period or else as a result of extension to the ventricular system of a parenchymatous cerebral haemorrhage. Exclusion of such cases will leave a group of patients in which the distinctive clinical picture of “spontaneous subarachnoid haemorrhage” will be recognized. The work of Symonds2 suggested that this syndrome usually results from rupture of an aneurysm of one of the arteries of the circle of Willis or its branches, and this opinion has been amply confirmed, although it is now clear that an identical picture may sometimes be produced by the rupture of a previously asymptomatic cerebral angioma. However, although aneurysmal or angiomal rupture undoubtedly accounts for the majority of cases, from time to time numerous other pathologic conditions may underlie a brisk attack of subarachnoid bleeding. Sometimes the primary lesion will have produced symptoms or signs beforehand, but on other occasions the haemorrhage may be the presenting feature; in such cases recognition of the aetiologic lesion is important from the standpoint of therapy. It is hoped that, by reporting a series of cases of spontaneous subarachnoid haemorrhage of unusual aetiology, attention will be drawn to this small, largely neglected, yet important group of cases.