The incidence of radiologically demonstrable aneurysm and arteriovenous malformation in spontaneous subarachnoid haemorrhage.

The incidence of radiologically demonstrable aneurysm and arteriovenous malformation (AVM) in patients admitted to the Midland Centre for Neurosurgery and Neurology (MCNN) with the diagnosis of spontaneous subarachnoid haemorrhage (SAH) between 1959-80 inclusive was determined. Bilateral carotid angiography (BCA) showed 65·8% to have one or more aneurysms and 7·5% an AVM, each figure including 0·6% with both conditions. When BCA was negative, 65·8% proceeded to vertebral angiography (VA) and of these 12·5% were shown to have an aneurysm and 4·2% an AVM. The probability of demonstrating an aneurysm by either of these radiological methods is an important factor in deciding whether or not to proceed to angiography, especially in patients presenting an above average anaesthetic or operative risk, bearing in mind the high mortality of untreated aneurysm in this condition and the improved prognosis when successful surgical management is possible.