• mycotic
• aneurysm

A 64 year old woman with one week of low grade fever and malaise was found unconscious at home. On arrival at hospital, she was obtunded but had intact brainstem reflexes. She was febrile and a heart murmur was auscultated. Head computed tomography revealed subarachnoid haemorrhage in the left sylvian fissure. Transoesophageal echocardiography demonstrated multiple mitral valve vegetations (fig 1, arrows) with bileaflet prolapse and severe mitral regurgitation (fig 1A). Moderate posterior mitral annular calcification was evident with an associated mobile vegetation (fig 1B, arrowhead). Multiple blood cultures grew Staphylococcus aureus. While magnetic resonance angiography (MRA) was unremarkable, gadolinium-enhanced T1 weighted axial magnetic resonance imaging (MRI) revealed an enhancing lesion in continuity with distal parietal branches of the left middle cerebral artery (fig 2A, arrow). Cerebral angiography corroborated the diagnosis of mycotic aneurysm (fig 2 B, arrow).

Subarachnoid haemorrhage is an infrequent yet devastating complication of bacterial endocarditis, typically resulting from rupture of a mycotic aneurysm. The distal location and small size characteristic of mycotic aneurysms may preclude detection with MRA.¹ Gadolinium-enhanced MRI may identify such lesions despite normal MRA. Enhancement may be indicative of the highly inflammatory nature of these lesions.

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Figure 1

Transoesophageal echocardiogram demonstrating multiple mitral valve vegetations (arrows). Associated findings included mitral valve prolapse with severe mitral valve regurgitation (A) and moderate posterior mitral annular calcification with mobile vegetation (arrowhead, B).

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Figure 2

(A) Gadolinium-enhanced T1 weighted axial MRI and (B) left internal carotid angiogram showing a mycotic aneurysm in a distal branch of the left middle cerebral artery (arrows).