To document the response of mycotic aneurysms to antibiotic therapy and correlate these findings with patient outcome.

Clinical findings, CT studies, and serial cerebral angiograms of patients with endocarditis related aneurysms seen over 10 years were retrospectively reviewed.

In 14 patients infective endocarditis was diagnosed. The patients presented with subarachnoid haemorrhage (4 patients), stroke (9 patients), and seizure (1 patient). CT findings were intracerebral hematoma (5 patients), infarcts (4 patients), subarachnoid hemorrhage (4 patients), and aneurysms (2 patients). On angiography, 10 (71%) patients had single aneurysms, and 4 (29%) patients had multiple aneurysms. Eighteen aneurysms were detected, of which 6 (33%) were centrally located, and 12 (66%) were located peripherally. The most common site was the peripheral middle cerebral artery (56%). Serial angiography during antibiotic treatment demonstrated complete resolution of 6 aneurysms (33%), with 12 aneurysms remaining after 6 weeks of treatment. Of the latter, there was no change in size in 6 aneurysms (33%), a decrease in size in 3 aneurysms (17%) and an increase in size in 3 aneurysms (17%). No new aneurysms appeared. Surgery was performed on 10 patients with residual aneurysms, 11 aneurysms being excised or clipped. After 6 weeks' treatment, there was complete recovery in 7 (50%) patients, permanent neurologic deficits in 6 patients, and death from aneurysm rebleed in 1 patient.

Follow-up angiography is recommended in all patients with mycotic aneurysms to assess response to antibiotic therapy, to detect new aneurysms, and to identify those aneurysms with no response or with enlargement.