Culture Negative Infective Endocarditis Atypically Diagnosed From Mycotic Cerebral Aneurysm

Cerebral mycotic aneurysms (CMA) are a rare consequence of infective endocarditis (IE). We report a case of a 75-year-old left-handed male with comorbidities who was admitted to our facility with left-sided weakness, dysarthria, and left-sided facial droop. Initial computed tomography of the head without contrast and angiography of the head showed acute hemorrhage in the paramedian right frontal lobe with extension into the right lateral ventricle, occlusion of the left intracranial internal carotid artery, and an associated 0.3 cm aneurysm involving the distal right anterior cerebral artery. C-reactive protein and erythrocyte sedimentation rate were elevated but blood cultures showed no growth for more than five days. The patient underwent a two-vessel cerebral angiogram, primary coil embolization of the aneurysm, and selective catheterization of the left common carotid artery, right internal carotid artery, and right anterior cerebral artery. Transesophageal echocardiography showed an echogenic, highly mobile structure attached to the aortic valve suggestive of vegetation. The patient was subsequently started on a vancomycin regimen and stably discharged for further outpatient follow-up. This case highlights an uncommon presentation of CMA and the retroactive diagnosis of IE.