Cerebral mycotic aneurysms (MAs) also called infective aneurysms, are uncommon and are usually encountered in patients with infective endocarditis. These aneurysms often present with intracranial hemorrhage. MAs may resolve on treatment with antibiotics alone. However prognosis with medical management alone is unpredictable. Good prognosis with surgery has been reported for single accessible ruptured MAs. However surgery is associated with significant morbidity. Endovascular treatment of MAs along with appropriate antibiotics is emerging as an acceptable option for these patients.

A 17-year-old male, a known case of rheumatic heart disease (RHD), presented with on and off high grade fever and sudden onset of right sided hemiparesis. Blood investigations showed leucocytosis and a negative blood culture. 2D-Echocardiography revealed severe aortic regurgitation and mild aortic stenosis with large vegetations seen on the aortic valve. Plain computed tomography (CT) of the brain revealed an intraparenchymal hematoma in left parieto-occipital region. Cranial digital subtraction angiography (DSA) showed an irregular aneurysm arising from the parieto-occipital branch of left posterior cerebral artery (Figure ​(Figure1A1A,​,B).B). The patient was started on broad spectrum antibiotics. Twelve weeks later the patient showed improvement in hemiparesis. Follow-up angiography, however, showed an increase in size of the aneurysm and therefore endovascular embolization was planned.

A 27-year-old female, a known case of RHD, presented with headache and fever along with weakness of right lower limb and aphasia. Magnetic resonance imaging of the head showed an intraparenchymal hematoma in the left perisylvian region (Figure ​(Figure2A).2A). 2D Echocardiography revealed severe mitral regurgitation with trivial aortic regurgitation with a large vegetation on the anterior mitral leaflet. Blood cultures were positive for streptococcus viridians. Cranial DSA showed an irregular aneurysm arising from frontal branch of left middle cerebral artery (Figure ​(Figure2B).2B). Under general anesthesia superselective catheterization of the branch was carried out by Ultraflow microcatheter and Mirage guidewire (ev3, MTI, Irvine, CA, USA). Fluoroscopically (IDF (GE) subtraction fluoroscopy) monitored controlled injection of glue was performed to occlude the stem of the parent vessel leading to the aneurysm and the aneurysm itself (Figure ​(Figure2C).2C). Delayed imaging showed retrograde filling of the distal branch through collaterals, but no filling of the aneurysm (Figure ​(Figure2D).2D). The patient was managed conservatively for the hematoma and treated with appropriate antibiotics. At discharge the patient was conscious, oriented and following commands with no motor or sensory deficits except aphasia.

The formation of a mycotic aneurysm (MA) starts with the lodgment of a septic embolus in the vascular tree followed by necrosis and inflammation of the vessel wall that becomes fragile leading to a pseudoaneurysm formation ⁵. Most MAs occur in patients with infective endocarditis¹ and are seen in 2-10% of these patients¹⁰. Other causes include contiguous extension of infection from meningitis, osteomyelitis, sinusitis and cavernous sinus infection. Streptococcus is the most common causative organism followed by staphylococci, enterococci, pneumococcus and haemophilus species ¹. When endocarditis is associated with a distal aneurysm, the diagnosis of a MA is usually clear ⁷.