Introduction: Intracranial mycotic aneurysms (IMA) are rare but serious complications of infective endocarditis (IE).
Methods and Results: In this retrospective study (1980-2011) we used original Duke criteria to diagnose IE in 1149 episodes (1081 patients; 81% definite, 80% native valve). Neuro complications occurred in 28%, stroke in 22% (202 infarcts, 53 hemorrhages) and 1% had TIA/TMB. N=33 IMA were detected in 23 (2%) patients. IMA were detected in 8% with focal neuro deficits, 13% with seizures, and 3% with encephalopathy. IMA-related symptoms were present in 22 of 23 cases: headache 48%, seizure 13%, altered sensorium 35% and focal deficits 61%. IMA were detected in 0/885 without stroke, 5.4% with infarcts and 22.6% with hemorrhages (p<0.001); the latter included 9/36 (25%) with ICH, 3/13 (23%) with SAH, and 0/4 with SDH. Of the 23 IMA patients 61% had hemorrhage, 30% had SAH and 57% had infarcts. IMAs were detected by DSA in 21/166 (12.7%). The mean size was 3.6±2.4 mm; 30% multiple; 61% located in distal segments; and 67% in MCA branches. On MRI, 31 had any SAH and 45 had any ICH; IMA detected in 6/9 with diffuse SAH, 2/22 with convexal SAH, 11/45 with ICH, and 11/202 with infarcts. Patients with IMA had higher rates of women, hypertension, known cardiac valve disease, mitral regurgitation, mitral vegetation and S.viridians infection (all p<0.05). On multivariable analysis, mitral regurgitation with vegetation (OR 5.9, 95% CI 2.5-14.0, p<0.001) was the only independent predictor of IMA. Clipping was performed in 8 (all pre-2000); endovascular treatment in 7 (all post-1997); 2 died pre- treatment; 1 detected on autopsy; 1 no follow-up available, and 4 regressed/disappeared with antibiotics. Patients with and without IMA showed no difference in rates of in-hospital mortality (22% v. 19%, p=0.93), and length of stay (32d v. 24d, p=0.28). IMA rates did not decrease during the study period (2.2% in 784 episodes 1980-2000 vs. 1.6% of 365 episodes 2001-2011, p=0.653).
Conclusion: IMA are invariably heralded by neurological symptoms and stroke (especially hemorrhages) on brain imaging. Mitral IE has the highest risk for IMA. IMAs can resolve with antibiotics however studies are needed to determine the efficacy of different treatment approaches.