Rupture of asymptomatic mycotic aneurysm after valve replacement in infective endocarditis

Mycotic cerebral aneurysms (MCA) are one of the most serious complications of infective endocarditis. The rupture of MCA in patients under anticoagulant therapy following valve replacement carries high mortality. We encountered this serious complication in a patient who had no neurologic symptoms. A 12-year-old girl was scheduled for mitral valve replacement (MVR) 5 weeks after antibiotic therapy for infective endocarditis caused by Staphylococcus aureus. Before the surgery, she did not have any neurologic symptoms or abnormal findings in CT scanning examination. The surgery to remove her mitral valve with bacterial vegetations and replace it with an artificial valve proceeded smoothly and she appeared to begin an uneventful postoperative recovery. However, she suddenly began to complain of severe headache and became unconscious on the fifth days after MVR. A CT scan showed cerebral herniation due to a major subdural hematoma. A ruptured MCA was detected in the orbito-frontal artery and clipped in an emergency operation. She was transferred to the intensive care unit and given continuous infusion of barbiturate to prevent increase of her intracranial pressure. CT scanning and arteriography 10 days after the MCA clipping, revealed a new subdural hematoma and MCA just proximal to the previous clip. It is important to bear in mind that patients with infective endocarditis can have mycotic cerebral aneurysms without any clinical neurologic symptoms.