Development and rupture of a de novo basilar artery aneurysm after surgical removal of a cerebellar arteriovenous malformation.

Background: The de novo development of an aneurysm in an previously normal artery is an uncommon event. We describe a patient who developed a de novo bleeding aneurysm of the basilar artery in the three weeks following the surgical removal of a large cerebellar AVM. METHOD-FINDINGS: A 48-year-old man suddenly developed transient headache, vertigo and disturbance of balance. Neuroradiological examinations showed the presence of a large AVM of the right cerebellar hemisphere. The AVM was removed successfully; following the operation there were repeated bleeding episodes at the operating site, requiring surgical evacuation. Three weeks after the AVM removal he suffered from a massive subarachnoid haemorrhage due to the rupture of an aneurysm developed de novo in the basilar artery.

Interpretation: This is the first reported case, to our knowledge, of a de novo aneurysm developed in an artery hemodynamically related to a surgically removed AVM. This complication was probably due to the postoperative hemodynamic changes in the vessels afferent to the AVM, associated with arterial wall dysplasia.