Rapid growth of a basilar aneurysm.

We describe a patient who developed, over a 22-month period, a giant aneurysm of his basilar artery. A prior MRI of the brain done for nonspecific symptoms showed a normal brainstem and basilar artery. At presentation, he had a repeat MRI scan for a 4-month history of a partial right oculomotor nerve palsy and left hemiparesis. The MRI revealed a giant aneurysm of the top of the basilar artery. This was treated by angiographic placement of Guglielmi detachable coils (GDC) after surgical intervention was deemed unfeasible. This case illustrates the acquired nature of intracranial aneurysms. All inoperable intracranial aneurysms should be closely monitored and MRI and MR angiography may currently be the best noninvasive methods for this purpose. Intra-arterial GDC embolization of aneurysms is an alternative treatment when surgery is not possible.