Delayed appearance of basilar trunk small atypical aneurysms in nontraumatic, initially angiogram-negative subarachnoid hemorrhage: A report of three patients.

Background: Repeat angiography will identify vascular pathology in approximately 10% of cases following angiogram-negative subarachnoid hemorrhage (anSAH), but small atypical aneurysms of the basilar artery are very uncommon.

Objective: To report a case series of delayed appearance of nontraumatic basilar artery small atypical aneurysms.

Methods: IRB approval was obtained for this retrospective case series and patient consent was waived.