Ruptured Basilar Artery Perforator Aneurysm Definitely Diagnosed With Intraoperative Microsurgical Findings: Case Report and Literature Review

Background: Initial three-dimensional computed tomography angiography and cerebral angiography fail to identify any aneurysm in 20% of cases of subarachnoid hemorrhage. Basilar artery (BA) perforator aneurysm is rare and about 30–60% were not identified by initial angiography. Case presentation: A 71-year-old male was transferred with sudden onset of headache and loss of consciousness. Computed tomography demonstrated subarachnoid hemorrhage, but no ruptured aneurysm was detected. Repeat preoperative cerebral angiography indicated bifurcation aneurysm of the circumflex branch of the superior cerebellar artery perforator but microsurgical observation identified BA perforator aneurysm. Conclusions: : If the location of the BA perforator aneurysm cannot be clearly identified, as in this case, repeat angiography should be considered, and the treatment strategy should be decided based on detailed consideration of the site of the aneurysm.