Background: Multiple intracranial aneurysms (IAs) are encountered in 20-30% of the subarachnoid hemorrhages (SAH). Neuroimaging and clinical examination are usually sufficient to detect the bleeding source, but sometimes it can be misdiagnosed with catastrophic consequences.
Methods: We reviewed our diagnostic work-up for all patients admitted from January 2016 to December 2020 for SAH with multiple IAs accounting for our rate of diagnostic failure. Then, we grouped the patients into 4 categories according to aneurysms topography and described our operative protocol in case of uncertain bleeding origin.
Results: Sixty-two patients harboring 161 IAs were included. The bleeding source was identified in 56 patients (90.3%), who harbored other 81 bystander aneurysms. In 6 cases (9.7%) with a total of 24 aneurysms we failed the bleeding source identification. According to IAs topography, we grouped the IAs multiplicity in: 1) anterior plus posterior circulation IAs; 2) multiple posterior circulation IAs; 3) bilateral anterior circulation IAs; and 4) multiple ipsilateral anterior circulation IAs. In case of unidentified bleeding source, key-elements favoring the simultaneous multiple IAs treatment were their number, morphology, topography, clinicians' experience, and management modality as endovascular treatment allows a faster exclusion of multiple IAs distant one each other compared with surgery. MCA involvement represented the more frequent reason to prefer multiple clipping rather than multiple coiling.
Conclusions: In a small percentage of patients with SAH with multiple IAs, bleeding source identification can be difficult. Until the routinely availability of new tools such as vessel wall imaging or computational fluid dynamics, an experienced neurovascular team and strategies aiming to simultaneously exclude multiple IAs remain mandatory.