A systematic review of 20 human studies reveals significantly reduced gut microbial alpha diversity in patients with ruptured intracranial aneurysms compared to controls. The meta-analysis identified protective bacterial taxa including Ruminococcus1, Bilophila, Fusicatenibacter, and Porphyromonadaceae that appear to lower aneurysm-related outcomes through Mendelian randomization evidence. This represents the first comprehensive synthesis of human data connecting gut microbiome alterations to brain aneurysm rupture, the leading cause of spontaneous subarachnoid hemorrhage with substantial mortality rates. The gut-brain vascular connection likely operates through inflammatory pathways and microbial metabolites affecting endothelial integrity. While promising for identifying at-risk patients and potential therapeutic targets, this evidence comes from observational studies that cannot establish causation. The microbiome's role in cerebrovascular health represents an emerging frontier that could revolutionize aneurysm prevention strategies. However, as this analysis is a preprint awaiting peer review, these findings require validation before clinical application. The research suggests maintaining gut microbial diversity through diet and lifestyle interventions might offer unexpected neuroprotective benefits.