Search for Biomarkers of Intracranial Aneurysms: A Systematic Review

INTRODUCTION: Intracranial aneurysms (IAs) remain a devastating clinical challenge, and the pathogenesis of IA formation and progression continues to be unclear. Biomarker analysis can help us understand IA development. The authors performed a systematic review of current literature on genetic and serum biomarkers for IAs in an attempt to identify diagnostic/prognostic factors for ruptured and unruptured aneurysms. METHODS: All relevant studies on PubMed that reported blood/cerebrospinal fluid (CSF) biomarkers and genes that regulate biomarker levels for IAs were assessed for whether the biomarkers/genes studied correlated with IA formation and rupture. RESULTS: Thirty-three studies were reviewed. IAs are associated with an increase in levels of immunologic markers, particularly complement C3 and C9, immunoglobulins IgG and IgM, M1/M2 macrophages, monocytes, and B and T lymphocytes; increase in blood and CSF levels of adhesion molecules; selectins found on vascular endothelium, platelets, and leukocytes; doubled ratios of elastase-toealpha-1-antitrypsin as controls; elevated levels of neurofilament heavy chain SM135 and S-100 post rupture; and locus 19q13 with many candidate genes. CONCLUSION: Though the pathophysiology of the disease remains unclear, the current literature supports the role of inflammatory and cell adhesion molecules, enzymes and hormones that effect cerebral vasculature, and other cerebral proteins related to brain and vascular damage in both the formation and progression to rupture of IAs. Future investigations are needed to validate results from previous studies and identify new diagnostic/prognostic biomarkers of IAs.