Circulating miRNA signatures for the prediction of delayed cerebral ischemia (DCI) and cerebral vasospasm: scoping review.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is a critical neurovascular emergency with high morbidity, mortality, and long-term neurological sequelae. Delayed cerebral ischemia (DCI) and Cerebral vasospasm (CVS) drive poor outcomes, yet early biomarkers are lacking. This scoping review systematically evaluates the circulating microRNA (miRNA) signatures across cerebrospinal fluid (CSF) and peripheral biofluids in predicting DCI and CV following aSAH. METHOD: A systematic search of PubMed, Scopus, Cochrane Central, and ScienceDirect was conducted in accordance with PRISMA-ScR guidelines. Identifying, 14 observational studies (n = 841). miRNA expression was analysed in CSF and peripheral biofluids using quantitative real-time PCR, microarray and next-generation sequencing. Diagnostic performance was assessed via ROC-AUC, fold change, and statistical significance. RESULTS: Several miRNAs, including miR-221-3p, miR-21, miR-24, and miR-34c, demonstrated consistent differential expression and strong predictive performance (AUC 0.70-1.00). Early alterations in miRNA profiles within 24-48 h post-ictus enabled pre-symptomatic risk stratification. CSF-derived signatures exhibited greater discriminatory accuracy compared to peripheral markers. Mechanistically, these miRNAs regulate pathways involved in endothelial dysfunction, neuroinflammation, apoptosis, and vascular remodeling. CONCLUSION: Circulating and CSF-derived miRNA signatures represent promising minimally invasive biomarkers for early prediction of DCI and CVS following aSAH. Further large-scale, multi-center studies with standardized methodologies are warranted to validate these findings.