Intracranial aneurysms often remain asymptomatic until rupture, causing aneurysmal subarachnoid hemorrhage (aSAH). aSAH frequently leads to cerebral vasospasm (CVS) and delayed cerebral ischemia (DCI), significantly increasing the risk of severe neurological deficits and mortality. Identifying reliable biomarkers, such as lipid peroxidation metabolites (LPMs), is crucial for early prediction and timely intervention. This study summarizes current knowledge on LPMs as potential biomarkers for CVS and DCI after aSAH. A systematic review was conducted following PRISMA guidelines. Two independent authors searched PubMed, Web of Science, and Scopus for articles studying the association between non-enzymatic and enzymatic lipid metabolites and CVS or DCI after aSAH. Quality and risk of bias were evaluated using the Newcastle-Ottawa Scale. Extracted data included metabolite concentrations, biological sample types, timing of collection, patient demographics, clinical severity of aSAH, Fisher’s grade, DCI definition, and relationship to DCI. Of 519 records screened, 17 studies were included. Lipid metabolites were measured in blood (5 studies), cerebrospinal fluid (11 studies), and urine (2 studies). F2-isoprostanes (F2-IsoPs), studied in 7 articles, were linked to increased DCI risk, with elevated levels observed within three days post-aSAH. Isofurans (IsoFs) predicted DCI risk between days 5 and 8 post-aSAH, while elevated cholesteryl ester hydroperoxide (CEOOH) levels on day 2 linked to symptomatic vasospasm. Enzymatic arachidonic acid (AA) metabolites, including 6-keto-prostaglandin F1-α, prostaglandin D2, and leukotriene C4, were also associated with early DCI risk. To the best of our knowledge, this review is the first to comprehensively assess all LPMs in relation to CVS and DCI. Elevated concentrations of F2-IsoPs and enzymatic AA derivatives may serve as biomarkers for DCI prediction in aSAH. These findings highlight the need to explore the potential of LPMs, paving the way for risk stratification and timely interventions to improve patient outcomes and aid researchers in developing predictive scoring systems for DCI. Clinical trial number Not applicable.

Cerebral vasospasm (CVS) is a severe complication associated with significant morbidity and in-hospital mortality. While well characterized in aSAH, its occurrence following AVM-related hemorrhage remains less understood. To address this gap, a meta-analysis adhering to PRISMA guidelines was conducted, with two independent authors searching PubMed, Scopus, and Web of Science from inception to July 2024, seeking studies on CVS risk factors following AVM-related hemorrhage. Study quality was assessed using the Newcastle-Ottawa Scale (NOS). Dichotomous variables were pooled into an overriding odds ratio (OR) with a 95% confidence interval (CI), while continuous variables were analyzed using the mean difference (MD) with a 95% CI, both using a random-effects model. Out of 2360 screened articles, 4 studies met the inclusion criteria, totaling 7483 AVM-related hemorrhage patients, 958 of whom developed CVS. All studies were rated high quality, according to NOS. A total of 10 extractable demographic, behavioral, clinical, and radiographic variables reported in the literature were assessed. The following CVS risk factors were statistically significant: younger age (MD = -4.99; 95% CI [-9.40 to -0.57]; p = 0.03), female sex (OR = 1.72; 95% CI [1.50–1.98]; p < 0.00001), and intraventricular hemorrhage (OR = 1.24; 95% CI [1.04–1.48]; p = 0.02). Subarachnoid hemorrhage was close to significance (OR = 1.17; 95% CI [1.00–1.36]; p = 0.05). This is the first systematic review and meta-analysis to identify risk factors for CVS in the context of AVM-related hemorrhage. The presented findings may aid clinicians in recognizing high-risk individuals. Further research is warranted to develop a reliable risk scoring system that can predict AVM-associated CVS in clinical settings and to further explore the differences between CVS following aSAH and AVM-related hemorrhage.

Purpose: Moyamoya disease (MMD) is a chronic cerebrovascular disorder characterized by progressive arterial stenosis and fragile collateral formation, elevating stroke risk. Revascularization is the standard treatment, yet up to 27% of patients experience ischemic events within a year due to bypass insufficiency. While digital subtraction angiography (DSA) remains the gold standard for assessing bypass function, it is invasive and time-consuming. This study evaluates ultrasonography (US) as a noninvasive, cost-effective tool to assess bypass capacity post-revascularization in MMD. Methods: A systematic search was conducted following PRISMA guidelines. PubMed, Web of Science, and Scopus were searched for studies reporting US parameters with control imaging confirming bypass capacity. Study quality was assessed using the Newcastle–Ottawa Scale. Mean difference (MD) values were calculated using random-effects models. High bypass capacity was defined as good patency or favorable collateral development. Results: Eight cohort studies comprising 264 MMD patients and 301 operated hemispheres were included, with 180 demonstrating high bypass capacity. Within two weeks post-surgery, increased superficial temporal artery (STA) peak systolic velocity (PSV, MD = 28.26, p < 0.0001), mean flow velocity (MFV, MD = 22.97, p = 0.03), end-diastolic velocity (EDV, MD = 33.45, p < 0.0001), and decreased resistance index (RI, MD = –0.09, p = 0.006) were predictive. External carotid artery (ECA) EDV (MD = 13.92, p = 0.04) was also significant. At 3–6 months, elevated EDV in both STA (MD = 8.13, p = 0.006) and ECA (MD = 8.71, p = 0.0002) remained predictive. In the indirect subgroup, lower anterior cerebral artery (ACA) MFV within 0–3 months predicted favorable outcomes (MD = –64.98, p = 0.001). Conclusions: Changes in STA and ECA US parameters measured following revascularization surgery predict high bypass capacity. Decreased ACA MFV suggests effective revascularization after indirect surgery. Ultrasound modality offers a valuable, noninvasive tool for postoperative assessment in MMD.

Background: Accurate presurgical localization of eloquent cortex and subcortical pathways is essential in neurosurgery, guiding the balance between maximal safe resection and preservation of neurological function. This narrative review compares the clinical utility of task-based functional magnetic resonance imaging (tb-fMRI) and resting-state functional magnetic resonance imaging (rs-fMRI) in neurosurgical populations, with emphasis on brain tumors and epilepsy. Methods: This narrative review was based on a non-systematic literature search of PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar from database inception to March 2026. The review focused on tb-fMRI and rs-fMRI for presurgical functional mapping in neurosurgical populations, including clinical utility, feasibility, validation, limitations, and workflow integration. Results: Tb-fMRI remains the most established noninvasive modality for motor and language mapping and language lateralization because of its task-specific activation maps and established role in clinical workflows. However, its use is limited by dependence on patient cooperation, task performance, and intact neurovascular coupling; thus, aphasia, cognitive impairment, fatigue, paresis, pediatric age, sedation, and tumor-related neurovascular uncoupling may render tb-fMRI inconclusive or misleading. Rs-fMRI offers a task-free alternative based on intrinsic functional connectivity, enabling simultaneous mapping of multiple resting-state networks from a single acquisition and providing particular value in non-cooperative, cognitively impaired, aphasic, pediatric, or sedated patients. Evidence indicates that rs-fMRI is most robust for sensorimotor mapping, with reported agreement with tb-fMRI and intraoperative direct electrical stimulation, whereas language mapping remains less consistent and more dependent on analytical methodology. Neither modality replaces intraoperative stimulation, which remains the reference standard. Conclusions: Current evidence supports a multimodal presurgical strategy in which tb-fMRI is used first-line in cooperative patients; rs-fMRI is added when task-based mapping is limited or infeasible, and both are interpreted alongside tractography, neuronavigation, and intraoperative mapping.