The findings of this systematic review are constrained by the same methodological limitations that characterize the underlying literature. All included studies were retro- spective, with inherent sele

The gap

Consensus across the literature

Supporting evidence — 3 representative gaps

• Cognitive Outcomes After Stenting vs. Endarterectomy: A Systematic Review with Meta-Analysis (2026) · doi

  Available literature on cognitive outcomes after carotid revascularization was highly heterogeneous with substantial variability in patient selection, design, periprocedural management, and cognitive assessment strategies between studies. Additionally, our analysis had no true control to compare outcomes due to limited reporting of controls in individual studies, making a comparison to best medical treatment nonsensical. medRxiv preprint The copyright holder has placed this preprint (which was not certified by peer review) in the Public Domain. It is no longer restricted by copyright. Anyone can legally share, reuse, remix, or adapt this material for any purpose without crediting the original authors. https://doi.org/10.64898/2026.05.04.26351899 this version posted May 10, 2026. doi: ; Inconsistent test selection, follow-up timing, and reporting of changes in scores meant meta analysis was restricted to the most commonly reported global screening instruments (MoCA and MMSE). This approach excludes other studies assessing global cognition with other individual tests (Mini-Cog, ACE-III, GPCOG, etc.), limiting our study selection. Additionally, domain specific outcomes were summarized qualitatively using direction of change categories without meaningful interpretation. This allowed for synthesis across instruments and should be interpreted as descriptive only. The inclusion of both symptomatic and asymptomatic carotid stenosis populations represents an additional limitation. Baseline cognitive status, cerebrovascular reserve, and vulnerability to peri-procedural injury are likely to differ between these groups, yet these factors were inconsistently reported and adjusted for across studies. Most included studies were observational, introducing potential confounding related to vascular comorbidities, educational attainment, baseline cognition, and treatment selection. Practice effects and regression to the mean may also have influenced observed improvements, particularly in studies lacking appropriate control groups or repeated baseline testing. As noted earlier, follow-up timing was inconsistent across studies and cognitive trajectories after carotid revascularization may vary over time. To enable quantitative synthesis, follow-up intervals were divided into early and late time points. While this approach allows for cross-study comparison and prevents double counting, it sacrifices temporal granularity and can obscure short-term fluctuations. This study was not registered to PROSPERO, an additional limitation to our study.

  Keywords: cognitive selection outcomes carotid follow across baseline revascularization additionally control reporting individual comparison treatment preprint
• Management of pediatric brain arteriovenous malformation: a systematic review of retrospective studies (2026) · doi

  The findings of this systematic review are constrained by the same methodological limitations that characterize the underlying literature. All included studies were retro- spective, with inherent selection bias and confounding by indication. Outcome definitions—particularly oblitera- tion—were inconsistent (DSA-confirmed cure vs. MRI- based assessments), and follow-up ascertainment varied across cohorts, limiting comparability and precluding robust pooled estimates. Notably, no minimum follow-up duration was pre-specified for inclusion because the crite- rion required only that at least one post-management out- come be reported. This permissive threshold introduces substantial heterogeneity in follow-up duration (ranging from 3 months to a median of 19.1 years across cohorts) and limits the comparability of recurrence and oblitera- tion estimates across studies. Angioarchitectural report- ing beyond SM grade was incomplete and nonuniform, with nidus size reported as diameter or volume using het- erogeneous thresholds. Finally, reporting of functional outcomes and complications was variably structured and often not standardized across modalities. These limita- tions substantiate the rationale for a descriptive synthesis and reinforce that inference should remain modality- and cohort-contextual rather than comparative. 1 3Neurosurgical Review (2026) 49:424  424 Page 14 of 15

  Keywords: across follow review oblitera tion cohorts comparability estimates duration reported systematic constrained methodological limitations characterize
• Transradial versus transfemoral access for diagnostic cerebral angiography: a systematic review and meta-analysis of randomized and prospective studies with grade assessment (2026) · doi

  A major methodological innovation of the present meta‑ analysis is the deliberate restriction of eligible studies to randomized controlled trials and prospective observa‑ tional cohorts, with systematic exclusion of retrospective datasets commonly included in prior pooled analyses. This choice of study design is justified on multiple bases. Retrospective studies are inherently susceptible to selec‑ tion bias as operators performing TRA might select anatomically favourable patients with favourable vessel conditions, hence underestimating complications. More‑ over, retrospective studies are unable to control for tem‑ poral trends in operator experience, institution‑specific protocols, and the concomitant evolution of equipment, all of which confound outcome attribution. Furthermore, the inclusion of studies from multiple international cen‑ ters improves the external validity and generalizability of the pooled findings across diverse neurointerventional settings. Prospective studies ensure comparable baselines, specified outcome definitions, and standardized follow‑ up, thereby reducing the selection bias. The inclusion of RCTs and prospective observational studies allowed subgroup analysis to evaluate the source of heterogene‑ ity, which would have been obscured in a single‑design meta‑analysis. Lastly, the use of a random‑effects model throughout, validated sensitivity analyses, GRADE‑based certainty assessment, and Newcastle‑Ottawa Scale evalu‑ ation of cohort quality further strengthened confidence in the robustness of the pooled estimates. This design choice differentiates the present analysis from prior pooled studies and strengthens confidence in the comparative estimates. However, this study had multiple limitations. First, the total number of events recorded for outcomes such as neurological complications and access‑site complications was relatively low, reducing the statistical power and wid‑ ening the confidence intervals. Second, high heterogene‑ ity was observed for time to ambulation (I2 = 99%) and access‑site complications (I2 = 81%), reflecting variations in operator experience, learning curve phases, and insti‑ tutional protocols. Lastly, patient‑reported outcomes, including satisfaction, pain scores, and quality of life, were not uniformly reported and could not be analyzed despite their clinical importance. Publication bias could Khan et al. Egyptian Journal of Neurosurgery (2026) 41:99 not be formally assessed because only a few studies were available per outcome.

  Keywords: pooled complications prospective retrospective design multiple bias outcome confidence present meta prior analyses choice favourable