Direct, Indirect, and Combined Extracranial-to-Intracranial Bypass for Adult Moyamoya Disease: An Updated Systematic Review and Meta-Analysis
Bibliographic record
Abstract
Background: Moyamoya disease is a chronic, progressive cerebrovascular disease involving occlusion or stenosis of the terminal portion of the internal carotid artery. We conducted an updated systematic review and meta-analysis to investigate clinical and angiographic outcomes comparing direct, combined, and indirect bypass for the treatment of moyamoya disease in adults. Methods: Two independent authors performed Preferred Reporting Items for Systematic reviews and Meta-Analyses guided literature searches in December 2021 to identify articles reporting clinical/angiographic outcomes in adult moyamoya disease patients undergoing bypass. Primary end points used were ischemic and hemorrhagic strokes, clinical outcomes, and angiographic revascularization. Study quality was evaluated with Newcastle-Ottawa and the Oxford Center for Evidence-Based Medicine scales. Results: Four thousand four hundred fifty seven articles were identified in the initial search; 143 articles were analyzed. There were 3827 direct, 3826 indirect, and 3801 combined bypasses. Average length of follow-up was 3.59±2.93 years. Pooled analysis significantly favored direct (odds ratio [OR], 0.62 [0.48–0.79]; P <0.0001; OR, 0.44 [0.32–0.59]; P <0.0001; OR, 0.56 [0.42–0.74]; P <0.0001; OR, 3.1 [2.5–3.8]; P =0.0001) and combined (OR, 0.53 [0.41–0.69]; P <0.0001; OR, 0.28 [0.2–0.41]; P <0.0001; OR, 0.41 [0.3–0.56]; P <0.0001; OR, 3.1 [2.8–4.3]; P =0.0001) over indirect bypass for early stroke, late stroke, late intracerebral hemorrhage, and favorable outcomes, respectively. Indirect bypass was favored over combined (OR, 3.1 [1.7–5.6]; P <0.0001) and direct (OR, 4.12 [2.34–7.25]; P <0.0001) for early intracerebral hemorrhage. The meta-analysis significantly favored direct (OR, 0.37 [0.23–0.60]; P <0.001; OR, 0.49 [0.31–0.77]; P =0.002) and combined (OR, 0.23 [0.12–0.43]; P <0.00001; OR, 0.30 [0.18–0.49]; P <0.00001) bypass over indirect bypass for late stroke and late hemorrhage, respectively. Combined bypass was favored over indirect bypass for favorable outcomes (OR, 2.06 [1.18–3.58]; P =0.01). Conclusions: Based on combined meta-analysis (43 articles) and pooled analysis (143 articles), the existing literature indicates that combined and direct bypasses have significant benefits for patients suffering from late stroke and hemorrhage versus indirect bypass. Combined bypass was favored over indirect bypass for favorable outcomes. This is a strong recommendation based on low-quality evidence when utilizing the Grades of Recommendation, Assessment, Development, and Evaluation system. These findings have important implications for bypass strategy selection.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.013 | 0.032 |
| Meta-epidemiology (narrow) | 0.003 | 0.002 |
| Meta-epidemiology (broad) | 0.017 | 0.037 |
| Bibliometrics | 0.007 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".