In Vivo Animal Models of Cerebral Vasospasm: A Review
Bibliographic record
Abstract
BACKGROUND: Cerebral vasospasm is delayed-onset cerebral arterial narrowing in response to blood clots left in the subarachnoid space after spontaneous aneurysmal subarachnoid hemorrhage (SAH). Ideally, studies on the pathogenesis and treatment of cerebral vasospasm in humans should be conducted using human cerebral arteries. Because in vivo experiments using human vessels are not possible, and postmortem pathological examination of human arteries in vasospasm provides only a limited amount of information, a number of animal models of vasospasm have been developed. METHODS: The literature was searched to find all references to in vivo animal models of SAH and vasospasm. An online search of the medical database MEDLINE was initially performed using the key words “cerebral,” “vasospasm,” “subarachnoid,” “hemorrhage,” “animal,” and “model.” References were checked to determine the first description of each in vivo animal model. RESULTS: Fifty-seven models of SAH and vasospasm were identified. These models used one of three techniques to simulate SAH: 1) an artery was punctured allowing blood to escape and collect around the artery and its neighbors; 2) an artery was surgically exposed, and autologous blood obtained from another site was placed around the artery; or 3) blood from another site was injected into the subarachnoid space and was allowed to collect around arteries. Each technique has advantages and disadvantages. The majority of animal models of SAH and vasospasm use intracranial arteries; however, extracranial arteries have also been used recently in vasospasm experiments. These studies seem easier and less costly to perform, but concerns exist regarding the physiological dissimilarity between systemic and cerebral arteries. CONCLUSION: The model of SAH and vasospasm used most frequently is the canine “two-hemorrhage” model, in which two injections of blood into the dog’s basal cistern performed 48 hours apart result in greater arterial vasoconstriction than that effected by a single injection of blood. On the basis of its ability to accurately predict what occurs in human SAH, the best model of vasospasm seems to be the primate model in which a blood clot is surgically placed around the large cerebral vessels at the base of the monkey’s brain.
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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 | 0.002 | 0.003 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.003 | 0.002 |
| Bibliometrics | 0.008 | 0.006 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
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".