Attenuation of cerebral vasospasm by systemic administration of an endothelin-A receptor antagonist, TBC 11251, in a rabbit model of subarachnoid hemorrhage

Neuroinflammatory response after subarachnoid hemorrhage: A review of possible treatment targets

A serious neurosurgical emergency, subarachnoid hemorrhage (SAH) is characterized by vascular and neuropathy, as well as complex pathological mechanisms like vascular lesions, inflammatory responses, and nerve cell damage. The inflammatory response is an essential aspect of SAH's pathophysiology, causing the release of a number of inflammatory mediators and oxidative stress products like TNF-α, MCP-1, MMPs, and so on, which either directly or indirectly contribute to the development of SAH.It has recently been discovered that some antibodies against inflammatory mediators, antioxidant stress, botanicals, and traditional Chinese medicine decrease the inflammatory response of SAH. Additionally, certain biomarkers linked to inflammation may serve as a foundation for clinical diagnosis.Although these mechanisms are still not completely understood, we can explore potential therapeutic targets by studying the role of inflammatory responses and bioactive molecules in the formation of SAH.

Effect of endothelin receptor antagonists on clinically relevant outcomes after experimental subarachnoid hemorrhage: a systematic review and meta-analysis

In clinical trials, endothelin receptor antagonists (ETRAs) reduced vasospasm but did not improve functional outcome after subarachnoid hemorrhage (SAH). We assessed the effects of treatment with ETRAs on clinically relevant outcomes in animal studies modelling SAH by performing a systematic review of the literature for controlled animal studies of ETRAs for the treatment of SAH. Primary outcomes were neurobehavioral outcomes and case fatality. Secondary outcomes were cerebral vasospasm and cerebral blood flow. Summary estimates were calculated using normalized mean difference random effects meta-analysis. We included 27 studies (55 experiments, 639 animals). Neurobehavioral scores were reported in none of the experiments, and case fatality in 8 (15%). Treatment with ETRAs was associated with a pooled odds ratio for case fatality of 0.61 (95% confidence interval (CI), 0.27 to 1.39); a 54% increase (95% CI, 39 to 69) in cerebral arterial diameter; and a 93% increase (95% CI, 58 to 129) in cerebral blood flow. We conclude that there is no evidence from animal studies that treatment with an ETRA improves clinically relevant outcomes after SAH. The reduction in cerebral vasospasm observed in animal studies is consistent with that observed in clinical trials, an effect that is not associated with better functional outcome in patients.

The rabbit shunt model of subarachnoid haemorrhage

Aneurysmal subarachnoid haemorrhage (SAH) is a disease with devastating complications that leads to stroke, permanent neurological deficits and death. Clinical and ex-perimental work has demonstrated the importance of the contribution of delayed cerebral vasospasm (DCVS) indepen-dent early events to mortality, morbidity and functional out-come after SAH. In order to elucidate processes involved in early brain injury (EBI), animal models that reflect acute events of aneurysmal bleeding, such as increase in intracranial pressure (ICP) and decrease in cerebral perfusion pressure, are needed. In the presented arterial shunt model, bleeding is initially driven by the pressure gradient between mean arterial blood pressure and ICP. SAH dynamics (flow rate, volume and duration) depend on physiological reactions and local anatomical intrathecal (cistern) conditions. During SAH, ICP reaches a plateau close to diastolic arterial blood pressure and the blood flow stops. Historical background, anaesthesia, perioperative care and monitoring, SAH induction, technical considerations and advantages and limitations of the rabbit blood shunt SAH model are discussed in detail. Awareness of technical details, physiological characteristics and appropriate monitoring methods guarantees successful implementation of the rabbit blood shunt model and allows the study of both EBI and DCVS after SAH.

Pharmacologic reduction of angiographic vasospasm in experimental subarachnoid hemorrhage: systematic review and meta-analysis

Animal models have been developed to simulate angiographic vasospasm secondary to subarachnoid hemorrhage (SAH) and to test pharmacologic treatments. Our aim was to evaluate the effect of pharmacologic treatments that have been tested in humans and in preclinical studies to determine if animal models inform results reported in humans. A systematic review and meta-analysis of SAH studies was performed. We investigated predictors of translation from animals to humans with multivariate logistic regression. Pharmacologic reduction of vasospasm was effective in mice, rats, rabbits, dogs, nonhuman primates (standard mean difference of -1.74; 95% confidence interval -2.04 to -1.44) and humans. Animal studies were generally of poor methodologic quality and there was evidence of publication bias. Subgroup analysis by drug and species showed that statins, tissue plasminogen activator, erythropoietin, endothelin receptor antagonists, calcium channel antagonists, fasudil, and tirilazad were effective whereas magnesium was not. Only evaluation of vasospasm >3 days after SAH was independently associated with successful translation. We conclude that reduction of vasospasm is effective in animals and humans and that evaluation of vasospasm >3 days after SAH may be preferable for preclinical models.