Efficacy of alpha-calcitonin gene-related peptide in dilating cerebral arteries: protocol for a systematic review and meta-analysis of in vivo animal studies

Aneurysmal subarachnoid haemorrhage (SAH) is a type of stroke causing up to 70% of patients to either die or be dependent on others at six months. Delayed cerebral ischaemia (DCI) is the most important cause of poor outcome after the initial injury. Oral nimodipine is the only pharmaceutical treatment with proven benefits and alternative therapies are needed. There are strong associations between DCI and cerebral vessel narrowing but interventions to treat DCI by improving vessel narrowing have been largely ineffective. Alpha-calcitonin gene-related peptide (αCGRP) is a potent microvascular vasodilator which may be effective in treating DCI by preventing cerebral vessel narrowing after SAH. This protocol outlines the methodology for a systematic review and meta-analysis investigating the effect of αCGRP on cerebral vessel narrowing and neurological outcomes after SAH from in vivo animal studies.