Introduction Stellate ganglion block has been reported to expand cerebral vessels and alleviate vasospasm after aneurysmal subarachnoid hemorrhage. However, the causal relationship between early stellate ganglion block and cerebral vasospasm prevention has not yet been established. Methods/design This is a single-center, prospective, randomized, controlled, blinded-endpoint assessment trial to explore the effectiveness and safety of early stellate ganglion block as a preventive treatment for

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... ebral vasospasm and delayed cerebral ischemia. A total of 228 patients will be randomized within 48 h of aneurysmal subarachnoid hemorrhage onset in a 1:1 ratio to two groups with an additional e-SGB or only a camouflaging action before craniotomy aneurysm clipping. The primary efficacy outcome is the incidence of symptomatic vasospasm within 14 days after aSAH. Further safety and efficacy parameters include the incidence of radiographic vasospasm, new cerebral infarction, postoperative delirium, and complications up to 90 days, postoperative cerebral hemodynamics, mini-mental state examination, the modified Rankin scale and all-cause mortality up to 90 days.Discussion This is the first randomized controlled trial to explore the effectiveness and safety of early stellate ganglion block as a preventive treatment to reduce cerebral vasospasm in patients with aneurysmal subarachnoid hemorrhage. If the result is positive, it may provide a new direction for the prevention and treatment of cerebral vasospasm and delayed cerebral ischemia.Trial registration ClinicalTrials.gov NCT04691271