Relationship between cerebral vasospasm vascular territory and functional outcome after aneurysmal subarachnoid hemorrhage

Vasospasm following aneurysmal subarachnoid hemorrhage (SAH) contributes significant morbidity and mortality after brain aneurysm rupture. However, the association between vascular territory of vasospasm and clinical outcome has not been studied. We present a hypothesis-generating study to determine whether the location of vasospasm within the intracranial circulation is associated with functional outcome after SAH. A retrospective analysis of a prospective, intention-to-treat trial for aneurysmal SAH was performed to supplement trial outcomes with in-hospital angiographic imaging and treatment variables regarding vasospasm. The location of vasospasm and the position on the vessel (distal vs proximal) were evaluated. Modified Rankin scale (mRS) outcomes were assessed at discharge and 6 months, and predictive models were constructed. A total of 406 patients were included, 341 with follow-up data at 6 months. At discharge, left-sided vasospasm was associated with poor outcome (odds ratio (OR), 2.37; 95% CI, 1.25 to 4.66; P=0.01). At 6 months, anterior cerebral artery (ACA) vasospasm (OR, 3.87; 95% CI, 1.29 to 11.88; P=0.02) and basilar artery (BA) vasospasm (OR, 6.22; 95% CI, 1.54 to 27.11; P=0.01) were associated with poor outcome after adjustment. A model predicting 6-month mRS score and incorporating vasospasm variables achieved an area under the curve of 0.85 and a net improvement in reclassification of 13.2% (P<0.01) compared with a previously validated predictive model for aneurysmal SAH. In aneurysmal SAH, left-sided vasospasm is associated with worse discharge functional status. At 6 months, both ACA and BA vasospasm are associated with unfavorable functional status.