Clot volume and clearance rate as independent predictors of vasospasm after aneurysmal subarachnoid hemorrhage

Abstract

Object. This study was conducted for two purposes. The first was to determine whether a combination of measurements of subarachnoid clot volume, clearance rate, and density could improve prediction of which patients experience vasospasm. The second was to determine if each of these three measures could be used independently to predict vasospasm. Methods. Digital files of the cranial computerized tomography (CT) scans obtained in 75 consecutive patients admitted within 24 hours of subarachnoid hemorrhage (SAH) were analyzed in a blinded fashion by an observer who used quantitative imaging software to measure the volume of SAH and its density. Clot clearance rates were measured by quantifying SAH volume on subsequent CT scans. Vasospasm was defined as new onset of a focal neurological deficit or altered consciousness 5 to 12 days after SAH in the absence of other causes of deterioration, diagnosed with the aid of or exclusively by confirmatory transcranial Doppler ultrasonography and/or cerebral angiography. Univariate analysis showed that vasospasm was significantly associated with the SAH grade as classified on the Fisher scale, the initial clot volume, initial clot density, and percentage of clot cleared per day (p < 0.05). In multivariate analysis, initial clot volume and percentage of clot cleared per day were significant predictors of vasospasm (p < 0.05), whereas Fisher grade and initial clot density were not. Conclusions. Quantitative analysis of subarachnoid clot shows that vasospasm is best predicted by initial subarachnoid clot volume and the percentage of clot cleared per day.