Early identification of patients at risk for symptomatic vasospasm after aneurysmal subarachnoid hemorrhage

Objective: To develop a scheme for early identification of individuals at risk for symptomatic vasospasm after subarachnoid hemorrhage (SAH). Design: Analysis of prospectively collected data from the placebo-treated group in a multicenter clinical trial. Settings: Fifty-four neurosurgical centers in North America. Measurements and Main Results: We identified independent predictors of symptomatic vasospasm using stepwise logistic regression analysis from demographic, clinical, laboratory, and neuroimaging characteristics of the participants. We developed a scoring system (symptomatic vasospasm risk index) based on a combination of these predictors. Out of 283 patients in the analysis (all treated with oral nimodipine), 93 (33%) developed symptomatic vasospasm within 14 days after SAH. There were four independent predictors of symptomatic vasospasm: thickness of subarachnoid clot on computed tomographic scan (odds ratio [OR], 4.1; 95% confidence interval [CI], 1.8-10.0); early rise in middle cerebral artery mean flow velocity (MCA-MFV), defined as a value ≥110 cm/sec recorded on or before post-SAH day 5 (OR, 1.9; 95% CI, 1.1-3.3), Glasgow Coma Scale score <14 (OR, 1.8; 95% CI, 1.1-3.1); and rupture of anterior cerebral or internal carotid artery aneurysm (OR, 1.9; 95% CI, 1.0-3.4). The probability of identifying patients who would develop symptomatic vasospasm (percentage of area under receiver operating characteristics curve ± SEM) was higher with symptomatic vasospasm risk index (68% ± 8%) compared with thickness of clot (62% ± 8%; p = .08) or MCA-MFV (45% ± 7%, p < .05) criteria alone. Conclusions: Patients at high risk for symptomatic vasospasm can be identified early in the course of SAH using a risk index. A risk index based on a combination of variables may represent a predictive paradigm superior to conventionally used criteria based on clot thickness or MCA-MFV criteria.