Leukocytosis as an independent risk factor for cerebral vasospasm following aneurysmal subarachnoid hemorrhage

Object. The identification of patients at an increased risk for cerebral vasospasm after subarachnoid hemorrhage (SAH) may allow for more aggressive treatment and improved patient outcomes. Note, however, that blood clot size on admission remains the only factor consistently demonstrated to increase the risk of cerebral vasospasm after SAH. The goal of this study was to assess whether clinical, radiographic, or serological variables could be used to identify patients at an increased risk for cerebral vasospasm. Methods. A retrospective review was conducted in all patients with aneurysmal or spontaneous nonaneurysmal SAH who were admitted to the authors' institution between 1995 and 2001. Underlying vascular diseases (hypertension or chronic diabetes mellitus), Hunt and Hess and Fisher grades, patient age, aneurysm location, craniotomy compared with endovascular aneurysm stabilization, medications on admission, postoperative steroid agent use, and the occurrence of fever, hydrocephalus, or leukocytosis were assessed as predictors of vasospasm. Two hundred twenty-four patients were treated for SAH during the review period. One hundred one patients (45%) developed symptomatic vasospasm. Peak vasospasm occurred 5.8 ± 3 days after SAH. There were four independent predictors of vasospasm: Fisher Grade 3 SAH (odds ratio [OR] 7.5, 95% confidence interval [CI] 3.5-15.8), peak serum leukocyte count (OR 1.09, 95% CI 1.02-1.16), rupture of a posterior cerebral artery (PCA) aneurysm (OR 0.05, 95% CI 0.01-0.41), and spontaneous nonaneurysmal SAH (OR 0.14, 95% CI 0.04-0.45). A serum leukocyte count greater than 15 × 10⁹/L was independently associated with a 3.3-fold increase in the likelihood of developing vasospasm (OR 3.33, 95% CI 1.74-6.38). Conclusions. During this 7-year period, spontaneous nonaneurysmal SAH and ruptured PCA aneurysms decreased the odds of developing vasospasm sevenfold and 20-fold, respectively. The presence of Fisher Grade 3 SAH on admission or a peak leukocyte count greater than 15 × 10⁹/L increased the odds of vasospasm sevenfold and threefold, respectively. Monitoring of the serum leukocyte count may allow for early diagnosis and treatment of vasospasm.