BACKGROUND AND PURPOSE: A proinflammatory prothrombotic state may increase the 
risk of delayed cerebral ischemia (DCI) after aneurysmal subarachnoid hemorrhage 
(SAH). We studied the relationship of levels of leukocytes, platelets, 
C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) with the 
development of DCI and with clinical outcome in patients with aneurysmal SAH.
METHODS: In 125 patients admitted within 72 h after aneurysmal SAH, we 
dichotomized initial blood levels at their median values and investigated the 
prediction of DCI with Cox proportional hazard analysis and of poor clinical 
outcome with logistic regression analysis. We also analyzed concentrations 
before and after onset of DCI with the paired-samples t test and compared 
changes with those in patients without DCI.
RESULTS: During the development of DCI (unrelated to treatment), patients had a 
larger increase in counts of platelets (difference 49 x 10(9)/l; 95% CI: 2-98) 
and leukocytes (difference 2.6 x 10(9)/l; 95% CI: 0.4-5.0) than patients without 
DCI during the same period. CRP increased during DCI and decreased in patients 
without DCI (difference 14 mg/l; 95% CI: -29 to 58). ESR increased slightly in 
both groups (difference 3 mm/h; 95% CI: -15 to 20). None of the determinants at 
baseline predicted the development of DCI. An increased risk of poor outcome 
predicted by a high initial leukocyte count (OR 2.5; 95% CI: 1.1-5.7) decreased 
after adjustment for clinical variables (OR 2.1; 95% CI: 0.8-5.5).
CONCLUSION: Counts of platelets and leukocytes disproportionally increase during 
the occurrence of DCI after aneurysmal SAH. Drugs with anti-thrombotic or 
anti-inflammatory properties should be studied for prevention and treatment of 
DCI.