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(Stroke. 2008;39:355.)
© 2008 American Heart Association, Inc.

Original Contributions

Early Neutrophilia Is Associated With Volume of Ischemic Tissue in Acute Stroke

Brian H. Buck, MD; David S. Liebeskind, MD; Jeffrey L. Saver, MD; Oh Young Bang, MD, PhD; Susan W. Yun, BSc; Sidney Starkman, MD; Latisha K. Ali, MD; Doojin Kim, MD; J. Pablo Villablanca, MD; Noriko Salamon, MD; Tannaz Razinia, BSc Bruce Ovbiagele, MD

From the Division of Neurology (B.H.B.), Sunnybrook Health Sciences Centre, University of Toronto, Canada; the Stroke Center and Department of Neurology (B.H.B., D.S.L., J.L.S., O.Y.B., S.W.Y., S.S., L.K.A., D.K., T.R., B.O.), University of California, Los Angeles; the Department of Neurology (O.Y.B.), Samsung Medical Center, Sungkyunkwan University, South Korea; the Stroke Center and Department of Radiology (J.P.V., N.S.), University of California, Los Angeles; and the Department of Emergency Medicine (S.S.), University of California, Los Angeles.

Correspondence to Brian H. Buck MD, FRCPC, Division of Neurology, Sunnybrook Health Sciences Centre, 2075 Bayview Avenue, room A421, Toronto, Ontario, Canada M4N3M5. E-mail brianhbuck{at}gmail.com

Background and Purpose— Few data exist on the relationship between differential subpopulations of peripheral leukocytes and early cerebral infarct size in ischemic stroke. Using diffusion-weighted MR imaging (DWI), we assessed the relationship of early total and differential peripheral leukocyte counts and volume of ischemic tissue in acute stroke.

Methods— All included patents had laboratory investigations and neuroimaging collected within 24 hours of stroke onset. Total peripheral leukocyte counts and differential counts were analyzed individually and by quartiles. DWI lesions were outlined using a semiautomated threshold technique. The relationship between leukocyte quartiles and DWI infarct volumes was examined using multivariate quartile regression.

Results— 173 patients met study inclusion criteria. Median age was 73 years. Total leukocyte counts and DWI volumes showed a strong correlation (Spearman rho=0.371, P<000.1). Median DWI volumes (mL) for successive neutrophil quartiles were: 1.3, 1.3, 3.2, and 20.4 (P for trend <0.001). Median DWI volumes (mL) for successive lymphocyte quartiles were: 3.2, 8.1, 1.3, and 1.5 (P=0.004). After multivariate analysis, larger DWI volume remained strongly associated with higher total leukocyte and neutrophil counts (both probability values <0.001), but not with lymphocyte count (P=0.4971). Compared with the lowest quartiles, DWI volumes were 8.7 mL and 12.9 mL larger in the highest quartiles of leukocyte and neutrophil counts, respectively.

Conclusions— Higher peripheral leukocyte and neutrophil counts, but not lymphocyte counts, are associated with larger infarct volumes in acute ischemic stroke. Attenuating neutrophilic response early after ischemic stroke may be a viable therapeutic strategy and warrants further study.

Key Words: diffusion-weighted imaging • inflammation • ischemic • leukocytosis • magnetic resonance imaging • stroke