Admission Leukocytosis in Acute Cerebral Ischemia: Influence on Early Outcome

Background: Leukocytes are the first cells that arrive in the stroke region(s), and they increase in peripheral blood. The contribution or leukocytes in the early acute phase of cerebral ischemia has not yet been investigated.

Methods: In consecutive first-ever acute ischemic stroke patients whose symptoms had started <12 hours earlier, we aimed to establish whether admission leukocyte count affects the short-term neurologic outcome, and whether there are differences between the various clinical syndromes of stroke. The National Institutes of Health Stroke Scale (NIHSS) was assessed at admission (NIHSS(0)) and after 72 hours (NIHSS(72)). Modified Rankin scale (mRS) scores were evaluated at discharge. The Spearman rank correlation was used for the correlation between leukocytes and outcome measures.

Results: Eight hundred and eleven patients were included (median age 77 years [range 68-82]; 418 [53%] were male; the median NIHSS(0) score was 7 [range 4-12], the median NIHSS(72) score was 6 [range 3-12], and the median mRS score was 2 [range 2-4]). The median leukocyte count at admission was 8100/mm(3) (range 6500-10300). Higher leukocyte levels predicted a worst clinical presentation and a poor functional outcome (NIHSS(0)P < .001; NIHSS(72)P < .001; mRS P < .001). The correlation between leukocyte count and outcome measures remained significant after multivariate analysis (NIHSS(0)P < .001; NIHSS(72)P < .001; mRS P < .008). Focusing on clinical syndromes, a higher leukocyte count predicted severe NIHSS(0) and NIHSS(72) scores in patients with total anterior cerebral stroke (P = .001), partial anterior cerebral stroke (P = .004), or posterior cerebral stroke (P = .026).

Conclusions: An elevated leukocyte count in the acute phase of cerebral ischemia is a significant independent predictor of poor initial stroke severity, poor clinical outcome after 72 hours, and discharge disability. The involved underlying mechanism is still to determined.