The Volume of the Spleen and Its Correlates after Acute Stroke

Background: Animal studies describe changes in the spleen following a stroke, with an immediate reduction in volume associated with changes in the counts of specific blood white blood cell (WBCs). This brain-spleen cell cycling after stroke affects systemic inflammation and the brain inflammatory milieu and may be a target for emerging therapeutic studies. This study aimed to evaluate features of this brain-spleen model in human patients admitted for acute stroke. Methods: Medical and imaging records were retrospectively reviewed for 82 consecutive patients admitted for acute stroke in whom an abdominal computed tomography scan was performed. Results: Mean +/- SD splenic volume was 224.5 +/- 135.5 cc. Splenic volume varied according to gender (P = .014) but not stroke subtype (ischemic versus hemorrhagic, P = .76). The change in splenic volume over time was biphasic (P = .04), with splenic volumes initially decreasing over time, reaching a nadir 48 hours after stroke onset, then increasing thereafter. Splenic volume was related inversely to percent blood lymphocytes (r = -.36, P = .001) and positively to percent blood neutrophils (r = .30, P = .006). Conclusions: Current results support that several features of brain-spleen cell cycling after stroke described in preclinical studies extend to human subjects, including the immediate contraction of splenic volume associated with proportionate changes in blood WBC counts. Splenic volume may be useful as a biomarker of systemic inflammatory events in clinical trials of interventions targeting the immune system after stroke.