Human Intracerebral Hemorrhage and Brain Edema: Dose-Response Effect? A Diffusion-weighted Magnetic Resonance Imaging Study
Introduction: Although laboratory research in brain edema pathogenesis after intracerebral hemorrhage (ICH) continues to provide more insight into mechanisms of secondary neuronal injury, perhaps triggered by blood and its by-products, our knowledge of the nature and progression of brain edema after human ICH remains limited. Recently, Diffusion-Weighted Imaging (DWI) has demonstrated consistent apparent diffusion coefficient (Dav) elevation in perihematoma brain tissue, suggesting vasogenic edema. Objective: To study the relationship between ICH volume and the degree of Dav elevation as surrogate marker of intensity of brain edema in 6 consecutive ICH patients. Design and Methods: Patients with acute supratentorial ICH were prospectively evaluated using DWI. Dav elevation in perihematoma brain tissue and its relation to the original hematoma volume, obtained using validated computerized MRI volumetric techniques, were analyzed. Results: Six patients, mean age of 64.5 (range 44 to 87) years, were enrolled. Mean time from symptom-onset to initial MRI was 3.2 (range 2 to 6) days; mean hematoma volume was 29.9 (range 4.6–64.9) cc. Davin perihematoma regions was 179.4 (range 120.1 to 302.5) x 10-5mm2/sec and 88.5 (range 76.5 to 102.1) x 10-5mm2/sec in contralateral corresponding regions of interest (p=0.01). Significant correlation between hematoma volume and Dav in perihematoma edema was found using Spearman’s correlation analysis (correlation coefficient rho = 0.9; p = 0.01). Dav in contralateral, homologous regions did not correlate with hematoma volume (rho = 0.6; p = 0.2) Conclusions: We report significant direct correlation between ICH volume and the degree of Dav elevation in perihematoma brain edema regions. These results suggest a dose-effect relationship between volume/concentration of blood products and intensity of surrounding vasogenic edema. Larger, prospective studies are needed to confirm this biologically meaningful correlation in ICH patients. If reproduced, this knowledge has the potential to further guide therapeutic trials in ICH research.