Natural history of perihematomal edema in patients with hyperacute spontaneous intracerebral hemorrhage

Background and Purpose - The natural history of perihematomal edema in human hyperacute spontaneous intracerebral hemorrhage (ICH) has not been well described. Methods - This study was a secondary analysis of a previously reported prospective, population-based study of hematoma growth in 142 patients with spontaneous [CH. Patients were first imaged within 3 hours of onset, then 1 and 20 hours later. We excluded patients with anticoagulant use (n=7), underlying aneurysm/vascular malformation (n=9), trauma (n= 1), incomplete data (n=20), infratentorial ICH (n= 17), and no consent (n=2), leaving an overall study population of 86 patients. From this overall group we further excluded patients with intraventricular extension (n=38), subsequent surgery (n=5), or death (n=2) before 20-hour postbaseline CT. This second, "restricted" analysis group of 41 patients was relatively devoid of clinical or radiological variables likely to confound edema measurement. Absolute and relative edema volumes (edema volume divided by hematoma volume) were descriptively summarized. Correlations between baseline edema volumes and relevant clinical and radiological variables were then performed. Results - Overall, median absolute edema volume increased from 6.93 to 14.4 cm³ during the first 24 hours after ICH, and median relative edema volume increased from 0.47 to 0.81. In the restricted group, median absolute edema volume was 7.4 cm³ at baseline and 11.0 cm³ at 24 hours after ICH, and median relative edema volume increased from 0.55 to 0.81. Baseline relative edema volume was significantly negatively correlated with subsequent change in relative edema volume from baseline to 20-hour CT (r=0.57, P=0.0002) but was not significantly correlated with other clinical and radiological variables, including hematoma volume or change in hematoma volume. Conclusions - Perihematomal edema volume increases by approximately 75% during the first 24 hours after hyperacute spontaneous ICH. Patients with the least amounts of baseline relative edema volume were most likely to develop significant additional amounts of edema during the first 24 hours after spontaneous ICH.