Background: Recent reports suggest that when thrombolytic agents are administered within the clot, lysis rate accelerates at the expense of increased risk of worsening edema. To test this hypothesis, we report on the volumetric analysis of (1) the intraparenchymal hematoma and, (2) perihematomal edema in a cohort of ICH patients treated with intraclot rtPA.
Methods: A convenience sample of highly selected ICH patients underwent frameless stereotactic aspiration and thrombolysis (FAST) of the clot. Two milligrams of rtPA were administered every 12 h until ICH volume < or =10 cc, or catheter fenestrations were no longer in continuity with the clot. ICH and perihematomal edema volumes were calculated from CT scans. Using random effects linear regression we estimated the rate of hematoma and edema volume resolution as well as their relationship during the first 8 days of lytic therapy.
Results: Fifteen patients were treated, mean age: 60.7 years, median time from ictus to FAST: 1 (range 0-3) day. Using a random effects model that considered volume resolution over the first 8 days following lytic therapy we found that the both percentage hematoma and percentage perihematoma edema resolution per day were quadratic with respect to time. Percentage residual hematoma volume on day K = 97.7% - [24.36%*K] + [1.89%*K (2)]; P < 0.001 for both terms. Percentage residual edema on day K = 97.4% - [13.94%*K] + [1.30%*K (2)]; P < 0.001 for K and P = 0.01 for K (2). Examination of each patient's volume data suggests that there exists a strong direct relationship between perihematoma edema volume and same day hematoma volume.
Conclusions: In this cohort of ICH patients treated using FAST, volumetric analysis of ICH and perihematomal edema seems to suggest that local use of rtPA does not exacerbate brain edema formation. Furthermore, there seems to be a strong association between reduction in ICH volume and reduction in edema volume, as would be expected following the concept of "hemotoxicity" postulated by some investigators.