Gratz PP, El-Koussy M, Hsieh K, von Arx S, Mono ML, Heldner MR, et al. Preexisting Cerebral Microbleeds on Susceptibility-Weighted Magnetic Resonance Imaging and Post-Thrombolysis Bleeding Risk in 392 Patients. Stroke. 2014
Jung et al. explore the topic of whether cerebral microbleeds (CMB) increase the risk of hemorrhage after receiving IV tPA or endovascular reperfusion therapy. Specifically, they used pre-treatment susceptibility-weighted MR to identify CMB and then reimaged patients after they had IV thrombolysis, endovascular therapy, or IV thrombolysis followed by endovascular therapy. They found that CMB detected on pretreatment SWI did not increase the risk for symptomatic or asymptomatic intracerebral hemorrhage.
There have been a few studies that have looked at the relationship between CMB, thrombolysis and the risk of ICH. The data are not consistent and, at this point, do not affect our decision making process when considering patients for thrombolysis. The research by Jung’s team is thoughtful but has largely left the issue of CMB and post-thrombolysis ICH unresolved. As the authors point out, one of the major limiting factors of their work was the fact that it was underpowered which leads to somewhat inconclusive information. Furthermore, their data suggest that even if there is a risk, whatever that risk may be, it is too small to change our approach to thrombolysis.
Regarding post-thrombolysis hemorrhage, we know that in addition to the thrombolytic therapy, risk factors for clinically significant hemorrhagic transformation are stroke size, stroke severity and age. It is difficult to know what to make of CMB; however, for now, it is clear that they should not influence our decisions regarding thrombolytic therapy in the acute stroke setting.