Microthromboemboli in acute infarcts: analysis of 40 autopsy cases

We investigated the distribution and frequency of microthromboemboli (MTE) in acute infarcts in humans and determined whether MTE in the contralateral circulation resulted in histological changes.

Forty patients dying within the first month after unilateral infarct were investigated. Infarct etiology was determined mainly on the pathological findings. Whole brain sections from the region of maximal necrosis were stained for fibrin. Fibrin-containing MTE were transferred to a schematic drawing and counted. Sections from 20 patients without infarcts served as controls.

Infarct sections had significantly more MTE than controls. Infarcts of thrombotic (n=6) and thromboembolic (n=21) origin had more MTE than infarcts of embolic origin (n=13). Thromboembolic infarcts had the highest number of MTE within the region assumed to be the ischemic penumbra, other arterial territories, and the contralateral hemisphere. Patients with large infarcts and those with short clinical courses had a higher number of MTE. Sixteen patients had recent micronecroses in the contralateral hemisphere.

There seems to be a pattern of MTE in acute infarcts that is dependent on cause, size, and clinical duration. Our findings of contralateral micronecroses emphasize that acute infarcts may result in more widespread cerebral injury than clinically expected. Given the many variables influencing stroke and death in humans, the results have to be interpreted with caution.