Traumatic microbleeds may predict worse outcomes following head injury

Written by Sharon Salt, Editor

Using advanced imaging techniques, researchers have revealed new information regarding traumatic microbleeds – these appear as small, dark lesions on MRI scans after a head injury, however, they are typically too small to be detected on CT scans.  

The findings, which have been published in Brain, suggest that traumatic microbleeds may be a form of injury in relation to blood vessels in the brain and may predict worse outcomes.  

“Traumatic microbleeds may represent injury to blood vessels that occur following even minor head injury,” commented senior author, Lawrence Latour (Center for Neuroscience and Regenerative Medicine, MD, USA). “While we know that damage to brain cells can be devastating, the exact impact of this vascular injury following head trauma is uncertain and requires further study.”   

Within the study, 439 adults who experienced head injury were examined and treated in the emergency department. The participants underwent MRI scans within 48 hours post-injury and again during four subsequent visits. Behavioral and outcome questionnaires were also completed by the individuals.   

The team reported that 31% of all participants had microbleeds on their brain screens. In addition to this, 58% of participants who had severe head injury displayed microbleeds, as did 27% of mild cases. The presentation of the microbleeds on the scans appeared as either linear streaks or dotted (also known as punctate lesions). In accordance with this, the researchers reported that most individuals who exhibited microbleeds had both types of these presentations.  

Furthermore, their findings also revealed that the region of the brain that was most likely to exhibit microbleeds included the frontal lobe.  

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According to the researchers, individuals who had microbleeds were more likely to have a greater level of disability compared with patients who did not have a microbleed.  

Following completion of the study, one participant died, and their brain was donated for further analysis. The investigators imaged the brain using a more powerful MRI scanner and conducted detailed histological analysis.  

The results demonstrated that iron, which indicates the presence of blood, was present in macrophages that were present along the vessels seen within the initial MRI as well as in extended areas beyond that seen on the MRI.  

Combining these technologies and methods allowed us to get a much more detailed look at microbleed structure and get a better sense of just how extensive they are,” explained first author, Allison Griffin (Center for Neuroscience and Regenerative Medicine).  

The researchers anticipate that microbleeds following a brain injury could be a potential biomarker for identifying individuals who may benefit from treatments that target vascular injury.  

Sources: Griffin AD, Turtzo LC, Parikh GY et al. Traumatic microbleeds suggest vascular injury and predict disability in traumatic brain injury. Brain doi:10.1093/brain/awz290 (2019) (Epub ahead of print); www.eurekalert.org/pub_releases/2019-10/nion-mmw100919.php