MRI scans connect head injury microbleeds to poor outcomes

MRI scans of patients with traumatic head injuries revealed that microbleeds appear in the form of small, dark lesions and may predict worse outcomes, according to a new study published in Brain.

The lesions were also detected among those with a mild form of head injury and, according to researchers from the National Institute of Neurological Disorders and Stroke (NINDS), are often too small to be detected on CT scans.

“Traumatic microbleeds may represent injury to blood vessels that occur following even minor head injury,” senior author Lawrence Latour, PhD, NINDS researcher, said in a statement. “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.”

Latour—along with colleagues at Cold Spring Harbor Laboratory in New York and the Uniformed Services University of the Health Sciences in Bethesda, Maryland—analyzed 439 adults who were treated for head injury in the emergency department. Patients received an MRI within 48 hours of their injury and another four scans during periodic follow-up visits. Participants completed behavioral and outcome surveys to track progression and determine their well-being after injury.

Overall, 58% of patients with severe head injury had microbleeds on MRI, as did 27% of patient scans in mild cases.

Microbleeds appeared on MRI as either linear or dotted streaks and were most commonly seen in the frontal lobe regions of the brain. Patients with microbleeds were more likely to have a greater level of disability compared to those without.

The researchers also imaged the donated brain of a study participant who died after the research was completed. Scans produced by a “powerful” MRI scanner showed there was iron, indicating blood, in the brain’s immune cells. This offered further insight into how microbleeds impacted the brain, beyond the MRI scans performed during the study period.

"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 Allison Griffin, first author of the paper.

Microbleeds could be a biomarker for determining which patients will benefit from vascular injury-targeted treatments, the researchers noted, but more research is needed on that front. Latour et al. also maintained that, as of now, MRI scans should not replace CTs for analyzing suspected head injury.