Published in the journal Brain, researchers have found that microbleeds that can be seen on MRI but not CT may be predictive for recovery from traumatic brain injury, including mild traumatic brain injury (mTBI; also known as concussion). Microbleeds appeared as small streaks or punctate lesions on MRI and, typically, were too small to be detected with CT. This finding suggests that postinjury microbleeds following may be a potential biomarker for identifying which patients are candidates for treatments targeting vascular injury.
Evidence of microbleeds on MRI was seen in 58% of those with severe brain injury and 27% of those with mTBI. Microbleeds occurred most often in the frontal lobes. Higher levels of disability after injury correlated with having microbleeds (P <.05; odds ratio = 2.5). In 1 individual, whose died after his injury and whose family donated his brain for further study, higher-resolution MRI and histologic analysis showed iron in macrophages tracking along the vessels seen on the initial MRI and in extended areas beyond that seen on MRI.
“Traumatic microbleeds may represent injury to blood vessels that occur following even minor head injury,” said Lawrence Latour, PhD, NINDS researcher and senior author of the study. “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.”
In this study, 439 adults who had experience brain injury and been treated in an emergency department had a brain MRI within 48 hours of injury and during 4 follow-up visits. Participants completed behavioral and outcome questionnaires as well.
Future studies to validate these findings and identify potential treatments for microbleeds are still needed as are studies to determine who should have MRI after a brain injury. Currently there is not enough evidence to suggest that MRI should replace CT for suspected head injury.