Traumatic Microbleeds in Mild Traumatic Brain Injury: Stability, Distribution, and Association with Other Injuries

This study aimed to investigate whether the amount of traumatic microbleeds (TMBs) detected on magnetic resonance imaging (MRI) changes in different brain regions after a 3-month follow-up in adult patients with mild traumatic brain injury (mTBI). A 3 T MRI of the brain was conducted at baseline (3-17 days after trauma) and at 3 months after patients were diagnosed with mTBI according to the World Health Organization criteria. The TMBs were evaluated, counted, and assigned locations by a neuroradiologist according to the Common Data Elements for Neuroimaging of Traumatic Brain Injury (CDE-TBI). At baseline, 22 out of 113 (19%) patients had at least one TMB. After initial imaging, 22 patients dropped out, resulting in 88 patients, of whom 21 (24%) had at least one TMB. Across these patients, a total of 129 TMB lesions were detected at baseline, all of which were visible at follow-up imaging. No new TMB lesions that were not detected at baseline were seen at follow-up imaging. The most common CDE-TBI regions for TMBs were the frontal (77/129, 60%), temporal (33/129, 26%), and parietal (8/129, 6%) subcortical white matter. For each patient, the TMB lesions were located in one region in 10% (9/88), two regions in 3% (3/88), three regions in 3% (3/88), and four or more regions in 7% (6/88) of the CDE-TBI regions. Twenty-five out of 88 (28%) patients also had other trauma-related intracranial abnormalities: 10/25 (40%) of which had at least one TMB, which was true only for 17% (11/63) for those without (p < 0.05). In conclusion, initial TMBs can still be reliably found with conventional MRI after 3 months in patients with mTBI: delayed imaging does not necessarily compromise the detection of these lesions. Other radiological abnormalities are linked with higher prevalence of TMBs, possibly suggesting increased injury burden within the mTBI population.