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Updated: Jan 22, 2026
05:30
Controlled Cortical Impact Model for Traumatic Brain Injury
Published on: August 5, 2014
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Traumatic Microhemorrhages Are Not Synonymous With Axonal Injury
Karinn Sytsma1, Rhonda Mittenzwei1, Heather Maioli2
1Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, USA.
Annals of Clinical and Translational Neurology
|January 21, 2026
Summary
Diffuse axonal injury (DAI), a consequence of traumatic brain injury (TBI), is often identified by microbleeds on susceptibility-weighted MRI (SWI). However, this study found axonal injury in only 64% of these microbleeds, revealing a complex injury pattern.
Area of Science:
- Neuroscience
- Radiology
- Pathology
Background:
- Diffuse axonal injury (DAI) results from shearing forces in white matter tracts during traumatic brain injury (TBI).
- Susceptibility-weighted MRI (SWI) detects microbleeds, considered a hallmark of DAI for prognostication.
- Existing assumptions about SWI microbleeds as definitive DAI markers lack robust radiologic-pathologic correlation.
Purpose of the Study:
- To investigate the direct correlation between SWI-identified microbleeds and actual axonal injury in severe TBI.
- To assess the reliability of SWI microbleeds as the sole indicator of DAI.
Main Methods:
- Ex vivo SWI was performed on three human brains from severe TBI patients.
- Immunohistochemistry for amyloid-beta precursor protein was used to identify and assess axonal injury.
- Microscopic examination focused on areas surrounding SWI-detected microbleeds.
Main Results:
- Axonal injury was detected in 64% of the microbleeds identified by SWI.
- This indicates that not all SWI microbleeds are associated with DAI.
- The findings highlight a heterogeneous response of white matter to TBI.
Conclusions:
- SWI microbleeds are not uniformly indicative of diffuse axonal injury.
- Radiologic findings of microbleeds in TBI require careful interpretation alongside pathological evidence.
- Further research is needed to understand the full spectrum of white matter injury in TBI.
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