Does white matter and vascular injury from repetitive head impacts lead to a novel pattern on T2 FLAIR MRI? A hypothesis proposal and call for research

Abstract

The goal of this paper is to introduce the hypothesis that white matter (WM) and vascular injury are long-term consequences of repetitive head impacts (RHI) that result in a novel T2 fluid attenuated inversion recovery (FLAIR) magnetic resonance imaging pattern. A non-systematic literature review of autopsy and FLAIR studies of RHI-exposed adults was first conducted as a foundation for our hypothesis. A case series of RHI-exposed participants is presented to illustrate the unique FLAIR WM hyperintensities (WMH) pattern. Current literature shows a direct link between RHI and later-life WM/vascular neuropathologies, and that FLAIR WMH are associated with RHI, independent of modifiable vascular risk factors. Initial observations suggest a distinctive pattern of WMH in RHI-exposed participants, termed RHI-associated WMH (RHI-WMH). RHI-WMH defining features are as follows: (1) small, punctate, non-confluent, (2) spherical, and (3) proximal to the gray matter. Our hypothesis serves as a call for research to empirically validate RHI-WMH and clarify their biological and clinical correlates.

Highlights

• Repetitive head impacts (RHI) have been associated with later-life white matter (WM) and vascular neuropathologies.
• T2 FLAIR MRI of RHI-exposed participants reveals a potentially unique WM hyperintensity (WMH) pattern that is termed RHI-associated WMH (RHI-WMH).
• RHI-WMH are characterized as (1) small, punctate, and non-confluent, (2) spherical, and (3) proximal to the gray matter at an area anatomically susceptible to impact injury, such as the depths of the cortical sulci.