Assessing MRI Biomarkers in a Rat Model of Concussion
Concussion, a subset of mild traumatic brain injury (mTBI), is gaining prominence as a serious medical and societal issue worldwide. Of particular concern are individuals in combative arenas, as there is emerging evidence to suggest that recurring mTBIs may result in cumulative and chronic neurological impair ments, mental illness and neurodegenerative disease. Locally, there is growing media coverage on the risk to AFL players, from grassroots to elite level, and on going debate over the manage ment of concussion and return to play decisions. Although the pathophysiological effects of concussion are still not fully under stood, is has been proposed that the detrimental effects are in part due to the recurring mTBIs occurring while the brain has not yet recovered from the initial mTBI and is in a period of increased vulnerability.
The current clinical management is based on assessing for the resolution of neurocognitive impairments, however an asymp tomatic state may not accurately indicate that the brain has fully recovered. Although more conventional MR methods have failed to identify changes associated with mTBI, advanced methods are potentially sensitive to the subtle changes that occur in the con cussed brain.
A research team lead by Dr Sandy Shults at the University of Mel bourne have employed an internationally unique animal model of single and repeated mTBI, in conjunction with MRI and be havioural biomarkers, to investigate: (a) whether MRI can detect injury and assess recovery from concussion; (b) the relationship between MRI and behavioural biomarkers; and (c) to assess the effects of repeated concussion.
MR measures included diffusion weighted, perfusion and sus ceptibility weighted imaging and magnetic resonance spectros copy. Preliminary results suggest that MRI can detect structural abnormalities long after the resolution of behavioural impair ments in animals given a single concussion. In particular, tractography is especially sen sitive to the effects of concussion identifying a number of brain regions that are poten tially affected.
A second injury, given after the full recovery of behavioural impairments but before the recovery of structural abnormalities iden tified with MRI, results in exacerbated mo tor deficits, persisting cognitive deficits and worsened structural damage as shown with MRI.
These results together suggest that the post concussive monitoring of patients with MRI may be a more accurate method of assess ing recovery than current clinical methods.