Citation

Fehily B, Fitzgerald M. Cell Transplant. 2016; ePub(ePub): ePub.

Copyright

(Copyright © 2016, Cognizant Communication)

DOI

10.3727/096368916X692807

PMID

27502467

Abstract

Mild traumatic brain injury (mTBI) represents a significant public healthcare concern, accounting for the majority of all head injuries. While symptoms are generally transient, some patients go on to experience long-term cognitive impairments and additional mild impacts can result in exacerbated and persisting negative outcomes. To date, studies using a range of experimental models have reported chronic behavioural deficits in the presence of axonal injury and inflammation following repeated mTBI; assessments of oxidative stress and myelin pathology have thus far been limited. However, some models employed induce acute focal damage more suggestive of moderate-severe brain injury and not relevant to repeated mTBI. Given that the nature of mechanical loading in TBI is implicated in downstream pathophysiological changes, the mechanisms of damage and chronic consequences of single and repeated closed head mTBI remain to be fully elucidated. This review covers literature on potential mechanisms of damage following repeated mTBI, integrating known mechanisms of pathology underlying moderatesevere TBIs, with recent studies on adult rodent models relevant to direct impact injuries rather than blast-induced damage. Pathology associated with excitotoxicity and cerebral blood flowmetabolism uncoupling, oxidative stress, cell death, blood brain barrier dysfunction, astrocyte reactivity, microglial activation, diffuse axonal injury and dysmyelination are discussed, followed by a summary of functional deficits and pre-clinical assessments of therapeutic strategies. Comprehensive characterisation of the pathology underlying delayed and persisting deficits following repeated mTBI is likely to facilitate further development of therapeutic strategies to limit long-term sequelae.

Language: en