Blood biomarkers for assessment of mild traumatic brain injury and chronic traumatic encephalopathy.

Mild traumatic brain injuries (mTBI) are prevalent and can result in significant debilitation. Current diagnostic methods have implicit limitations, with clinical assessment tools reliant on subjective self-reported symptoms or non-specific clinical observations, and commonly available imaging techniques lacking sufficient sensitivity to detect mTBI. A blood biomarker would provide a readily accessible detector of mTBI to meet the current measurement gap. Suitable options would provide objective and quantifiable information in diagnosing mTBI, in monitoring recovery, and in establishing a prognosis of resultant neurodegenerative disease, such as chronic traumatic encephalopathy (CTE). A biomarker would also assist in progressing research, providing suitable endpoints for testing therapeutic modalities and for further exploring mTBI pathophysiology. This review highlights the most promising blood-based protein candidates that are expressed in the central nervous system (CNS) and released into systemic circulation following mTBI. To date, neurofilament light (NF-L) may be the most suitable candidate for assessing neuronal damage, and glial fibrillary acidic protein (GFAP) for assessing astrocyte activation, although further work is required. Ultimately, the heterogeneity of cells in the brain and each marker's limitations may require a combination of biomarkers, and recent developments in microRNA (miRNA) markers of mTBI show promise and warrant further exploration.

Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion.

Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16-37 yrs) performed three timed tests: Tandem Gait (TG); Finger-to-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (+/-SD) for each measure were averaged across three trials. Time to complete TG was 11.2+/-1.2s. FTN for the dominant and non-dominant arm were 2.9+/-1.1s and 3.0+/-1.2s, respectively. SLS values for dominant and non-dominant leg were 20.4+/-3.0s (firm), 3.4+/-1.6s (foam), and 21.0+/-2.9s (firm), 3.3+/-1.6s (foam), respectively. For TG, there was an order effect (P<.001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P<.001), sex (P=.006), BMI (P=.043) and order effects (P<.001). SLS demonstrated an order effect on the firm surface (P=.009) and an order (P<.001) and BMI (P=.001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion.