Every year in Canada, an average of 200,000 concussions are diagnosed (Brain Injury Canada, n.d.). However, this number is believed to be an underrepresentation as many concussions go unreported, attributed to lack of public education, resources, etc. (Brain Injury Canada, n.d.). Sports-related concussions are described as one of the most difficult injuries to diagnose and treat in sports medicine (Brain Injury Canada, n.d.). For males aged 5-14, ice hockey is the leading sport for concussions and other TBIs (Brain Injury Canada, n.d.). For female youth, ringette was found to cause the highest number of concussions/other TBIs (BrainInjury Canada, n.d.). Since 2010, the number of pediatric visits to the emergency room or physician clinics for concussion-related symptoms has quadrupled in Ontario (Brain Injury Canada, n.d.).
A concussion is defined as a traumatic brain injury caused by direct or indirect forces to the head, neck, face or elsewhere in the body (Daneshvar et al., 2011). These forces includes linear acceleration-deacceleration, as well as rotation (Collins et al., 2014). When sustaining a concussion, the impact begins at the cellular level and has a cascading effect on the hierarchy of systems, resulting in the symptoms we see at a macroscopic level (Kenzie et al., 2018). After impact to the brain, the cytoskeletal structure of neurons, glia, vasculature and the structural extracellular matrix can become affected, as a result of the stretch/strain induced from deformation (Kenzie et al., 2018). This leads to the activation of several neural, inflammatory and vascular processes (Kenzie et al., 2018). Loss of consciousness can occur if the brainstem cortical connections are impaired from forces intersecting with the brainstem (Kenzie et al., 2018). As well, it creates an energy crisis due to an abundance of glutamate being released and ions being in flux, specifically potassium, sodium and calcium (Kenzie et al., 2018; Collins et al., 2014). This can all cause mitochondrial dysfunction, oxidative stress and an extended hypometabolic state (Kenzie et al., 2018). Physical damage, as well as activation of astrocyte and microglial cells, can make the blood brain barrier permeable, while leukocytes and additional compounds cause neuroinflammation (Kenzie et al., 2018). Prolongation of these effects can then result in neuronal damage (Kenzie et al., 2018).
At the network level, these cellular effects interrupt neural transmission, inducing both general and local functional impairment (Kenzie et al., 2018). This impairment is worsened by damage to long fiber tracts and hub disruption and improved by neuroplasticity, reroutingand reorganization processes (Kenzie et al., 2018). Symptoms of post-concussion syndrome are a result of network dysfunction within the primary network (associated with the specific symptom) and that between all other networks (Kenzie et al., 2018). These network impairments are displayed as a diverse set of physical, behavioral, cognitive, emotional and somatic symptoms (Kenzie et al., 2018; Collins et al., 2014). This can include sleep disturbances, irritability, impaired sensorimotor integration, headaches/tension, decreased reaction times and more (Kenzie et al., 2018; Collins et al., 2014).
In terms of treatment, there is no one method that is deemed as the gold standard, as each individual is impacted differently. However, there are general guidelines that should be followed closely when recovering from a concussion. After sustaining a concussion, the first 24-48 hours should be dedicated to complete physical and cognitive rest (Schneider et al., 2017). This no longer means isolate in a dark room for two days but rather avoid performing physical or cognitive activity, while paying particular attention to social interaction, hydration and nutrition (King, 2020). After 48 hours, focus should shift to subthreshold physical and cognitive activity, which refers to light and gradual activity that does not worsen pre-existing symptoms or bring on any new symptoms (walking, reading for short periods, etc.) (Schneider et al., 2017). A concussion protocol, specific to the return aim (return-to-work, return-to-sport, return-to-school) should be followed closely during concussion rehabilitation (King, 2020). Parachute Canada has resources listed for return-to-play andreturn-to-sport, as well as most university level sport governing bodies (Parachute, n.d.). For persisting symptoms, treatment should be sought specific to the symptoms, e.g., vision therapy for ocular symptoms or vestibular therapy for vestibular symptoms (Schneider et al., 2017). Research has shown that a collaborative treatment approach may be best, one that combines a variety of treatments including cognitive-behavioural therapy, pharmacotherapy and manual therapy (Schneider et al., 2017).
References
Brain Injury Canada. (n.d.). Statistics on Brain Injury. https://www.braininjurycanada.ca/en/statistics-brain-injury
Collins, M. W., Kontos, A. P., Reynolds, E., Murawski, C.D., & Fu, F. H. (2014). A comprehensive, targeted approach to the clinical care of athletes following sport-related concussion. Knee Surgery, Sports Traumatology, Arthroscopy, 22(2), 235-246. doi: 10.1007/s00167-013-2791-6
Daneshvar, D.H., Nowinski, C. J., McKee, A. C., & Cantu, R. C. (2011). The epidemiology of sport-related concussion. Clinics in Sports Medicine, 30(1), 1 - vii. https://doi.org/10.1016/j.csm.2010.08.006
Kenzie, E. S.,Parks, E. L., Bigler, E. D., Wright, D. W., Lim, M. M., Chesnutt, J. C.,Hawryluk, G. W. J., Gordon, W., & Wakeland, W. (2018). The Dynamics of Concussion: Mapping Pathophysiology, Persistence, and Recovery with Causal-Loop Diagramming. Frontiers in Neurology, 9, 203. https://doi.org/10.3389/fneur.2018.00203
King, C. (2020, November). Concussion Assessment and Rehab. [PowerPoint Slides]. PowerPoint.
Parachute.(n.d.). Canadian Guideline on Concussion in Sport. https://parachute.ca/en/professional-resource/concussion-collection/canadian-guideline-on-concussion-in-sport/
Schneider, K. J., Leddy, J. J., Guskiewicz, K. M., Seifert,T., McCrea, M., Silverberg, N. D., Feddermann-Demont, N., Iverson, G. L., Hayden, A., & Makdissi, M. (2017). Rest and treatment/rehabilitation following sport-related concussion: a systematic review. British Journal of Sports Medicine, 51(12), 930-934. http://dx.doi.org/10.1136/bjsports-2016-097475