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Review
. 2013 Nov;119(5):1235-45.
doi: 10.3171/2013.7.JNS121822. Epub 2013 Aug 23.

Role of Subconcussion in Repetitive Mild Traumatic Brain Injury

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Review

Role of Subconcussion in Repetitive Mild Traumatic Brain Injury

Julian E Bailes et al. J Neurosurg. .

Abstract

Research now suggests that head impacts commonly occur during contact sports in which visible signs or symptoms of neurological dysfunction may not develop despite those impacts having the potential for neurological injury. Recent biophysics studies utilizing helmet accelerometers have indicated that athletes at the collegiate and high school levels sustain a surprisingly high number of head impacts ranging from several hundred to well over 1000 during the course of a season. The associated cumulative impact burdens over the course of a career are equally important. Clinical studies have also identified athletes with no readily observable symptoms but who exhibit functional impairment as measured by neuropsychological testing and functional MRI. Such findings have been corroborated by diffusion tensor imaging studies demonstrating axonal injury in asymptomatic athletes at the end of a season. Recent autopsy data have shown that there are subsets of athletes in contact sports who do not have a history of known or identified concussions but nonetheless have neurodegenerative pathology consistent with chronic traumatic encephalopathy. Finally, emerging laboratory data have demonstrated significant axonal injury, blood-brain barrier permeability, and evidence of neuroinflammation, all in the absence of behavioral changes. Such data suggest that subconcussive level impacts can lead to significant neurological alterations, especially if the blows are repetitive. The authors propose "subconcussion" as a significant emerging concept requiring thorough consideration of the potential role it plays in accruing sufficient anatomical and/or physiological damage in athletes and military personnel, such that the effects of these injuries are clinically expressed either contemporaneously or later in life.

Comment in

  • Subconcussion in traumatic brain injury.
    Sagher O. Sagher O. J Neurosurg. 2013 Nov;119(5):1233; discussion 1233-4. doi: 10.3171/2013.4.JNS13538. Epub 2013 Aug 23. J Neurosurg. 2013. PMID: 23971959 No abstract available.
  • Concussion: neurosurgery's mission in social awareness.
    Moon K, Theodore N. Moon K, et al. World Neurosurg. 2014 Feb;81(2):213-4. doi: 10.1016/j.wneu.2013.12.005. Epub 2013 Dec 17. World Neurosurg. 2014. PMID: 24355518 No abstract available.
  • Role of subconcussion and repetitive TBI.
    Sosa I, Stemberga V. Sosa I, et al. J Neurosurg. 2014 Mar;120(3):789-90. doi: 10.3171/2013.10.JNS132097. Epub 2014 Jan 17. J Neurosurg. 2014. PMID: 24438537 No abstract available.
  • Response.
    Bailes JE. Bailes JE. J Neurosurg. 2014 Mar;120(3):789-90. J Neurosurg. 2014. PMID: 24724179 No abstract available.

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