Thursday, July 11, 2013

Concussion in Sport

I love my job because I get paid to keep learning new things. Over the past couple years I've been becoming more knowledgeable about traumatic brain injury and its diagnosis and treatment. Specifically, we've become interested in how standard EEG can be used to study concussion as well as for the assessment of chronic traumatic encephalopathy. I've recently joined a multidisciplinary team at Temple to study this problem from several angles and we're putting together an NIH proposal for later this summer.

One of my colleagues directed me to this great article, the "Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012". You can read the article in full by clicking here. As the title would suggest, it contains a summary of the most up-to-date knowledge on concussion in sport.

There were a couple of observations that surprise me in that the up-ened some minconceptions I've apparently had about sports concussions. Specifically:
  • "There is no good clinical evidence that currently available protective equipment will prevent concussion." The authors go on to discuss that protective equipment has been proven effective for preventing a variety of injuries. But concussion per se has not been demonstrated to be reduced by use of protecting equipment.
  • It is not clear if or how concussions cause or lead to chronic traumatic encephalopathy. "... a cause and effect relationship has not as yet been demonstrated between CTE and concussions or exposure to contact sports." This was perhaps my biggest surprise in reading this article. I'd assumed that the link between CTE and concussions from contact sports was proven, but apparently not. I consulted a colleague and he told me that much is unknown about the genesis of CTE. For example, unknown questions include how concussion trauma could translate into CTE development, how many blows to the head (of what severity; of what frequency) put someone at CTE risk, and why so many contact sport athletes never develop CTE. Is poor concussion management a risk?
  • Rule changes are as good a method as any for reducing concussion incidence
  • Risk compensation (where players compensate for more protective equipment with more aggressive or risky play) is a problem.

A number of other (more procedural) issues stood out to me as well.

  • Although the terms are often conflated (most often in US-based literature) concussion and mild traumatic brain injury are not equivalent, technically speaking
  • Although symptoms often occur immediately, some evolve over "minutes to hours"
  • Concussion is typically characterized by functional deficits, not structural ones. This means that there's not much you can expect to diagnose with conventional imaging since all the structures are intact.
  • Posture and balance tests are good ways of assessing severity of injury
  • Neuropsychological assessment is clinically valuable but only supplements (not replaces) other clinical assessment tools. It is typically only performed when the patient is otherwise asymptomatic (in order to prevent test-induced exertion from exacerbating the concussion)
  • Treatment is usually physical and cognitive rest; in all but 10% of the cases, symptoms improve over 1-2 weeks. Risk of re-injury is heightened during recovery and in those cases re-recovery is much harder.
  • Loss of consciousness is not a good predictor of injury severity: there may be no loss of consciousness in a sever concussion or conversely loss of consciousness in a mild concussion.

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