Posted by Matthew Mac Partlin on Thursday, March 28, 2013

The American Academy of Neurology released their guidelines on concussion in sport this month. They serve as an update to the existing guidelines, orginally published in 1997. The evidence is mostly drawn from field sports; rugby, soccer, hockey, basketball. 7 of the 12 panel of experts were non-neurologists, drawing from other specialties that are involved in managing concussed athletes. The 2013 guidelines involved a review of all available evidence on sports concussion between 1955 and June 2012 and they employed the GRADE system of guideline recommendations

The guideline paper sought to provide answers to 4 key questions:

1) For athletes, what factors increase or decrease concussion risk?

2a) For athletes suspected of having sustained concussion, what diagnostic tools are useful in identifying those with concussion?

2b) For athletes suspected of having sustained concussion, what diagnostic tools are useful in identifying those at increased risk for severe or prolonged early impairments, neurologic catastrophe, or chronic neurobehavioral impairment?

3) For athletes with concussion, what clinical factors are useful in identifying those at increased risk for severe or prolonged early postconcussion impairments, neurologic catastrophe, recurrent concussions, or chronic neurobehavioral impairment?

4) For athletes with concussion, what interventions enhance recovery, reduce the risk of recurrent concussion, or diminish long-term sequelae?

The attempt to answer these questions with the available evidence is followed by practice recommendations. These recommendations focus on three components:

  • preparticipation counseling recommendations
  • recommendations related to assessment, diagnosis, and management of suspected concussion
  • recommendations for management of diagnosed concussion, including acute management, return to play and retirement.

AAN 2012 Sports Concussion Guideline summary

Most of the concussion risk factors identified related to field sports and were really only at the level of association rather than concrete risk. Even then, most of the associations were phrased as "probably".

  • Concussion is a clinical diagnosis. The new guidelines support the use of Neuropsychiatric tests, including sideline screening tests, but state that while these tests may be helpful in identifying concussed athletes they should be an adjunct to clinical assessment and should not be used in isolation. These tests may miss up to 1 in 3 incidences of concussion and may have a 1 in 5 false positive rate, depending on which test is used. So while a positive test may be used to back up a decision to pull an athlete off the field, a negative test may not be reliable and furthermore their use in guiding return to play has to be questioned.
  • Any athlete suspected of having sustained a concussion should be stepped down from competition, in order to reduce the risk of further injury (Level B) ... Fair enough, as they mean "reduce the risk of any further injury", not just the controversial "second hit syndrome".
  • Sustaining more than 1 concussive injury is a risk factor for further concussive injuries.
  • The peak risk of an athlete sustaining a further concussive injury following the first concussion "appears to be" within 10 days of that first injury.
  • There is little evidence available to support the incidence of the "second hit syndrome".
  • There level of evidence for chronic traumatic encephalopathy was so sparse that it was not even considered when developing the new concussion guidelines. There may be a link with the ApoE4 tau protein generating gene.
  • A concussed athlete should not return to play until assessed by a "licensed healthcare professional with training in the diagnosis and management of concussion and the recognition of severe brain truama." (Level B) .... Who is this? The "licensed healthcare profesional" is described in the document as "an individual who has acquired knowledge and skills relevant to evaluation and management of sports concussions and is practicing within the scope of his or her training and experience" but it is not specified whether this must be a doctor, or even a specific specialty (Neurologist? Psychologist? GP?), or if it can be a physiotherapist or nurse or a first aid practicioner.
  • The timing of return to play, a hugely controversial aspect of sports concussion management, is left to the judgement of the "licensed health care practicioner" (Level B recommendation). How the LHCP should determine an athlete's fitness to return is not specified and the option of using either or both of clinical features and neuropsychiatric testing is left open (Level C). Graded return to play schedules are left as an optional Level C recommendation.
  • The guidelines also recommend that an athlete is kept from play until they are assymptomatic without medication. (Level B)
  • However there is insufficient evidence to support absolute rest following concussion and activities that do not worsen symptoms may be reasonable.
  • Severity of concussion is not of itself helpful in guiding the duration an athlete should be kept from active competition. Rather return to play should be tailored to the individual.
  • There is insufficient evidence available to recommend any particular intervention to speed up concussion recovery or reduce long term sequelae of concussion. Cognitive restructuring, a form of psychological counselling involving "education, reassurance and (hmmm!) reattribution of symptoms", is mentioned as having reported success reducing post concussion syndrome in non-sports settings. It is left as a Level C option to possibly help shorten the duration of concussive symptoms.
  • Athletes who have sustained multiple concussions and have persistent subjective neuropsychiatric deficits, should be guided towards retiring from contact sports. The number of concussive injuries nor the period over which the concussions have been sustained are not specified (previously 3 or more episodes of concussion in a single season meant recommending that athlete sat out the rest of the season).  This is made a Level C recommendation but is probably a practical one given the lack of hard data. The use of neuropsychiatric tests to facilitate this is left as an option.
  • There is no evidence available for paediatric sports concussion under high school (secondary school).
  • Younger athletes appear to take longer to recover after concussion and clinicians are advised to be even more conservative when managing paediatric sports concussion.

The data supporting the guidelines appears to be largely a list of associations with no hard cause and effect relationships identified. This is not surprising as the majority of the evidence base appears to be in the form of database analysis rather than RCT. Therefore various forms of bias preclude drawing firm conclusions and the data serves only to highlight areas in need of proper trials.

What does all of this mean for managing concussion in motor sports?

Well, not a whole lot really. There were no representatives of motor sports on the expert panel that developed the 2013 AAN guidelines. All of the evidence used was drawn from the usual sources - field and contact sports such as rugby, American gridiron, ice hockey, boxing, Australian rules football, soccer and basketball. The closest non-contact sport that was represented was showjumping. So for motor sports, we are still left with extrapolating probabilities. Time for some collaborative research between the major ASNs and groups like the FIA Institute, methinks.

Bottom line:
  • Concussion is a clinical diagnosis
  • Neuropsychiatric tests are too unreliable to be used in isolation from clinical assessment
  • Reaffirms the coaches mantra of "if in doubt, sit them out"
  • Concussion increases the risk of subsequent injury, but the evidence for concussion-specific syndromes such as the "second hit syndrome" and "chronic traumatic encephalopathy" is thin at best.
  • Guidance on optimal timing of return to play is an evidence free zone that is sorely in need of research. Clinical assessment appears to be the most useful guide.
  • Be even more conservative for concussion in children and adolescents.

Update 06/05/2013

On April 17th published a review article on the updated AAN Sports Concussion guidelines, following a press event that was attended by AAN Sports Concussion guideline lead authors Dr Christopher Giza and Dr Jeffrey Kutcher.

The article highlights similar aspects of the updated guidelines as above and puts particular focus on the apparent broad definition of a "licensed health care practitioner" and the difficulties around the determination of fitness to return to competition with a number of screening options available but the final decision left to the best judgement of the treating clinician. The Medscape review points out the available loophole in the absence of a valid, reliable, objective assessment tool whereby athletes could deliberately "cheat" the system by denying symptoms or fall victim to an early negative test due to delayed onset of concussive features.

Finally, the Medscape article poses the conundrum that it yet remains unclear whether a competitor is best served by complete rest following concussion or if an earlier return to play may in fact promote faster healing.

Clearly, there is a lot that remains unclear about sports related concussion. Who's up for some high quality research?