Diagnosing concussion

Tator’s1 review of concussion is welcomed. When writing about concussions, the popular press has created a belief held by the public and many medical professionals that a cause-and-effect link has been shown between repeated or frequent concussions or subconcussive blows and chronic traumatic encephalopathy (CTE). This very question was hotly debated in Zurich in 2012, following a presentation on CTE by Dr. McKee, from the Boston University Center for the Study of Traumatic Encephalopathy.2 The audience contested the idea that repeated concussions and CTE were cause-and-effect, although the relationship between the 2 entities was readily admitted. The consensus statement3 reported on CTE as follows:

“Clinicians need to be mindful of the potential for long-term problems in the management of all athletes. However, it was agreed that chronic traumatic encephalopathy (CTE) represents a distinct tauopathy with an unknown incidence in athletic populations. It was further agreed that a cause and effect relationship has not as yet been demonstrated between CTE and concussions or exposure to contact sports. At present, the interpretation of causation in the modern CTE case studies should proceed cautiously. It was also recognised that it is important to address the fears of parents/athletes from media pressure related to the possibility of CTE.”

Because there is no current in vivo marker or easily accessible method for following the markers of CTE in an athlete, the diagnosis remains a postmortem diagnosis. Currently, there are longitudinal studies proposed at various centres in North America to follow markers and radiological studies in high-risk groups to develop tools to identify and predict the possibility of CTE or chronic neurological impairment in live participants. These studies will require lengthy periods of time, monetary resources and the commitment of investigators and participants to provide a better answer to the possibility of cause-and-effect with respect to CTE and repeated mild traumatic brain injury.

As a clinician involved in the care of sport-related concussions, I deal with parents and athletes who raise the concern of CTE and chronic neurologic impairment at almost every encounter. I believe that to share with parents and athletes the Concussion in Sport Group’s statement3 on CTE is more appropriate than to promulgate the belief of proven cause-and-effect.