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Timely information and insights into the world of evidence-based medicine as it applies to IMEs and other health-related services across Canada. Your feeback and suggestions are welcome.

Part 1. The Invisible Injury: Diagnosing Concussions and Mild Traumatic Brain Injuries.


The spotlight is currently shining bright on mild traumatic brain injuries (TBI), particularly concussions. Spurred on by both professional sports leagues attempting to protect their players, “weekend warriors” playing recreational team sports, as well as the parents of young athletes seeking to safeguard the health of their children, this type of injury has entered the public discourse in a major way.

Of course, on-field competition is far from the only venue where individuals are at risk for concussion, with accidents in the workplace, in automobiles, as a cyclist, or even simple falls and spills creating conditions for the head impacts and whiplash brain movement and shaking that cause this type of brain injury. Brain Injury Canada estimates that 160,000 Canadians suffer from a mild TBI each year, and over half a million are living with the consequences of concussions1.

There are two approaches to take when making a mild TBI diagnosis. The first is to consider the exact circumstances of the incident suspected to have caused the trauma. Clinical practice guidelines from the American Congress of Rehabilitation Medicine consider an incident where consciousness was lost to automatically qualify a patient as having suffered a brain injury2.

Unfortunately, there are many types of mild traumatic brain injury that can occur without this type of clear-cut loss of consciousness as a marker. In fact, concussion symptoms can often be delayed for hours, if not days, before presenting. This can pose a challenge when attempting to pinpoint the exact incident that lead to the trauma in question. A symptoms-based TBI diagnosis relies primarily on a patient's self-reported state, which can be further buttressed by formalized cognitive assessment tools. These symptoms are often grouped under the name 'post-concussive syndrome', or PCS*.

Non-cognitive symptoms that typically present themselves after a mild traumatic brain injury include difficulty with vision and balance (dizziness), nausea, sensitivity to light, fatigue, as well as headaches. Patients may also display behavioural issues such as insomnia, oversleeping, depression, poor impulse control, anxiety, apathy, and irritability2,3**.

From a cognitive perspective, post-concussion syndrome and mild TBI often manifest in the form of memory problems - which can be specific to certain types of memory, such as verbal, or which can take the form of amnesia regarding the incident - as well as the inability to concentrate ('fogginess')2,3**.

There are also several cognitive tests that can be performed on a patient, such as ImPACT (Immediate Post-Concussion Assessment and Cognitive Testing)4, Controlled Oral Word Association, Wechsler Letter Number Sequencing Test, and the Pace Auditory Serial Addition Test5. However, this type of testing is not capable of providing a diagnosis of concussion, but rather is useful in assessing the extent of the injury6. Even then, in the absence of a cognitive baseline for comparison (which not all patients will be able to provide), results from an ImPACT test are not always conclusive7. On the imaging side, standard neurological scans are not capable of reliably detecting physical manifestations of mile traumatic brain injuries, with this type of technology only starting to be deployed by specialized research-aimed efforts8.

Finally, it's important to take into account that any past history of mild TBI makes a patient significantly more susceptible to future brain injury, as well as more amplified symptoms9. Individuals being assessment may not be aware of past brain trauma, especially if the symptoms associated with it were minor or went unnoticed, but cumulative effects can be significant as a risk factor. Talking to a patient in an effort to delve deeper into their past history of head trauma, especially minor trauma, can be helpful when making a diagnosis.

*There are various names for this condition

** The symptoms mentioned above do not represent the entire range of possible symptoms, and can be associated with other conditions.”

  1. Brain Injury Canada. About Acquired Brain Injury (ABI). https://www.braininjurycanada.ca/acquired-brain-injury/ (accessed May 7, 2018).
  2. Marshall S, Bayley M, McCullagh S, et al. Clinical practice guidelines for mild traumatic brain injury and persistent symptoms. Canadian Family Physician. March 2012;58(3):257-267.
  3. Arciniegas D, Anderson C A, Topkoff J, et al. Mild traumatic brain injury: a neuropsychiatric approach to diagnosis, evaluation, and treatment. Neuropsychiatr Dis Treat. December 2005;1(4):311-327.
  4. Duke SciPol. Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT). http://scipol.duke.edu/content/immediate-post-concussion-assessment-and-cognitive-testing-impact (accessed May 7, 2018).
  5. National Athletic Trainers’ Association Position Statement: Management of Sport-Related Concussion. Journal of Athletic Training 2004;39(3):280–297.
  6. Scolaro Moser, Rosemarie. Ahead of the Game: A Parent's Guide To Youth Sports Concussion. Dartmouth College Press, 2012.
  7. Arnett P, Meye J, Merritt V, et al. Neuropsychological Testing in Mild Traumatic Brain Injury: What to Do When Baseline Testing Is Not Available. Sports Medicine and Arthroscopy Review. September 2016;24(3):116-122.
  8. International Brain Injury Association. Mild Traumatic Brain Injuries were previously undiagnosable, and therefore treatment uncertain, and damages speculative. http://www.internationalbrain.org/mild-traumatic-brain-injuries-were-prev-undiagnosable-therefore-treatment-uncertain-and-damages/ (accessed May 7, 2018).
  9. Guskiewicz K, McCrea M, Marshall S, et al. Cumulative Effects Associated With Recurrent Concussion in Collegiate Football Players - The NCAA Concussion Study. JAMA. 2003;290(19):2549-2555.