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Persistent Post-Concussion Syndrome May Be More Widespread than Previously Thought

Posted April 22, 2017

By  Jonathan A. Karon

For years, it’s been widely accepted that approximately 15% of people who sustain a concussion (also known as a mild traumatic brain injury or MTBI) will continue to suffer from symptoms more than a year after their injury, a condition referred to as persistent post-concussion syndrome.  There have been several theories advanced as to why this group of people, sometimes dismissively referred to in the literature as “the miserable minority” continue to experience impaired cognitive function and symptoms such as headaches, fatigue, irritability, anxiety and depression.  Although some researchers theorized that psychological factors alone or in combination with an actual physical injury were complicating recovery, others suggested that present imaging studies were just not sensitive enough to detect the physical brain damage sustained by these individuals.

In recent years, more sensitive techniques, most notably diffusion tensor imaging (DTI) have allowed researchers and clinicians to visualize additional structural brain damage such as diffuse axonal injuries (DAI) which could not be detected by more conventional means such as MRI’s or CT scans.  Canadian researchers at Dalhousie University in Halifax, Nova Scotia, wondered why, given that it is now established that a single concussion causes significant changes to the physical structure of the brain and the ability of neurotransmitters to properly function, that only 15% of persons suffered from persistent post-concussion syndrome.  They theorized that the 15% figure might be grossly underestimating the number of people with persistent MTBI symptoms.

To answer this question, they performed a “scoping review” of the scientific literature concerning short and long term function of persons with a single concussion.  Contrary to the 15% figure, their review indicated that “in contrast to the prevailing view that most symptoms of concussion are resolved within 3 months post-injury, approximately half of individuals with a single mTBI demonstrate long-term cognitive impairment.” Thus, they conclude that the 15% figure is “likely a gross underestimation” of the persons suffering from cognitive impairment more than three months after a mild traumatic brain injury.

The complete article, entitled “Mild Traumatic Brain Injury (mTBI) and chronic cognitive impairment: A scoping review” was published in an on-line open access journal and is available for free at

Although the results of this literature review should not be discouraging for concussion sufferers, for whom the prospects of recovery are generally good, it should provide some re-assurance to persons who are experiencing more persistent symptoms that they are not alone and that their continued impairments reflect the result of a real physical injury.





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