The state-of-the-art on the science and evidence of what we know about concussion


In contrast to what some clinicians and lay persons may believe, there is no such thing as a concussion test. While brain scans are necessary to differentiate between mTBIs and complicated-mild TBIs, they cannot exclusively be relied upon to diagnose mTBI. In other words, neuroimaging is not a concussion test. Similarly, neuropsychological testing and computerized cognitive screening can help clarify the nature and extent of cognitive symptoms experienced following a concussion, but also are not concussion tests. Additional examinations and tests can help inform healthcare professionals and family members about various aspects of the youngster’s condition following a concussion, but none of them is a concussion test per se. Such exams and tests include the following: biomarker assays (e.g., S-100B serum levels; Oris et al. 2018), electroencephalography (EEG), neurological exam, physical exam, postural stability (i.e., balance) testing, graded symptom checklists, and various phone apps. Although these assessment methods are of value in the clinical management of children and teens following concussion, they should not be misinterpreted as concussion tests.


Bender and Matusewicz (2013) articulated their concerns about the postconcussional syndrome diagnosis. These authors pointed out that the symptoms of postconcussional syndrome (e.g., headache, dizziness, emotional, or cognitive changes) are not specific to concussion and may not actually be a direct result of the concussion, but may flow from other sources, including pre-concussion psychiatric problems or substance abuse. Although not as applicable to young children, this would be important to consider with teenagers diagnosed with postconcussional syndrome. Similarly, neurodevelopmental delays, delivery complications (e.g., anoxia (lack of oxygen) at birth), and pregnancy irregularities (Kaufman et al. 2016) should be considered when trying to draw conclusions about postconcussional syndrome symptomatology. Bender and Matusewicz noted that concussion checklists can lead to overreporting of symptoms and that scores on such checklists predicted worse scoring on performance validity tests, raising questions about the validity of a postconcussional syndrome diagnosis, which is based entirely on self-report. Finally, these authors asserted that “the literature strongly suggests that postconcussional syndrome lacks specificity and that it has questionable diagnostic utility” (p. 114). Failure to appreciate the non-specific nature of postconcussional symptoms can lead to misdiagnosis of postconcussional syndrome and persistent symptomatology (Larrabee 1997; Larrabee 2005).


The power of authority commanded by healthcare professionals who diagnose postconcussional syndrome can trigger or fuel psychological mechanisms that contribute to or underlie the postconcussional symptoms. Put plainly, the healthcare professional making this diagnosis [i.e., postconcussional syndrome] can literally bring the diagnosis to life…thereby having an iatrogenic (i.e., harmful) effect on the patient. This phenomenon has been studied as is sometimes called response expectancy (Suhr and Wei 2013), a subtype of which is diagnosis threat (Suhr and Gunstad 2002). Thus, children and teens undergoing neuropsychological assessment in the context of concussion might underperform on the tests because they have come to believe that their symptoms were caused by the concussion. This is more likely if parents fuel such beliefs, which is not uncommon, especially if the parent has been misinformed.


More research on the long-term sequelae is needed to better understand the incidence and prevalence of CTE [i.e., chronic traumatic encephalopathy] and other neurological conditions among former athletes. The causes of mental health and cognitive problems in former athletes, like the general population, are broad and diverse including genetics, life stress, general medical problems (eg, hypertension, diabetes and heart disease), chronic bodily pain, substance abuse, neurological conditions and disease (eg, cerebrovascular disease) and neurodegenerative diseases (eg, Alzheimer’s disease, Parkinson’s disease and ALS).The extent to which repetitive neurotrauma causes static or progressive changes in brain microstructure and physiology, and contributes to later lifemental health and cognitive problems, is poorly understood and requires further study. (p. 8)


…high school football is associated with an increased risk of concussion, and yet no causative link has been established between playing high school football and neurodegenerative diseases (e.g., MCI or dementia), is consistent with the most common clinical outcome among youth athletes who experience a concussion. Namely, they generally get better within about 10 days or less. This encouraging theme in the literature was described by Kirkwood et al. (2012) as follows:

…existing prospective controlled studies indicate that most high school and older athletes appear to return to baseline within 7-10 days after a concussion…Some percentage of athletes can be expected to display concussion-related problems beyond 1-2 weeks…

Although noncontrolled studies may be able to provide the number of athletes who display persistent postconcussive problems, they fail to account for the base rate occurrence of common postconcussive symptoms among non-head-inured individuals or account for false positives—that is, the number of nonconcussed athletes who would report ‘postconcussive’ symptoms or would be classified as impaired on objective testing at the time of postinjury measurement. (p. 345)

In other words, while a very small minority of concussed young athletes experience concussion-related symptoms beyond the typical timeframe of 7 to 10 days, the evidence of persisting symptoms is confounded by the fact that youngsters without a history of concussion experience these same symptoms for other reasons that have nothing to do with head injury.

It is important to emphasize that SIS (Second Impact Syndrome) is believed to be very uncommon and that it may even be a mischaracterization of some other neurobiological process. According to McCrory (2001), for example, SIS is more accurately viewed as diffuse cerebral swelling.

Recommendations for Pediatric Neuropsychologists

First, perhaps the most important recommendation is to know what a concussion is, and what it is not. In contrast to what is communicated in the media (Carone 2014), a concussion is not a grave or indelibly harmful injury, so parents, teachers, and other concerned parties should not worry about long-term negative consequences as a result of a concussion. Even though “The expected duration of symptoms in children with [sport-related concussion] is up to 4 weeks…” (McCrory et al. 2017) (p. 7), most children will probably experience a full recovery within 7–10 days. It is, therefore, recommended that pediatric neuropsychologists share this valuable information with those they serve.

Fifth, perhaps counterintuitively, it is recommended that pediatric neuropsychologists encourage a quick return to normal activities (Carroll et al. 2004; Ponsford et al. 2001), following the brief period of rest over the first 24 to 48 h. This does not, however, mean a quick return to activities that carry an increased risk for another concussion, as explained above.

Sixth, because there are no concussion tests, it is recommended that pediatric neuropsychologists disabuse parents and other relevant parties of the belief that such a test exists.

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