Concussion: Introduction—The Controversy

Vin Shen Ban, MA, MB, BChir, MRCS, MSc AFHEA

Richard G. Ellenbogen, MD

H. Hunt Batjer, MD, FACS

None of the following authors or any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this article: Dr. Ban, Dr. Batjer, and Dr. Ellenbogen.

According to the 1991 National Health Interview Survey, about 300,000 Americans sustain sports-related concussions each year.¹ This figure was then extrapolated to 1.6 to 3.8 million based on several other factors that were not taken into account previously.² The Centers for Disease Control and Prevention (CDC) estimated that, between 2001 and 2009, an annual average of 173,285 traumatic brain injury (TBI)–related emergency department (ED) visits were reported in those 19 years of age or younger.³ This number grew from 153,375 in 2001 to 248,418 in 2009. The true incidence of concussion is difficult to ascertain, partly because of the lack of objective diagnostic criteria⁴ and thus inconsistencies in reporting.⁵ Furthermore, the majority of patients with a presumed concussion likely do not seek evaluation in the ED but instead are self-diagnosed or treated in their primary care physician’s offices. The increasing trend in the reported ED visits is hypothesized to be the result of clearer, more publicized criteria for diagnosing concussions, and the media attention focused on concussions and their potential long- term effects on the athlete’s health.⁶^,⁷^,⁸^,⁹^,¹⁰ Outreach and educational events, especially those in the Internet and printed media, have also played a part in raising the public’s awareness on the signs and symptoms of concussion.¹¹^,¹²^,¹³

There has been an exponential increase in the number of peer reviewed articles published with the keyword “concussion” in the past 5 years (Figure 23-1), reflecting the growing interest in the subject, both from the scientific community and from the public at large.⁸ Research in concussion and TBI in general has spanned the entire spectrum from the bench to the bedside, with an increasing number of large-scale initiatives attempting to bridge the extremes.¹⁴^,¹⁵ On the molecular level, scientists have provided us with a comprehensive review of the neurometabolic cascade of concussion.¹⁶ In line with the overall objectives of this book, our focus in this section is on the practical aspects of the diagnosis and management of concussion, as relevant to clinicians caring for student and elite athletes.

The terms “concussion” and “mild TBI” (mTBI) are often used interchangeably.⁴ Concussion is a form of TBI on the milder range of the spectrum of brain injury. The “mTBI” designation can be misleading because a minority of these can sustain significant sequelae of their injury.

Distinguishing Between Cervical and Vestibular Injury and Concussion

It is common for sports-related blows to the head to have a concomitant transfer of force to the cervical spine.¹⁷^,¹⁸ As it has been discussed in the section on cervical spine injuries, athletes may experience a range of symptoms from neck pain, dizziness, and cognitive disturbances to headaches. These whiplash-associated disorders (WADs) have common features with concussion,¹⁹^,²⁰^,²¹ and their mechanisms of injuries are often identical,¹⁷^,¹⁸ suggesting that concussions may not be purely a brain phenomenon.²² If this is indeed true, that is, if concussion is a constellation of symptoms attributable, at least in part, to the type of cervical spinal injury seen in WAD, then there will be significant implications for the management of these patients. WAD has been treated with active mobilization, injections (steroids, botulinum toxin), manipulation techniques, and radiofrequency neurotomy,²³^,²⁴ while concussions are currently being treated with rest or active rehabilitation.⁴

Distinguishing between a head injury and a cervical spine injury by symptoms alone can be challenging.¹⁹ Often, the mechanism of trauma is witnessed, and the patient can articulate his or her symptoms, making the diagnosis and treatment more straightforward. When there is any doubt, it is best to remain suspicious of both
a spine and a head injury. Therefore, standard precautions should be taken to immobilize the cervical spine while removing the athlete from the field for further assessment. After clearing the primary survey, the sports clinician may then proceed to obtain a history and assess the cervical spine (as described in Chapters 9–15).

FIGURE 23-1 Number of publications by year through a MEDLINE search of “concussion” up until the end of 2014.

The Controversies

Despite the growing literature, every aspect of concussion remains a controversial subject to include definition, diagnosis, treatment, and prognosis. Many groups have published their own guidelines and recommendations for sports-related concussions; these groups include the American Academy of Neurology,²⁵ the American Medical Society for Sports Medicine,²⁶ the International Conference on Concussion in Sport,⁴ and the Brain Trauma Foundation.²⁷ A detailed comparison of the guidelines has been undertaken by West and Marion.²⁸

In this section of the book, encompassing Chapters 23 through 28, we review the current state of knowledge and practice and highlight areas of controversy. For ease of reference, the chapters in this section are arranged according to the chronological order of events after a (suspected) concussion in an athlete. All of the authors here are leading experts in their fields, and they have provided authoritative overviews of their respective chapters. You will also recognize them as part of the writing committees developing the concussion guidelines mentioned earlier. It is important to emphasize that although much remains to be uncovered in the world of concussions, it would simply be impossible to include everything that we do know in the space of these few chapters. The main purpose, therefore, is to highlight areas pertinent to the clinical practice of a healthcare expert caring for patients with sports related concussions.

Definition, Diagnosis, and On-Field Evaluation

The diagnosis is the first step in the concussion management pathway. In Chapter 24, Dr. Stan Herring and colleagues review the elements of the currently accepted diagnostic criteria, including the symptoms that are commonly reported and the physical signs to look out for. The role of commonly used assessment tools is also discussed, along with plans for preseason, on-the-field, and sideline assessments. This is then followed by a video by Leigh Weiss and Ronnie Barnes demonstrating the on-field assessment of an athlete with a suspected concussion. In the video, several key elements and tools are reviewed, including the Maddock’s questionnaire, Sport Concussion Assessment Tool 3 (SCAT3), and National Football League (NFL) Sideline Assessment (Go v. No-Go, symptom inventory, Standardized Assessment of Concussion [SAC], memory recall), cervical spine and neurologic examinations, balance testing, and upper limb coordination testing.

Objective means of diagnosing concussions are currently being studied. There has been increasing interest in developing a biomarker that could either predict susceptibility to concussions or be used as part of the diagnostic criteria.²⁹ S100β,³⁰^,³¹^,³²^,³³^,³⁴^,³⁵^,³⁶^,³⁷^,³⁸^,³⁹^,⁴⁰^,⁴¹ glial fibrillary acidic protein
(GFAP),³⁴^,³⁷^,³⁹^,⁴⁰^,⁴¹^,⁴² neuron-specific enolase,³⁵^,³⁶^,³⁷^,³⁸ apolipoprotein E4,⁴³^,⁴⁴^,⁴⁵ neurofilament light protein,⁴⁰^,⁴¹^,⁴² amyloid beta,³⁹^,⁴¹^,⁴² tau protein,³⁹^,⁴⁰^,⁴¹^,⁴² brain-derived neurotrophic factor (BDNF),³⁷^,³⁹ creatinine kinase,³⁴^,³⁸ heart-type fatty acid binding protein (h-FABP),³⁷^,⁴¹ prolactin,³¹ cortisol,³⁸ and albumin⁴⁰ are among the biomarkers that have been studied. The number of references associated with each biomarker provides a relative indication on the frequency with which they have been studied, but they are by no means exhaustive. Most of these studies were small pilot studies with some conflicting evidence and are certainly of insufficient strength to support their use in clinical practice so far.

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