SportsMed: Updates on sports concussions
A concussion consists of clinical symptoms stemming from a brain shaken by external forces. It is a type of traumatic brain injury (TBI) and is sometimes called a “mild TBI,” although this term is used for injuries other than those sustained in sports.
The comparative incidence of concussions in interscholastic sports and the concussion rate appear to be increasing. About two to four million concussions in the U.S. are related to sports, including those athletes with sports-related concussions who received no medical care. A growing focus on concussions at every level of sports is apparent.2The highest concussion rates are found in football, wrestling, soccer and girls basketball, according to the U.S. Centers for Disease Control and Prevention. It has been shown that about 10 percent of all high school athletic injuries were concussions. Possible risk factors for concussions in football include an individual’s concussion history, characteristics unique to the individual (age, competition level and body mass index) and the type of protective equipment worn by the players.3
Girls sports appear to have approximately twice the concussion risk, and increases in athletic trainer coverage may be leading to an increase in the rates of diagnosis of concussions. Concussion outcomes appear to be worse in females than in males, and females appear to have different baseline and post-concussion outcomes compared to those of males. This may occur partly because of the finding that females are more willing to report injuries, leading to a potential bias toward increased concussion detection in females.
A consensus statement, recently formulated in Zurich, on concussions in sports redefined concussions as brain injuries resulting from complex pathophysiological processes affecting the brain and induced by biomechanical forces. Features include clinical, pathologic and biomechanical injuries.
The statement concluded:
- Concussions may be caused either by a direct blow to the head, face, neck or elsewhere on the body, with an ‘‘impulsive” force transmitted to the head.
- Concussions typically result in the rapid onset of short-lived impairment of neurological function that resolves itself spontaneously; however, in some cases, symptoms and signs may evolve over a period of minutes to hours.
- Concussions may result in neuropathological changes, but the acute clinical symptoms largely reflect a functional disturbance rather than a structural injury and, as such, no abnormality is seen in standard structural neuro-imaging studies.
- Concussions may result in a graded set of clinical symptoms that may or may not involve a loss of consciousness.
A sequential course of increasing physical and cognitive activity is typically followed by the resolution of cognitive and clinical symptoms. In some cases, symptoms may be prolonged. While the recovery time may be longer in children and adolescents, 80 to 90 percent of concussions resolve themselves in seven to 10 days.1
A detailed concussion history is an important part of the evaluation of the injured athlete and in the sports pre-participation examination. Improvements in a previously released, second Sport Concussion Assessment Tool (SCAT2) have occurred: the SCAT3 and Child SCAT3, which are forms easily searchable on the Internet and are used in the assessment of possibly concussed athletes.
These forms record somatic symptoms, such as headaches; cognitive symptoms, such as feeling like being in a fog; and emotional symptoms, such as constant changes. These forms also record physical signs, such as loss of consciousness; behavioral changes, such as irritability; cognitive impairment and sleep disturbance. If any one or more of these components occurs, a concussion should be suspected and an appropriate management strategy should be instituted.
Any signs of a concussion should lead to the player being evaluated by a physician or other licensed healthcare provider on site, using standard emergency management principles. Particular attention should be given to excluding the possibility of a neck injury.
Whether the athlete can continue participating is up to the healthcare provider. If no healthcare provider is available, the player should be safely removed from the practice or game for evaluation. Once first-aid issues are addressed, an assessment of the athlete should be made using the SCAT3 or other sideline assessment tools. The player should not be left alone, and serial monitoring for deterioration is essential in the first few hours following a possible concussion.
Diagnosis of a concussion and an athlete’s fitness to play must be based on clinical judgment. The assessment on the sidelines is crucial for this determination. Attention and memory can be tested with the SCAT3. Just asking about time, place and surrounding people has been shown to be unreliable in the sports setting.1
The key features of the first comprehensive examination of a concussed athlete should include:
- A medical assessment, including a comprehensive history and detailed neurological examination and thorough assessment of mental status, cognitive functioning, gait and balance.
- A determination of the clinical status of the patient, including whether there has been improvement or deterioration since the time of injury — a task that may involve seeking additional information from parents, coaches, teammates and eyewitnesses to the injury.
- A determination of the need for emergent neuro-imaging to exclude the possibility of a more severe brain injury involving a structural abnormality.
Concussions may be investigated by other means, although what is almost always normal to use is conventional structural neuroimaging. Still, if an intracerebral or structural lesion, such as a skull fracture, exists, brain computed tomography (CT) or an MRI should be used, even though they contribute little to the actual concussion evaluation.
Worsening symptoms, focal neurological deficits and a prolonged disturbance of the conscious state may warrant such imaging. Symptom severity and recovery from concussion have been shown to correlate with functional MRI (fMRI) findings as well. This finding provides additional insight into pathophysiological mechanisms, although an fMRIis not part of the routine assessment of concussed athletes.
Compelling findings have been found with alternative imaging technologies, such as positron emission tomography, diffusion tensor imaging, magnetic resonance spectroscopy and functional connectivity. However, their use is mostly in research at this point, as their use for diagnosing concussions is in the early stages of development. Acute postural stability deficits lasting approximately 72 hours following a sports-related concussion have been detected by the use of clinical balance tests, such as the Balance Error Scoring System (BESS) and force plate technology.1
The assessment of cognitive function should be an important component in the overall assessment of concussed athletes and in any return-to-play protocol because cognitive recovery overlaps with symptom recovery and may occasionally precede or more commonly follow clinical symptom resolution.
Management decisions should not be based solely on neuropsychological assessment, as it should just be an aid to clinical decision-making, with a range of different clinical domains and investigational results. Overall management of concussed athletes should include a clinical neurological assessment, including an assessment of their cognitive function. 1
Medical clearance and return to play can only occur after acute symptoms resolve, but the effect of rest on a sports-related concussion is still relatively poorly studied.
One to two days of rest following injury, within the acute symptomatic period, have been helpful.1 The optimal amount and type of rest, and its long-term outcome, still need to be studied. As there is scant evidence on how to approach return to play in athletes, it makes sense that this return should be made gradually, especially when it involves returning to school and social activities prior to contact sports. Such a return has to be done in a manner that does not result in a significant exacerbation of symptoms.
For those who are slow to recover, low-level exercise may be helpful, although the timing for the initiation of this treatment is currently unknown. As mentioned, most athletes recover spontaneously over seven to 10 days. After such recovery, it is expected that the previously symptomatic athlete is able to proceed progressively through a stepwise return-to-play strategy. 1
If asymptomatic at a current level in the return-to-play strategy, the athlete should continue to proceed to the next level in the stepwise progression. Approximately one week should pass in the full rehabilitation protocol once an athlete is asymptomatic at rest and with exercise meant to provoke symptoms, as each step in the protocol should take 24 hours. The athlete should drop back to the previous asymptomatic level and try to progress again after 24 hours if any symptoms occur.
Ten to 15 percent of concussed athletes go on to have persistent symptoms for more than 10 days.1 At this point, other pathologies should be considered. Management at this point should be multidisciplinary and done by providers with experience in sports-related concussions.
Although the highest percentages of concussions occur in high-impact sports, efforts to detect, treat and prevent concussion should not be limited to those sports. Helmeted sports had highest percentages of concussions, suggesting that protection from concussion may involve a multifaceted approach to injury prevention. More recent evidence suggests that a focus on concussion detection, treatment and prevention should not be limited to those sports traditionally associated with concussion risk. 2
Helmets today are heavier, larger and designed to absorb and dissipate the impact of forces to a greater extent than earlier models. Manufacturers state that helmets cannot prevent concussions or eliminate the risk of serious injury.
Helmet brand, age, and helmet condition status appear not to be associated with a lower risk of concussions, although the use of generic mouth guards did appear to lower the risk of concussions in some limited studies, and the majority of studies have led to inconsistent results. Potential protective mechanisms include absorbing the force of a blow to the jaw, increasing the separation of the head of the condyle and mandibular fossa, and limiting the muscle activation of the neck musculature.
Players with custom mouth guards may feel that they have greater protection against concussions and play with less regard for or fear of sustaining such injuries. Sports experience has not been shown to be associated with an increased or decreased risk of concussions. Rule changes, such as disallowing full-body checking, have been shown to decrease concussion rates significantly, however. 3
- McCrory, P., Meeuwisse, W. H., Aubry, M. et al. Consensus statement on concussion in sport: the 4th International Conference on Concussion in Sport held in Zurich, November 2012. Br J Sports Med 2013: 47, 250–258. doi:10.1136/bjsports-2013-092313.
- Lincoln, A. E., Caswell, S. V., Almquist, J. L. et al. Trends in concussion incidence in high school sports: a prospective 11-year study. Am J Sport Med 2011: 39(5), 958–63.
- McGuine, T. A., Hetzel, S., McCrea, M. et al. Protective equipment and player characteristics associated with the incidence of sport-related concussion in high school football players, a multifactorial prospective study. Am J Sports Med 2014: 20(10), 1–9.