Submitted by Gregory B. Bonds, William W. Edwards and Brandon D. Spradley
Concussions continue to be a mainstay topic of conversation among the media, health professionals, and the general public. In 2013, the American Medical Society for Sports Medicine (AMSSM) released a position statement that estimated as many as 3.8 million concussions occur within sports annually with up to 50% of concussion injuries unreported. Advancements in the areas of diagnosis, treatment, playing rules, equipment, education, and technology have heightened the awareness on the dangers of concussion injuries and the need to provide better protection for sports participants. The current (2014) position statement from the National Athletic Trainers Association recommends a thorough neurologic assessment for a “history of concussion, seizure disorder, cervical spine stenosis, or spinal cord injury”. In 2014, prominent organizations such as the National Collegiate Athletic Association (NCAA) and the National Football League (NFL) have taken a proactive approach to commission research projects to study the short term and long-term effects of concussion injuries. Results of these research efforts should enhance the welfare and protection of participants. The purpose of this paper is to review and explore advancements in concussion prevention, diagnosis, treatment, playing rules, equipment, education, and technology.
The terms concussion and mild traumatic brain injury (mTBI) are at times used interchangeably. However, evidence of a concussion is an important component in the evaluation of mTBI (28). A concussion is the result of brain trauma and refers to a pathophysiological disruption of the brain instigated by intense physical force to the body. Concussion can originate by targeted contact to the head and neck area. The resulting impact is temporary neurological interference that can last momentarily or for several hours (28). Extended ailments related to fatigue, weak concentration, mood swings, and sleep deprivation are referred to as Postconcussive Syndrome (PCS). Detrimental effects of PCS include interruption of academic requirements, work schedules, and daily normal endeavors (25).
The purpose of this paper is to review and explore advancements in concussion prevention, diagnosis, treatment, playing rules, equipment, education, and technology. Based on the volume of head and brain injuries suffered on an annual basis, sports concussions may be considered a critical public health concern. The Centers for Disease Control and Prevention (CDC) reported 207,830 trips to an emergency room annually between 2001 and 2005 due to sports participation injuries (9). In 2010, brain injuries with no hospitalization or loss of consciousness occurred in about 1.5 million people in the United States. A comparable amount lost consciousness occurring from a brain injury and required an extended hospital stay (13). In a 2013 report, concussions attributed to sports participation account for an estimated 3.8 million injuries (19). As a result, educational efforts geared toward parents, participants, coaches, and the community to raise awareness on the symptoms of concussions and the possible lifelong consequences were implemented (36).
Chronic traumatic brain injury (CTBI) is the compounding and everlasting neurological result of multiple blows to the head. CTBI is generally associated with the sport of boxing. However, participants of other contact sports such as football, soccer, and ice hockey can be affected by CTBI (35). As suggested by Potter and Brown (2012), current treatment options are limited (34). As a result, diminishing the frequency and intensity of sports-related head injuries must be a priority by increasing awareness, wearing protective gear, emphasizing playing rules, improving strength and conditioning, ensuring proper coaching techniques, and supervising sports medicine interventions (35).
REVIEW OF LITERATURE
Diagnosis of Concussions
The typical concussion diagnosis includes an evaluation of symptoms, physical evidence, cognitive depreciation, change in behavior, and sleep disruption. Classic concussion symptoms include headache, grogginess, impaired consciousness, memory loss, mood change, delayed reaction times, and sleeplessness (28). Neurological history is crucial, as evidenced by the 2014 National Athletic Trainers’ Association (NATA) Position Statement: Preparticipation Physical Examinations and Disqualifying Conditions. This position statement recommends, “If the athlete has a history of concussion, seizure disorder, cervical spine stenosis, or spinal cord injury, a thorough neurologic assessment is necessary” (10, p. 104).
The Sport Concussion Assessment Tool – 3rd Edition (2013), also known as SCAT3, supersedes the SCAT and SCAT2 from 2005 and 2009, respectively (28). The SCAT3 is a systematic method used by licensed health care professionals for assessing wounded participants 13 years of age or older for concussion (28). The SCAT3 is comprised of eight distinct assessment areas. These areas include the Glasgow Coma Scale (GCS), which measures the best eye response, the best verbal response, and the best motor response. The Maddocks Score is utilized primarily for sideline judgment for concussion diagnosis. The Symptom Evaluation component assesses traits such as headache, nausea, dizziness, memory loss, confusion, light sensitivity, and irritability. The cognitive assessment is devoted to immediate memory related to date and time. A neck examination is performed to record range of motion, tenderness, and upper and lower limb strength. The balance examination is centered on the Modified Balance Error Scoring System (BESS) testing. Key components of BESS testing are the double leg stance, single leg stance, tandem stance, and tandem gait. The coordination examination is performed utilizing the finger to nose test. With arms extended, the participant touches the nose then returns the arms to the original outstretched position. The Standardized Assessment of Concussion (SAC) Delayed Recall is conducted after the Balance and Coordination examination to measure memory recall (28).
Covassin, Stearne, and Elbin (2008) studied the affiliation of previous concussion injuries and post-concussion neurocognitive actions and evidence among intercollegiate athletes (12). The purpose was to examine if intercollegiate athletes, who have suffered at least two or more concussions, exhibited neurocognitive deterioration when measured to concussed athletes without a history of concussion injuries. The cohort was comprised of 57 intercollegiate athletes from five northeastern colleges and universities. Thirty-six of the athletes did not have previous concussions and 21 experienced at least two or more concussions. Sports represented in this study included the male sports of basketball, soccer, lacrosse, baseball, football, and wrestling. Female sports in this study included basketball, soccer, lacrosse, gymnastics, softball, volleyball, and cheerleading (12).
The Immediate Post-Concussion Assessment Cognitive Testing (ImPACT) computerized software system was utilized in the Covassin et al. (2008) study to gauge neurocognitive capacity and concussion symptoms (12). The software system includes neurocognitive exams to interpret attention, verbal recognition memory, visual working memory, visual processing speed, reaction time, numerical sequencing, and learning. Additionally, these neurocognitive exams produce four distinct recordings in the areas of verbal memory, visual memory, reaction time, and visual processing speed (12). The findings from Covassin et al. (2008) suggest that acutely concussed athletes with a positive concussion history may need extended recovery time for verbal memory and reaction versus athletes with an unremarkable concussion history (12). Guskiewicz, Weaver, Padua, and Garrett, Jr. (2000) suggested three or more concussions could increase the chances of enduring another concussion within the same season and face extended recovery times following future concussions (17).
Gessel, Fields, Collins, Dick, and Comstock (2007) considered the incidence and prevalence of concussions by comparing a large population of high school and college athletes (16). The purpose was to examine the health ramifications of concussions in high school competitors in comparison to intercollegiate competitors during the 2005-2006 academic year. The cohort consisted of 100 high schools and 180 four-year colleges in the United States. The specific sports included in this study were the male sports of football, soccer, basketball, wrestling, and baseball and the female sports of soccer, volleyball, basketball, and softball. A total of 4,431 injuries were disclosed with 396 (8.9%) specified as concussions in high school sports and 482 (5.8%) in collegiate sports.
The data was collected from the Gessel et al. (2007) study and analyzed from the injury databases associated with the High School Reporting Information Online (RIO) and the National Collegiate Athletic Association Injury Surveillance System to compute concussion rates, trends, and risk exposure (16). The findings cite 396 (8.9%) concussion injuries in high school participants and 482 (5.8%) concussion injuries in college participants. When combining the high school and collegiate groups, participants in the sports of football and soccer suffered the highest rates of concussions. In the comparable high school sports of soccer and basketball, played by males and females, females endured a greater rate and proportion of concussions than males. For all sports, collegiate participants endured a greater rate of concussions over high school participants. However, concussions indicated a higher proportion of injures in high school participants (16).
Treatment of Concussions
At present, there is no definitive pharmaceutical evidence-based treatment for sport-related concussion (25). Various medications have been evaluated with regard to concussion treatment. Examples include corticosteroids, free radical atoms, antioxidants, medication to restrain arachidonic acid inflammatory response and monamine neurotransmitters, glutamate receptor antagonists, calcium blockers, thyrotrophin-releasing hormone, and hyperbaric oxygen therapy (25).
The traditional treatment protocol for PCS is rest and abstention from activities, which risk further brain trauma, and care for the symptoms that arise. Headaches and altered sleep patterns are the most conveyed concussion symptoms. Since sleep depravity can aggravate other concussion symptoms, sedative type prescriptions can be recommended to help resolve any inability to sleep. Ritalin may be prescribed for concussions, deficiencies in concentration and memory due to the effects of headaches (25). An alternative treatment procedure for PCS is the consumption of Omega-3, which has been identified as having considerable health advantages for the brain. Omega-3 aids in counteracting inflammation to dwindle the manufacturing of prostaglandins and decrease brain injury inflammation (25).
McCrea et al. (2003) studied the immediate instantaneous symptoms and cognitive recuperation process of concussed collegiate football players (27). The purpose of the study was to assess the critical ramifications of concussion and the progression to restoration of intercollegiate football players. The cohort consisted of 1,631 football student-athletes from 15 National Collegiate Athletic Association (NCAA) Division I, II, and II colleges and universities. This cohort was part of a larger study that occurred during the 1999, 2000, and 2001 seasons and totaled 2,410 participants. All student-athletes in the study experienced a preseason baseline assessment along with a health history questionnaire. The Graded Symptom Checklist (GSC), the Standardized Assessment of Concussion (SAC) and the Balance Error Scoring System (BESS) were utilized to gather outcome measure characteristics. Inaugural data was charted for symptoms, cognition, and balance during the designated timeframe with a 95% confidence interval. Due to the extended length of the surveillance data for the injuries, predictor equation patterns, identity markers, Gaussian residual variation analysis, and an independent correlation matrix were used. This protocol was used to predict the average differences in the final data collected for injured and non-injured players during the designated timeframe (27).
The findings from McCrea et al. (2003) show that 94 (56.8%) players suffered from a concussion in practice or during competition (27). Concussion symptoms were most visible at the time of concussion injury with various symptoms lasting through the fifth day following injury. Seven days was the average length of time for injured players to recover from concussion symptoms. Ninety-one percent of the concussed players rebounded to initial baseline testing levels within seven days after enduring a concussion. These findings assist in the treatment of concussions in better understanding the length of time required to return a student-athlete to baseline health after suffering a concussion injury (27).
Rules of Engagement
Strict adherence to and enforcement of the playing rules and regulations of a particular sport demonstrate a fundamental safety component to protect the participants of all levels from concussion injuries (16). Rule changes may decrease concussion risk. Oftentimes these changes are unique to a specific sport. For example, in soccer, research studies report that upper body to head contact while heading a ball contributed toward 50% of concussions (3). Referees can play a vital role in the reduction of injuries by invoking the rules and issuing penalties to offenders (14).
In the 2013 collegiate football season, the penalty for targeting became a controversial topic among coaches and athletic administrators. Targeting an opposing player is a serious offense and can result in critical injuries, especially to a defenseless competitor. Rule 9-1-3 from the NCAA Football 2013 and 2014 Rules and Interpretations rule book states “no player shall target and initiate contact against an opponent with the crown of his helmet” (30, pp. FR-86-87). Furthermore, NCAA targeting rule 9-1-4 states that “no player shall target and initiate contact to the head or neck area of a defenseless opponent with the helmet, forearm, hand, fist, elbow, or shoulder” (30, pp. FR-87-88). An infraction of the targeting rule results in ejection from the contest. Changes in sports rules to increase the safety of the head and neck are designed, in part, to decrease concussion risk. Implementation of the rules and citing of infractions are moves to increase safety and decrease the risk of brain injury (30).
Sporting Gear Advancements
Advancements in sporting gear assist in reduction of concussion incidence. The evolution of safety standards among football equipment companies is apparent in the new helmet designs that decrease the chance of concussion injuries. Companies such as Adams USA Pro Elite, Riddell Revolution, Schutt Sport Air Varsity Commander (AVC), and DNA have been industry leaders in the area of helmet design (39).
Viano et al. (2006) studied the endurance of contemporary football helmets with the VSR-4 football helmet in ten replays of National Football League (NFL) plays in which concussion occurred (39). The purpose of this study was to evaluate proportional data to establish the efficacy of contemporary football helmets by diminishing the dangers associated with concussion and mild traumatic brain injury. This investigation revealed the force of contact and biomechanical reactions with concussions in the NFL. Pellman, Viano, Tucker, Casson, and Waeckerle (2003) disclosed an elevated percentage of low and tilted contact to the side and rear of the helmet since older helmets were equipped inside with comfort foam (33). Advancements in research have resulted in better-equipped helmets with foam lining throughout the helmet. These advancements in helmet construction and function were designed to diminish risks for concussion injuries. Additionally, the NFL testing practices with concussions have been broadly calculated and communicated with the helmet manufacturers and the National Operating Committee on Standards for Athletic Equipment (NOCSAE) (39).
Pellman et al. (2003) replayed 31 impact tackles from NFL games for the purpose of analyzing helmet design proficiency (33). Twenty-five of these helmet-to-helmet contacts and ground contacts resulted in concussions. In this study, 10 episodes of concussion and five new helmet models were compared with the Riddell VSR-4 helmet. This evaluation established baseline measurements for the older helmet models so that newer models could be assessed for improved efficacy. This protocol considered the certification from earlier testing to establish the baseline measurements for the older helmet models (39). The results of the data show that 32 of 50 recreated episodes indicated more than a 10% decrease in concussion injury with newer helmets judged against the older Riddell VSR-4 helmet. Interestingly, four of the 50 episodes demonstrated an increase. The mean decline in concussion danger with modern helmets of 10.8% with a range of 6.9% – 16.7%. For translational acceleration the decline was 9.7% with a range of 6.5% – 13.9%. For rotational acceleration the decline was 18.9% with a range of 10.6% – 23.4% (39).
In conclusion, modern football helmets result in 10% – 20% less risk of concussion injuries as a result of redesigned NFL game gear. Conversely, a small number of episodes have revealed an increase. The assessment of football helmets relative to NOCSAE concussion standard criterion ought to advance industry standards reform in helmet designs to reduce concussion injuries (39).
Educational Advancements of Concussion Management
Advancements in the education of health care and sports medicine providers have improved concussion management. The controversial timeframe balance of concussion diagnosis and return to play protocols can be extremely demanding on sports medicine health care providers. In the 20th century, protocols for return to play following a concussion were variable. Medical determinations relied upon team doctors or specialists in the field, rather than diagnosis based on experiential data (24). In a 2004 paper, Lovell and colleagues (2004) noted more than 20 management guidelines and focused on practical suggestions for “the evaluation and management of sports-related concussion…for making return to play decisions” (24, p. 421). These suggestions addressed the need for standard guidelines for sports medicine health care providers.
As reviewed by Lovell et al. (2004), Cantu (1992) recommended a grading scale and principles on the basis of medical experience, which would accompany and support medical opinions. These guidelines permitted an athlete to return to play on the same date of injury if the athlete did not display concussion symptoms while resting or after physical activity. For players who suffered unconsciousness and a grade 3 concussion, inactivity for one month was suggested. For players who suffered a grade 2 concussion, return to play was permitted in two weeks if no signs of concussion were demonstrated for a period of seven days (6).
The Colorado Guidelines (1991) were enforced in 1991 after a high school player died after suffering a second concussion. These guidelines permitted a player to return to play if concussion symptoms were resolved within 20 minutes of being injured. More serious injuries such as a grade 3 concussion resulted in instant transportation to a hospital for observation. Subsequently, the AAN (1997) recommended changing the Colorado Guidelines by allowing participants to return to play within 15 minutes after injury if concussion symptoms had subsided. Players with grade 2 concussion diagnosis were allowed to return to play within one week if no concussion symptoms were demonstrated. In 2001, Cantu revised return to play protocols to permit a player to participate on the same day if the concussion symptoms were resolved (7).
After years of following the guidelines recommended by Cantu (1992), the Colorado Guidelines, the American Academy of Neurology, and the American Orthopaedic Society for Sports Medicine (AOSSM) proposed changes to the current guideline practices (40). The AOSSM recommendations did not diverge greatly from preceding guidelines. However, the new strategy varied from the previous reliance of the numbering scale for resolution of return to play subsequent to concussion injuries. The new standards implemented by the AOSSM placed the initial emphasis on personal attention to injury care over the application of past standards and guidelines (24).
In November 2001, Vienna, Austria hosted the inaugural International Conference on Concussion in Sport (4). This conference was supported by the Federation Internationale de Football Association, the Medical Commission of the International Olympic Committee and the International Ice Hockey Federation. The purpose of this conference was to bring together medical doctors, neuropsychologists, and sports commissioners to enhance and promote safety and welfare measures to decrease injuries associated with sports-related concussions. The discussions from the stakeholders at this meeting resulted in a document that outlined recommendations for the diagnosis and management of sports-related concussions. Specifically, the group determined that prior published literature did not provide sufficient coverage and management for every concussion situation. Furthermore, the attendees advocated the use of preseason baseline testing and neuropsychological testing following concussion injuries as a fundamental management policy in the return to play decision-making process (4).
Precise recommendations from the leadership group included removing the athlete from competition after displaying concussion symptoms, prohibiting return to play in current contest, medically assessing following an injury, and a stepwise returning to play procedure which calls for no activity and designated respite until concussion symptoms disappear (4). The recommendations further discussed the incremental return to play which included delicate aerobic exercise, sport-specific exercise, noncontact participation, full-contact participation, and return to competition. Ideally, these phases would be implemented every 24 hours if improvement is shown. However, if concussion symptoms reappear, the concussed participant must fall back to the preceding phase. Additionally, the leadership group set aside any recommendations for neuroimaging testing such as computed tomography (CT) and magnetic resonance imaging (MRI) for concussed participants unless evident signs of hemorrhaging or other physical head trauma exist. However, the leadership group did recognize the future potential benefits of neuroimaging testing of concussed athletes but withheld that recommendation since functionality is in the infant period of development (24).
Subsequent conferences were held by the International Consensus Conference on Concussion in Sport in Prague in 2004, Zurich in 2008, and again in Zurich in 2012. After four conferences, the authors agreed that the discipline of concussion research is ongoing and the return to play determination should be based on clinical evaluation and personal welfare (28). The 2012 Zurich conference provided the latest recommendations for return to play protocols. The gradual return to play protocol for athletes is a stepwise progression of five rehabilitation stages.
The stepwise goals of concussion rehabilitation are to advance to the next component if concussion symptoms are not present at the current stage level. Under normal conditions, each level should last roughly 24 hours, which would take approximately one week to complete the entire cycle. Conversely, if postconcussion symptoms occur during one of the steps, the athlete should return to the preceding level and attempt to move forward following another 24 hours of recuperation (28).
The five modern rehabilitation stages in the gradual return to play protocol begin with the first step of no activity. The practical function of this step is to rest the body and mind. The second rehabilitation stage is light aerobic activity, which may include walking, swimming, or riding a stationary bicycle. The purpose of this step is to elevate the heart rate. The third rehabilitation stage is sport specific activities but without contact to the head. The purpose of this step is to increase movement. The fourth rehabilitation stage is noncontact sport specific activities, which may include resistance training to increase physical and cognitive demands. The fifth rehabilitation state is full-contact activities following medical consent. This final stage should include an evaluation of physical performance and subsequent clearance by sports medicine personnel (28).
Additional recommendations from the 2012 Zurich conference include the prohibition of return to play on the same day a concussion injury took place. Research data on interscholastic and intercollegiate athletes exist which reveal that athletes permitted to return to play on the same day may exhibit neuropsychological symptoms after the injury that did not exist during a sideline examination (28).
Chronic traumatic encephalopathy (CTE) is a degenerative brain disease found in individuals who have suffered recurring brain damage. In sports participants, multiple concussion injuries are a key contributor to CTE by accelerating the decay of brain tissue while augmenting an aberrant protein called tau. These distortions to the brain may activate at any time following the final concussion or the conclusion of a playing career. Symptoms of CTE include, but are not limited to, loss of memory, disorientation, derangement, aggression, and depression. Sadly, the only way to validate the diagnosis of CTE is to perform an autopsy of a deceased individual (36).
The sport of boxing has received the most attention about the long-term consequences of recurring head trauma due to multiple blows to the head. Medical and pathological evidence describes elevated stages of amyloid-ᵝ two hours following a serious brain trauma and remnants of amyloid plaques in 30% of patients (20). Data estimates 10% – 20% of professional boxers endure lingering default in mobility, cognitive, and conduct capacity (23). Confirmation of thirty-nine reports of CTE in boxers has been documented. Furthermore, clinical reports indicate boxers have suffered the longest from CTE for as much as 46 years with the diagnosed disease (29).
Reports of incident of CTE in sports other than boxing are increasing. In 2005, Omalu et al. reported on the first substantiation of CTE in a National Football League (NFL) player (31). In this case, the player died of atherosclerotic disease 12 years following the end of 17 years of professional football play. Relatives conveyed that the player had experienced loss of memory and symptoms of Parkinson’s disease (31). In 2006, Omalu et al. reported on another case of a retired NFL player diagnosed with CTE (32). In this case, after battling severe depression, the player committed suicide 12 years following the end of 14 years of playing professional football (32). Seven additional diagnoses of CTE, including one football player, one wrestler, and one soccer player, have been confirmed since 2006. Familiar symptoms included mood swings, loss of memory, and paranoia (29).
The traditional scan imaging of the brain cannot uncover or provide the delicate details that transpire with critical concussion injuries. Magnetic resonance imaging (MRI) can be utilized to assess chronic issues associated with atrophy, white matter lacerations, dead tissue, and neuron damage. However, these conclusions lack specificity (8). The diffusion tensor imaging (DTI) is available to assess microstructural variances that may happen in concussion injuries. In 2006, Zhang, Heier, Zimmerman, Jordan, and Ulug reviewed the MRIs of 49 boxing professionals (41). These professionals demonstrated normal or nonspecific white matter evidence on the traditional MRI. However, diffusion anisotropy analysis illustrated a decline in the average diffusion constant and the entire brain diffusion constant. The alterations in concussion imaging may advance the reaction to concussion injuries in athletes, discover structural modification, and assist in recognizing continuous neurological differences (41).
The American Psychological Association (APA) has sanctioned protocols for computer-based testing and interpretations to distinguish promising advantages with the help of computers in a clinical setting (2). Schatz and Zillmer (2003) examined the advantages and disadvantages of computer-based valuation of sports-related concussion injuries (37). The primary advantages of computer-based testing include the relevance of the patron, access by the clinician, compatibility with conventional testing forms, and cost effectiveness. Disadvantages of computer-based testing include a lack of validity and reliability from certain tests, cognitive challenges associated with concussion symptoms, lack of personal interaction between the concussed athlete and medical practitioner, and common computer glitches (37).
Three progressive software programs, CogSport, Concussion Resolution Index (CRI), and the Immediate Post Concussion Assessment and Cognitive Testing (ImPact), now exist to provide valid and all-inclusive testing instruments to assess cognitive symptoms associated with sports-related concussions (37). CogSport is a software program designed to measure alterations in cognitive performance by computing reaction time and precision to measure concentration, memory, problem solving, consistency, and spatial skills. CRI is a neurocognitive software program that also measures reaction time and decision processing (37). A strength of the CRI is ability to recognize symptoms associated with postconcussion injuries without going through a series of multiple testing (15). ImPact is another software program instrument that measures concentration, memory processing, and reaction time. ImPact is popular with high schools, colleges, and professional sports teams and includes a feedback form for reporting personal symptoms, a concussion history questionnaire, and preseason baseline testing statistics (37).
Further technological advancements include the head impact telemetry system (HITS), a wireless device that measures actual time head impact acceleration throughout practice and competition. The HITS sensor and encoder package include impact sensors, a processor, and a transmitter and can revamp helmets and headgear into a head-impact monitor. A computer system receives constant impact data from encoders located at various distances and can observe dozens of participants concurrently. Notification alerts can also be transmitted if any contact measures an elevated threshold signifying potential injury. Data collection is accumulated, stockpiled, and time stamped for every impact including peak linear acceleration, rotational acceleration, impact duration, and location (5).
At Virginia Tech University, HITS was utilized during the 2003 and 2004 football seasons for a study to measure, document, and analyze linear head acceleration impacts. Each supervised player wore a Riddell VSR-4 large or extra-large football helmet with six spring-mounted linear accelerometers formatted to the head and one temperature sensor. For each practice and day of competition, as many as 18 players were observed all together during the 2003 and 2004 football seasons. Over two years, 52 players were chosen by the sports medicine staff to supply a broad-based participation based on body profile and position played. Overall, data was gathered from 67 practices and 22 games between the two seasons (5).
The findings show for the 2003 and 2004 football seasons that 11,604 head impacts were documented with 2,970 taking place in 22 games and 8,634 taking place in 67 practices among 52 players. The acceleration distribution data were analyzed and right-skewed with a median impact acceleration scale of 15.3, a mean score of 20.9 g, and a highest score of 172.6 g. Most of the impacts had small peak acceleration scores; a climax acceleration of 75 g or higher was recorded in 290 of the impacts (5). From this actual time data analysis, very few instances of brain injury occurred. The application of this research is the establishment of precise brain trauma limits for participants and guidance for helmet and headwear protective equipment manufacturers. Furthermore, clinical assessment on the sideline supported by HITS provides a benefit to sports medicine providers by giving immediate notice on the severity of the impact (5).
Further research by Hanlon and Bir (2010) attempted to substantiate the head impact telemetry system (HITS) in order to study head accelerations during soccer practice or competition. Fifteen full force settings were exercised to replicate contacts frequently endured during practice or competition. Linear and angular acceleration data was collected by formatting the HIT system to a Hybrid III (HIII) head and neck simulator. The linear and angular data was analyzed to determine the compatibility between the HIII and HITS headwear. Data for the HITS system was prepared by a simulated annealing optimization algorithm to explain linear and angular acceleration from six accelerometer appraisals. Linear regression was utilized to contrast both systems for ball to head force, head collision force, and all forces collectively. A root mean square (RMS) error and cross correlation was also utilized to assess the collision of linear head acceleration (18). The findings exhibit a strong correlation score of r = .95 for ball to head contact and r = .96 for head collision contacts. Furthermore, the HIII and HITS systems demonstrated a lasting correlation among RMS error, linear and angular head acceleration, and cross correlation scores (18).
The epidemiology of sports concussion management is complex. Research continues to explore the long-term detrimental health effects associated with concussions and traumatic brain injuries. At present, chronic traumatic encephalopathy (CTE) can only be confirmed with an autopsy. The detection of CTE at the end of life and the resulting public outcry is pressuring concussion management reform throughout the youth, high school, college, and professional levels.
Advancements in concussion prevention, diagnosis, and treatment over the past century are significant. These advancements, especially in technology, will continue to promote safety and welfare. From studying amateur and professional boxers between 1900 and 1940, laboratory mannequins with football helmets, and accelerometers to record real-time impact force, the evaluation of the mechanisms of sport concussion will continue to advance (5, 11, 39).
APPLICATIONS TO SPORT
The benefits of sports participation far outweigh the potential risk of concussion injury if an effective sideline cognitive evaluation for concussion injuries is in place, rigorous return to play policies and procedures are established, safe and certified protective equipment are being worn, sport playing rules are being strictly enforced, and heightened educational awareness on the dangers of concussion injuries are promoted.
- American Academy of Neurology. (1997). Practice parameter: The management of concussion in sports (summary statement). Report of the Quality Standards Subcommittee. Neurology, 48(3), 581-585.
- American Psychological Association. (1986). Guidelines for computer-based tests and interpretations. Washington, DC: Author
- Anderson, T., Arnason, A., Engebretsen, L., & Bahr, R. (2004). Mechanism of head injuries in elite football. British Journal of Sports Medicine, 38, 690-696.
- Aubry, M., Cantu, R., Dvorak, J., Graf-Baumann, T., Johnston, K.M., Kelly, J., Lovell, M., McCrury, P., Meeuwisse, W,. & Schamasch, P. (2002). Summary and agreement statement of the first international conference on concussion in sport. Clinical Journal of Sports Medicine, 12, 6-11.
- Brolinson, P.G., Manoogian, S., McNeely, D., Goforth, M., Greenwald, R., & Duma, S. (2006). Analysis of linear head accelerations from collegiate football impacts. Current Sports Medicine Reports, 5, 23-28.
- Cantu, R.C. (1992). Cerebral concussion in sport: Management and prevention. Sports Medicine, 14(1), 64-74.
- Cantu, R.C. (2001). Posttraumatic retrograde and antterograde amnesia: Pathophysiology and implications in grading and safe return to play. Journal of Athletic Training, 36(3), 244-248.
- Casson, I. R., Siegel, O., Sham, R., Campbell, E. A., Tarlau, M., & DiDomenico, A. (1984). Brain damage in modern boxers. Journal of the American Medical Association, 251(20), 2663-2667.
- Center for Disease Control and Prevention (CDC). (2013). Heads up: Concussion. Retrieved December 1, 2013, from http://www.cdc.gov/concussion/headsup/
- Conley, K.M., Bolin, D.J., Carek, P.J., Konin, J.G., Neal, T.L., & Violette, D. (2014). National Athletic Trainers’ Association Position Statement: Preparticipation Physical Examinations and Disqualifying Conditions. Journal of Athletic Training, 49(1), 102-120.
- Corsellis, J.A.N., Bruton, C.J., & Freeman-Browne, D. (1973). The aftermath of boxing. Psychological Medicine, (3), 270-303.
- Covassin, T., Stearne, D., & Elbin III, R. (2008). Concussion history and postconcussion neurocognitive performance and symptoms in collegiate athletes. Journal of Athletic Training, 43(2), 119-124.
- DeKosky, S.T., Ikonomovic, M.D., & Gandy, S. (2010). Traumatic brain injury – football, warfare, and long-term effects. The New England Journal of Medicine, 363(14), 1293-1296.
- Dvorak, J. (2009). Give Hippocrates a jersey: Promoting health through football/sport. British Journal of Sports Medicine, 43(5), 317-322.
- Erlanger, D.M., Saliba, E., Barth, J., Almquist, J., Webright, W., & Freeman, J. (2001). Monitoring resolution of postconcussion symptoms in athletes: Preliminary results of a web-based neuropsychological protocol. Journal of Athletic Training, 36, 280-287.
- Gessel, L.M., Fields, S.K., Collins, C.L., Dick, R.W., & Comstock, R.D. (2007). Concussions among united states high school and collegiate athletes. Journal of Athletic Training, 42(4), 495-503.
- Guskiewicz, K.M., Weaver, N.L., Padua, D.A., & Garrett, Jr., W.E. (2000). Epidemiology of concussion in collegiate and high school football players. American Journal of Sports Medicine, 28(5), 643-650.
- Hanlon, E., & Bir, C. (2010). Validation of a wireless head acceleration measurement system for use in soccer play. Journal of Applied Biomechanics, 26, 424-431.
- Harmon, K. G., Drezner, J. A, Gammons M., Guskiewicz, K.M., Halstead, M., Herring, S.A., Kutcher, J.S., Pana, A., Putukian, M., & Roberts, W. O. (2013). American Medical Society for Sports Medicine position statement: concussion in sport. British Journal of Sports Medicine, 47,15-26.
- Ikonomovic, M. D., Uryu, K., Abrahamson, E. E., Ciallella, J. R., Trojanowski, J. Q., Lee, V. M. Y., Clark, R.S., Marion, D.W., Wisniewski, S.R., & DeKosky, S. T. (2004). Alzheimer’s pathology in human temporal cortex surgically excised after severe brain injury. Experimental Neurology, 190(1), 192-203.
- Kelly, J.P., Nichols, J.S., & Filley, C.M. (1991). Concussion in sports: Guidelines for the prevention of catastrophic outcome. The Journal of the American Medical Association, 266(20), 2867-2869.
- Lehman, E.J., Hein, M.J., Baron, S.L., & Gersic, C.M. (2012). Neurodegenerative causes of death among retired national football league players. Neurology, 70(19), 1970-1974.
- Loosemore, M., Knowles, C.H., & Whyte, G.P. (2007). Amateur boxing and risk of chronic traumatic brain injury: Systemic review of observational studies. British Medical Journal, 335, 809-812.
- Lovell, M., Collins, M., & Bradley, J. (2004). Return to play following sports related concussion. Clinics in Sports Medicine, 23, 421-441.
- Maroon, J.C., & Bost, J. (2011). Concussion management at the NFL, college, high school, and youth sports levels. Clinical Neurosurgery, 58, 51-56.
- McAffrey, M.A., Mihalik, J.P., Crowell, D.H., Shields, E.W., & Guskiewicz, K.M. (2007). Measurement of head impacts in collegiate football players: Clinical measures of concussion after high- and low-magnitude impacts. Neurosurgery, 61(6), 1236-1243. doi:10.1227/01.NEU.0000280153.11614.69
- McCrea, M., Guskiewicz, K.M., Marshall, S.W., Barr, W., Randolph, C., Cantu, R.C., Onate, J.A., Yang, J., & Kelly, J.P. (2003). Acute effects and recovery time following concussion in collegiate football players. The Journal of the American Medical Association, 290(19), 2556-2563.
- McCrory, P., Meeuwisse, W.H., Aubry, M., Cantu, R.C., Dvorak, J., Echemendia, R.J., Engebretsen, L., Johnston, K., Kutcher, J.S. Raftery, M., Sills, A., Benson, B.W., Davis, G.A., Ellenbogen, R., Guskiewicz, K.M., Herring, S.A., Iverson, G.L., Jordan, B.D., Kissick, J., McCrea, M., McIntosh, A.S., Maddocks, D., Makdissi, M., Purcell, L., Putukian, M., Schneider, K., Tator, C.H,. & Turner, C.H. (2013). Consensus statement on concussion in sport: The 4th international conference on concussion in sport, Zurich, November 2012. Journal of Athletic Training, 48(4), 554-575.
- McKee, A.C., Cantu, R.C., Nowinski, C.J., Hedley-Whyte, T., Gavett, B.E., Budson, A.E., Santini, V.E., Lee, H., Kubilus, C.A., & Stern, T.A. (2009). Chronic traumatic encephalopathy in athletes: Progressive tauopathy after repetitive head injury. Journal of Neuropathology & Experimental Neurology, 68(7), 709-735.
- National Collegiate Athletic Association. (2013). 2013 and 2014 football rules and interpretations. Retrieved February 28, 2014, from http://www.ncaapublications.com/productdownloads/FR14.pdf
- Omalu, B.I., DeKosky, S.T., Minster, R.L., Kamboh, M.I., Hamilton, R.L., & Wecht, C.H. (2005). Chronic traumatic encephalopathy in a national football league player. Neurosurgery, 57, 128-134. DOI: 10.1227/01.NEU0000163407.92769.ED
- Omalu, B. I., DeKosky, S. T., Hamilton, R. L., Minster, R. L., Kamboh, M. I., Shakir, A. M., & Wecht, C. H. (2006). Chronic traumatic encephalopathy in a national football league player: Part II. Neurosurgery, 59(5), 1086-1093.
- Pellman, E.J., Viano, D.C., Tucker, A.M., Casson, I.R., & Waeckerle, J.F. (2003). Concussion in professional football: Location and direction of helmet impacts – part 2. Neurosurgery, 53, 1328-1341.
- Potter, S., & Brown, R.G. (2012). Cognitive behavioural therapy and persistent post- concussional symptoms: Integrating conceptual issues and practical aspects in treatment. Neuropsychological Rehabilitation, 22(1), 1-25.
- Rabadi, M.H., & Jordan, B.D. (2001). The cumulative effect of repetitive concussion in sport. Clinical Journal of Sport Medicine, 11, 194-198.
- Saffary, R., Chin, L.S., & Cantu, R.C. (2012). From concussion to chronic traumatic encephalopathy: A review. Journal of Clinical Sport Psychology, 6, 351-362.
- Schatz, P., & Zillmer, E.A. (2003). Computer-based assessment of sports-related concussion. Applied Neuropsychology, 10(1), 42-47.
- Solomon, G.S., & Sills, A.K. (2013). Pharmacologic treatment of sport-related concussion: A review. Journal of Surgical Orthopaedic Advances, 22(3), 193- 197.
- Viano, D.C., Pellman, E.J., Withnall, C., & Shewchenko, N. (2006). Concussion in professional football: Performance of new helmets in reconstructed game impacts – part 13. Neurosurgery, 59(3), 591-606.
- Wojyts, E.D., Hovda, D., Landry, G., Boland, A., Lovell, M.R., McCrea, M., & Minkoff, J. (1999). Concussion in sports. American Journal of Sports Medicine, 27, 676-686.
- Zhang, L., Heier, L.A., Zimmerman, R.D., Jordan, B., & Ulug, A.M. (2006). Diffusion anisotropy changes in the brains of professional boxers. American Journal of Neuroradiology, 27, 2000-2004.