Concussion in the National Football League: An Overview for Neurologists

doi:10.1016/j.ncl.2007.11.005

Neurologic Clinics

Volume 26, Issue 1, February 2008, Pages 217-241

https://doi.org/10.1016/j.ncl.2007.11.005 Get rights and content

The authors' studies have yielded a great deal of data regarding the biomechanics of head injury and the clinical picture of mild traumatic brain injury (MTBI) in the National Football League (NFL). The research has demonstrated the link between the effects of biomechanical forces on the brain and the clinical symptomatology of the concussed players. New insights into the mechanisms of injury are leading to new ways of protecting football players from the effects of MTBI. The clinical data validate the effectiveness of the current NFL physician approach to the evaluation and treatment of the player who sustains MTBI. There are still many more questions to answer and much more knowledge to be gained from continuing research in this area.

Section snippets

Biomechanics

The biomechanical information was generated from studies performed under the auspices of the NFL MTBI Committee, with the assistance of Biokinetics and Associates (Ottawa, Canada). The data were collected using video analysis of a number of NFL head impacts, some resulting in an MTBI and some not resulting in MTBI. After video analysis, the impacts were reconstructed in the laboratory using Hybrid III test dummies (General Motors, Detroit, Michigan) [1].

Regarding impacts that resulted in

Epidemiology

The authors performed a 6-year clinical study of MTBI in the NFL. Data were collected prospectively. We collected complete injury data, initial clinical evaluation data, and follow-up clinical evaluation data for 787 MTBIs that occurred in preseason, regular, or playoff games for 6 seasons between 1996 and 2001. One hundred additional MTBIs from practice sessions were included in the database as well. Data were collected from forms filled out by team physicians and athletic trainers at the time

Concussion management guidelines

A number of practitioners have developed and promoted guidelines for the evaluation and management of concussion in sport [15], [16], [17], [18]. Based on the authors' experience in the NFL and our studies of concussion in the NFL, we do not believe that any of these guidelines are applicable or relevant to the NFL experience. The rationale for these guidelines is flawed. The authors of the guidelines indicate that the reasons why such guidelines are necessary include the prevention of second

Chronic traumatic encephalopathy

That there is a chronic traumatic encephalopathy (CTE) of boxers is not in doubt. The same, however, cannot be said about CTE of football players. There is an extensive medical literature documenting the clinical picture (ie, combinations of dysarthria, cerebellar dysfunction, extrapyramidal dysfunction, pyramidal dysfunction, cognitive-behavioral impairments), radiologic findings (ie, enlarged third and lateral ventricles, cerebral atrophy, cavum septum pellucidum) and distinctive

Summary

The authors' studies have yielded a great deal of data regarding the biomechanics of head injury and the clinical picture of MTBI in the NFL. The research has demonstrated the link between the effects of biomechanical forces on the brain and the clinical symptomatology of the concussed players. New insights into the mechanisms of injury are leading to new ways of protecting football players from the effects of MTBI. Our clinical data validate the effectiveness of the current NFL physician

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Neurosurgery
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Concussion in professional football: location and direction of helmet—part 2
Neurosurgery
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Concussion in professional football: biomechanics of the striking player—part 8
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Concussion in professional football: players returning to the same game—part 7

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Concussion in professional football: neuropsychological testing—part 6

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Concussion in professional football: recovery of NFL and high school athletes assessed by computerized neuropsychological testing—part 12

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Cited by (24)

The King-Devick test and sports-related concussion: Study of a rapid visual screening tool in a collegiate cohort
2011, Journal of the Neurological Sciences
Citation Excerpt :
Younger athletes are particularly susceptible to third-party pressures to return to play preemptively, even before assessment [10–14]. Without the data from rapid screening tests to make proper decisions on the side lines, athletes may be at risk for chronic neurological symptoms and pathological changes that have been associated with concussion [15–30]. Concussion, defined by an impulse blow to the head or body that results in transient neurologic signs or symptoms, is largely the result of functional rather than structural injury to the brain [25].
Concussion, defined as an impulse blow to the head or body resulting in transient neurologic signs or symptoms, has received increasing attention in sports at all levels. The King–Devick (K–D) test is based on the time to perform rapid number naming and captures eye movements and other correlates of suboptimal brain function. In a study of boxers and mixed martial arts (MMA) fighters, the K–D test was shown to have high degrees of test–retest and inter-rater reliability and to be an accurate method for rapidly identifying boxers and mixed martial arts fighters with concussion. We performed a study of the K–D test as a rapid sideline screening tool in collegiate athletes to determine the effect of concussion on K–D scores compared to a pre-season baseline.
In this longitudinal study, athletes from the University of Pennsylvania varsity football, sprint football, and women's and men's soccer and basketball teams underwent baseline K–D testing prior to the start of the 2010–11 playing season. Post-season testing was also performed. For athletes who had concussions during the season, K–D testing was administered immediately on the sidelines and changes in score from baseline were determined.
Among 219 athletes tested at baseline, post-season K–D scores were lower (better) than the best pre-season scores (35.1 vs. 37.9 s, P = 0.03, Wilcoxon signed-rank test), reflecting mild learning effects in the absence of concussion. For the 10 athletes who had concussions, K–D testing on the sidelines showed significant worsening from baseline (46.9 vs. 37.0 s, P = 0.009), with all except one athlete demonstrating worsening from baseline (median 5.9 s).
This study of collegiate athletes provides initial evidence in support of the K–D test as a strong candidate rapid sideline visual screening tool for concussion. Data show worsening of scores following concussion, and ongoing follow-up in this study with additional concussion events and different athlete populations will further examine the effectiveness of the K–D test.
Concussion in athletes: Information for team physicians on the neurologic evaluation
2010, Seminars in Spine Surgery
Citation Excerpt :
For example, although recent clinical studies indicate that LOC is not the only factor influencing time to recovery, they also demonstrate that LOC is one of the significant risk factors for the development of post concussion syndrome, leading many experts in the field to agree with the guidelines that players with observed LOC on the day of the concussion are not good candidates for RTP on the day of the concussion.5,6,12 In addition, modern concussion management and the guidelines are in agreement that injured athletes should only be considered for return to play when the athlete is completely asymptomatic at rest and with exertion and has a normal neurological examination, including mental status.5,6,26 This does not mean that every athlete who meets these criteria should automatically be medically cleared to return to play; it means that athletes who are symptomatic and/or have abnormalities on neurological examination should not be considered for return to play at that time.
The evaluation and management of concussion (ie, mild traumatic brain injury) in athletes is typically the responsibility of team or school physicians. The great majority of these physicians are orthopedists, family physicians, internists, pediatricians, or sports medicine specialists who have not had specialty training in neurology or neurosurgery. The evaluation and management of mild traumatic brain injury is primarily guided by a neurological clinical evaluation of the patient. The purpose of this article is to review relevant aspects of the neurological history and examination as well as the neurological approach to the concussed athlete.
Computational biology - Modeling of primary blast effects on the central nervous system
2009, NeuroImage
Recent military conflicts in Iraq and Afghanistan have highlighted the wartime effect of traumatic brain injury (TBI). The reason for the prominence of TBI in these particular conflicts as opposed to others is unclear but may result from the increased survivability of blast due to improvements in body armor. In the military context blunt, ballistic and blast effects may all contribute to CNS injury, however blast in particular, has been suggested as a primary cause of military TBI. While blast effects on some biological tissues, such as the lung, are documented in terms of injury thresholds, this is not the case for the CNS. We hypothesized that using bio-fidelic models, allowing for fluid–solid interaction and basic material properties available in the literature, a blast wave would interact with CNS tissue and cause a possible concussive effect.
The modeling approach employed for this investigation consisted of a computational framework suitable for simulating coupled fluid-solid dynamic interactions. The model included a complex finite element mesh of the head and intra-cranial contents. The effects of threshold and 50% lethal blast lung injury were compared with concussive impact injury using the full head model allowing upper and lower bounds of tissue injury to be applied using pulmonary injury as the reference tissue.
The effects of a 50% lethal dose blast lung injury (LD₅₀) were comparable with concussive impact injury using the DVBIC-MIT full head model.
CNS blast concussive effects were found to be similar between impact mild TBI and the blast field associated with LD₅₀ lung blast injury sustained without personal protective equipment. With the ubiquitous use of personal protective equipment this suggests that blast concussive effects may more readily ascertained in personnel due to enhanced survivability in the current conflicts.
Overview of Traumatic Brain Injury (TBI)
2019, Traumatic Brain Injury: A Clinician’s Guide to Diagnosis, Management, and Rehabilitation: Second Edition
Investigation of the use of a mouthguard for decreasing the incidence and/or severity of sportrelated concussions
2016, Medecine Buccale Chirurgie Buccale
Right Brain: Concussion (film)
2016, Neurology

View all citing articles on Scopus

: This work was supported in part by research sponsored by the NFL and NFL Charities.

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Concussion in the National Football League: An Overview for Neurologists

Section snippets

Biomechanics

Epidemiology

Concussion management guidelines

Chronic traumatic encephalopathy

Summary

Concussion in professional football: reconstruction of game impacts and injuries

Neurosurgery

Concussion in professional football: location and direction of helmet—part 2

Neurosurgery

Concussion in professional football: biomechanics of the striking player—part 8

Neurosurgery

Concussion in professional football: biomechanics of the struck player—part 14

Neurosurgery

Concussion in professional football: brain responses by finite element analysis—part 9

Neurosurgery

Concussion in professional football: helmet testing to assess impact performance–part 11

Neurosurgery

Concussion in professional football: newer helmet performance in reconstructed NFL impacts—part 13

Neurosurgery

Concussion in professional football: epidemiological features of game injuries and review of the literature—part 3

Neurosurgery

Proceedings of the Congress of Neurological Surgeons: Report of the Ad Hoc Committee to Study Head Injury Nomenclature

Clin Neurosurg

Concussion in professional football: repeat injuries—part 4

Neurosurgery

Concussion in professional football: injuries involving 7+ days out—part 5

Neurosurgery

Concussion in professional football: players returning to the same game—part 7

Neurosurgery

Concussion in professional football: neuropsychological testing—part 6

Neurosurgery

Concussion in professional football: recovery of NFL and high school athletes assessed by computerized neuropsychological testing—part 12

Neurosurgery

American Academy of Neurology: Practice parameter: the management of concussion in sports (summary statements)

Neurology