Suzanne Leclerc

Concussions among university football and soccer players

ObjectiveA study to examine the incidence and characteristics of concussions among Canadian university athletes during 1 full year of football and soccer participation. DesignRetrospective survey. ParticipantsThree hundred eighty Canadian university football and 240 Canadian university soccer players reporting to 1999 fall training camp. Of these, 328 football and 201 soccer players returned a completed questionnaire. Main Outcome MeasuresBased on self-reported symptoms, calculations were made to determine the number of concussions experienced during the previous full year of football or soccer participation, the duration of symptoms, the time for return to play, and any associated risk factors for concussions. ResultsOf all the athletes who returned completed questionnaires, 70.4% of the football players and 62.7% of the soccer players had experienced symptoms of a concussion during the previous year. Only 23.4% of the concussed football players and 19.8% of the concussed soccer players realized they had suffered a concussion. More than one concussion was experienced by 84.6% of the concussed football players and 81.7% of the concussed soccer players. Examining symptom duration, 27.6% of all concussed football players and 18.8% of all concussed soccer players experienced symptoms for at least 1 day or longer. Tight end and defensive lineman were the positions most commonly affected in football, while goalies were the players most commonly affected in soccer. Variables that increased the odds of suffering a concussion during the previous year for football players included a history of a traumatic loss of consciousness or a recognized concussion in the past. Variables that increased the odds of suffering a concussion during the previous year for soccer players included a past history of a recognized concussion while playing soccer and being female. ConclusionsUniversity football and soccer players seem to be experiencing a significant amount of concussions while participating in their respective sports. Variables that seem to increase the odds of suffering a concussion during the previous year for football and soccer players include a history of a recognized concussion. Despite being relatively common, symptoms of concussion may not be recognized by many players.

Long-term and cumulative effects of sports concussion on motor cortex inhibition.

OBJECTIVE Using transcranial magnetic stimulation paradigms, this study investigated motor cortex integrity as a function of an athletes prior history of concussions. PATIENTS AND METHODS Motor cortex excitatory and inhibitory mechanisms were studied in athletes using four different transcranial magnetic stimulation protocols, namely 1) resting motor threshold, 2) intracortical inhibition and intracortical facilitation in a paired-pulse paradigm, 3) excitability of the corticospinal system using an input-output curve, and 4) intracortical inhibition in a cortical silent-period paradigm. Motor-evoked potentials were recorded from the first dorsal interosseous muscle of the right hand. RESULTS Cortical silent-period duration in athletes who have experienced multiple concussions was prolonged when compared to that of normal control participants. Linear regression suggested that concussion severity was the main factor explaining motor cortex dysfunction. Moreover, when we retested the athletes, the cortical silent period was more prolonged in those who sustained another concussion after baseline testing had occurred. CONCLUSION Findings from this study indicate that sports-related concussions result in long-term motor system dysfunctions that seem to be attributable to subclinical intracortical inhibitory system abnormalities. This study also shows that sustaining subsequent concussions exacerbates this deficit, and thus provides additional support for the contention that the adverse effects of sports-related concussions on intracortical inhibitory systems are cumulative.

Neurophysiological anomalies in symptomatic and asymptomatic concussed athletes.

OBJECTIVE:Concussion in sports is a problem of such magnitude that improvements in diagnosis and management are desirable. The aim of the present study was to investigate the effect of concussion on event-related potentials, in symptomatic as well as in asymptomatic athletes. METHODS:Twenty symptomatic and asymptomatic athletes who sustained a concussion were compared with 10 control athletes in a modified auditory Oddball task. The task included a sequence of tones containing standard and deviant stimuli. Participants were asked to respond to the target tone presented in the left ear and to ignore tones presented in the right ear. The electroencephalogram was recorded from 28 electrodes during the task. RESULTS:The results showed a reduction in the amplitude of N1, P2, and P3 components in symptomatic and asymptomatic athletes in comparison with control athletes. No between-group differences were observed in reaction times or in latency of the event-related potentials components, except for P3 latency, in which the controls showed shorter latency than the concussed groups. CONCLUSION:Concussions seem to produce deficits in the early and late stages of auditory information processing, which possibly reflect impaired brain functioning in symptomatic and asymptomatic concussed athletes. The fact that asymptomatic athletes have an electrophysiological profile similar to that of symptomatic athletes challenges the validity of return-to-play guidelines for which the absence of symptoms is a major issue.

Concussions during the 1997 Canadian Football League season

ObjectiveTo examine the incidence and characteristics of concussions for one season in the Canadian Football League (CFL). Design Retrospective survey. Participants 289 players reporting to CFL training camp. Of these, 154 players had played in the CFL during the 1997 season. Main Outcome MeasuresBased on self-reported symptoms, calculations were made to determine the number of concussions experienced during the previous season, the duration of symptoms, the time for return to play after concussion, and any associated risk factors for concussions. ResultsOf all the athletes who played during the 1997 season, 44.8% experienced symptoms of a concussion. Only 18.8% of these concussed players recognized they had suffered a concussion. 69.6% of all concussed players experienced more than one episode. Symptoms lasted at least 1 day in 25.8% of cases. The odds of experiencing a concussion increased 13% with each game played. A past history of a loss of consciousness while playing football and a recognized concussion while playing football were both associated with increased odds of experiencing a concussion during the 1997 season. ConclusionMany players experienced a concussion during the 1997 CFL season, but the majority of these players may not have recognized that fact. Players need to be better informed about the symptoms and effects of concussions.

Visual P300 Effects Beyond Symptoms in Concussed College Athletes

In order to assess whether cerebral anomalies may be observed in the absence of clinical symptoms, the current study compared the effects of concussions on attentional capacities (reaction times, accuracy) and Event-Related Potentials (ERPs) in concussed athletes with (n = 10) or without (n = 10) symptoms as well as in athletes who never had a concussion (n = 10). The P300 response was recorded from 28 electrodes during a modified visual oddball paradigm. Participants were instructed to press a key upon the appearance of the frequent stimuli as well as when a rare nontarget stimulus followed the frequent one. The other key was to be pressed when the subsequent rare stimuli (rare target) appeared until a frequent one reappeared. The symptomatic athletes displayed longer reaction times than the other two groups of athletes. The P300 amplitude to the rare target stimuli was significantly more attenuated in the symptomatic athletes than in the other two groups. Moreover, the P300 amplitude varied inversely with the severity of postconcussion symptoms but was not influenced by time elapsed since injury. Although the clinical significance of the P300 differences shown by the symptomatic athletes is still uncertain, the results do indicate that symptom severity may be a crucial indicator of functional impairments following mild traumatic brain injury.

Metabolic changes in concussed American football players during the acute and chronic post-injury phases

BackgroundDespite negative neuroimaging findings many athletes display neurophysiological alterations and post-concussion symptoms that may be attributable to neurometabolic alterations.MethodsThe present study investigated the effects of sports concussion on brain metabolism using 1H-MR Spectroscopy by comparing a group of 10 non-concussed athletes with a group of 10 concussed athletes of the same age (mean: 22.5 years) and education (mean: 16 years) within both the acute and chronic post-injury phases. All athletes were scanned 1-6 days post-concussion and again 6-months later in a 3T Siemens MRI.ResultsConcussed athletes demonstrated neurometabolic impairment in prefrontal and motor (M1) cortices in the acute phase where NAA:Cr levels remained depressed relative to controls. There was some recovery observed in the chronic phase where Glu:Cr levels returned to those of control athletes; however, there was a pathological increase of m-I:Cr levels in M1 that was only present in the chronic phase.ConclusionsThese results confirm cortical neurometabolic changes in the acute post-concussion phase as well as recovery and continued metabolic abnormalities in the chronic phase. The results indicate that complex pathophysiological processes differ depending on the post-injury phase and the neurometabolite in question.

Sleep following sport-related concussions.

OBJECTIVES Sleep and vigilance disorders are among the most commonly reported symptoms following a concussion. The aim of the study was thus to investigate the effects of sport-related concussions on subjective and objective sleep quality. METHODS Ten concussed athletes and 11 non-concussed athletes were included. Concussed athletes had a history of 4.6+/-2.1 concussions with at least one concussion during the last year. They were recorded for two consecutive nights in the laboratory and during a 10-min period of wakefulness. They completed questionnaires related to sleep quality and symptoms as well as neuropsychological tests and the CogSport computer battery. RESULTS Concussed athletes reported more symptoms and worse sleep quality than control athletes, but no between-group differences were found on polysomnographic variables or on REM and NREM sleep quantitative EEG variables. However, concussed athletes showed significantly more delta activity and less alpha activity during wakefulness than did control athletes. CONCLUSION In spite of the subjective complaints in sleep quality of concussed athletes, no change was observed in objective sleep characteristics. However, concussions were associated with an increase in delta and a reduction in alpha power in the waking EEG. Sport-related concussions are thus associated with wakefulness problems rather than sleep disturbances.

Neuropsychological and neurophysiological assessment of sport concussion in children, adolescents and adults

Objective: To determine whether age differences exist with respect to neuropsychological and electrophysiological functioning following a sport concussion. Design: Cross-sectional study. Participants: Ninety-six athletes (9–12 years, n = 32; 13–16 years, n = 34; adults, n = 30), half of whom had a sport concussion. Intervention: Cognitive functioning was assessed using standardized neuropsychological tests and event-related potentials elicited by a visual 3-stimulus oddball paradigm. The PCSS was used to assess symptoms experienced at the time of injury. Main outcome measurements: Neuropsychological assessment with an adaptation of the battery used by the National Hockey League. Latencies and amplitudes of the P3a and P3b were analysed in terms of group (concussed vs. control) and age. Results: All concussed athletes had significantly lower amplitude for the P3b component compared to their non-injured teammates (p > 0.05). Adolescents also showed persistent deficits in working memory (p > 0.05). Conclusions: These data suggest persistent neurophysiological deficits that are present at least 6 months following a concussion. Moreover, adolescents are more sensitive to the consequences of concussions than are children or adults.

Persistent Motor System Abnormalities in Formerly Concussed Athletes

CONTEXT The known detrimental effects of sport concussions on motor system function include balance problems, slowed motor execution, and abnormal motor cortex excitability. OBJECTIVE To assess whether these concussion-related alterations of motor system function are still evident in collegiate football players who sustained concussions but returned to competition more than 9 months before testing. DESIGN Case-control study. SETTING University laboratory. PATIENTS OR OTHER PARTICIPANTS A group of 21 active, university-level football players who had experienced concussions was compared with 15 university football players who had not sustained concussions. INTERVENTION(S) A force platform was used to assess center-of-pressure (COP) displacement and COP oscillation regularity (approximate entropy) as measures of postural stability in the upright position. A rapid alternating-movement task was also used to assess motor execution speed. Transcranial magnetic stimulation over the motor cortex was used to measure long-interval intracortical inhibition and the cortical silent period, presumably reflecting y-aminobutyric acid subtype B receptor-mediated intracortical inhibition. MAIN OUTCOME MEASURE(S) COP displacement and oscillation regularity, motor execution speed, long-interval intracortical inhibition, cortical silent period. RESULTS Relative to controls, previously concussed athletes showed persistently lower COP oscillation randomness, normal performance on a rapid alternating-movement task, and more M1 intracortical inhibition that was related to the number of previous concussions. CONCLUSIONS Sport concussions were associated with pervasive changes in postural control and more M1 intracortical inhibition, providing neurophysiologic and behavioral evidence of lasting, subclinical changes in motor system integrity in concussed athletes.

Prolonged neuropsychological impairments following a first concussion in female university soccer athletes

Objective:Although research is accumulating on the cognitive sequelae from sports-related concussions in men, little to nothing is known about the prolonged cognitive outcome after a concussion in women. This point is important because recent evidence suggests that female athletes are at greater risk of sustaining a concussion. Design:We assessed cognitive functioning after a first concussion in female soccer players, 6 to 8 months after their injury. The first-time concussed athletes were compared with a group of age-matched teammates who had never experienced a concussion. Setting and Participants:A total of 22 female university-level soccer players participated in the study. Main Outcome Measurements:Paper-and-pencil and computerized tasks were used to assess different neuropsychological functions. Results:Short- and long-term verbal memory, attention, and simple reaction time were normal. In contrast, compared with the control group, the concussed athletes were significantly slower on tasks that required decision making (complex reaction time), inhibition and flexibility (Stroop), and planning (Tour of London task). Conclusions:The results of this study suggest that cognitive functions related to cognitive processing speed are most vulnerable to a sports-related concussion and are still impaired for a half year after injury in university-level female soccer players.