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PubMed2004

Incidence and risk factors for concussion in high school athletes, North Carolina, 1996-1999.

A prospective cohort study was used to quantify risk factors for sports concussions. Analysis was based on a stratified cluster sample of North Carolina high school athletes followed during 1996-1999. Clustering was by school and sport, and the sample included 15,802 athletes with 1-8 seasons of follow-up per athlete. Concussion rates were estimated for 12 sports, and risk factors were quantified using generalized Poisson regression. Concussion rates ranged from 9.36 (95% confidence interval: 1.93, 16.80) per 100,000 athlete-exposures in cheerleading to 33.09 (95% confidence interval: 24.74, 41.44) per 100,000 athlete-exposures in football, where "athlete-exposure" is one athlete participating in one practice or game. The overall rate of concussion was 17.15 (95% confidence interval: 13.30, 21.00) per 100,000 athlete-exposures. Cheerleading was the only sport for which the practice rate was greater than the game rate. Almost two thirds of cheerleading concussions involved two-level pyramids. Concussion rates were elevated for athletes with a history of concussion, and they increased with the increasing level of body contact permitted in the sport. After adjustment for sport, body mass index, and year in school, history of concussion(s) remained a moderately strong risk factor for concussion (rate ratio = 2.28, 95% confidence interval: 1.24, 4.19). The fact that concussion history is an important predictor of concussion incidence, even in this young population, underscores the importance of primary prevention efforts, timely identification, and careful clinical management of these injuries.

Adolescent↗
PubMed2003

Concussion in professional football: reconstruction of game impacts and injuries.

OBJECTIVE: Concussion in professional football was studied with respect to impact types and injury biomechanics. A combination of video surveillance and laboratory reconstruction of game impacts was used to evaluate concussion biomechanics. METHODS: Between 1996 and 2001, videotapes of concussions and significant head impacts were collected from National Football League games. There were clear views of the direction and location of the helmet impact for 182 cases. In 31 cases, the speed of impact could be determined with analysis of multiple videos. Those cases were reconstructed in laboratory tests using helmeted Hybrid III dummies and the same impact velocity, direction, and head kinematics as in the game. Translational and rotational accelerations were measured, to define concussion biomechanics. Several studies were performed to ensure the accuracy and reproducibility of the video analysis and laboratory methods used. RESULTS: Concussed players experienced head impacts of 9.3 +/- 1.9 m/s (20.8 +/- 4.2 miles/h). There was a rapid change in head velocity of 7.2 +/- 1.8 m/s (16.1 +/- 4.0 miles/h), which was significantly greater than that for uninjured struck players (5.0 +/- 1.1 m/s, 11.2 +/- 2.5 miles/h; t = 2.9, P < 0.005) or striking players (4.0 +/- 1.2 m/s, 8.9 +/- 2.7 miles/h; t = 7.6, P < 0.001). The peak head acceleration in concussion was 98 +/- 28 g with a 15-millisecond half-sine duration, which was statistically greater than the 60 +/- 24 g for uninjured struck players (t = 3.1, P < 0.005). Concussion was primarily related to translational acceleration resulting from impacts on the facemask or side, or falls on the back of the helmet. Concussion could be assessed with the severity index or head injury criterion (the conventional measures of head injury risk). Nominal tolerance levels for concussion were a severity index of 300 and a head injury criterion of 250. CONCLUSION: Concussion occurs with considerable head impact velocity and velocity changes in professional football. Current National Operating Committee on Standards for Athletic Equipment standards primarily address impacts to the periphery and crown of the helmet, whereas players are experiencing injuries in impacts to the facemask, side, and back of the helmet. New tests are needed to assess the performance of helmets in reducing concussion risks involving high-velocity and long-duration injury biomechanics.

Acceleration↗
PubMed1997

Duration of cognitive dysfunction after concussion, and cognitive dysfunction as a risk factor: a population study of young men.

OBJECTIVES: To establish how long cognitive dysfunction lasts after concussion, and the extent to which it may be a predisposing risk factor for concussion, by examining the prevalence of cognitive dysfunction among young men who have sustained concussion. DESIGN: Observational study. SETTING: Denmark. SUBJECTS: 1220 young men who had been admitted to hospital for concussion between the ages of 16 and 24 (identified in a national register of admissions) and who had also been cognitively tested by the Danish conscription draft board. MAIN OUTCOME MEASURE: Score on the draft board's cognitive screening test, dichotomised as dysfunctional or non-dysfunctional (20.4% of the general population of Danish men appearing before the draft board had a dysfunctional score). RESULTS: 700 of the 1220 men had been tested after sustaining concussion; 520 had been tested before concussion. Four (50%) of the eight men who were tested less than seven days after the injury had a dysfunctional score. Among groups of the remaining 692 men who were tested at later time points after injury, the rates were only marginally raised (range 21.4% to 26.5%) above the population level. Among men tested before injury, the rate of dysfunctional scores was higher (30.4% (158/520)). Apart from suggesting cognitive dysfunction as a risk factor for concussion, this higher proportion seems to relate to the fact that they were typically injured as young adults, whereas those men who were tested after concussion had more often been injured as adolescents. The relative risk for concussion in the presence of cognitive dysfunction is estimated to be 1.57 (95% confidence interval 1.32 to 1.86). CONCLUSIONS: Cognitive dysfunction is not only a short term consequence of concussion but also a predisposing risk factor for concussion, more so for young adults than for adolescents.

Adolescent↗
PubMed2003

Symptom-based assessment of the severity of a concussion.

OBJECT: Current grading systems of concussion and return-to-play guidelines have little empirical support. The authors therefore examined the relationships of the characteristics and symptoms of concussion and the history of concussion to three indicators of concussion severity-number of immediate symptoms, number of symptoms at the initial follow-up examination, and duration of symptoms--to establish an empirical basis for grading concussions. METHODS: Forty-seven athletes who sustained concussions were administered alternate forms of an Internet-based neurocognitive test until their performances were within normal limits relative to baseline levels. Assessments of observer-reported and self-reported symptoms at the sideline of the playing field on the day of injury, and at follow-up examinations were also obtained as part of a comprehensive concussion management protocol. Although loss of consciousness (LOC) was a useful indicator of the initial severity of the injury, it did not correlate with other indices of concussion severity, including duration of symptoms. Athletes reporting memory problems at follow-up examinations had significantly more symptoms in general, longer durations of those symptoms, and significant decreases in scores on neurocognitive tests administered approximately 48 hours postinjury. This decline of scores on neurocognitive testing was significantly associated with an increased duration of symptoms. A history of concussion was unrelated to the number and duration of symptoms. CONCLUSIONS: This paper represents the first documentation of empirically derived indicators of the clinical course of postconcussion symptom resolution. Self-reported memory problems apparent 24 hours postconcussion were robust indicators of the severity of sports-related concussion and should be a primary consideration in determining an athlete's readiness to return to competition. A decline on neurocognitive testing was the only objective measure significantly related to the duration of symptoms. Neither a brief LOC nor a history of concussion was a useful predictor of the duration of postconcussion symptoms.

Adolescent↗
PubMedDate not supplied

Current trends in athletic training practice for concussion assessment and management.

CONTEXT: Athletic trainers surveyed in 1999 demonstrated little consensus on the use of concussion grading scales and return-to-play criteria. Most relied on clinical examination or symptom checklists to evaluate athletes with concussion. OBJECTIVE: To investigate the current trends of certified athletic trainers in concussion assessment and management. DESIGN: Subjects were invited to participate in a 32-question Internet survey. SETTING: An Internet link to the survey was e-mailed to the subjects. PATIENTS OR OTHER PARTICIPANTS: A total of 2750 certified athletic trainers and members of the National Athletic Trainers' Association were randomly e-mailed and invited to participate. MAIN OUTCOME MEASURE(S): Survey questions addressed topics including years of certification, number of concussions evaluated each year, methods of assessing concussion, and guidelines used for return to play. Compliance with the recent position statement of the National Athletic Trainers' Association on sport-related concussion was also evaluated. RESULTS: Certified athletic trainers averaged 9.9 +/- 7.3 years of certification and evaluated an average of 8.2 +/- 6.5 concussions per year. To assess concussion, 95% reported using the clinical examination, 85% used symptom checklists, 48% used the Standardized Assessment of Concussion, 18% used neuropsychological testing, and 16% used the Balance Error Scoring System. The most frequently used concussion grading scale and return-to-play guideline belonged to the American Academy of Neurology (30%). When deciding whether to return an athlete to play, certified athletic trainers most often used the clinical examination (95%), return-to-play guidelines (88%), symptom checklists (80%), and player self-report (62%). The most important tools for making a return-to-play decision were the clinical examination (59%), symptom checklists (13%), and return-to-play guidelines (12%). Only 3% of certified athletic trainers surveyed complied with the recent position statement, which advocated using symptom checklists, neuropsychological testing, and balance testing for managing sport-related concussion. CONCLUSIONS: Our findings suggest that only a small percentage of certified athletic trainers currently follow the guidelines proposed by the National Athletic Trainers' Association. Various assessment methods and tools are currently being used, but clinicians must continue to implement a combination of methods and tools in order to comply with the position statement.

Journal Article↗
PubMed1976

[Autoradiographic investigations in repeated experimental brain concussion (author's transl)].

Single brain concussion in rabbits causes an increased proliferation of glial and mesenchymal cells. Repeated experimental concussions in rabbits (3 times at intervals of 24 h) led to an increased incorporation of H3-thymidine in glial and mesenchymal cells with a maximum at 48 h after the third concussion. This is interpreted as an indication of increased cell proliferation. The first and the second concussion did not cause a comparable reaction, thus suggesting that concussions may inhibit DNA synthesis under the conditions of our experimental setup. When the concussions were induced at an interval of 48 h the result was different: 48 h after each concussion we found an increase of labeled cells compared with the controls. After the second concussion the reaction was still more enhanced compared with the reaction following the first concussion. In contrast to this the number of labeled cells after the third concussion was significantly decreased compared with those after the second one. Parallels with pugilistic encephalopathy are discussed.

Animals↗
PubMed2004

Presentation and mechanisms of concussion in professional Rugby League Football.

The present study prospectively recorded the circumstances, incidence, mechanisms, injury detection and presentation of concussion in Rugby League. Forty-three consecutive concussions were recorded over three competitive seasons in 175 professional Rugby League players. Data showed (i) the incidence of concussion ranged from 5.9 to 9.8 injuries/1000 player hours across grades - except when age-group players were mismatched (18.4): (ii) 'head-high tackles' accounted for a significant number of concussions; (iii) concussion rarely involved a loss of consciousness with the most common indicators of concussion being amnesia, headache and unsteadiness, with the mechanism of injury often missed: and (iv) concussion often occurs concurrently with other injuries. Concussion (including repeated episodes) is a common injury in Rugby League. Systematic mental status questioning is warranted whenever concussion is suspected. Coaches, trainers and players need more education in the recognition and management of concussion. Stricter penalties for illegal 'head-high' tackling are strongly recommended.

Adult↗
PubMed2006

Mechanisms of injury for concussions in university football, ice hockey, and soccer: a pilot study.

OBJECTIVE: To examine the mechanisms of injury for concussions in university football, ice hockey, and soccer. DESIGN: Prospective analysis. SETTING: McGill University. PATIENTS: All athletes participating in varsity football, ice hockey, and soccer. MAIN OUTCOME MEASURES: Athletes participating in university varsity football, ice hockey, and soccer were followed prospectively to determine the mechanisms of injury for concussions, whether certain mechanisms of injury causing concussions were more common in any of the three sports, whether different areas of the body seem to be more vulnerable to a concussion after contact, and whether these areas might be predisposed to higher grades of concussion after contact. RESULTS: There were 69 concussions in 60 athletes over a 3-year period. Being hit in the head or helmet was the most common mechanism of injury for all 3 sports. The side/temporal area of the head or helmet was the most probable area to be struck, resulting in concussion for both football and soccer. When examining the body part or object delivering the concussive blow, contact with another player's helmet was the most probable mechanism in football. CONCLUSION: The mechanisms of injury for concussions in football are similar to previously published research on professional football players. The mechanisms of injury for concussions in soccer are similar to past research on Australian rules football and rugby.

Adolescent↗
PubMed2005

Sensory gating impairment in development of post-concussive symptoms in mild head injury.

Post-concussive symptoms reported by mild head injury (MHI) patients have been inadequately understood. Post-concussive symptoms reported by patients with MHI have so far been explained in terms of impairment in neurocognitive functions or deficits in modulation of flow of information. There are no studies that have looked into sensory gating impairment in MHI and its relation to post-concussive symptoms. The purpose of the present paper was to investigate the role of sensory gating impairment in post-concussive symptoms in mild head injury patients. Thirty MHI patients were evaluated for their neuropsychological functions, sensory gating deficits, and post-concussive symptoms. Neuropsychological functions were in the domain of attention, executive functions, and learning and memory. Sensory gating was assessed by Structured Interview for Assessing Perceptual Anomalies and post-concussive symptoms were assessed using the Neurobehavioral Rating Scale. Multiple regression method was used to identify predictors for post-concussive symptoms. Post-concussive symptoms were predicted by sensory gating deficits when sensory gating deficit was one of the predictors along with neuropsychological functions. Post-concussive symptoms were predicted by scores of Digit Vigilance and Digit Symbol Substitution Test, when predictors were restricted to neuropsychological functions. Sensory gating deficits were correlated with performance on Digit Symbol Substitution test. Post-concussive symptoms reported by MHI patients are the result of poor modulation of incoming sensory information.

Adolescent↗
PubMed2002

The impact of face shield use on concussions in ice hockey: a multivariate analysis.

OBJECTIVE: To identify specific risk factors for concussion severity among ice hockey players wearing full face shields compared with half face shields (visors). METHODS: A prospective cohort study was conducted during one varsity hockey season (1997-1998) with 642 male ice hockey players (median age 22 years) from 22 teams participating in the Canadian Inter-University Athletics Union. Half of the teams wore full face shields, and half wore half shields (visors) for every practice and game throughout the season. Team therapists and doctors recorded on structured forms daily injury, participation, and information on face shield use for each athlete. The main outcome measure was any traumatic brain injury requiring assessment or treatment by a team therapist or doctor, categorised by time lost from subsequent participation and compared by type of face shield worn. RESULTS: Players who wore half face shields missed significantly more practices and games per concussion (2.4 times) than players who wore full face shields (4.07 sessions (95% confidence interval (CI) 3.48 to 4.74) v 1.71 sessions (95% CI 1.32 to 2.18) respectively). Significantly more playing time was lost by players wearing half shields during practices and games, and did not depend on whether the athletes were forwards or defence, rookies or veterans, or whether the concussions were new or recurrent. In addition, players who wore half face shields and no mouthguards at the time of concussion missed significantly more playing time (5.57 sessions per concussion; 95% CI 4.40 to 6.95) than players who wore half shields and mouthguards (2.76 sessions per concussion; 95% CI 2.14 to 3.55). Players who wore full face shields and mouthguards at the time of concussion lost no playing time compared with 1.80 sessions lost per concussion (95% CI 1.38 to 2.34) for players wearing full face shields and no mouthguards. CONCLUSIONS: The use of a full face shield compared with half face shield by intercollegiate ice hockey players significantly reduced the playing time lost because of concussion, suggesting that concussion severity may be reduced by the use of a full face shield.

Adult↗
PubMedDate not supplied

Grade 1 or "ding" concussions in high school athletes.

BACKGROUND: Recent concussion management guidelines have suggested that athletes with mild (grade 1) concussions may be returned to play if asymptomatic for 15 minutes. The purpose of this study was to assess the utility of a current concussion management guideline in classifying and managing mild concussion. HYPOTHESIS: High school athletes diagnosed with a grade 1 concussion will demonstrate measurable decline in neuropsychological functioning that persists during the 1st week of recovery. STUDY DESIGN: Prospective study designed to evaluate neuropsychological functioning both prior to and following concussion. METHODS: Forty-three high school athletes completed neuropsychological test performance and symptom ratings prior to the season and at two times during the 1st week following mild concussion. RESULTS: Thirty-six hours after injury, mildly concussed high school athletes demonstrated a decline in memory (P < 0.003) and a dramatic increase in self-reported symptoms (P < 0.00001) compared to baseline performance. CONCLUSIONS: Athletes with grade 1 concussion demonstrated memory deficits and symptoms that persisted beyond the context in which they were injured. These data suggest that current grade 1 return-to-play recommendations that allow for immediate return to play may be too liberal. CLINICAL RELEVANCE: A reconsideration of current concussion grading systems appears to be warranted.

Adolescent↗
PubMed2001

Incidence of concussion in high school football players of Ohio and Pennsylvania.

Football injuries account for more concussions than any other sport in North America. A 1977 survey of high school football players in Minnesota found that 19% of players reported at least one concussion (characterized by loss of awareness) during a season. These results have not been confirmed in subsequent studies. This study sought to estimate the incidence of concussion among high school football players in our region, establish the frequency of the most common symptoms, and determine the duration of subsequent restriction from participation in the sport. The athletic boards of area high schools distributed a three-page survey to 450 high school football players. Of the 450 surveys distributed, 234 (52%) were returned, only 1 of which was excluded because of contradictory information. The incidence of concussion in football players was 47.2% (110/233, P < .001 versus a previously determined rate of 19%). Eighty-one of 233 players (34.9%) had multiple concussions. A total of 376 concussions were reported. The distribution of severity of the 376 reported concussive events was grade I, 87.8%; grade II, 9.9%; and grade III, 2.4%. Only 12 athletes were required to stop play for one or more games. The incidence of high school football players sustaining a concussion is much higher than previously established. The majority of these are mild (grade I) concussions. Further research is needed since multiple low-grade concussions may incur cumulative neuropsychologic impairments.

Adolescent↗
PubMed1999

Retrospective report on the effectiveness of a polyurethane football helmet cover on the repeated occurrence of cerebral concussions.

This report reviews the literature and unpublished data and presents survey results related to the use of a polyurethane football helmet cover. Two hundred forty-five individuals, identified by the helmet manufacturer as having purchased at least one device, were sent a survey after the 1992, 1993, and 1994 football seasons; 155 (63.3%) of the surveys were returned. The questionnaire, designed to be completed by the athlete, required a detailed history of concussions occurring both prior to and during the period the device was used. Individuals used the device as a result of having incurred at least one concussion. Rates of concussion reoccurrence while the device was worn were grouped by the number of previous concussions (1, 2, 3, or 4+) that occurred over a 4year period prior to use of the device. The rate of concussion reoccurrence was 2.4%, 7.3%, 15.8%, and 33.3%, respectively, over a 4-year period. The range appeared to reflect a parallel relationship between pre- and post-device concussion experiences: the more concussions experienced prior to adopting the device, the higher the rate of concussion reoccurrence while using the device. The natural history of repeated occurrences of concussive events may not be affected by the use of a polyurethane football helmet cover. We suggest that such a device not be routinely used prophylactically, but instead be reserved for individuals with 1 to 2 prior concussion injuries. However, at this time, we neither recommend nor discommend the device.

Adolescent↗
PubMed1988

How long does it take to recover from a mild concussion?

Twenty-two adults with mild concussions were assessed 5 times during the first 3 months after injury. The initial tests were performed within 72 hours of injury. Each evaluation included a neurological examination and neuropsychological reaction time (RT) tests of simple and choice RT variations. The concussed subjects were compared with control subjects matched for age, sex, and education. The time of day of the testing was equated for the two groups. None of the concussed subjects had a significant neurological deficit and none was hospitalized. There was no significant difference in the number of errors by the two groups on the RT tests. On the simple RT test, requiring a predetermined response to a specific signal, there was no significant difference between the groups, although the concussed group was approximately 28 ms slower on the average than the control group. On the choice RT tests, however, which demand an increased amount of attention and information processing, the concussed subjects were significantly slower than the normal control group, especially during the 1st month after injury. Even after 3 months, the concussed subjects had not yet attained the skill of the control group. Analysis of the response curves over time suggested two processes: an improvement in the concussed group and a slowing in the control group. Within the concussed group, there was no correlation of RT with the severity of the concussion. Even mild concussions can cause significant attentional and information processing impairment in the absence of any apparent neurological problems. Specific neuropsychological tests are necessary to reveal the deficit. A significant impairment seems to last for several weeks.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

[Brain concussion--a minor craniocerebral injury].

INTRODUCTION: Brain concussion is a brain dysfunction without any macroscopic structural damage, caused by mechanical force. This research paper presents the occurrence and basic characteristics of patients with brain concussion without skull fracture. The second aim of this paper is to answer questions, related to this problem, neurosurgeons are most often asked by doctors of other specialties. MATERIAL AND METHODS: Posttraumatic amnesia (patient unable to remember events before and/or after injury) was a condition to diagnose the brain concussion. In 1995 there were 240 patients with brain concussions without skull fracture at the Department of Urgent Surgery of our Institute. Eighty of them (33%) have been admitted to the Neurosurgical Clinic for observation and/or treatment. In all patients with brain concussion the following diagnostic procedure was applied: personal history, physical and neurological examination, basic blood tests and skull x-rays. CT imaging of the brain is not a routine because of our economic and technical circumstances. RESULTS: 240 patients were examined; 67% were males. Glasgow coma score (GSC) was 13-15 in all patients, while in nonhospitalized patients it was 15 (GSC = 15). 54% of patients were 15-40 years old; 35% were 41-60 years old and 11% were older than 60 years of age. Average hospitalization lasted for 3.48 days. According to the Glasgow outcome scale all patients had a good recovery. DISCUSSION: Patients with brain concussion have always amnesia with normal neurologic status. Legal and clinical definition of the minor head injury are not completely equal. Brain concussion is legally always a minor head injury. Patients with organic damage of brain (legally severe injury) can clinically look like having minor injury initially or till the end of the illness. Risk for brain damage in patients with amnesia is about 3%. Posttraumatic amnesia is always established by asking patients to remember events and not asking them if they were unconscious. Brain concussion is often associated with headache, vegetative or/and psychotic difficulties. Diagnostic protocol should comprise at least personal history, physical and neurological examination and skull x-ray. Consultation of a neurosurgeon and hospitalization are not indicated in all cases. In our series it was done in 33% according to indications which are established. In these cases patients should be transported with documents describing the type of injury, diagnostic results and treatment performed. The therapy is symptomatic. After brain concussion gradual return to everyday activities is indicated. Sick leave of 7-10 days is usually sufficient. Postconcussion syndrome (headache, vegetative or psychotic disturbances) occurs often and may last for a long period of time. CONCLUSION: We tried to describe a doctrine for diagnostic and treatment of patients suffering from brain concussion most appropriate according to our technical and economical circumstances.

Adolescent↗
PubMed2026

Investigating genetic susceptibility to concussion through rare variants in ion channel and neurotransmission genes.

Some individuals appear more susceptible to concussion or mild traumatic brain injury (mTBI) and the severity, range, and the persistence of post-concussion symptoms vary considerably between affected individuals. Genetic factors are likely to contribute to this variability. Symptomatic overlap of post-concussion syndrome with neurological conditions such as familial hemiplegic migraine (FHM) caused by rare pathogenic variants in ion channel and synapse protein genes, with high sensitivity to head trauma for some patients, suggests that variation in similar pathways may influence concussion susceptibility and recovery. To investigate this hypothesis, we performed whole exome sequencing in 93 unrelated individuals who had sustained a single or multiple concussions and examined rare protein-altering variants in FHM genes, other neuronal ion channel and transporter genes, and genes involved in neurotransmission. We identified 62 different rare missense variants across 24 genes in 59 participants (63%), with 26 individuals carrying 2 or more variants. The prevalence of specific likely damaging rare variants in the 16 ion channel-related genes that were identified was approximately fivefold higher than that observed from gnomAD population controls (Odds Ratio = 5.44, 95% CI [4.13,7.18], P < 0.0001). Notably, voltage-gated calcium and sodium channel genes, including SCN9A, together with neurotransmission-related genes such as SNCAIP, harboured multiple potentially deleterious variants. These findings suggest that rare deleterious variants in genes involved in ion homeostasis and neurotransmission may contribute to an individual's susceptibility to concussion or more severe post-concussion symptoms. This study provides a foundation for future genetic and functional investigations aimed at improving our understanding of concussion susceptibility and outcomes. Further validation in larger cohorts and mechanistic studies is warranted to determine their utility as biomarkers of concussion risk and prognosis.

Humans↗
PubMed2003

Does age play a role in recovery from sports-related concussion? A comparison of high school and collegiate athletes.

OBJECTIVE: To evaluate symptoms and neurocognitive recovery patterns after sports-related concussion in high school and college athletes. STUDY DESIGN: College athletes (n = 371) and high school athletes (n = 183) underwent baseline neuropsychological evaluation between 1997 and 2000. Individuals who received a concussion during athletic competition (n = 54) underwent serial neuropsychologic evaluation after injury and were compared with a noninjured within-sample control group (n = 38). Main outcome measures included structured interview, four memory measures, and Concussion Symptom Scale ratings. Baseline to postinjury change scores and multiple analyses of variance were used to compare recovery curves within and between groups. RESULTS: High school athletes with concussion had prolonged memory dysfunction compared with college athletes with concussion. High school athletes performed significantly worse than age-matched control subjects at 7 days after injury (F = 2.90; P <.005). College athletes, despite having more severe in-season concussions, displayed commensurate performance with matched control subjects by day 3 after concussion. Self-report of postconcussion symptoms by student athletes was not predictive of poor performance on neuropsychologic testing. CONCLUSIONS: Caution and systematic evaluation should be undertaken before returning athletes with concussion to competition. Sole reliance on the self-report of the athlete may be inadequate. Preliminary data may suggest a more protracted recovery from concussion in high school athletes.

Adolescent↗
PubMed1995

Concussion-induced retrograde amnesia in rats.

Three experiments were conducted to investigate the characteristics of retrograde amnesia (RA) induced by concussion in rats. In Experiment 1, rats receiving experimental concussion shortly after training in a single punishment trial exhibited severe forgetting on a retention test 48 h later. In the second experiment, rats receiving a concussion within 6 h after training showed severe RA, while those receiving concussion one day to five days after training exhibited progressively weaker amnesia. In Experiment 3, amnesic animals in one group received pretest noncontingent foot shock as a reminder treatment. This pretest cue significantly increased the cross-through latency, thus indicating a reduction in the memory deficit resulting from concussion. These results suggest that experimental concussion can be an effective method to induce retrograde memory loss in rats; that the RA caused by concussion is time-dependent; and that concussion-induced RA can be alleviated by a pretest cue indicating that the underlying mechanism of concussion-induced RA is more likely to be a retrieval deficit than a consolidation failure.

Amnesia, Retrograde↗