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Purpose of the study. Concussion does not cause any lesions available for visualization using computed tomography and magnetic resonance imaging. However, it can cause changes at the microstructural level, which can be detected by the diffusion-tensor imaging. The purpose of this study is to identify the effect of acute concussion on diffusion parameters in the corpus callosum, corticospinal tract, and thalamus in children.Patients and methods. Fractional anisotropy and the apparent diffusion coefficient were determined in 11 patients with a diagnosis of concussion (41 ± 19 hours from the moment of injury) and in 11 healthy subjects. Philips Achieva dStream 3T magnetic resonance imager was used. Diffusion tensor imaging data were processed in the Philips Intellispace Portal program in the Fibertrack section.Results. Fractional diffusion anisotropy significantly increases and the apparent diffusion coefficient decreases in the thalamus of patients with concussion. In corpus callosum there is a growth trend in fractional anisotropy.Conclusion. The detected changes indicate the initial stage of cell edema in the thalamus caused by concussion. Diffusion-tensor imaging is the only magnetic resonance imaging method which may be sensitive to this pathology.

Background: Brain concussion (BC) is seen as a public health priority due to its high incidence and morbidity rate, among thousands of people around the world. There are needs for fast identification, accurate diagnosis and correct management in order to reduce the short and long-term problems relating to BC. Proper knowledge of BC in the population and among clinicians is a critical factor in achieving this. Objectives: To evaluate the level of self-reported BC knowledge and gaps/misconceptions, and to identify variables correlated with this level. Methods: A cross-sectional descriptive survey was performed. A Brain Concussion Knowledge Questionnaire (BCKQ) that had been created to capture data was widely distributed. Total scores, domain partial scores and percentages of correct and incorrect answers were calculated to ascertain the level of knowledge relating to BC. Results: The sample was formed by 1,247 Brazilian adults (age: 41.7±11.8 years). Partial scores of the BCKQ revealed the existence of poor knowledge and misconceptions in all domains of the questionnaire, especially regarding questions about recovery from and management of BC. Moderate correlations between BCKQ scores and professions (p=0.312; P=0.00) or previous brain concussion knowledge (p=0.489; P=0.00) were observed. In a multiple linear regression model, age, profession and sports practice were predictors of BC knowledge. Conclusion: This first study to analyze the level of BC knowledge in a sample of Brazilian adults suggests that poor knowledge and misconceptions are present. Thus, meaningful and useful information was provided by this study for developing health education programs about BC for the population in order to improve fast diagnosis and correct BC management. RESUMO Introdução: A concussão cerebral (CC) é considerada prioridade em saúde pública devido à sua alta incidência e taxa de morbidade. Há necessidade de identificação rápida, diagnóstico acurado e manejo correto após essas lesões, com objetivo de reduzir problemas de curto e longo prazo. O conhecimento apropriado da população, atletas e de clínicos é primordial para que isto seja alcançado. Objetivos: Avaliar o nível de conhecimento autorrelatado sobre CC, descrever lacunas/equívocos e identificar variáveis correlacionadas com este nível. Métodos: Foi realizada uma pesquisa descritiva transversal. O Questionário de Conhecimento sobre Concussão Cerebral (QCCC) criado foi amplamente distribuído. Pontuações totais e parciais em domínios e porcentagens de respostas corretas e incorretas foram calculadas para obter o nível de conhecimento sobre CC. Resultados: A amostra foi formada por 1.247 brasileiros adultos (41,7±11,8 anos). Pontuações parciais do QCCC revelaram baixo nível de conhecimento, principalmente em questões sobre recuperação e manejo. Observou-se correlações moderadas entre a pontuação no QCCC e a profissão dos participantes (p=0,312, P=0,00) ou conhecimento prévio sobre CC (p=0,489, P=0,00). A regressão linear múltipla mostrou que a idade, profissão e prática de esportes podem ser preditoras do conhecimento sobre CC. Conclusão: Esse primeiro estudo a analisar o nível de conhecimento sobre CC em uma amostra de adultos brasileiros sugere baixo conhecimento e equívocos sobre esta condição. Assim, informações úteis e significantes foram fornecidas para o desenvolvimento de programas de educação em saúde sobre CC para o público, com objetivo de melhorar a identificação rápida e o manejo correto de concussões.

The decision of returning an athlete to competition following a cerebral concussion is complex and dynamic. A premature return to play (RTP) can result in catastrophic injury that may terminate the career or the life of the athlete. Some physicians have a great deal of training and experience in the diagnosis and management of sports-related concussion while many do not. Given the importance and the dynamic nature of the RTP decision it is imperative that physicians charged with the decision-making role seek training and consultation when returning an athlete to sport. The team itself is an important element in the RTP decision. Although neuropsychological approaches and instruments have long been used in the assessment of mild traumatic brain injury, it is only recently that neuropsychological data have been used in the RTP decision. The player is the central figure in any RTP decision yet very little attention has been focused on player variables in the RTP decision.

Objetivo: Presentar la reducción progresiva en la frecuencia de conmociones cerebrales en los Campeonatos Mundiales de Karate, a partir de los cambios en el reglamento de la Federación Mundial de Karate (FMK). Material y Método: Estudio prospectivo de las conmociones cerebrales ocurridas en los campeonatos del mundo de Madrid (2002), Monterrey (2004), Tampere (2006), Tokio (2008), Belgrado (2010) y París (2012). Resultados: La frecuencia de conmociones cerebrales, definidas según la Conferencia Internacional de Conmoción en el Deporte (Viena 2001, Praga 2004, Zurich 2008 y 2012) ha disminuido progresivamente en los Campeonatos del Mundo de Karate: una conmoción cada 230 combates en Madrid, una cada 196 en Monterrey, una cada 99 en Tampere, una cada 612 en Tokio, una cada 512 en Belgrado, y una cada 1.140 en París. Discusión y Conclusión: El uso de protecciones, la aplicación rigurosa del reglamento del karate deportivo y la educación continua en la prevención de lesiones de los competidores, técnicos y árbitros, ha disminuido la frecuencia de conmociones cerebrales en los Campeonatos del Mundo, haciendo del karate deportivo una disciplina más segura, cumpliendo con los principios del Olimpismo.

The present review paper aims to update the definition and classification of cerebral concussion, highlighting its pathophysiological mechanisms. The high prevalence of cerebral concussion in emergency rooms around the world makes it necessary to know its proper management to avoid its late sequelae, which traditionally compromise cognitive aspects of behavior. New evidence on potential neuroprotective treatments is being investigated.

Background: We investigated differences in corpus callosum (CC) injuries between patients with concussion and those with diffuse axonal injury (DAI) by using diffusion tensor tractography (DTT). Methods: Twenty-nine patients with concussion, 21 patients with DAI, and 25 control subjects were recruited. We reconstructed the whole CC and 5 regions of the CC after applying Hofer classification (I, II, III, IV, and V). The whole CC and each region of the CC were analyzed to measure DTT parameters (fractional anisotropy [FA], apparent diffusion coefficient [ADC], and fiber number [FN]). Results: In the whole CC, significant differences were observed in all DTT parameters between the concussion and control groups and the DAI and control groups (P

Introduction We investigated differences in the ascending reticular activating system (ARAS) injuries between patients with mild traumatic brain injury (mTBI) and cerebral concussion by using diffusion tensor tractography (DTT). Methods Thirty-one patients with mTBI, 29 patients with concussion, and 30 control subjects were recruited. We used DTT to reconstruct the lower ventral and dorsal ARAS, and the upper ARAS. The fractional anisotropy (FA) value and the fiber number (FN) of the lower ventral and dorsal ARAS, and the upper ARAS were determined. Results Significant differences were observed in the FA values of the lower ventral and dorsal ARAS on both sides between the mTBI and control groups and between the concussion and control groups (p < 0.05). The FN value was significantly different in the lower ventral ARAS on both sides between the concussion and control groups and between the mTBI and concussion groups (p < 0.05). Conclusion Both the mTBI and concussion patients suffered injuries in the lower ventral and dorsal ARAS, with the concussion patients exhibiting more severe injury in the ventral ARAS than that in the mTBI patients. These results suggest that the terms mTBI and concussion should be used differentially, even though they have used interchangeably for a long time.

Zusammenfassung. Die überwiegende Mehrzahl der 20 000 pro Jahr in der Schweiz wegen Schädel-Hirn-Trauma hospitalisierten Patienten läuft unter dem Diagnose-Kontinuum mildes Schädel-Hirntrauma/Commotio cerebri. Glücklicherweise erholt sich die Mehrzahl dieser Patienten nach Tagen bis Wochen vollständig. Allerdings muss bei ca. 15 % dieser Patienten mit prolongierten bis hin zu persistierenden Beeinträchtigungen gerechnet werden, was u.U. erheblich negative Auswirkungen auf deren Lebensqualität hat. Dies trifft insbesondere auf Patienten zu, die sich wiederholte milde Hirnverletzungen (z.B. im Rahmen von Kontaktsport) zugezogen haben. Unglücklicherweise werden viele dieser Patienten nie richtig diagnostiziert und oft als Hypochonder oder Simulanten abgestempelt. Das verhindert eine adäquate Rehabilitation und Unterstützung. Diese Mini-Review hat zum Ziel, den aktuellen Stand des Wissens bezüglich pathophysiologischen und klinischen Auswirkungen des milden Schädel-Hirn-Traumas darzulegen und einige Informationen zur Diagnostik und Behandlung auf Basis bestehender Guidelines zu vermitteln.

Objective – analyze the neurophysiological indexes of the mild severity brain injury according to official electroencephalogram data in fighting men of anti-terrorist operation in a distant period.Material and methods. 42 fighting men with a concussion of the brain, 41 АТО fighting men with a contusion of the brain of mild severity in a distant period and 35 healthy persons, who formed the control group were inspected using the neurophysiological method registration and computer processing electroencephalogram. The EEG survey was conducted with the help of the complex DXNT 32, the protocol consisted of seven samples, record was conducted on 16 channels in leads Fp1, Fp2, F3, F4, F7, F8, T3, T4, T5, T6, C3, C4, P3, P4, O1, O2. Indices of spectral power rhythm signals of the following frequency ranges: θ – 4.0 до 7.0 Hz; α – 8.0 до 13.0 Hz; β – 14.0 до 18.0 Hz were calculated. Statistical processing of data and evaluation of reliability indicator changes were conducted with the help of twin Student Criterion.Results. Spectral analysis has revealed changes in EEG rhythms across all frequency ranges in the soldiers with the brain concussion and contusion of mild severity in comparison with the control group. The group of fighting men with contusion of the brain of mild severity differed from the control group with more significant indicators of EEG spectra in all frequency ranges. The growth of the θ activity in soldiers with craniocerebral injury can be the evidence of functional changes of the hypothalamus, but a violation of the spatial organization of the α rhythm and its displacement in the anterior parts of the cortex gives reason to think about dysfunction of the diencephalic structures. Reduction of α rhythm in the posterior regions of both hemispheres in the concussion of the brain indicates a decrease activity of the thalamic cortical system.Conclusion. It has been established that EEG parameters in the trauma of the brain of a mild degree are the subject to changes and should be used as diagnostic criteria for an objective assessment of the functional state of the brain for further therapeutic measures.

Cerebral concussion is a brain injury, that involves a complex pathophysiological process that affects the brain as a result of biomechanical forces. With the increasing prevalence, it is important that the public is knowledgeable about concussion and its symptoms, so that they can bring attention to individuals with concussion symptoms soon after onset, for appropriate care. The aim of this study was to determine the knowledgeability of young adults. Secondary aims were to compare the knowledgeability of young adults of different age, of different countries of residence, of different sex, and of different perceived knowledge about concussions. An online survey was circulated to young adults in Canada, the US and the UK. The survey consisted of three components – a consent form, respondent demographics and eight questions to assess each respondent’s knowledgeability of concussions. The knowledgeability of each respondent was determined by the summation of the number of correct responses to the knowledge questions. A total of 307 respondents consented and completed the survey in its entirety. The mean knowledge score was 4.25 out of 8. None of the cohort analyses based on demographics – 19 years old and under vs. 20 years and older; North Americans vs. non-North Americans; females vs. males – suggested that one group was more knowledgeable than the other group. These results suggest that educational programs can be developed to increase awareness of concussions. As each cohort seems to have similar starting knowledge levels, it seems appropriate to develop a uniform program to first try to increase knowledgeability, and then produce specialised programs to raise knowledge of certain cohorts. However, prior to the establishment of programs, further studies should be conducted to verify the results disclosed herein.

Studies of football athletes have implicated repetitive head impact exposure in the onset of cognitive and brain structural changes, even in the absence of diagnosed concussion. Those studies imply accumulating damage from successive head impacts reduces tolerance and increases risk for concussion. Support for this premise is that biomechanics of head impacts resulting in concussion are often not remarkable when compared to impacts sustained by athletes without diagnosed concussion. Accordingly, this analysis quantified repetitive head impact exposure in a cohort of 50 concussed NCAA Division I FBS college football athletes compared to controls that were matched for team and position group. The analysis quantified the number of head impacts and risk weighted exposure both on the day of injury and for the season to the date of injury. 43% of concussed athletes had the most severe head impact exposure on the day of injury compared to their matched control group and 46% of concussed athletes had the most severe head impact exposure for the season to the date of injury compared to their matched control group. When accounting for date of injury or season to date of injury, 72% of all concussed athletes had the most or second most severe head impact exposure compared to their matched control group. These trends associating cumulative head impact exposure with concussion onset were stronger for athletes that participated in a greater number of contact activities. For example, 77% of athletes that participated in ten or more days of contact activities had greater head impact exposure than their matched control group. This unique analysis provided further evidence for the role of repetitive head impact exposure as a predisposing factor for the onset of concussion. The clinical implication of these findings supports contemporary trends of limiting head impact exposure for college football athletes during practice activities in an effort to also reduce risk of concussive injury. Published version

This study intended to determine if an acute bout of soccer heading alters postural control and pronounced self-reported symptoms of cerebral concussion. Collegiate soccer players were randomly assigned to one of 2 groups. Each participant completed a baseline postural control assessment prior to heading. Participants either simulated (control group; CG) or performed (experimental group; EG) 10 headers at 11.2 m/s in 10 min. The postural assessment was repeated post heading at hrs 1, 24, and 48. The postural control parameter assessed was the root mean square (RMS) of the center of mass (COM). COM RMS were calculated for the anterior-posterior (AP) and medial-lateral (ML) time series. Compared to the CG, for the AP and ML time series COM RMS values were significantly higher in the EG at hr 24 (p0.05). An acute bout of heading results in quantifiable alterations in postural control that are detectable 24 h post heading and dissipate within an additional 24 h. The significant findings may be due to the dynamic postural control assessment that incorporated robust discordant environmental conditions.

In brief: Cerebral concussion occurs frequently in contact sports; more than 250,000 concussions occur annually in football alone. Definitions and classifications of severity of concussion vary, which makes evaluation of data extremely difficult. By combining elements of various definitions, the author has developed a practical, on-the-field grading scheme for identifying concussion in contact sports (grade 1: mild, with no loss of consciousness; grade 2: moderate, with less than five minutes of unconsciousness or more than 30 minutes of posttraumatic amnesia; grade 3: severe, with five or more minutes of unconsciousness or 24 or more hours of posttraumatic amnesia). Also discussed are management of concussion and guidelines for determining when an athlete may safely return to play.

Cerebral concussion and mild traumatic brain injury (TBI) have been used interchangeably, although the two terms have different definitions. Traumatic axonal injury (TAI) is a more severe subtype of TBI than concussion or mild TBI. Regarding the evidence of TAI lesions in patients with concussion or mild TBI, since the 1960's, several studies have reported on TAI in patients with concussion who showed no radiological evidence of brain injury by autopsy. However, conventional CT and MRI are not sensitive to detection of axonal injury in concussion or mild TBI, therefore, previously, diagnosis of TAI in live patients with concussion or mild TBI could not be demonstrated. With the development of diffusion tensor imaging (DTI) in the 1990's, in 2002, Arfanakis et al. reported on TAI lesions in live patients with mild TBI using DTI for the first time. Subsequently, hundreds of studies have demonstrated the usefulness of DTI in detection of TAI and TAI lesions in patients with concussion or mild TBI. In Korea, the term "TAI" has rarely been used in the clinical field while diffuse axonal injury and concussion have been widely used. Rare use of TAI in Korea appeared to be related to slow development of DTI analysis techniques in Korea. Therefore, we think that use of DTI analysis techniques for diagnosis of TAI should be facilitated in Korea.

Depression, fatigue, irritability, confusion, and general mood disturbance are frequently reported after cerebral concussion in sport. Recent trends in research point to the importance of examining postconcussive emotional disturbances more thoroughly, empirically, and clinically. An overview of the complexity of human emotion and its study is provided herein, followed by a review of emotional correlates identified in the existing sparse literature. The significance and clinical implications of identifying emotional correlates of concussion in sport and athletics are discussed.

Scientific knowledge of omega-3 fatty acids (FAs) has grown in the last decade to a greater understanding of their mechanisms of action and their potential therapeutic effects. Omega-3 FAs have shown therapeutic potential with respect to hyperlipidemia, depression, attention-deficit hyperactivity disorder, and mild cognitive impairment. Laboratory evidence and clinical interest have grown such that omega-3 FAs have now assumed a role in concussion management. This has coincided with recent research that has also helped to increase the scientific understanding of cerebral concussion; although concussion or mild traumatic brain injury was assumed to be a malfunctioning brain without anatomical damage, we now know that there is the potential for damage and dysfunction at the cellular and microstructural levels. Specifically, with concussion abnormal metabolism of glucose may occur and intracellular mitochondrial dysfunction can persist for several days. In this article, we discuss the role of omega-3 FAs, particularly docosahexaenoic acid, in concussion management.

This article reviews concussion management in the military, with specific reference to the acute assessment and management of injured combat military personnel. Recent research on concussion and recovery is used as a foundation for understanding issues unique to a military population, as well as universal issues in the care of concussed individuals. We explain current uses of neuropsychological testing in military, as well as suggest future directions. A protocol for the acute management and assessment of concussions sustained through military service is provided, as are recommendations for the treatment of more chronic postconcussion symptoms and other trauma-related conditions which may present following concussion.

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in postural control by applying a nonlinear dynamic measure known as 'approximate entropy'. Approximate entropy shows promise as a valuable means of detecting previously unrecognised, subtle physiological changes after concussion. It is recommended as an important supplemental assessment tool for determining an athlete's readiness to resume competitive activity.

The objective of this study is to investigate rates of concussion and selected factors related to its occurrence in American football players. A prospective epidemiological study followed a national sample of high school and college players for two seasons. There were a total of 14,997 player-seasons, over 1 million Athlete-Exposures to the possibility of injury, and 595 concussions recorded. The concussion rate for high school players is 0.56 concussions per 1,000 Athlete-Exposures; for college players, 0.58 per 1,000 Athlete-Exposures, and 0.57 overall. Concussion is the second (high school) or third (college) most frequent injury, is 9 to 10 times more likely to occur in games than in practices, and more than half are the results of helmet-to-helmet contact. The risk of sustaining a concussion is six times greater for individuals with a history of concussion than for individuals with no history. Further commentary on these and other results is presented. The injury surveillance project, from which the ...

Clinicians regularly assess concussion according to the symptoms that an athlete manifests at the time of injury, as well as during subsequent evaluations. The subjectivity involved with symptom assessment, however, often leaves the clinician without a clear picture of the athlete's true mental status. Neuropsychologic testing has become very popular in the sports medicine community for assessing the cognitive domain of neurologic functioning, and postural stability testing is gaining credence for assessing the motor domain. The objective of this review was to determine the efficacy of postural stability testing as an adjunct to concussion assessment of athletes. Multiple studies, using both sophisticated force plate technology, as well as those using less sophisticated clinical balance tests, have identified postural stability deficits lasting several days following sport-related concussion. It appears that postural stability testing provides a useful tool for objectively assessing the motor domain of neurologic functioning, and should be considered a reliable and valid adjunct to the assessment of athletes suffering from concussion. Although symptom severity, neurocognitive function, and postural stability are often affected initially following concussion, they are not necessarily related or even affected to the same degree.

Background and Purpose: Several changes have occurred in Olympic boxing in last few decades. In March 2013, the use of headgear was banned to reduce the incidence of cerebral concussion. This reduced the concussion rate to 0.17% but affected the boxer's psychology and also the way boxers and coaches prepare. The boxers feel safer to take the risk wearing headgear that they simply would not do if they are not wearing one. Furthermore, three fatal incidents of professional boxing make it important to find out the prevalence of injuries in competitive boxers. The aim of this study was to find out the prevalence of injuries in national level boxers of India that occurred during the bout or training. Materials and Methods: The study was conducted as a retrospective and was carried on 54 national level boxers ranging between 11 and 35 years. Results: Fifty-four boxers reported with 820 injuries in 2 years. Each boxer sustained 15.18 injuries in 2 years on an average, i.e., 7.59 injuries/year on an average. The injury rate per boxer was 9.64/1000 h of training. The injuries of head and face (42.92%) are more frequent followed by the injuries of upper limb (33.90%). Soft tissue lacerations and contusions are common. Furthermore, frequent low back pain (5%), calf cramp (3.41%), and high ankle sprain (4.4%) were reported because of training. Conclusions: The study suggests that the most common type of injuries in boxers is the soft tissue lacerations and contusions, and the most common site of injury is the head and face region. Common injuries due to training are low back pain, calf cramp, and high ankle sprain.

This article explains the various stresses (tensile, compressive, and shearing) that can affect the brain, and how they may produce the different types of brain injury. The biomechanical forces and dynamics that produce coup versus contra coup injury are covered, as are the common intracranial athletic head injuries, i.e. concussion and the various intracranial haematomas (epidural, subdural, subarachnoid and intracerebral). Though less common in occurrence, because their outcome is so catastrophic, space is also devoted to the recognition, the treatment and (especially in the latter case) the prevention of the malignant brain oedema syndrome of the adolescent and the second impact syndrome of the adult. A major emphasis of this paper is the recognition of the 3 grades of cerebral concussion and the delineation of clear guidelines as to when it is safe to return to collision sports after sustaining such injuries, for the first, second or third time during a given season. Clear guidelines are also presented as to when to discontinue collision sport competition for the remainder of the season after multiple concussions. Because of the concern for the second impact syndrome, the requirement to never allow an athlete with postconcussion syndrome symptoms to return to competition is emphasised. Also covered is the prevention of head injuries, which sports are at greatest risk, and the need for additional research on the cumulative effects of concussion.

Background Neurocognitive testing has been endorsed as a “cornerstone’ of concussion management by recent Vienna and Prague meetings of the Concussion in Sport Group. Neurocognitive testing is important given the potential unreliability of athlete self-report after injury. Relying only on athletes'ormalities after injury. Study Design Case control study; Level of evidence, 3. Methods High school and college athletes with a diagnosed concussion were tested 2 days after injury. Postinjury neurocognitive performance (Immediate Postconcussion Assessment and Cognitive Testing) and symptom (postconcussion symptom) scores were compared with preinjury (baseline) scores and with those of an agex and education-matched noninjured athlete control group. “Abnormal” test performance was determined statistically with Reliable Change Index scores. Results Sixty-four percent of concussed athletes reported a significant increase in symptoms, as judged by postconcussion symptom scores, compared with preinjury baseline at 2 days after injury. Eighty-three percent of the concussed sample demonstrated significantly poorer neurocognitive test results relative to their own baseline performance. The addition of neurocognitive testing resulted in a net increase in sensitivity of 19%. Ninety-three percent of the sample had either abnormal neurocognitive test results or a significant increase in symptoms, relative to their own baseline; 30% of a control group demonstrated either abnormalities in neurocognitive testing or elevated symptoms, as judged by postconcussion symptom scores. For the concussed group, use of symptom and neurocognitive test results resulted in an increased yield of 29% overreliance on symptoms alone. In contrast, 0% of the control group had both symptoms and abnormal neurocognitive testing. Conclusion Reliance on patients’ self-reported symptoms after concussion is likely to result in underdiagnosis of concussion and may result in premature return to play. Neurocognitive testing increases diagnostic accuracy when used in conjunction with self-reported symptoms.

Objective:To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.Methods:The study was a retrospective, case series analysis of centre of pressure (COP) data collected during the Sensory Organization Test (SOT) from NCAA Division I (USA) athletes prior to and within 48 h after injury. Subjects were 21 male and six female athletes from a variety of sports who sustained a cerebral concussion between 1997 and 2003. After injury, athletes displayed normal postural stability equivalent to preseason levels. For comparison, COP data also were collected from 15 male and 15 female healthy non-athletes on two occasions. ApEn values were calculated for COP anterior-posterior (AP) and medial-lateral (ML) time series.Results:Compared to healthy subjects, COP oscillations among athletes generally became more regular (lower ApEn value) after injury despite the absence of postural instability. For AP time series, declines in ApEn values were much larger in SOT conditions 1 and 2 (approximately three times as large as the standard error of the mean) than for all other conditions. For ML time series, ApEn values declined after injury in all sensory conditions (F1,55 = 6.36, p = 0.02).Conclusions:Athletes who demonstrated normal postural stability after concussion nonetheless displayed subtle changes in postural control. Changes in ApEn may have represented a clinically abnormal finding. ApEn analysis of COP oscillations may be a valuable supplement to existing concussion assessment protocols for athletes.

A high incidence of cerebral concussion has been reported among soccer players. We studied whether long-term or chronic neuropsychological dysfunction was present in collegiate soccer players. Two hundred forty subjects from a National Collegiate Athletic Association division I institution were stratified into three groups: soccer athletes (91), nonsoccer athletes (96 women's field hockey, women's lacrosse, and baseball players), and controls (53 college students). Subjects completed a concussion history questionnaire and underwent preseason baseline neuropsychological testing before the start of either the freshman or sophomore year. Data were collected on the results of six neuropsychological tests and from a concussion history questionnaire for number of previous concussions, Scholastic Aptitude Test results, and exposure to soccer and heading. Despite an average of 15.3 seasons of soccer exposure and a higher prevalence of previous concussions, the soccer athletes did not demonstrate impaired neurocognitive function or scholastic aptitude when compared with the nonsoccer athletes or the student nonathletes. Additionally, there was no significant relationship between a history of soccer-related concussion and either neurocognitive performance or scholastic aptitude. Neither participation in soccer nor a history of soccer-related concussions was associated with impaired performance of neurocognitive function in high-level United States soccer players.

The following comments convey the assembled keynote points made at a summit called by Commissioner Roger Goodell involving all leading medical personnel in the National Football League, outside experts and players union representatives.

Years ago we developed a rat model that was consistently comatose for 1-2 seconds following 50 G acceleration of the head. Motor normalcy returned in about 10 seconds, and normal memory in an hour. There were immediate electroencephalogram and transmitter changes. All these returned to normal within an hour following 1 or 20 such concussions. We could find no light or electron microscopic changes. Halothane anesthesia precludes measurement of coma and introduces distortion of metabolite findings. To date our findings indicated concussion at this level is completely reversible.

Commotio cerebri (a slight concussion of the brain) is a sudden, brief, traumatic impairment of cerebral function attended by loss of consciousness and/or amnesia and without a demonstrable anatomic lesion of the brain (Verjaal and Van’t Hooft 1975).

Early neurophysiological changes and pathological findings were studied following experimental cerebral concussion in rabbits. The animals were lightly anesthetized and subjected to occipital trauma with a pendulum impactor. Experimental concussion was defined as fulfillment of at least two of the three following criteria: apnea for more than 10 seconds, absence of the light reflex for more than 10 seconds, and bradycardia or tachycardia (less than 50% or more than 10% of the preimpact rate, respectively). There were 13 cases of lethal concussion, 16 of nonlethal concussion, and 15 of nonconcussion. The resultant head acceleration ranged from 250 to 1660 G and its duration was 0.8 to 5.5 msec. During the first 30 seconds after impact, electroencephalographic activity showed little change even in cases of lethal concussion, but slowed over the next several minutes due to respiratory suppression. The duration of apnea in cases of nonconcussion was under 9 seconds and, in cases of nonlethal concussion, averaged 21 seconds. Five of the rabbits with lethal concussion were apneic throughout the observation period, and the remaining eight exhibited apnea for an average of 46 seconds after impact. The light reflex was absent for less than 9 seconds in nonconcussion cases and for an average of 71 seconds in cases of nonlethal concussion. One animal with lethal concussion exhibited absence of the light reflex throughout, and the remaining 12 animals for an average of 39 seconds. Bradycardia was seen in 15 cases of nonlethal and two cases of lethal concussion. Six rabbits with lethal concussion had tachycardia. Two animals without concussion showed bradycardia and the remainder showed no change.(ABSTRACT TRUNCATED AT 250 WORDS)

I N A :PREVIOUS report 23 an experimental surgical technic in which the convex portion of the monkey skull is replaced by a transparent lucite calvarium was described. Because a large area of both cerebral hemispheres is exposed through the lucite window, the method is ideally suited for the study of intracranial phenomena under "closed box" conditions. I t may be of interest to mention that the technic was developed primarily to study the effects of cranial trauma on the underlying brain. The patterns of brain motion resulting from blows to both the freely movable and the immobile head were recorded by high-speed cinematography. I t is stressed that these experiments were conducted to study the motion patterns of the cerebral mass and any other visible physical change. I t is not a study of cerebral concussion. Although brain movement and concussion are probably closely interrelated the mechanism of concussion is not explainable in the light of our findings. I t is hoped, however, that this study may furnish additional data toward the eventual solution of the problem of cerebral concussion. HISTORICAL BACKGROUND

T HE pathogenesis of cerebral concussion has long been debated. The present experiments were undertaken to clarify the nature of acute cerebral disorders resulting from head injury. Concussion was defined by Denny-Brown as a "transitory and reversible nervous reaction with immediate onset following physical stress of sufficient violence and brevity, and characterized by progressive recovery thereafter. ''~ There are two main theories concerning the pathogenesis of concussion: the excitation theory of Walker, e t al., 4a and the paralytic theory of Denny-Brown and Russell2 These two theories, which postulate opposite mechanisms, will be reviewed. Walker and his associates 43 observed the appearance of fast activity in the electroencephalogram (EEG) with little change in amplitude immediately after a compressive impact applied to the exposed dura and brain in experimental animals. This was followed by '"extinction." The EEG changes were frequently accompanied by tonic extension movements of the extremities. They suggested that this type of concussion resulted from excitation of the central nervous system. An opposite view was proposed by Denny-Brown and Russell. Based on experimental observations of concussion produced by a pendulum striking the freely moving head (acceleration concussion), they concluded that this type of concussion was due to temporary paralysis of nervous function. In man, concussion is characterized by transient loss of neural function, accompa

Computer tomography (CT) and spectrophotometry of CSF were performed in 30 patients with the clinical diagnosis of cerebral concussion or contusion. The patients with concussion all had normal CT-findings. Spectrophotometry of CSF was sometimes positive for cerebral contusion with normal CT-findings, but the two methods were complementary so that the extent of the lesion was determined by CT and spectrophotometry of CSF indicated the cause.

Mechanical impacts were delivered by an air propelled striker to the front, side, rear and top of rigid protective caps worn by six anesthetized monkeys. These tests were to produce reversible concussion and to determine differences in tolerance to concussion among the four impact sites. Striker force and cap accelerations were measures of the impact severity and animal blood pressure, respiration and ECG changes were measures of the physiological effects. By distributing the blow with a protective cap, allowing free head movement after impact, skull fracture was eliminated and simple reversible concussion could be produced without symptoms of residual neurological deficit. Higher linear and angular accelerations produced longer periods of unconsciousness (more than 3 times) on the side than at any of the other locations. It is hypothesized that the decrease in concussion tolerance accompanied by higher accelerations for side impacts may be the result of lower mechanical impedance due to the oval shape of the animal head. For the covering abstract of the conference see HS-036 716. (Author/TRRL)

The aim of this study was to examine whether it was possible by a reaction time (RT) test to predict if a patient was to complain of sequelae after a cerebral concussion. 55 patients had an RT test performed 1-5 days after concussion. The test showed a significant (P less than 0.02) prolongated RT in patients having postconcussional sequelae (median 186 ms) after 1 month (27 patients, 49%) compared to the patients without sequelae (median 168 ms). Patients with sequelae after 3 months (12 patients, 22%) also had a prolongation of RT (median 183 ms) although non-significant. These results supports a structural organic etiology for postconcussional sequelae.

Cognitive impairment has been reported to occur in minor head injury (concussion). The value of the P300 evoked potential as a measure of cerebral concussion was studied in 20 patients with minor head injury and compared with the data from 20 normal subjects. Significant abnormalities of the P300 latency and amplitude were noted in these patients in the post-concussion period. The abnormalities improved completely on repeat testing. The correlation of the P300 to other parameters of head injury is discussed. The P300 constitutes a simple laboratory test that is sensitive measure of cerebral dysfunction in concussive head injuries.

In addition, our previous observations of patients with craniocerebral in- juries, when radioactive iodinated hmnan serum albumin and chromium-51 tagged red blood cells were used, indicated that in 80 per cent of these there was an alteration in blood volume from the calculated normal levels. In those cases in which cerebral trauma clinically appeared to be of a more severe degree, there was a progressive loss of red-cell mass and a blood- volume increase. There developed also an anemia as a result of these two physiological changes. In order to obtain more precise information as to what may be occurring in the physiological milieu during concussion, we thought it worth while to get a visual representation of the red-cell distribu- tion under controlled conditions. This paper is a summary of the blood volume and of the red-cell distribu- tion in experimentally produced concussion as determined with radioactive chromium-51 tagged cells. This pattern (profile) of the red-cell mass, specifi- cally of the spleen and the splanchnic area, was obtained by means of an im- proved scanning device. MATERIALS

Impacts have been analyzed in terms of degree of injury, head injury criterion (HIC), and average acceleration as a function of time for frontal impacts against the following surfaces: 1. Rigid flat surface-fractured cadaver skull. 2. Astroturf-head drop of football-helmeted cadaver. 3. Windshield penetrating impact of a dummy. 4. Airbag-dynamic test by human volunteers. It is concluded that the linear acceleration/time concussion tolerance curve may not exist and that only impacts against relatively stiff surfaces producing impulses with short rise times can be critical. The authors hypothesize that if a head impact does not contain a critical HIC interval of less than 0.015 s, it should be considered safe as far as cerebral concussion is concerned.

A method of extending the results of experiments on concussion-producing head rotations on lower primate subjects to predict the rotations required to produce concussions in man is presented. A rational scheme of development of the overall investigation is outlined. Theoretical scaling factors are derived and discussed and the results of concussion-producing tests on the Rhesus monkey are presented in chart form. A chart of angular acceleration required to produce concussion in the Rhesus monkey indicates that an acceleration of 40,000 radians per second sq will have a >99 percent probability of producing concussion. The scaling factors presented herein tentatively indicate that an acceleration of 7,500 radians per second sq will have the same probability of producing concussion in man.

It is largely on the basis of experimental work performed during the past decade that concussion of the brain can with confidence be described as a discrete, traumatic cerebral affliction. It is induced instantaneously when the head strikes an object, or is struck, under conditions in which the cofactors of transfer of adequate mechanical energy to the brain, in a sufficiently brief interval, are operative. Concussion can occur as an uncomplicated phenomenon, and as such may be either reversible or, in animals and presumably in man, irreversible terminating in death. It can, in addition, prevail as a complication in the more overt forms of brain injury, and here, likewise, it may be reversible, or it may be the sole or a contributing cause of death. Henceforth in this paper, we shall deal only with uncomplicated, reversible concussion. A good deal of awkwardness of expression is encountered in discussing concussion. This stems from the usage of the term 'concussion' to characterize both the mechanical incident which produces injury and the state of the injured individual for some indefinite interval afterwards. Further complication is introduced by use of the term 'post-concussion,' which can be no more precise in meaning than the word from which it is compounded. As a remedy, it is suggested that the term 'concussion' be applied only to the state of an individual in whom appropriate functional and structural alterations exist following a mechanical shock to the brain, but that the term 'concussion' never be used to refer to the mechanical events which initiated the changes. Concussion may be divided into three phases: basic, early, and late. The basic phase is a fleeting episode in which the brain is overwhelmed by the concussing shock and much of its nervous structure acutely altered in organization and activity. The most recent theory of the genesis of these alterations is the wellconceived notion that the formation and collapse of scattered, minute cavities in the fluid component of the brain tissue, respectively during and after the brief negative phase of the percussion wave passing through it, produce transient local shearing forces which affect the tissues (16). All the histological and functional changes which ensue are direct consequences of the injuries inflicted upon the nervous tissue in the basic phase. In the early phase, disturbed organization and function tend to be gradually restored, but some neural elements, damaged beyond repair, progressively degenerate. The late phase is a residual state, char

Cerebral concussion is a mild head injury which results in loss of consciousness not to exceed thirty minutes (or a variable period of amnesia). Objective neurologic findings are fleeting. Scattered chromatolysis of nerve cells and temporary increase in water content of the brain occurs. The persistence of subjective symptoms after mild head injury (posttraumatic syndrome) can be greatly reduced if not obviated by a plan of management of initial active reduction of the water content of the brain, followed by early ambulation and graduated exercise with insistence upon an early resumption of usual activity.

OBJECTIVES Mild traumatic brain injury in the form of concussion is extremely common, and the potential effects on pulmonary priming have been underestimated. The aim of this study was to characterize the pulmonary response following mild traumatic brain injury and assess the pulmonary susceptibility to lung injury after a subsequent innocuous pulmonary insult. DESIGN Experimental in vivo study. SETTING University research laboratory. SUBJECTS Male CD1 mice. INTERVENTIONS We developed a model of concussive traumatic brain injury in mice followed by pulmonary acid microaspiration. To assess the dependent role of neutrophils in mediating pulmonary injury, we specifically depleted neutrophils. MEASUREMENTS AND MAIN RESULTS Lateral fluid percussion to the brain resulted in neuronal damage and neutrophil infiltration as well as extensive pulmonary interstitial neutrophil accumulation but no alveolar injury. Following subsequent innocuous acid microaspiration, augmented alveolar neutrophil influx led to the development of pulmonary hemorrhage that was reduced following neutrophil depletion. CONCLUSIONS This model shows for the first time that innocuous acid microaspiration is sufficient to induce neutrophil-mediated lung injury following mild concussion and that the extracranial effects of mild traumatic brain injury have been underestimated.

IT HAS been common practice to include all the injuries to the spinal cord arising out of indirect violence in the one term "spinal concussion." For the purpose of this paper, the more definite term "concussion of the spinal cord" seems better and will be used. It signifies the presence in the spinal cord of a physiologic state similar to that in the cerebrum when the term "cerebral concussion" is used. In concussion of the spinal cord a transitory functional, and perhaps structural, disturbance of the spinal cord is incurred consequent to indirect trauma to the cord. This definition emphasizes the functional reversibility of the injury to the cord and makes it evident that recovery occurs in a relatively short time, that is, from a few hours to a few days. The reports in the literature and my experience in World War II indicate that functional recovery should occur in

IN PREVIOUS papers we have reported that when the dog is used as an experimental animal the common carotid blood flow and arterial pressure responses to electroconvulsive shock and experimental concussion are similar.* Under the conditions of these experiments we inferred that the observed changes in common carotid blood flow were indicative of cerebral blood flow variations. 2 To test this hypothesis, a series of experiments were performed with electroconvulsive shock on rhesus macaque monkeys. 3 Measurement of the internal carotid blood flow in these animals indicates the status of cerebral blood flow. 4 The pattern of flow and pressure changes following electroconvulsive shock in the monkeys was similar to that obtained in dogs. 3 Furthermore, the pattern of arterial pressure responses following electroconvulsive shock therapy in psychotic patients is similar in time and direction of change to the pattern observed in dogs and monkeys after such stimuli. 5 The

Headache and dizziness have always been recognized as common sequelae of cerebral concussion and trauma. In many cases these distressing symptoms persist even after the most conservative treatment in the acute stage of concussion. There is, however, another important sequel of cerebral concussion which thus far has not received the attention it deserves. This sequel is change in character. In many cases change in character has been observed following cerebral trauma, but its true significance has not been appreciated because the majority of cases showing alterations in personality following head injury have been classified as cases of traumatic neurosis. This diagnosis presupposes that the symptoms are purely functional, and the fact that many persons with posttraumatic symptoms either apply for or receive compensation has usually inclined the clinician toward this diagnosis. It was not until the development of the technic of encephalography that the full significance of the sequelae of

In this day and generation a justification is desirable when a single case is reported. This is particularly in order when the case is one of cerebral concussion. Nevertheless, on account of the extraordinary symptom-complex and course of the case in question, I offer no apology for its presentation. History.— August 6, 1910, E. D., male, aged 6½ weight 49 pounds, in robust health, fell while running on the porch, striking the left side of his head. The time of the accident was about 4 p. m. Judging from the position of the echymosis, which was very slight, the point of impact must have been about 4 cm. above and 2 cm. behind the external canthus of the left eye. I saw the child within ten minutes of the accident. The nurse said that after he fell he got upon his feet immediately, crying lustily. He was very pale, and