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PubMed1984

The effect of experimental concussion on somatosensory evoked potentials.

Cortical somatosensory evoked potentials (SEPs) were recorded following experimental acceleration concussion in the rat. Immediately after head injury there was a general reduction in the amplitude of the SEP, and all its components were either temporarily abolished or increased in latency. The early components of the SEP recovered much more rapidly than did the amplitude and latencies of the later potentials. The purpose of the study was to investigate the relative effects of concussion on the lemniscal system (whose activity is reflected by the discrete early components of the SEP) and the reticular activating system (whose activity is reflected by the diffuse high amplitude late component of the SEP). Contrary to a widely accepted theory, there was a delay in transmission of somatosensory information through the lemniscal pathways as well as through the reticular system following head injury. Such an observation is consistent with recent studies of SEPs recorded from humans comatose after head trauma. As the changes in the morphology of the waveform of the SEP following concussion can be simulated by simply recording evoked potentials at high rates of stimulation, this suggests that the delays are caused by a failure or malfunction of synaptic transmission, but the level at which this is occurring remains to be determined.

Animals↗
PubMed1992

Administration of excitatory amino acid antagonists via microdialysis attenuates the increase in glucose utilization seen following concussive brain injury.

Immediately following concussive brain injury, cells exhibit an increase of energy demand represented by the activation of glucose utilization. We have proposed that this trauma-induced hypermetabolism reflects the effort of cells to restore normal ionic balance disrupted by massive ionic fluxes through transmitter-gated ion channels. In the present study, changes in local CMRglc following fluid-percussion concussive injury were determined using [14C]2-deoxy-D-glucose autoradiography, and the effects of in situ administration (via microdialysis) of excitatory amino acid (EAA) antagonists [kynurenic acid (KYN), 2-amino-5-phosphonovaleric acid (APV; 100 microM, 1 mM, and 10 mM), and 6-cyano-7-nitroquinoxaline-2,3-dine (CNQX; 300 microM, 1 mM, and 10 mM] on glucose utilization were investigated. Animals that did not receive dialysis showed a remarkable increase (up to 181% of normal control) in cortical glucose utilization following injury. In contrast, this high demand for glucose was reduced in areas infiltrated with KYN, APV, and CNQX. These results indicate that EAA-activated ion channels are involved in the posttraumatic increase in glucose utilization, reflecting the energy demand of cells required to drive pumping mechanisms against an ionic perturbation seen immediately following the concussive injury. The effects of KYN, APV, and CNQX suggest that although all subtypes of the glutamate receptor appear to be involved in this phenomenon, N-methyl-D-aspartate-activated channels may play a major role.

2-Amino-5-phosphonovalerate↗
PubMed2006

Tracking neuropsychological recovery following concussion in sport.

PRIMARY OBJECTIVE: The purpose of this study was to illustrate the serial use of computerized neuropsychological screening with ImPACT to monitor recovery in a clinical case series of injured athletes. METHODS AND PROCEDURES: Amateur athletes with concussions (n= 30, average age= 16.1, SD= 2.1 years) underwent pre-season testing and three post-concussion evaluations within the following intervals: 1-2 days, 3-7 days (M= 5.2 days) and 1-3 weeks (M= 10.3 days). The study selection criteria increased the probability of including athletes with slow recovery. RESULTS: Repeated measures ANOVAs revealed significant main effects for all five composite scores (verbal memory, visual memory, reaction time, processing speed and total symptoms). In group analyses, performance decrements and symptoms relating to concussion appeared to largely resolve by 5 days post-injury and fully resolve by 10 days. Athletes' scores were examined individually using the reliable change methodology. At 1 day post-injury, 90% had two or more reliable declines in performance or increases in symptom reporting. At 10 days, 37% were still showing two or more reliable changes from pre-season levels. CONCLUSIONS: This study illustrates the importance of analysing individual athletes' test data because group analyses can obscure slow recovery in a substantial minority of athletes.

Adolescent↗
PubMed1997

Does premorbid depression influence post-concussive symptoms and neuropsychological functioning?

We examined the contribution of premorbid affective disturbance to persistent post-concussive symptoms and neuropsychological functioning following a mild traumatic brain injury. No differences were observed on self-reported post-concussive symptoms, MMPI scales, or neuropsychological measures between two case-matched groups of patients with and without a history of pre-injury depression. Clinicians are urged to use caution in attributing post-concussive symptoms or neuropsychological deficits to the presence of a pre-existing affective disorder.

Adult↗
PubMed2005

One-year follow-up of mild traumatic brain injury: post-concussion symptoms, disabilities and life satisfaction in relation to serum levels of S-100B and neurone-specific enolase in acute phase.

OBJECTIVE: To investigate, in patients with mild traumatic brain injury, serum concentrations of S-100B and neurone-specific enolase in acute phase and post-concussion symptoms, disabilities and life satisfaction 1 year after the trauma. DESIGN: Prospective study. PATIENTS: Eighty-eight patients (age range 18-87 years). METHODS: Blood samples were taken on admission and about 7 hours later. At follow-up 15 +/- 4 months later, the patients filled in questionnaires about symptoms (Rivermead Post Concussion Symptoms), disability (Rivermead Head Injury Follow-up) and life satisfaction (LiSat-11). RESULTS: Concentrations of S-100B and neurone-specific enolase were regularly increased in the first blood sample. Of the 69 patients participating in the follow-up, 45% reported post-concussion symptom, 48% exhibited disability and 55% were satisfied with "life as a whole". In comparison with the "sick-leave" situation on admission to hospital, 3 patients were on sick-leave at the time of follow-up because of the head trauma. Stepwise forward logistic regression analysis revealed a statistically significant association (p<0.05) between disability and S-100B and dizziness. CONCLUSION: In spite of frequent persistent symptoms, disabilities and low levels of life satisfaction, the sick-leave frequency was low at follow-up. The association between S-100B and disability supports the notion that long-term consequences of a mild brain injury may partly be a result of brain tissue injury.

Adolescent↗
PubMed2006

Application of virtual reality graphics in assessment of concussion.

Abnormal balance in individuals suffering from traumatic brain injury (TBI) has been documented in numerous recent studies. However, specific mechanisms causing balance deficits have not been systematically examined. This paper demonstrated the destabilizing effect of visual field motion, induced by virtual reality graphics in concussed individuals but not in normal controls. Fifty five student-athletes at risk for concussion participated in this study prior to injury and 10 of these subjects who suffered MTBI were tested again on day 3, day 10, and day 30 after the incident. Postural responses to visual field motion were recorded using a virtual reality (VR) environment in conjunction with balance (AMTI force plate) and motion tracking (Flock of Birds) technologies. Two experimental conditions were introduced where subjects passively viewed VR scenes or actively manipulated the visual field motion. Long-lasting destabilizing effects of visual field motion were revealed, although subjects were asymptomatic when standard balance tests were introduced. The findings demonstrate that advanced VR technology may detect residual symptoms of concussion at least 30 days post-injury.

Adolescent↗
PubMed1998

Future directions for the neuropsychological assessment of sports concussion.

This article argues in favor of using newly developed computerized, complex reaction time (RT)-based neuropsychological procedures for the study of sports-related concussion. Recent studies show that by using these complex RT procedures, significant differences between concussed and control samples can be observed. The magnitude of RT differences is 110 ms or less, levels that are not meaningfully measured with stopwatch-based procedures. RT-based procedures also have the advantage of permitting analysis of variability of RT, and several recent studies have shown that brain dysfunction is accompanied by erratic and inconsistent RT. A currently ongoing sports concussion study using measures of complex RT and variability of RT is described.

Athletic Injuries↗
PubMed2000

Concussions in athletes produce brain dysfunction as revealed by event-related potentials.

We have used event-related potentials (ERP) to assess cerebral activity following mild traumatic brain injuries in 20 college athletes practising contact sports. Concussion victims showed a striking decrease in P300 amplitude, an effect presumed to reflect alterations in attentional-cognitive processes. Moreover, the degree of impairment was strongly related to the severity of post-concussion symptoms. Our data suggest that concussions cause objectively measurable changes in the electrophysiological markers of brain activity and hence in the functions of the structures from which they originate. ERPs may thus constitute a reliable method to accurately monitor the clinical course and recovery of head injuries in athletes.

Adult↗
PubMed1999

Does loss of consciousness predict neuropsychological decrements after concussion?

OBJECTIVE: To investigate the importance of loss of consciousness (LOC) in predicting neuropsychological test performance in a large sample of patients with head injury. DESIGN: Retrospective comparison of neuropsychological test results for patients who suffered traumatic LOC, no LOC, or uncertain LOC. SETTING: Allegheny General Hospital, Pittsburgh, Pennsylvania. PATIENTS: The total number of patients included in this study was 383. MAIN OUTCOME MEASURES: Neuropsychological test measures, including the visual reproduction, digit span, and logical memory subtests of the Wechsler memory scale (revised), the Trail Making test, Wisconsin Card Sorting test, Hopkins Verbal Learning test, Controlled Oral Word Association, and the Galveston Orientation and Amnesia test (GOAT). RESULTS: No significant differences were found between the LOC, no LOC, or uncertain LOC groups for any of the neuropsychological measures used. Patients who had experienced traumatic LOC did not perform more poorly on neuropsychological testing than those with no LOC or uncertain LOC. All three groups demonstrated mildly decreased performance on formal tests of speed of information processing, attentional process, and memory. CONCLUSION: The results of this study cast doubt on the importance of LOC as a predictor of neuropsychological test performance during the acute phase of recovery from mild traumatic brain injury. Neuropsychological testing procedures have been shown to be sensitive in measuring cognitive sequelae of mild traumatic brain injury (concussion) in athletes. The failure of this study to find any relationship between LOC and neuropsychological functioning in a large sample of patients with mild head trauma calls into question the assignment of primary importance to LOC in grading severity of concussion. This study also does not provide support for the use of guidelines that rely heavily on LOC in making return-to-play decisions. Continued research is necessary to determine the relative importance of markers of concussion in athletes.

Adult↗
PubMed2006

Delayed intracranial complications after concussion.

BACKGROUND AND METHODS: The incidence of readmissions because of delayed intracranial complications within 3 weeks after observation for the sole diagnosis of concussion was examined in a national cohort. A nested case-control design was used to analyze the association between clinical factors as well as early computed tomography (CT) scan examination and these complications. RESULTS: Out of 100,784 patients hospitalized because of concussion during ten years, 127 (0.13%) patients were readmitted because of a delayed intracranial complication. High clinical severity grade (odds ratio [OR] 2.0, confidence interval [CI] 1.2-3.6), minor CT scan abnormalities (OR 1.7, CI 0.8-3.4) and male gender (OR 2.2, CI 1.4-3.5) were associated with an increased risk of delayed, intracranial complications. CONCLUSION: The incidence of delayed intracranial complications after primarily uncomplicated concussion was low. High clinical severity grade and male gender were risk factors. We failed to demonstrate an additional value of the acute CT scan examination to predict these complications.

Adult↗
PubMed2005

Can mouthguards prevent mandibular bone fractures and concussions? A laboratory study with an artificial skull model.

Some sports' accidents are responsible for inflicting traumatic brain injuries and mandibular bone fractures when impacts occur to the chin. It is often thought that mouth guards can prevent many of these injuries. However, such assertions may be insufficient without adequate research. It is therefore necessary to establish a systematic method of investigation to solve this problem. In the present laboratory study, tests were performed using pendulum impact equipment and an artificial skull model connected to strain gages and accelerometers to simulate and measure the surface distortions related to bone deformation or fractures and the acceleration of the head related to concussions. As impacts, direct blows to the mandibular undersurface were applied. As a result, wearing a mouth guard decreased (P < 0.01) the distortion to the mandibular bone and the acceleration of the head significantly compared with not wearing a mouth guard (54.7%: to the mandible -- measured at a total of three different points, 18.5%: to the head measured at a total of three different points). Within the limits of this study, the following conclusions were drawn: The present measuring system in this study was able to evaluate the distortion to the mandibular and the acceleration of the head from the direct blow to the mandibular undersurface. Mouth guards can reduce distortion to the mandibular and the acceleration of the head from the same blow. So mouth guards might have the possibility to prevent mandibular bone fractures and concussions. However, further well-designed and exhaustive studies are vital to show that mouth guards reduce the incidence of concussions and mandibular bone fractures.

Acceleration↗
PubMed1984

Activation of pontine cholinergic sites implicated in unconsciousness following cerebral concussion in the cat.

Low levels of cerebral concussion in the cat produce reversible behavioral suppression presumably associated with unconsciousness. This injury is also associated with increased rates of glucose utilization in regions within the dorsomedial pontine tegmentum. Microinjection of carbachol into these regions produced behavioral suppression resembling that following concussion. These data, together with previously published observations on cholinergic responses to brain injury, suggest that concussive unconsciousness may be attributable in part to activation of cholinergic pontine sites.

Animals↗
PubMed2005

Summary and agreement statement of the 2nd International Conference on Concussion in Sport, Prague 2004.

In November 2001, the 1st International Symposium on Concussion in Sport was held in Vienna, Austria to provide recommendations for the improvement of safety and health of athletes who suffer concussive injuries in ice hockey, football (soccer), and other sports. The 2nd International Symposium on Concussion in Sport was organised by the same group and held in Prague, Czech Republic in November 2004. It resulted in a revision and update of the Vienna consensus recommendations, which are presented here.

Athletic Injuries↗
PubMed2006

Concussion management by primary care providers.

OBJECTIVE: To assess current concussion management practices of primary care providers. METHODS: An 11 item questionnaire was mailed to primary care providers in the state of Maine, with serial mailings to non-respondents. RESULTS: Over 50% of the questionnaires were completed, with nearly 70% of primary care providers indicating that they routinely use published guidelines as a tool in managing patients with concussion. Nearly two thirds of providers were aware that neuropsychological tests could be used, but only 16% had access to such tests within a week of injury. CONCLUSIONS: Primary care providers are using published concussion management guidelines with high frequency, but many are unable to access neuropsychological testing when it is required.

Brain Concussion↗
PubMed2006

Concussive head injury in children and adolescents related to sports and other leisure physical activities.

OBJECTIVE: To compare the characteristics of children and adolescents with concussive head injury (CHI) sustained during organised sports or other leisure physical activity. METHODS: This was a case series study reviewing the medical records retrospectively over a four year period of children 6-16 years presenting to the emergency department with a CHI after participating in sport and/or recreation activity. RESULTS: There were 592 cases of sport and recreation related concussion over the study period (2000-2003). Most of the patients (n = 424, 71.6%) were male, with half (n = 304, 51.4%) being older than 10 years of age. A total of 152 (25.7%) cases of CHI were related to playing sports. Most cases (71.2%) were mild concussion. The cause of injury was a fall (n = 322, 54.4%) or a collision. Nearly a quarter of the children (n = 143, 24.2%) were admitted to hospital, with imaging performed in 134 (22.7%). Most children were treated appropriately and no adverse events were reported. CONCLUSIONS: A severe CHI in a child is six times more likely to have resulted from organised sport than from other leisure physical activities. Outcomes for CHI in children is excellent, although their management places a considerable burden on emergency services. The need for activity restriction and the benefits of this in reducing long term cognitive effects of CHI are uncertain.

Adolescent↗
PubMed2006

Sex differences in baseline neuropsychological function and concussion symptoms of collegiate athletes.

OBJECTIVE: To investigate sex differences in baseline neuropsychological function and concussion symptoms between male and female collegiate athletes. METHODS: A post-test only design was used to examine baseline neuropsychological test scores and concussion symptoms. A total of 1209 NCAA Division I collegiate athletes from five northeastern universities in the USA completed a baseline ImPACT test. ImPACT, a computerised neuropsychological test battery, was administered during an athlete's pre-season. RESULTS: Female athletes performed significantly better than male athletes on baseline verbal memory scores (p = 0.001), while male athletes performed significantly better than female athletes on baseline visual memory scores (p = 0.001). Female athletes endorsed a significant number of mild baseline symptoms as compared to male athletes. CONCLUSIONS: Male and female athletes exhibit differences on baseline neuropsychological test performance and concussion symptoms.

Athletic Injuries↗
PubMed2001

Knowledge of concussion guidelines among practitioners caring for children.

The objective of this study in Rochester, NY was to determine clinicians' knowledge of the Colorado Medical Society Guidelines (CMSG) on return to contact sports after a concussion. A survey was mailed to 1,140 pediatric, family practice, and emergency physicians, as well as 302 pediatric and family practice nurse practitioners in the Rochester, NY, area. Participants were given 3 hypothetical concussion scenarios and asked to pick 1 of 4 multiple-choice time intervals for when they would advise return to contact sports. Answers were compared with the latest version of the CMSG. The survey response rate was 57%. Only 7.6% responded correctly for Grade 1 concussion scenario, 56% for the Grade 2 scenario, and 28% for the Grade 3 scenario. Only 5.6% listed the CMSG as the source of the return-to-play advice they gave. Thus, respondents' knowledge of the CMSG was low, with few giving return-to-play advice consistent with the CMSG and even fewer acknowledging the CMSG as the source of such advice. Improving the availability of the CMSG may improve clinicians' knowledge and use of these guidelines.

Athletic Injuries↗
PubMed2000

Video analysis of acute motor and convulsive manifestations in sport-related concussion.

OBJECTIVES: To describe the motor and convulsive manifestations in acute sports-related head injury. METHODS: A total of 234 cases of concussive injuries during the 1995 through 1997 football seasons were obtained from the Australian Football League Medical Officers Association injury survey. Of these, 102 cases were recorded adequately on television videotape and were analyzed by two independent observers using a standardized recording form detailing injury mechanics and clinical features of the episodes. Motor and convulsive features were correlated with mechanical variables and with duration of loss of consciousness using linear modeling techniques. RESULTS: Tonic posturing occurred in 25 subjects, clonic movements in 6, righting movement in 40, and gait unsteadiness in 42. In one subject the tonic and clonic features were sufficiently prolonged to be deemed a concussive convulsion. The only risk factor for tonic posturing using logistic regression was the presence of loss of consciousness (p = 0.0001). There was a trend toward facial impact being an independent predictor of tonic posturing but this did not reach significance. No other independent variable predicted the development of clonic movements, righting movements, or gait unsteadiness. CONCLUSIONS: Subtle motor manifestations such as tonic posturing and clonic movements commonly occur in concussion; the main predictive factor for tonic posturing is the presence of loss of consciousness. The authors speculate that these clinical features are due to brainstem dysfunction secondary to biomechanical forces inducing a transient functional decerebration.

Brain Concussion↗