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PubMed2005

Assessing the enduring residual neuropsychological effects of head trauma in college athletes who participate in contact sports.

The present study examined the enduring residual neuropsychological effects of head trauma in college athletes using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), Postconcussion Syndrome Checklist, and the Stroop task. Based on a brief self-report concussion history survey, male and female athletes who participated in ice hockey, field hockey, lacrosse, and/or soccer were assigned to one of three concussion-history conditions: Non-concussed, Non-recent concussed (i.e., more than 2 years since last concussion), or Recent concussed (i.e., 2 years or less since last concussion). A fourth group of subjects consisting of non-concussed/non-athletes served in the control condition. Group differences emerged on the RBANS when immediate memory, delayed memory, and total scores were analyzed. Specifically, recent concussed athletes and, surprisingly, non-concussed athletes scored lower than control subjects in the two memory domains, whereas all three athlete groups had lower total RBANS scores than those of control subjects. Moreover, recent concussed athletes not only had lower immediate memory scores than control subjects, but also were impaired relative to non-recent concussed athlete subjects in this memory domain. No group differences were detected on the Stroop task or on the Postconcussion Syndrome Checklist. Interestingly, however, the severity of the Postconcussion Syndrome Checklist scores for the two athlete-concussed groups, taken in aggregate, correlated negatively with RBANS scores for attention (r = -.65) and delayed memory (r = -.61), and with the total RBANS score (r = -.59). In recent concussed athletes, lower delayed memory scores correlated with more severe Postconcussion Symptom Checklist scores (r = -.90), while more severe/higher number of concussions correlated with increased processing speed on the Stroop interference task (r = .90). These findings indicate that recent head injury produces alterations in neuropsychological function, especially that of memory, that resolve with time. More provocatively, the data also suggest that participation in contact sports may produce sub-clinical cognitive impairments in the absence of a diagnosable concussion presumably resulting from the cumulative consequences produced by multiple mild head trauma.

Adult↗

PubMed1990

[Experimental head injury of rabbits using pendulum impactor. An electron microscopic study].

Brain damage in the early stage of experimental head injury was studied under electron microscope, especially with respect to the permeability of the blood brain barrier and damage to nerve fibers. Lightly anesthetized rabbits were treated by intravenous injection of horseradish peroxidase (150-250 mg/kg) and were subjected to occipital impacts with a pendulum impactor. The animals were then perfused with a 2.5% glutaraldehyde mixture. Small blocks of the brain were sampled, incubated, postfixed, and embedded in Epon. These sections were observed under an electron microscope without staining. The authors' criteria of concussion have been previously published. There were three nonconcussion, 11 nonlethal concussion and seven lethal concussion animals. All cases of lethal concussion showed subarachnoid hemorrhage (SAH) in the brainstem and 57% of them showed microscopic parenchymal perivascular hemorrhages in the brainstem. Fifty-five percent of the nonlethal concussion cases showed SAH in the brainstem with a little parenchymal hemorrhage. The nonconcussion cases showed no hemorrhagic change except contusions and/or SAH of the cerebellum. Hemorrhagic changes were frequently seen in the cerebrum and cerebellum of nonlethal and lethal concussion cases without correlation to the severity of concussion. Under electron microscope, nonconcussion cases showed mild splitting of myelins. In nonlethal concussion cases, swelling of perivascular astrocytic feet was seen to a moderate degree in the cerebrum, pons, and medulla oblongata and damage to axons and myelins were mainly seen in the pons and medulla oblongata. Many cored dense bodies containing peroxidase were diffusely recognized in vascular endothelial cells. In lethal concussion cases, beside findings seen in nonlethal concussion, intravascular peroxidase was seen to leak from the intravascular space through an opened tight junction to the extracellular space, axons and neurophils.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1999

Broiler stunning and meat quality.

The effects of electrical and concussion stunning on meat and carcass quality of broilers were compared. Broiler chickens (n = 165) were subjected to treatments: 1) electrical stunning with no fibrillation, 2) electrical stunning with fibrillation, 3) concussion stunning with restraint, or 4) concussion stunning with no restraint. Electrical stunning (100 V, 80 mA, 50 Hz sinusoidal waveform alternating current) was applied for 3 s. Concussion was applied using a nonpenetrative captive bolt gun with or without restraint. We assessed broken bones, hemorrhages, meat quality defects, blood loss, pH at 10 min and 24 h, and texture from breasts filleted 3 h and 24 h postmortem. Electrically stunned birds showed a significantly higher incidence of broken bones (P < 0.0001), coracoid and furculum bone hemorrhages (P < 0.0001), and nonbone hemorrhages (P < 0.0001) than birds stunned by concussion. However, the incidence of red wing tips (P < 0.005) and shoulder hemorrhages was significantly higher (P < 0.05) in concussion-stunned birds than electrically stunned birds. Electrically stunned and nonfibrillated birds had the fastest blood loss rate. The pH value at 10 min was the lowest in concussion-stunned and unrestrained birds. Breast muscles from concussion-stunned birds that were filleted at 3 h postmortem were more tender than those from birds stunned electrically (P < 0.05). We concluded that concussion stunning could be advantageous for early filleting.

Animals↗

PubMed2002

Multiple head injuries in rats: effects on behavior.

BACKGROUND: Evidence suggests that mild head injuries in humans can result in cumulative damage. No investigation to date has considered the effects of multiple subacute mild head injuries in an animal model. METHODS: Forty-one male Long-Evans hooded rats were trained in a Morris water maze. All animals were fitted with a hollow intracranial screw. Concussions were generated using a fluid percussion device. Animals were then evaluated in the water maze until performance returned to baseline. Control animals received no concussions. The remaining animals were randomized to receive one, two, or three concussions. Animals were allowed to return to baseline after each concussion and were then killed. Motor performance was evaluated on a balance beam both before and after concussions. RESULTS: After one concussion, 85% of animals showed performance deviation from baseline as measured by time to reach the platform, returning to baseline within a mean of 14.0 trials. After two concussions, 48% of animals showed deviation, with a mean return to baseline of 6.8 trials. After three concussions, 25% of animals showed deviation, with a mean return to baseline of 2.3 trials. Of postconcussive animals, 42% developed new inconsistent baseline levels of performance. Balance beam performance was unaffected. CONCLUSION: Multiple concussions cause immediate transient impairment in spatial recognition and have extended effects on baseline performance in rats. Motor performance is not affected.

Animals↗

PubMed2004

A prospective functional MR imaging study of mild traumatic brain injury in college football players.

BACKGROUND AND PURPOSE: Although concussion is common among athletes, evidence-based methods for clinical evaluation, treatment, and recovery are lacking. We used a prospective, functional neuroimaging approach to assess sports-related concussion in which imaging was performed before injury so that brain changes resulting from concussion could be better understood. METHODS: Neurophysiologic correlates of sports-related concussion were investigated in eight college football players by using functional MR imaging. Preseason baseline levels of blood oxygen level-dependent (BOLD) activity were acquired during the performance of a test battery that included mathematical, memory, and sensorimotor coordination tasks. Four players who had a concussion repeated these baseline procedures within 1 week of injury. The remaining control players were retested at the end of the season. RESULTS: Specific neural signatures of concussion were detected in individual players by comparing postconcussion results to preconcussion baseline values. The validity of these indicators was confirmed by comparing them with the same measures in noninjured control subjects. When compared with control subjects, concussed players had marked within-subject increases in the amplitude and extent of BOLD activity during a finger-sequencing task. Effects were observed primarily in the parietal and lateral frontal and cerebellar regions. CONCLUSION: Differences in neural functioning were observed in the absence of observed deficits in behavioral performance, suggesting that this approach may increase sensitivity to concussion compared with neuropsychological evaluation alone. Though preliminary, the proposed prospective neuroimaging approach may have great potential for understanding mild traumatic brain injury and identifying mechanisms underlying recovery.

Adult↗

PubMed1986

Somatosensory evoked potentials after experimental head injury in the awake rat.

Experimental acceleration concussion was induced in 30 male rats who were immobilized with curare, artificially ventilated but not anaesthetised. Serial recordings of cortical somatosensory evoked potentials (SEPs) were made from the onset of concussion and for the following 30 min. Immediately after the head blow the initial three components of the SEP (P1, N1 and P2) were all either absent or markedly increased in latency. The late negative component (N2) was always abolished. All components reappeared and returned to approximately pre-concussion latencies within 5-6 min. The most persisting abnormality was in N2 whose post-concussion amplitude stabilized and remained depressed at only 50% of baseline value. The results suggest that experimental head injury produces a significant abnormality in every component of the evoked potential. The findings are therefore inconsistent with the theory that concussion differentially affects the diffuse nonspecific pathways whose activity is mediated by the reticular formation while leaving the lemniscal system comparatively intact. It is also shown that the morphology of the post-concussion SEP waveform can be quite accurately simulated by recording SEPs from normal animals at high rates of stimulation (50/s). This implies that the pathophysiology of concussion involves a temporary dysfunction in synaptic transmission although the level at which this is occurring has yet to be determined.

Afferent Pathways↗

PubMedDate not supplied

No evidence of impaired neurocognitive performance in collegiate soccer players.

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.

Adolescent↗

PubMed1997

Thyrotropin releasing hormone prevents abnormalities of cortical acetylcholine and monoamines in mice following head injury.

We investigated the effects of thyrotropin releasing hormone (TRH) on changes in cortical concentrations of acetylcholine (ACh) and monoamines produced by concussion in mice. Concussion was induced by dropping a metal rod on the head, and the concentration of ACh, norepinephrine (NE), dopamine (DA) and serotonin (5-HT) in the cerebral cortex were measured by HPLC. We also examined the arousal effects of 0.5 mg/kg of TRH and 0.015 mg/kg of L-pyro-2-aminoadipyl-histidyl-thiazolidine-4-carboxamide (MK-771), a TRH analogue, injected intraperitoneally 10 min before concussion, on neurotransmitter concentrations. Mice were sacrificed at 25 (representing the righting reflex time) and 210 s (representing spontaneous movement time). At 25 s after concussion, the concentration of ACh was significantly higher than in control mice, but pretreatment with TRH and MK-771 prevented the rise in ACh. In contrast, head injury significantly reduced NE concentration. TRH and MK-771 also prevented the fall in NE. Concussion did not change cortical concentrations of DA and 5-HT. Our results suggest that disturbances of consciousness produced by concussion may be due to increased ACh and diminished NE in the cerebral cortex. Our findings also suggest that the arousal effects of TRH on concussion-induced disturbances of consciousness are due to normalization of cortical cholinergic and noradrenergic neuronal systems.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2001

Loss of Consciousness: Pathophysiology and Implications in Grading and Safe Return to Play.

OBJECTIVE: To provide historical background and current concepts regarding the importance of loss of consciousness (LOC) in the evaluation of concussion and athletes. DATA SOURCES: A MEDLINE search identified scientific and clinical articles on sport concussion management published from 1966 to present. Discussions were held with authors of selected reports. Recent research findings reported at national meetings were reviewed. DATA SYNTHESIS: The relative importance of LOC in the evaluation of concussion was reviewed in light of scientific and clinical evidence in the literature. Comments made by authors of concussion grading scales were considered in the development of expert consensus statements. CONCLUSIONS/RECOMMENDATIONS: The observation of LOC at the time of concussion must be viewed as reflecting a potentially worrisome traumatic brain injury. LOC is followed by more severe acute mental status abnormalities and carries a greater risk of intracranial pathology than concussion without LOC. Prolonged LOC represents a neurologic emergency, which may require neurosurgical intervention. Lingering symptoms of concussion, even without LOC, should be monitored closely and managed according to established guidelines for safe return to play.

Journal Article↗

PubMed1999

Neuropsychological impairment in amateur soccer players.

CONTEXT: Soccer players incur concussions during matches and training sessions, as well as numerous subconcussive blows to the head from impacts with the soccer ball (headers). The combination of soccer-related concussions and the number of headers may be a risk for chronic traumatic brain injury (CTBI). OBJECTIVE: To determine whether amateur soccer players have evidence of CTBI. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of 33 amateur soccer players and 27 amateur athletes involved in swimming and track (controls) in the Netherlands who underwent interviews and neuropsychological testing. MAIN OUTCOME MEASURES: Performance of soccer players vs controls on 16 neuropsychological tests having 27 outcomes. RESULTS: Compared with control athletes, amateur soccer players exhibited impaired performance on tests of planning (39% vs 13%; P=.001) and memory (27% vs 7%; P=.004). Among soccer players, 9 (27%) had incurred 1 soccer-related concussion and 7 (23%) had had 2 to 5 concussions during their career. The number of concussions incurred in soccer was inversely related to the neuropsychological performance on 6 of the neuropsychological tests. CONCLUSIONS: Our results indicate that participation in amateur soccer in general and concussion specifically is associated with impaired performance in memory and planning functions. Due to the worldwide popularity of soccer, these observations may have important public health implications.

Adult↗

PubMedDate not supplied

Post-traumatic and emotional symptoms in different subgroups of patients with mild head injury.

Post-concussional symptoms, such as headache, dizziness and irritability, are thought to result from the emotional stress associated with decreased cognitive performance after a head injury. A questionnaire-based investigation was carried out in 71 patients with mild head injury (MHI), using a heterogeneous item pool in order to study the interrelationships between traditional post-concussive complaints, cognitive problems, and more emotional and functional complaints. Factor analysis indicated that post-concussive symptoms loaded together with items on problems associated with decreased work performance and fatigability on a first factor, whereas psychovegetative and emotional complaints loaded together on a second factor. Two rating scales were constructed from the relevant items and were used to compare between subgroups of MHI patients and non-concussed controls. Patients with uncomplicated MHI had significantly higher scores than non-concussed subjects on the post-concussive-cognitive scale, but not on the emotional-vegetative scale. Patients with multiple head injuries or pre-existing emotional problems had higher scores on both the post-concussive-cognitive scale and the emotional-vegetative scale than MHI patients without a history of emotional problems. Reliable rating scales may be useful in multidiagnostic studies of MHI patients.

Adult↗

PubMedDate not supplied

[Multimodal evoked potentials in the early period after cranio-cerebral trauma].

In 83 patients aged 17-68 years somatosensory evoked potentials by median nerve stimulation, and visual and auditory evoked potentials were studied 5-28 days after craniocerebral trauma. Brain concussion was diagnoses in 43 cases on the basis of neurological examination, CT and duration of unconsciousness. In the remaining 40 cases brain contusion was diagnosed. In SSEP the latency was calculated of waves N9, N13, P16, N20, P22, N35 and P40: in the visual evoked potentials the latency of the P100 component, and in auditory evoked potential the latency of waves I, III and V, and interpeak latency I-III, III-V and I-V SSEP changes were found in 39% of cases of brain concussion and 52.9% of brain contusion cases. The abnormalities in both groups involved mainly the component of latency and deviation P100 of visual evoked potential P40 and N35. Prolongation of the latency of P100 of the visual evoked potential was recorded in 20% of patients with brain concussion and 16.7% with brain contusion. Auditory evoked potentials were abnormal in 10.3% of brain concussion and 26.5% of brain contusion cases. In 64 cases all three types of evoked potentials were studied and pathological changes in at least one of these types were found in 56.4% of brain concussion and 72% of brain contusion cases. The results show that as least in a part of cases diagnosed as brain concussion according to generally accepted criteria, central nervous system injury is present.

Adolescent↗

PubMed2001

Monitoring Resolution of Postconcussion Symptoms in Athletes: Preliminary Results of a Web-Based Neuropsychological Test Protocol.

OBJECTIVE: A new Web-based neuropsychological test was field tested to determine usefulness in detecting and monitoring resolution of symptoms after sport-related concussions and in providing objective information for return-to-play decisions. DESIGN AND SETTING: We obtained neuropsychological baseline data on all subjects. After concussion, subjects were administered alternate, equivalent follow-up tests until symptoms resolved. Follow-up testing typically occurred at 1- to 2-day intervals after the concussion. SUBJECTS: Baseline testing was obtained for 834 athletes as part of ongoing field trials. Subsequently, 26 athletes sustained concussions and were studied. MEASUREMENTS: We administered The Concussion Resolution Index (CRI) at baseline and alternate forms posttrauma. Follow-up tests included a self-report inventory of neurophysiologic symptoms. RESULTS: A total of 88% of patients were identified as symptomatic on initial postconcussion testing. The CRI appeared relatively resistant to retest effects, and multiple administrations tracked resolution of symptoms over short and extended time periods. CONCLUSIONS: Although the CRI is still in field trials, preliminary data indicate that the CRI may be a useful method for athletic trainers and other professionals to expeditiously track resolution of symptoms after sport-related concussion.

Journal Article↗

PubMed2001

Implementation of Neuropsychological Testing Models for the High School, Collegiate, and Professional Sport Settings.

OBJECTIVE: To review models for the use of neuropsychological testing in the management of sport-related concussion at various levels of competition. BACKGROUND: As we come to understand the natural history of sport-related concussive brain injury, it is increasingly evident that significant neurologic risks are associated with this type of injury. These risks include (1) acute intracranial pathology, (2) catastrophic brain swelling from second-impact syndrome, and (3) the potential risk for markedly prolonged recovery or permanent cognitive dysfunction associated with multiple concussions. DESCRIPTION: Neuropsychological testing has proved to be a useful tool in the medical management of sport-related concussion. In this paper, I describe a systematic model for the implementation of neuropsychological assessment of athletes at various levels of competition. CLINICAL ADVANTAGES: The systematic model was designed to incorporate state-of-the-art techniques for the detection and tracking of neurocognitive deficits associated with concussion into recently formulated guidelines for the medical management of sport-related concussion. Current applications of the model are discussed, as well as ongoing studies designed to elaborate the empirical underpinnings of the model and refine clinical decision making in this area.

Journal Article↗

PubMed1991

Dynamic changes in local cerebral glucose utilization following cerebral conclusion in rats: evidence of a hyper- and subsequent hypometabolic state.

Following cerebral concussion, in which there is no evidence of direct morphological damage, cells are exposed to an increase in extracellular potassium as well as an accumulation of calcium. This concussion-induced ionic flux most likely alters the cellular energy demands thereby modifying metabolic processes. To investigate the metabolic changes after cerebral concussion, local cerebral metabolic rates for glucose (lCMRglc) utilizing [14C]2-deoxy-D-glucose were studied in rats (n = 98; 250-300 g) immediately, 30 min, 6 h, 1, 2, 3, 5 and 10 days following a unilateral frontoparietal fluid percussion (F-P) injury (3.7-4.3 atm). Compared to sham controls, animals exhibited bilateral hypermetabolism immediately following brain injury. However, this effect was more pronounced in structures ipsilateral to the site of F-P and was especially marked for the cerebral cortex (46.6-30.1% higher than control) and hippocampus (90.1-84.4% higher than control). By 30 min post-trauma many ipsilateral regions still showed evidence of hypermetabolism, although their lCMRglc had subsided. Beginning as early as 6 h following injury many regions within the ipsilateral cortex and hippocampus went into a state of metabolic depression (16.4-33.7% of control) which lasted for as long as 5 days. These results indicate that, although not mechanically damaged from the insult, cells exposed to concussive injury dramatically alter their metabolic functioning. This period of post-concussive metabolic dysfunction may delineate a period of time, following injury, during which cells are functionally compromised.

Animals↗

PubMed2006

Automated Neuropsychological Assessment Metrics sports medicine battery.

This paper describes the development and ongoing validation of the ANAM-sports medicine battery (ASMB) for use in concussion surveillance and management. A review of previous research utilizing the ASMB highlights current issues in concussion surveillance including: tracking cognitive recovery, effect of previous concussion history on acute concussion presentation, and clinical decision making using computerized measures. ASMB interpretation using reliable change indices or impairment indices is highlighted. Future development of the ASMB is discussed as it relates to interpretation of ASMB, development of appropriate norms, and defining adequate baseline assessment. This includes the definition of practice effects, the effects of maturation on test performance and definition of adequate baseline assessment that clearly defines a subject's normal cognitive performance level. ASMB is ready for cautious introduction into clinical practice for use by neuropsychologists with experience in both sports concussion and computerized testing.

Athletic Injuries↗

PubMedDate not supplied

Relationship between postconcussion headache and neuropsychological test performance in high school athletes.

BACKGROUND: The relevance of headache to outcome after sports-related concussion is poorly understood. HYPOTHESES: High school athletes reporting headache approximately 1 week after injury will have significantly more other concussion symptoms and will perform more poorly on neuropsychological tests than athletes not experiencing headache. STUDY DESIGN: Prospective cohort study. METHODS: Study participants included 109 high school athletes who had sustained concussion and who were divided into two groups: those reporting headache 7 days after injury and those reporting no headaches. The two groups were compared regarding on-field markers of concussion severity at the time of injury and symptoms and neurocognitive test results collected via ImPACT, a computerized neuropsychological test battery and postconcussion symptom scale, at a mean of 6.8 days after injury. RESULTS: Athletes reporting posttraumatic headache demonstrated significantly worse performance on reaction time and memory ImPACT neurocognitive composite scores. These athletes also reported significantly more symptoms other than headache and were more likely to have demonstrated on-field anterograde amnesia. CONCLUSIONS: Findings suggest that any degree of postconcussion headache in high school athletes 7 days after injury is likely associated with an incomplete recovery after concussion.

Adolescent↗

PubMed2004

Analysis and evolution of head injury in football.

OBJECTIVE: To review head injury in football through historical, anatomic, and physiological analysis. METHODS: We obtained data from a thorough review of the literature. RESULTS: The reported incidence of concussion among high school football players dropped from 19% in 1983 to 4% in 1999. During the 1997 Canadian Football League season, players with a previous loss of consciousness in football were 6.15 times more likely to experience a concussion than players without a previous loss of consciousness (P < 0.05). Players with a previous concussion in football were 5.10 times more likely to experience a concussion than players without a previous concussion (P = 0.0001). With the implementation of National Operating Committee on Standards for Athletic Equipment standards, fatalities decreased by 74% and serious head injuries decreased from 4.25 per 100,000 to 0.68 per 100,000. CONCLUSION: Significant declines in both the incidence and severity of head injury have been observed. The enhanced safety records in football can be attributed to the application of more stringent tackling regulations as well as the evolving football helmet. The role of a neurosurgeon is critical in further head injury prevention and guidelines in sport.

Adolescent↗