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At least 19 recordsLinked to original sources
PubMed1988

Concussion. Acceleration limits causing concussion.

Among the many features common to all species of the animal kingdom is the transient loss of function of the nervous system as the result of a jarring blow, a phenomenon known as concussion. Understanding of concussion has been hampered by the lack of a uniform definition, with many authors including cases with gross, irreversible changes. The phenomenon occurs only with a blow that significantly accelerates and thus is best defined as "a transient disturbance of neuronal function as a result of acceleration." There must be a threshold beneath which no loss of function occurs and a ceiling beyond which changes are not reversible. Experiments with nonanesthetized frogs revealed that at 33 g only the occasional frog would be stunned. From 50 to 230 g, consciousness was always lost but rapidly regained and retained, while beyond, the loss was not always reversible. The time of functional loss was increasingly proportional to acceleration.

Acceleration↗
PubMed1990

Neuropsychological deficits in symptomatic minor head injury patients after concussion and mild concussion.

Recent studies have concluded that most individuals who sustain minor head injury are free of persistent neuropsychological dysfunction. Nevertheless, a subgroup of patients experience continuing post-concussive difficulties and neuropsychological deficits. This study examined 53 symptomatic minor head injury patients referred for neuropsychological evaluation between one and 22 months after injury. These individuals performed significantly poorer than uninjured controls on four of eight neuropsychological tests. Patients who lost consciousness during injury obtained test scores similar to persons who experienced disorientation or confusion but no loss of consciousness. The results indicate that minor head injury patients who report post-concussive symptoms possess measurable neuropsychological deficits and the severity of these deficits is independent of neurological status immediately following injury.

Adult↗
PubMed1989

[Early pathophysiological findings in experimental concussion in rabbits].

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)

Animals↗
PubMed1976

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

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

Animals↗
PubMed1988

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

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

Adolescent↗
PubMed2026

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

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

Humans↗
PubMedDate not supplied

Concussions in college football. A multivariate analysis.

The purpose of this investigation was to examine risk patterns of concussion in college football. Multivariate models were used to interpret the data. Specifically, log-linear modeling and analysis techniques were incorporated into the investigation. An average of 49 college teams were studied over the 8 year period 1975 to 1982. This represented over 36,000 athlete-seasons and 395 team-seasons. The data selected were limited to 1,005 game-related concussions. The general hypotheses tested were the null hypothesis that the variables of team (offense and defense), player position, situation (rushing and passing), and activity (block and tackle) had no effect on the occurrence of these game-related concussions. It was found that concussions were a persistent and regular but relatively infrequent type of injury in college football. Concussions accounted for 75% of the total number of injuries on or about the head. The injuries were examined relative to player position, situation, and activity using a log-linear modeling technique, with interactions among the variables also established. The contribution of each variable was not always equal or completely interactive. Generally, the highest risk of concussion was associated with offensive and defensive players involved in a block on a rushing play. Specifically, running backs demonstrated the highest risk of concussion, regardless of activity. The lowest risk was for offensive linemen and quarterbacks while blocking on any type of play. On defense, the secondary exhibited the highest risk of concussion while being blocked on a running play. Similarly, linemen experienced their greatest risk while being blocked on plays run inside the tackle.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1985

[Early EEG in 300 cerebral concussions].

The EEGs of 300 concussed patients were examined at the last 48 h after trauma; 166 were younger than 20 years old and 134 were between 20 and 40 years old. Amongst the youngest group 145 cases had a benign concussion with 24% alterations, and 21 cases had a mild concussion with 81% alterations. Amongst the oldest group, 93 cases had a benign concussion with 15% alterations and 41 cases had a mild concussion with 41% alterations. The mostly transient EEG abnormalities are slowing, focal abnormalities or generalized bursts. Slowing is the most frequent abnormality in the youngest and focal abnormalities are most frequently observed in the mild concussion group.

Adult↗
PubMed1977

[Surgery of concussion foci in the cerebral hemispheres].

On the basis of observations in 144 patients operated on because of severe cerebral concussions, the importance of primary and secondary removal of the concussion focus is stressed. The diagnosis is made by means of EEG, angiography, and echo encephalography. Examinations of the concussion region with clearance etc. showed that the immediate vicinity of the cerebral lesion exhibits a considerably reduced blood flow which, due to the stimulus of the concussion, will further decrease within the following days. After six days, the blood supply stabilises in the zone of the oscillating reaction. The enlargement of the zone of necrosis intensifies the intracranial increase in pressure and can only be avoided by the removal of the concussion. Resection is carried out subpial in order to isolate the cerebral tissue from the dura mater. Lethality: With solitary concussion foci 22%, in case of combination with intracranial haematoma 60%, with multiple foci 67%, total 46%.

Action Potentials↗
PubMedDate not supplied

Coma associated with flaccidity produced by fluid-percussion concussion in the cat. II: Contribution of activity in the pontine inhibitory system.

In the preceding paper we reported that concussive levels of fluid-percussion head injury can produce transient flaccidity of postural muscles associated with other indices of coma. This reversible coma associated with flaccidity follows an initial period of generalized areflexia and occurs in the absence of EEG slow waves. The present study investigated the physiological mechanisms underlying the flaccidity following concussive head injury be recording dorsal and ventral root potentials of the spinal cord. Studies indicated that, during the initial period of generalized areflexia, afferent input transmission was depressed although the excitability of motoneuronal pools was increased. In contrast, during periods of flaccidity, spinal cord somatomotor functions were depressed while transmission of afferent inputs was recovering. Systematic transection of the brain stem showed that activity within structures lying between collicular and midpontine levels is necessary to produce this latter condition. Cholinergic activation of pontine inhibitory areas within this same region of the rostral pons can produce profound descending inhibitory influences on postural somatomotor function in conjunction with other features of coma including suppression of eye-opening responses. Such effects occur without EEG slow waves. Moreover, other data indicate that local rates of glucose utilization within this pontine inhibitory area increase following concussive head injury. Thus, it is possible that a predominance of activity within the pontine inhibitory area could provide at least one neural basis for the reversible comatose state following concussive head injury characterized by close association between flaccidity and other indices of coma. Possible relationships of these data to clinically observed features of concussion are discussed.

Animals↗
PubMed1990

Spinal cord concussion.

The hallmark of concussion injuries of the nervous system is the rapid and complete resolution of neurological deficits. Cerebral concussion has been well studied, both clinically and experimentally. In comparison, spinal cord concussion (SCC) is poorly understood. The clinical and radiological features of 19 SCC injuries in the general population are presented. Spinal cord injuries were classified as concussions if they met three criteria: 1) spinal trauma immediately preceded the onset of neurological deficits; 2) neurological deficits were consistent with spinal cord involvement at the level of injury; and 3) complete neurological recovery occurred within 72 hours after injury. Most cases involved young males, injured during athletics or due to falls. Concussion occurred at the two most unstable spinal regions, 16 involving the cervical spinal and three the thoracolumbar junction. Fifteen cases presented with combined sensorimotor deficits, while four exhibited only sensory disturbances. Many patients showed signs of recovery with the first few hours after injury and most had completely recovered within 24 hours. Only one case involved an unstable spinal injury. There was no evidence of ligamentous instability, spinal stenosis, or canal encroachment in the remaining 18 cases. Two patients, both children, suffered recurrent SCC injuries. No delayed deterioration or permanent cord injuries occurred. Spinal abnormalities that would predispose the spinal cord to a compressive injury were present in only one of the 19 cases. This suggests that, as opposed to direct cord compression, SCC may be the result of an indirect cord injury. Possible mechanisms are discussed.

Adolescent↗
PubMed2026

Near and distance vergence facility provides complementary clinical information in concussion-related convergence insufficiency.

PURPOSE: To compare near and distance vergence facility testing in adolescents and young adults with concussion-related convergence insufficiency and evaluate changes following office-based vergence/accommodative therapy (OBVAM). METHODS: This secondary analysis of the CONCUSS randomized clinical trial evaluated vergence facility at near (40&#xa0;cm) and distance (4&#xa0;m) using a 12&#x394; base out/3&#x394; base in prism flipper. Participants aged 11-25&#xa0;years with concussion-related convergence insufficiency were randomized to immediate or 6&#xa0;weeks delayed OBVAM. Vergence facility was assessed at baseline, outcome time 1 assessment (after 12 therapy sessions for the immediate group and 6&#xa0;weeks of watchful waiting for the delayed group), and outcome time 2 assessment (after both groups completed 16 therapy sessions). Agreement between near and distance vergence facility classifications was evaluated, and treatment-related changes were compared between groups. RESULTS: Of the 106 enrolled participants, 102 completed all study visits. At baseline, the near and distance vergence facility classifications demonstrated substantial discordance. Among 101 participants with both measures available, 49 demonstrated reduced distance vergence facility despite normal near vergence facility, whereas only two showed the opposite pattern (Cohen's &#x3ba;&#xa0;=&#xa0;0.12; p&#xa0;<&#xa0;0.0001). Vergence facility improved following therapy in both treatment groups, with larger early improvements in the immediate-treatment group. CONCLUSIONS: Near and distance vergence facility testing provided complementary rather than interchangeable clinical information in adolescents and young adults with concussion-related convergence insufficiency. Both measures improved following vergence/accommodative therapy, supporting consideration of both testing distances in clinical assessment.

Humans↗
PubMed1991

Concussion in sports. Guidelines for the prevention of catastrophic outcome.

Concussion (defined as a traumatically induced alteration in mental status, not necessarily with loss of consciousness) is a common form of sports-related injury too often dismissed as trivial by physicians, athletic trainers, coaches, sports reporters, and athletes themselves. While head injuries can occur in virtually any form of athletic activity, they occur most frequently in contact sports, such as football, boxing, and martial arts competition, or from high-velocity collisions or falls in basketball, soccer, and ice hockey. The pathophysiology of concussion is less well understood than that of severe head injury, and it has received less attention as a result. We describe a high school football player who died of diffuse brain swelling after repeated concussions without loss of consciousness. Guidelines have been developed to reduce the risk of such serious catastrophic outcomes after concussion in sports.

Adolescent↗
PubMed1975

Cumulative effect of concussion.

Twenty young adults were studied after a second concussion. The rate at which they were able to process information was reduced more than in controls who had been concussed only once, and they took longer to recover than the controls. The effects of concussion seem to be cumulative, and this has important implications for sports where concussion injury is common.

Adolescent↗
PubMed1988

Regional rates of glucose utilization in the cat following concussive head injury.

Injections of [14C]-deoxyglucose ([14C]DG) were used to study rates of local cerebral glucose utilization (LCGU) in control cats and cats subjected to concussive brain injury produced by a fluid-percussion device. Studies in separate groups of animals demonstrated that the injury level selected produced transient behavioral suppression probably associated with traumatic disturbances of consciousness. LCGU was sampled near the site of fluid-percussion injury and more caudally in pontine regions. Histopathologic studies examined the possibility of hemorrhage, contusion, or breakdown of the blood-brain barrier in regions within which LCGU was calculated. These studies yielded analyses indicating that (1) the [14C]DG technique can be applied usefully to infer changes in regional levels of brain activity after concussion, (2) concussive injury produces changes in brain function that differ reliably across various regions of the central nervous system and may include both depression and focal activation of specific brain sites. Data are discussed that suggest that changes in brain activity in specific regions indicated by changes in LCGU could contribute to acute neurologic disturbances after concussion including unconsciousness.

Animals↗
PubMed1988

Cognitive evoked potential (P300): a metric for cerebral concussion.

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.

Adolescent↗