Diffusion tensor tractography characteristics of axonal injury in concussion/mild traumatic brain injury

The main advantage of diffusion tensor tractography is that it allows the entire neural tract to be evaluated.In addition,configurational analysis of reconstructed neural tracts can indicate abnormalities such as tearing,narrowing,or discontinuations,which have been used to identify axonal injury of neural tracts in concussion patients.This review focuses on the characteristic features of axonal injury in concussion or mild traumatic brain injury(m TBI)patients through the use of diffusion tensor tractography.Axonal injury in concussion(m TBI)patients is characterized by their occurrence in long neural tracts and multiple injuries,and these characteristics are common in patients with diffuse axonal injury and in concussion(m TBI)patients with axonal injury.However,the discontinuation of the corticospinal tract is mostly observed in diffuse axonal injury,and partial tearing and narrowing in the subcortical white matter are frequently observed in concussion(m TBI)patients with axonal injury.This difference appears to be attributed to the observation that axonal injury in concussion(m TBI)patients is the result of weaker forces than those producing diffuse axonal injuries.In addition,regarding the fornix,in diffuse axonal injury,discontinuation of the fornical crus has been frequently reported,but in concussion(m TBI)patients,many collateral branches form in the fornix in addition to these findings in many case studies.It is presumed that the impact on the brain in TBI is relatively weaker than that in diffuse axonal injury,and that the formation of collateral branches occurs during the fornix recovery process.Although the occurrence of axonal injury in multiple areas of the brain is an important feature of diffuse axonal injury,case studies in concussion(m TBI)have shown that axonal injury occurs in multiple neural tracts.Because axonal injury lesions in m TBI patients may persist for approximately 10 years after injury onset,the characteristics of axonal injury in concussion(m TBI)patients,which are reviewed and categorized in this review,are expected to serve as useful supplementary information in the diagnosis of axonal injury in concussion(m TBI)patients.     

Epileptische Anf?lle nach leichten Sch?del-Hirn-Traumen

Formerly it was assumed that cerebral concussion and mild traumatic brain injury (MTBI) were not followed by posttraumatic epilepsy. Modern neuroimaging findings revealed, however, that a ??mild?? traumatic brain injury not infrequently only seems to be mild and MTBI may be followed by localized contusions and a diffuse axonal injury. It is well known that brain contusion may be followed by seizures but the question whether an isolated diffuse axonal injury may also be followed by seizures has to be clarified by further studies. Several studies have demonstrated an increased risk of epilepsy after MTBI. Whether repeated concussive or subconcussive blows cause permanent or cumulative brain injury is a complex and controversial question. The posttraumatic genesis of seizures after MTBI probably has to be accepted in medicolegal expert opinions more often than previously. The arguments arguing for or against a relationship between MTBI and epilepsy are discussed.     

The pathobiology of moderate diffuse traumatic brain injury as identified using a new experimental model of injury in rats

Experimental models of traumatic brain injury have been developed to replicate selected aspects of human head injury, such as contusion, concussion, and/or diffuse axonal injury. Although diffuse axonal injury is a major feature of clinical head injury, relatively few experimental models of diffuse traumatic brain injury (TBI) have been developed, particularly in smaller animals such as rodents. Here, we describe the pathophysiological consequences of moderate diffuse TBI in rats generated by a newly developed, highly controlled, and reproducible model. This model of TBI caused brain edema beginning 20 min after injury and peaking at 24 h post-trauma, as shown by wet weight/dry weight ratios and diffusion-weighted magnetic resonance imaging. Increased permeability of the blood-brain barrier was present up to 4 h post-injury as evaluated using Evans blue dye. Phosphorus magnetic resonance spectroscopy showed significant declines in brain-free magnesium concentration and reduced cytosolic phosphorylation potential at 4 h post-injury. Diffuse axonal damage was demonstrated using manganese-enhanced magnetic resonance imaging, and intracerebral injection of a fluorescent vital dye (Fluoro-Ruby) at 24-h and 7-day post-injury. Morphological evidence of apoptosis and caspase-3 activation were also found in the cerebral hemisphere and brainstem at 24 h after trauma. These results show that this model is capable of reproducing major biochemical and neurological changes of diffuse clinical TBI.     

Concentration of brain free magnesium following severe brain injury correlates with neurologic motor outcome

Recent studies have shown that brain intracellular free magnesium concentration significantly declines following mild to severe, focal and diffuse traumatic brain injury. However, little is known about how this decline or its attenuation by magnesium salts relates to neurologic outcome. This study uses phosphorus magnetic resonance spectroscopy and rotarod tests to characterise the relationship between brain free magnesium concentration and neurologic motor scores following severe, diffuse traumatic brain injury in rats. An intravenous bolus of MgSO(4) or MgCl(2) (100 mumoles/kg) at 30 min following brain injury significantly attenuated the postinjury brain free magnesium decline. This improved magnesium homeostasis was sustained for the entire postinjury monitoring period (1 week). There was an associated significant improvement in neurologic motor function in magnesium treated rats. Moreover, the brain free magnesium concentration over the one week period was linearly correlated with the neurologic motor function (r=0.70; P < 0.001) as assessed on a daily basis. We propose that brain free magnesium concentration may be used as a prognostic indicator of neurologic motor function after traumatic brain injury.     

脑震荡综合征与功能性核磁共振成像

脑震荡综合征是轻型外伤性颅脑损伤后常见的一组临床症候群。虽然大多数轻型颅脑损伤患者在一个月之内能治愈,但是部分患者在脑外伤后会持续存在脑震荡综合征达数月或数年,甚至终生。目前。关于脑震荡综合征的病理改变还不是很清楚,但是大家普遍认为脑震荡结局是功能的改变而不是解剖结构的改变。因此,应用功能性核磁共振技术就能发现结构性影像所不能发现的脑组织功能变化,对轻型外伤性颅脑损伤作出及时而准确的诊断。本文就功能性核磁共振成像技术在脑震荡综合征中的应用做一综述。     

Contributions of functional magnetic resonance imaging (fMRI) to sport concussion evaluation

Mild traumatic brain injury (mTBI) in contact sport is a problem of such magnitude that improved approaches to diagnosis, investigation and management are urgent. Concussion has traditionally been described as a transient, fully reversible, cerebral dysfunction. However, this seemingly 'mild' injury sometimes results in long-lasting and disabling post-concussion symptoms (PCS) and abnormal neuropsychological profiles characteristic of frontal and/or temporal lobe dysfunction. At present, the pathological changes following concussion remain unclear, but it is now widely accepted that concussion results mainly in functional disturbance rather than structural damage. Therefore, functional imaging techniques can help in demonstrating brain abnormalities undetectable by structural imaging methods. This paper will review the use of functional magnetic resonance imaging (fMRI) in studies of concussion. Our existing and ongoing fMRI studies will be described as examples to highlight the potential and contribution of this non-invasive functional neuroimaging technique in the assessment of sports-related concussion and its management.     

180例颅脑外伤后精神障碍的鉴定结果分析

目的探讨颅脑外伤后精神障碍的临床类型及相关因素。方法收集180例颅脑外伤后司法鉴定案例资料,并对精神障碍的临床类型及相关因素进行分析。结果精神障碍的鉴定诊断类型为:器质性遗忘综合征、器质性人格改变、器质性智能损害、器质性神经症样症状和器质性精神症状。以颞叶、额叶、弥漫性损伤多见,共163例,且CT显示多有颞叶、额叶软化灶等异常,共123例。影响智能损害的因素为颞叶或额叶损伤、外伤程度严重,CT及EEG异常。器质性神经症样症状多见于女性,外伤程度轻,多无弥漫性损伤,CT未见明显异常。结论颅脑外伤后精神障碍多见于颞叶、额叶、弥漫性损伤;智能损害者外伤程度严重,EEG异常率高;器质性神经症样症状与轻度脑损伤有关。     

Rehabilitation interventions after mild head injury

PURPOSE OF REVIEW: This review examines current management and rehabilitation strategies for mild traumatic brain injury, with emphasis on the need to address multiple potential causative factors in order to enhance outcomes and to conduct more controlled efficacy studies. RECENT FINDINGS: Whilst most individuals who sustain mild traumatic brain injury make a good recovery, a proportion experience significant ongoing disability. In some cases this is due to diffuse axonal injury and cognitive impairment, but in others symptoms are exacerbated by factors such as pain, stress, personality issues or litigation, or in children, previous head injury, behavioural or learning difficulties. Provision of information early after injury results in reduced symptom reporting in adults and children. There is also a need, however, to address these other factors in treatment. Psychological therapy using a cognitive behavioural approach may be helpful, but controlled evaluations of such interventions have been lacking. Recent uncontrolled studies have examined the impact of computer-mediated interventions to remediate visual and verbal processing and oculomotor problems and the impact of quantitative electroencephalography. More rigorous efficacy studies of these approaches are needed. Guidelines for management of sports-related concussion and timing of return to play also require a more solid scientific basis. SUMMARY: The evidence base for management of mild traumatic brain injury is still very limited. There is a need to conduct more carefully controlled prospective studies and examine the influence of factors not directly related to the brain injury as a basis for formulating more uniform management guidelines.     

Historical Perspectives on Postconcussion Symptoms

Self-reported symptoms that follow concussion without detectable structural brain injury have historically been described by a variety of syndromes. These syndromes are reviewed beginning with Erichsen's concept of spinal concussion and ending with Gronwall's finding of attentional deficits in the early stages after injury. The period covered is 1866 through 1974 and the syndromes reviewed include: traumatic neurasthenia (railway hysteria), vasomotorischen symptomencomplex, terror neurosis, head-wound syndrome, postcontusional syndrome, postconcussional syndrome, psychoneurosis, accident neurosis, and posttraumatic syndrome. These involved organic (structural brain injury), emotional (anxiety and depression), motivational (malingering),and personality (predisposing) explanations.     

Gait and Glasgow Coma Scale scores can predict functional recovery in patients with traumatic brain injury

Fifty-one patients with mild(n = 14),moderate(n = 10) and severe traumatic brain injury(n = 27) received early rehabilitation.Level of consciousness was evaluated using the Glasgow Coma Score.Functional level was determined using the Glasgow Outcome Score,whilst mobility was evaluated using the Mobility Scale for Acute Stroke.Activities of daily living were assessed using the Barthel Index.Following Bobath neurodevelopmental therapy,the level of consciousness was significantly improved in patients with moderate and severe traumatic brain injury,but was not greatly influenced in patients with mild traumatic brain injury.Mobility and functional level were significantly improved in patients with mild,moderate and severe traumatic brain injury.Gait recovery was more obvious in patients with mild traumatic brain injury than in patients with moderate and severe traumatic brain injury.Activities of daily living showed an improvement but this was insignificant except for patients with severe traumatic brain injury.Nevertheless,complete recovery was not acquired at discharge.Multiple regression analysis showed that gait and Glasgow Coma Scale scores can be considered predictors of functional outcomes following traumatic brain injury.     

Routine and quantitative EEG in mild traumatic brain injury.

This article reviews the pathophysiology of mild traumatic brain injury, and the findings from EEG and quantitative EEG (QEEG) testing after such an injury. Research on the clinical presentation and pathophysiology of mild traumatic brain injury is reviewed with an emphasis on details that may pertain to EEG or QEEG and their interpretation. Research reports on EEG and QEEG in mild traumatic brain injury are reviewed in this setting, and conclusions are drawn about general diagnostic results that can be determined using these tests. QEEG strengths and weaknesses are reviewed in the context of factors used to determine the clinical usefulness of proposed diagnostic tests. Clinical signs, symptoms, and the pathophysiologic axonal injury and cytotoxicity tend to clear over weeks or months after a mild head injury. Loss of consciousness might be similar to a non-convulsive seizure and accompanied subsequently by postictal-like symptoms. EEG shows slowing of the posterior dominant rhythm and increased diffuse theta slowing, which may revert to normal within hours or may clear more slowly over many weeks. There are no clear EEG or QEEG features unique to mild traumatic brain injury. Late after head injury, the correspondence is poor between electrophysiologic findings and clinical symptoms. Complicating factors are reviewed for the proposed commercial uses of QEEG as a diagnostic test for brain injury after concussion or mild traumatic brain injury. The pathophysiology, clinical symptoms and electrophysiological features tend to clear over time after mild traumatic brain injury. There are no proven pathognomonic signatures useful for identifying head injury as the cause of signs and symptoms, especially late after the injury.     

An overview of concussion in sport

Concussion is a sudden-onset, transient alteration of consciousness due to a combination of functional and structural brain disturbances following a physical impact transmitted to the brain. It is a common, although likely underreported, condition encountered in a wide range of sports. In the Australian Football League, concussion is estimated to occur at a rate of approximately seven injuries per team per season. While many instances of concussion are clinically mild, there is emerging evidence that a player’s full recovery from a concussive injury may be more delayed and the sequelae of repeated concussions more severe than previously thought. In this light, a more conservative and rigorous approach to managing players with concussive injuries may be warranted, with the guiding principle being the player’s immediate and long-term welfare. The current paper reviews the sports concussion literature. The definition, epidemiology, aetiology, pathophysiology, structural pathology, clinical features, assessment and investigation, treatment principles, and short-term and potential long-term complications of concussion are discussed. Special considerations in paediatric sports concussion, and the return-to-play implications of immediate, evolving and repetitive brain injury are also considered, as are the emerging concept and possible implications of subconcussive injury.     

脑中线区外伤性出血的治疗与预后

目的 探讨创伤性脑中线区出血的诊断、治疗和预后。方法 选择经CT证实脑中线区域有出血灶的重型颅脑损伤住院患12例。测算血肿体积和血肿距中线距离。急性期后隔日腰椎穿刺测CSF压力，计算平均CSF压力。采用Glasgow预后评定方法评估患预后。结果 预后不良4例(死亡1例、重残1例、中残2例)，恢复良好8例。平均腰椎穿刺CSF压力以及血肿体积在恢复良好和预后不良患组间无明显统计学差异，但预后不良组的血肿距中线距离则明显短于恢复良好组。结论 创伤性脑中线区域出血符合脑弥漫性轴索损伤(diffuse axonal injury，DAI)的病理改变，血肿距中线距离与患预后密切相关。     

创伤性颅脑损伤后血钠紊乱的危险因素与预后

目的探讨创伤性颅脑损伤发生血钠紊乱的危险因素以及对预后的影响。方法回顾性分析80例中、重型颅脑损伤病例资料。分析血钠紊乱的发生率,外伤性脑损伤后首次CT扫描时的伤情表现和意识状态。结果 36例发生血钠紊乱,20例表现为高钠血症,16例表现为低钠血症。血钠紊乱在硬膜下血肿、脑内血肿和弥散性轴索损伤的病例中发生率更高。弥漫性脑损伤的病例血钠紊乱的发生率比局限性脑挫裂伤组高。结论弥漫性脑损伤病例血钠紊乱的发生率比较高。局限性脑损伤与血钠紊乱的比例并没有相关性。     

The young brain and concussion: imaging as a biomarker for diagnosis and prognosis

Concussion (mild traumatic brain injury (mTBI)) is a significant pediatric public health concern. Despite increased awareness, a comprehensive understanding of the acute and chronic effects of concussion on central nervous system structure and function remains incomplete. Here we review the definition, epidemiology, and sequelae of concussion within the developing brain, during childhood and adolescence, with current data derived from studies of pathophysiology and neuroimaging. These findings may contribute to a better understanding of the neurological consequences of traumatic brain injuries, which in turn, may lead to the development of brain biomarkers to improve identification, management and prognosis of pediatric patients suffering from concussion.     

Traumatic brain injury and grey matter concentration: a preliminary voxel based morphometry study

BACKGROUND: Magnetic resonance imaging (MRI) studies have shown diffuse cerebral atrophy following traumatic brain injury. In the past, quantitative volumetric analysis of these changes was carried out by manually tracing specific regions of interest. In contrast, voxel based morphometry (VBM) is a fully automated technique that allows examination of the whole brain on a voxel by voxel basis. OBJECTIVE: To use VBM to evaluate changes in grey matter concentration following traumatic brain injury. METHODS: Nine patients with a history of traumatic brain injury (ranging from mild to severe) about one year previously were compared with nine age and sex matched healthy volunteers. T1 weighted three dimensional MRI images were acquired and then analysed with statistical parametric mapping software (SPM2). The patients with traumatic brain injury also completed cognitive testing to determine whether regional grey matter concentration correlated with a measure of attention and initial injury severity. RESULTS: Compared with controls, the brain injured patients had decreased grey matter concentration in multiple brain regions including frontal and temporal cortices, cingulate gyrus, subcortical grey matter, and the cerebellum. Decreased grey matter concentration correlated with lower scores on tests of attention and lower Glasgow coma scale scores. CONCLUSIONS: Using VBM, regions of decreased grey matter concentration were observed in subjects with traumatic brain injury compared with well matched controls. In the brain injured patients, there was a relation between grey matter concentration and attentional ability.     

重型颅脑损伤术中急性脑膨出应对措施

目的探讨重型颅脑损伤手术中急性脑膨出的机理与处理措施。方法回顾性分析58例在颅脑手术过程中发生脑膨出的重型颅脑损伤患者临床资料,影像学资料及应对措施,采用标准大骨瓣减压、过度通气、咬除颅底骨质、阶梯性减压、及时复查颅脑CT等综合措施。结果术后随访三月按GOS评定预后恢复良好19例、轻残11例、重残11例、植物生存5例、死亡12例。迟发性血肿(63.8%),弥漫性脑肿胀(27.6%)及脑梗死(8.6%)是重型颅脑损伤手术中急性脑膨出的主要原因。结论对重型颅脑损伤手术中急性脑膨出的患者要正确判断,区别原因采取相应的措施。     

Somatosensory evoked fields in comatose survivors after severe traumatic brain injury.

OBJECTIVE: To evaluate the cortical function quantitatively in patients in the chronic phase of severe traumatic brain injury. METHODS: Thirteen patients with severe traumatic brain injury due to traffic accident followed by persistent consciousness disturbance and disability were studied. Somatosensory evoked magnetic fields (SEFs) for unilateral median nerve stimulation were measured using a whole-head magnetoencephalography system. The latency and electrical current dipole (ECD) moment for the N20m, P30m, N45m and P60m components were calculated and compared with those of 14 age-matched healthy adults. RESULTS: The peak latency of N20m was longer (P<0.05) and those of P30m and N45m were shorter (P<0.01) in the patients than in normal adults. The ECD moment of N20m and P30m was smaller and that of N45m and P60m was larger in the patients than in normal adults (P<0.01). CONCLUSIONS: These results can be explained by the hypothesis that diffuse brain injury induces decreased and delayed input of the somatosensory afferent and compensational amplification of the response in the primary somatosensory cortex. Middle-latency SEFs may be applicable as a cortical functional measure for patients with severe traumatic brain injury.     

Diffuse axonal injury and traumatic coma in the primate

Traumatic coma was produced in 45 monkeys by accelerating the head without impact in one of three directions. The duration of coma, degree of neurological impariment, and amount of diffuse axonal injury (DAI) in the brain were directly related to the amount of coronal head motion used. Coma of less than 15 minutes (concussion) occurred in 11 of 13 animals subjected to sagittal head motion, in 2 of 6 animals with oblique head motion, and in 2 of 26 animals with full lateral head motion. All 15 concussed animals had good recovery, and none had DAI. Conversely, coma lasting more than 6 hours occurred in none of the sagittal or oblique injury groups but was present in 20 of the laterally injured animals, all of which were severely disabled afterward. All laterally injured animals had a degree of DAI similar to that found in severe human head injury. Coma lasting 16 minutes to 6 hours occurred in 2 of 13 in the sagittal group, 4 of 6 in the oblique group, and 4 of 26 in the lateral group; these animals had less neurological disability and less DAI than when coma lasted longer than 6 hours. These experimental findings duplicate the spectrum of traumatic coma seen in human beings and include axonal damage identical to that seen in severe head injury in humans. Since the amount of DAI was directly proportional to the severity of injury (duration of coma and quality of outcome), we conclude that axonal damage produced by coronal head acceleration is a major cause of prolonged traumatic coma and its sequelae.