Attentional control and slowness of information processing after severe traumatic brain injury

Attention is a basic cognitive function and a prerequisite for other cognitive processes and is frequently impaired after traumatic brain injury. In the present study, 29 severe traumatic brain injury patients and 30 control subjects completed a battery of three neuropsychological tests of attention (WCST, TMT, Stroop). The aim was to clarify the attentional mechanisms underlying tests performance and to explore the types of attentional impairment after severe traumatic brain injury. Significant differences were found between the control and clinical groups in almost all measures. However, some of these differences disappeared when the speed of information processing was controlled using covariance analysis. In addition, a factor analysis revealed a four-factor solution explaining 89.6% of the variance in the data, i.e. cognitive flexibility, speed of processing, interference and working memory. This result supports the view of at least four different subprocesses of attentional control underlie test performance and allows one to differentiate between high- and low-level processes. The implications for neuropsychological assessment and rehabilitation are discussed.     

Wisconsin Card Sorting Test in chronic severe traumatic brain injury: factor structure and performance subgroups

Objective : The present study further investigated the factor structure of the WCST in traumatic brain injury and investigated the construct validity and relationships among scores through the use of cluster analysis.

Design : Participants were 68 survivors of chronic severe TBI, living at a residential brain injury rehabilitation facility.

Methods and procedures : Three sets of WCST scores were submitted to factor analysis; the regression factor scores based on the standard WCST were examined using cluster analysis.

Results : Factor analysis of the WCST raw scores replicated the three-factor solution which has been previously reported. When t -scores were analysed, two-to-four-factor solutions could be justified. The cluster analysis identified four groups representing: (1) impaired response maintenance; (2) problem-solving deficits; (3) intact WCST performance; and (4) deficits in set shifting.

Conclusions : The results support previous research indicating that the WCST is sensitive to three distinct cognitive processes: cognitive flexibility, problem-solving, and response maintenance. However, unlike the cognitive processes underlying WCST performance, the WCST scores representing these processes are not independent. The potential clinical relevance of these results is discussed.     

Cognitive deficits following traumatic brain injury produced by controlled cortical impact.

Traumatic brain injury produces significant cognitive deficits in humans. This experiment used a controlled cortical impact model of experimental brain injury to examine the effects of brain injury on spatial learning and memory using the Morris water maze task. Rats (n = 8) were injured at a moderate level of cortical impact injury (6 m/sec, 1.5-2.0 mm deformation). Eight additional rats served as a sham-injured control group. Morris water maze performance was assessed on days 11-15 and 30-34 following injury. Results revealed that brain-injured rats exhibited significant deficits (p less than 0.05) in maze performance at both testing intervals. Since the Morris water maze task is particularly sensitive to hippocampal dysfunction, the results of the present experiment support the hypothesis that the hippocampus is preferentially vulnerable to damage following traumatic brain injury. These results demonstrate that controlled cortical impact brain injury produces enduring cognitive deficits analogous to those observed after human brain injury.     

Unusually rapid and severe cognitive deterioration after mild traumatic brain injury

A 56-year-old man (AB) presented with dramatic cognitive deterioration following a mild traumatic brain injury. There was no indication of severe brain injury or significant anoxic encephalopathy. Detailed history indicated no significant pre-morbid cognitive deficits. His pre-injury psychosocial and occupational functioning was intact. Cognition functioning was impaired immediately post-injury and remained impaired. Neuropsychological examination at 8 months post-injury showed severe cognitive deficits. The cognitive profile was consistent with Alzheimer's disease. MRI at 1-year post-injury showed minor ischaemic changes not consistent with hypoxic injury and insufficient to explain his cognitive problems. Early SPECT was consistent with a diagnosis of Alzheimer's disease and a repeat SPECT showed a significant deterioration in an Alzheimer pattern. AB was seen for detailed serial neuropsychological examination over a 3-year period, which revealed clear evidence of cognitive deterioration consistent with Alzheimer's disease. AB is presented as an unusual case of rapid progressive AD following a mild head injury.     

Modification of function in head-injured patients with Sinemet

The effects of Sinemet (levodopa + carbidopa) on 12 patients with head injury with diffuse brain damage were evaluated. All patients had suffered moderate to severe traumatic brain injury resulting in physical, cognitive, communicative, emotional and behavioural deficits. All patients had plateaued in their rehabilitation programmes for more than 2 weeks before initiation of Sinemet. All patients showed functional cognitive and behavioural improvement with Sinemet. The degree of improvement appears to depend on the pre-treatment condition and the time between injury and treatment. Larger controlled studies are recommended.     

Changes in fMRI activation following rehabilitation of reading and visual processing deficits in subjects with traumatic brain injury

In this case series fMRI was used to examine activation patterns during presentation of a reading comprehension (RC) task in three adult subjects with a history of severe traumatic brain injury (TBI). These subjects received cognitive rehabilitation therapy (CRT) for visual processing and acquired reading deficits. fMRI and neuropsychological testing occurred pre- and post-rehabilitation. The study's objective was to evaluate the neurobiological changes using fMRI occurring with CRT and to compare these results to repeat fMRI in matched control subjects. While improvements in neuropsychological testing occurred post-CRT, diffuse and variable activation patterns in the subjects with TBI were still demonstrated when compared to the control subjects repeat imaging. Multiple networks exist to accomplish the complex task of sentence reading and rehabilitation of the cognitive components of reading, such as visual processing; in subjects with TBI, can alter the activation pattern demonstrated during reading comprehension in subjects many years post-injury. This is the first demonstration of changes in network activation patterns post-CRT in patients with severe, chronic TBI on an fMRI task shown to have imaging stability in a normal control sample.     

Changes in fMRI activation following rehabilitation of reading and visual processing deficits in subjects with traumatic brain injury

In this case series fMRI was used to examine activation patterns during presentation of a reading comprehension (RC) task in three adult subjects with a history of severe traumatic brain injury (TBI). These subjects received cognitive rehabilitation therapy (CRT) for visual processing and acquired reading deficits. fMRI and neuropsychological testing occurred pre- and post-rehabilitation. The study's objective was to evaluate the neurobiological changes using fMRI occurring with CRT and to compare these results to repeat fMRI in matched controlsubjects. While improvements in neuropsychologicaltesting occurred post-CRT, diffuse and variable activation patterns in the subjects with TBI were still demonstrated when compared to the control subjects repeat imaging. Multiple networks exist to accomplish the complex task of sentence reading and rehabilitation of the cognitive components of reading, such as visual processing; in subjects with TBI, can alter the activation pattern demonstrated during reading comprehension in subjects many years post-injury. This is the first demonstration of changes in network activation patterns post-CRT in patients with severe, chronic TBI on an fMRI task shown to have imaging stability in a normal control sample.     

Traumatic brain injury rehabilitation.

Improved survival from severe traumatic brain injury has prompted the development of dedicated rehabilitation programs. Ideally, rehabilitation should begin during acute care in order to prevent later complications. Medically stable patients should be referred from acute care to acute rehabilitation programs for evaluation and then treatment or transfer as appropriate. Dedicated brain injury rehabilitation programs follow a method in which treatment is adapted to the major physical and cognitive impairments at each stage of recovery. Specialized treatment protocols have been developed for unconscious or agitated patients, partly on the basis of advances in neuropharmacology. Because of the long recovery course after severe brain injury, many patients are appropriate for postacute rehabilitation programs directed at community reentry, including return to work. Newer program models for patients with traumatic brain injuries, especially programs using cognitive rehabilitation techniques, are controversial because of inadequate research support and uncertain cost-effectiveness.     

Recovery of automatic and cognitive functions in traumatic brain injury using the functional independence measure

Automatic tasks are performed with minimal attentional guidance. Neural pathways subserving attention are often impaired in traumatic brain injury TBI . Therefore, the process of automatization is crucial in skill development, due to the fact that it allows attention to be directed towards the more abstruse components of task [1]. Automatic and cognitive categories were created by aggregating three of the motor items and three of the cognitive items respectively of the Functional Independence Measure FIM . The averages of these categories were calculated for every evaluation of the FIM, and their relationshp to each other was examined. Over a 9-month period 24 patients were selected from a TBI population with a major component of diffuse axonal injury (DAI). Eight-eight per cent (n = 21) of the patients reached independence for the automatic category, but only 29 % (v = 7) reached this level for the cognitive category. When independence was achieved, the average time to do so for the automatic category 6·7 weeks) was not significantly different from the time it took to reach cognitive independence (6·9 weeks). It was found that there were significant statistical differences in the scores between the two categories. Premorbid IQ had no effect on these categories. However, the rate which these two categories increased, from the time of admission to discharge, was not significantly different.     

Subject ordered pointing task performance following severe traumatic brain injury in adults

The utility of a non-verbal, untimed subject ordered pointing task for identifying memory deficit in adult patients with TBI was tested. Using a cross-sectional design, the working memory performance of 70 adults with severe traumatic brain injury (TBI) and 45 uninjured adults was investigated on a computerized, self-paced, non-verbal subject ordered pointing task. Persons with severe TBI were impaired on measures of working memory relative to the control subjects. In addition, the task appeared to be sensitive to severity of injury as measured by the Glasgow Coma Scale, even within a truncated range of severity (GCS scores 3-8). It was concluded that the subject ordered pointing task is useful in identifying memory deficits in persons with brain injury.     

等热量不同糖成分营养制剂对重型颅脑损伤患者血糖影响的随机对照研究

目的探讨持续泵人等热量不同糖成分营养制剂对重型颅脑损伤患者血糖的影响。方法60例重型颅脑损伤患者随机分为普通肠内营养制剂组（30例）和糖尿病专用型肠内营养制剂组（30例）,在相等非蛋白热量（104．6kJ／Kg·d）摄入条件下,进行14天不同糖成分的肠内营养制剂对重型颅脑损伤患者血糖影响的前瞻性随机对照研究。结果两组患者2周内每日平均血糖水平及每日平均胰岛素剂量比较差异无显著性（P〉0．05）。28天生存率和改良Rankin评分两组比较差异均无显著性（P〉0．05）。结论持续肠内泵入普通肠内营养制剂和糖尿病专用型肠内营养制剂对血糖影响差异不明显,重型颅脑损伤并发高血糖患者可选择该制剂。     

Working memory deficits after traumatic brain injury: catecholaminergic mechanisms and prospects for treatment -- a review

Primary objective: To review the neural circuitry and neurochemistry of working memory and outline the evidence for working memory deficits after traumatic brain injury, and the evidence for the use of catecholaminergic agents in the amelioration of these deficits. Current knowledge gaps and research needs are identified.

Main outcomes and results: Impairments in working memory are a core component of the cognitive deficits associated with traumatic brain injury. Recent progress in understanding the neural circuitry and neurochemistry of working memory suggests that catecholamines play a central role in the activation and regulation of working memory and thus lays a framework in which to consider the use of catecholaminergic agents (dopaminergic and alpha-2 adrenergic agonists) in the treatment of specific cognitive deficits after traumatic brain injury.

Conclusions: The combined methods of cognitive neuroscience, functional brain imaging and neuropharmacology are proposed as an excellent method for studying working memory deficits. A strong rationale exists for the targeted use of catecholaminergic agonists in the treatment of working memory deficits after traumatic brain injury.     

Recent advance and current status of management of head trauma in China

It is estimated that more than 1 million Chinese people sustain traumatic brain injury （TBI） annually, nearly 10% of whom are dead and 30% are compli-cated with physical, cognitive, behavioral and/or psychosocial impairments in China. A lot of experimental researches and clinical trials of head trauma have been made in China recently, which improves the understanding of pathological mechanisms and prognosis of severe traumatic brain injury.     

Functionally activated brain imaging (O-15 PET and fMRI) in the study of learning and memory after traumatic brain injury

Advances in functional imaging technology and cognitive neuropsychology have resulted in paradigms in which participants can perform cognitive tasks during functional image acquisition. We will discuss the application of two approaches (oxygen-15 positron emission tomography and functional magnetic resonance imaging) that have recently been used to examine components of learning and memory following traumatic brain injury (TBI). Activated functional brain imaging findings that we will discuss may suggest possible functional reallocation and reorganization of brain substrates involved in verbal learning and memory following brain injury. The findings also are clearly in line with other research that indicates a prominent role for the frontal lobes in learning and memory functioning, and support the concept of distributed neural networks for memory-related functions, cognitive load, and the potential for examining brain re-organization after injury.     

Monitoring emergence from coma following severe brain injury in an octogenarian using behavioural indicators, electrophysiological measures and metabolic studies: a demonstration of the potential for good recovery in older adults

This case study describes a multi-disciplinary investigation of the emergence from coma of an 80-year old female (KE) following severe traumatic brain injury. The relationship between cognitive/behavioural ability and the integrity of cerebral function was assessed using neuropsychological measures, positron emission tomography, electroencephalography, somatosensory evoked potentials and trans-cranial magnetic stimulation. These investigations were performed as KE was beginning to emerge from coma (4 weeks) and, again, ∼1 year following brain injury, when she was judged to have achieved her maximum level of recovery. Neuropsychological measures revealed improvement during the first year post-injury in KE's speed of information processing, memory and executive abilities. Electrophysiological and metabolic studies indicated a restoration of functional integrity that was consistent with the gradual recovery in higher brain function documented using behavioural procedures. This case study demonstrates the rehabilitation potential of pre-morbidly healthy older adults following severe traumatic brain injury.     

An fMRI study of executive functioning after severe diffuse TBI

Primary objective: Preliminary study of whether severe diffuse traumatic brain injury (TBI) increases extent of frontal tissue recruited by cognitive control tasks.

Research design: Functional magnetic resonance imaging (fMRI) on N-back working memory (WM) and arrows inhibition tasks in a 46 year old man who had severe diffuse TBI 1 year earlier, a 44 year old man (inhibition task) and three women (working memory task), age 20-26 years. Images were acquired by 1.5 T magnet with BOLD method and PRESTO pulse sequence and analysed using SPM.

Main outcomes and results: Frontal activation increased under 2-back relative to 1-back condition of working memory in all participants with more extensive activation in the TBI patient relative to controls. Frontal activation increased with inhibition on the arrows task, but was greater in the TBI patient.

Conclusion: Severe diffuse TBI results in recruitment of additional neural resources for cognitive control.     

单唾液酸四己糖神经节苷脂钠注射液治疗重型颅脑损伤的疗效观察

目的观察单唾液酸四己糖神经节苷脂钠注射液对重型颅脑损伤患者血浆肌酸激酶同工酶BB（CreatinekinaseBB,CK-BB）的动态变化以及临床疗效。方法将60例重型颅脑损伤患者（GCS≤8分）分成两组,观察组30例在常规治疗的基础上加用单唾液酸四己糖神经节苷脂钠注射液治疗,对照组30例采用常规治疗。观察患者血浆CK-BB变化,并两组于伤后6个月按GOS预后评分评定预后,同时比较两组患者的意识好转率。结果观察组患者血浆CK-BB明显低于对照组。观察组恢复良好率（17/30）与对照组（8/30）比较,差异有统计学意义（P〈0.05）。观察组治疗后1个月清醒23例,而对照组l3例,两组清醒率比较,差异有统计学意义（P〈0.01）。两组清醒时间比较,观察组为（14.56±6.56）天,对照组为（20.85±10.92）天。结论单唾液酸四己糖神经节苷脂钠注射液能有效降低重型颅脑损伤患者血浆CK-BB的水平,并且不仅能加速重型颅脑损伤患者清醒,还能促进预后,提高生活质量。单唾液酸四己糖神经节苷脂钠注射液是治疗重型颅脑损伤安全有效的药物,可以广泛地应用于临床。     

Driving following traumatic brain injury: prevalence, exposure, advice and evaluations

Survivors of traumatic brain injury often have long term sensory, cognitive and motor deficits that may impair vehicle operation. However, relatively little is known about the driving status and driving characteristics of brain injury survivors. To better understand driving following traumatic brain injury, a survey of driving status, driving exposure, advice received about driving and evaluations of driving competency was administered to a convenience sample of traumatic brain injury survivors (n=83). The majority of survey participants had experienced either moderate or severe traumatic brain injuries based on the Glasgow Coma Scale. A total of 60 of the survey participants reported that they were currently active drivers. Most individuals (>60%) who had returned to driving reported driving every day and more than 50 miles per week. Traumatic brain injury survivors frequently received advice about driving from family members, physicians or non physician health care professionals, but over half (63%) had not been professionally evaluated for driving competency. The presence of high driving exposure, coupled with a lack of widespread driving fitness testing, suggests that some traumatic brain injury survivors have characteristics that may evaluate their risk for vehicle crashes. However, subsequent prospective studies that directly assess driver safety will be needed to confirm this possibility.     

Attention and driving in traumatic brain injury: a question of coping with time-pressure

BACKGROUND: Diffuse and focal traumatic brain injury (TBI) can result in perceptual, cognitive, and motor dysfunction possibly leading to activity limitations in driving. Characteristic dysfunctions for severe diffuse TBI are confronted with function requirements derived from the hierarchical task analysis of driving skill. OBJECTIVE: Specifically, we focus on slow information processing, divided attention, and the development of procedural knowledge. Also the effects of a combination of diffuse and focal dysfunctions, specifically homonymous hemianopia and the dysexecutive syndrome, are discussed. Finally, we turn to problems and challenges with regard to assessment and rehabilitation methods in the areas of driving and fitness to drive.     

Effect of neuregulin-1 on histopathological and functional outcome after controlled cortical impact in mice

Neuregulin-1 is a pleiotropic endogenous growth factor that is neuroprotective in experimental models of cerebral ischemia. We tested the hypothesis that pretreatment with neuregulin-1 would be similarly protective after traumatic brain injury in mice. Mice were administered neuregulin-1 or equal amounts of vehicle intravenously immediately before controlled cortical impact. Injured mice were subjected to motor and cognitive testing, and brain tissue loss was quantitated at 4 weeks. Compared to vehicle, pretreatment with neuregulin-1 had no effect on brain tissue loss, motor function, or acquisition of a spatial learning task. However, neuregulin-1 treated mice showed improved retention of spatial memory versus vehicle-treated mice in subsequent probe trials (p<0.05). These proof-of-principle data suggest that neuregulin-1 may improve some functional outcomes after brain trauma. Further studies are therefore warranted to more carefully explore molecular mechanisms, dose-responses, and relationships between morphological outcome and long-term recovery.