Reversible neuropsychological deficits after mild traumatic brain injury

OBJECTIVES: To determine the influence of motivation on performance in a divided attention test of patients after mild traumatic brain injury (MBI). METHODS: Comparison of the performance of 12 patients with MBI with 10 patients with severe brain injury (SBI) and 11 healthy controls in a computer supported divided attention task before (T1) and after (T2) verbal motivation. RESULTS: At T1, the MBI group performed the same as the SBI group but significantly worse than the controls in all variables. At T2, the MBI group performed worse than the controls at T2 but the results were equal to the results of the controls at T1 and significantly better than the SBI group at T1 or T2. At T2 the MBI group performed at the level of published norms for the rest. CONCLUSION: Before verbal motivation the MBI group's results in the divided attention task were comparable with those from patients with severe brain injury. They failed to exploit their performance potential when it depended on self motivation but were able to perform at the level of the control group when external motivation was applied.     

Hydrogen-rich saline protects against oxidative damage and cognitive deficits after mild traumatic brain injury

Oxidative stress is the principal factor in traumatic brain injury (TBI) that initiates events that result in protracted neuronal dysfunction and remodeling. Importantly, antioxidants can protect the brain against oxidative damage and modulate the capacity of the brain to cope with synaptic dysfunction and cognitive impairment. However, no studies have investigated the effects of hydrogen-rich saline on cognitive deficits after TBI. In the present study, rats with fluid percussion injury (FPI) were used to investigate the protective effects of hydrogen-rich saline. The results showed that hydrogen-rich saline reduced the level of malondialdehyde (MDA) and elevated the level of silent information regulator 2 (Sir2). In addition, treatment with hydrogen-rich saline, which elevated the levels of molecules associated with brain-derived neurotropic factor (BDNF)-mediated synaptic plasticity, improved cognitive performance in the Morris water maze after mild TBI. These results suggest that hydrogen-rich saline can protect the brain against the deleterious effects of mild TBI on synaptic plasticity and cognition and that hydrogen-rich saline could be an effective therapeutic strategy for patients with cognitive deficits after TBI.     

Persistent cognitive dysfunction after traumatic brain injury: A dopamine hypothesis

Traumatic brain injury (TBI) represents a significant cause of death and disability in industrialized countries. Of particular importance to patients the chronic effect that TBI has on cognitive function. Therapeutic strategies have been difficult to evaluate because of the complexity of injuries and variety of patient presentations within a TBI population. However, pharmacotherapies targeting dopamine (DA) have consistently shown benefits in attention, behavioral outcome, executive function, and memory. Still it remains unclear what aspect of TBI pathology is targeted by DA therapies and what time-course of treatment is most beneficial for patient outcomes. Fortunately, ongoing research in animal models has begun to elucidate the pathophysiology of DA alterations after TBI. The purpose of this review is to discuss clinical and experimental research examining DAergic therapies after TBI, which will in turn elucidate the importance of DA for cognitive function/dysfunction after TBI as well as highlight the areas that require further study.     

Proactive inhibition deficits with normal perfusion after pediatric mild traumatic brain injury

Although much attention has been generated in popular media regarding the deleterious effects of pediatric mild traumatic brain injury (pmTBI), a paucity of empirical evidence exists regarding the natural course of biological recovery. Fifty pmTBI patients (12–18 years old) were consecutively recruited from Emergency Departments and seen approximately 1 week and 4 months post‐injury in this prospective cohort study. Data from 53 sex‐ and age‐matched healthy controls (HC) were also collected. Functional magnetic resonance imaging was obtained during proactive response inhibition and at rest, in conjunction with independent measures of resting cerebral blood flow. High temporal resolution imaging enabled separate modeling of neural responses for preparation and execution of proactive response inhibition. A priori predictions of failed inhibitory responses (i.e., hyperactivation) were observed in motor circuitry (pmTBI>HC) and sensory areas sub‐acutely and at 4 months post‐injury. Paradoxically, pmTBI demonstrated hypoactivation (HC>pmTBI) during target processing, along with decreased activation within prefrontal cognitive control areas. Functional connectivity within motor circuitry at rest suggested that deficits were limited to engagement during the inhibitory task, whereas normal resting cerebral perfusion ruled out deficits in basal perfusion. In conclusion, current results suggest blood oxygen‐level dependent deficits during inhibitory control may exceed commonly held beliefs about physiological recovery following pmTBI, potentially lasting up to 4 months post‐injury.     

Pharmacological enhancement of cognitive and behavioral deficits after traumatic brain injury

PURPOSE OF REVIEW: To provide the clinician with a reasonable overview of the modern pharmacological alternatives to treat the cognitive and behavioral sequels of traumatic brain injury. RECENT FINDINGS: Original research in this area is sparse and more than half of the articles published on the subject recently have been reviews. Of the three randomized controlled trials, one studied methylphenidate (n = 18), one methylphenidate and sertraline (n = 30) and one amantadine (n = 27). All these studies reported beneficial effects on various cognitive measures, but because of the study protocols, the evidence provided may be questioned. The various reviews, uncontrolled studies and case reports suggest that at least psychostimulants, cholinergic agents, dopaminergic agents and antidepressants may be beneficial in treating the cognitive and behavioral symptoms of traumatic brain injury. SUMMARY: The clinician trying to ameliorate the cognitive and behavioral symptoms of traumatic brain injury has to make decisions about pharmacotherapy that are still based mainly on clinical experience. Large randomized controlled trials giving high-quality evidence are so far missing. This review discusses the problems facing both the clinician and the scientist treating the cognitive and behavioral sequels of traumatic brain injury. A symptom-based approach is suggested for current practice.     

颅脑创伤患者记忆障碍比较研究

目的探讨不同类型颅脑创伤患者记忆障碍的特征。方法根据患者入院时GCS评分,按创伤严重程度将42例颅脑创伤患者分为轻度创伤组(GCS13～15分,16例)、中度创伤组(GCS9～12分,14例)和重度创伤组(GCS3～8分,12例)。采用临床记忆量表进行短时记忆测量并与42名健康受试者(对照组)进行比较,观察冲击点伤、对冲伤、混合伤及加速伤、减速伤、混合伤、切线伤对颅脑创伤患者记忆力的影响。结果与对照组相比,不同程度颅脑创伤患者的记忆商(MQ)均显著下降,其中轻度创伤组与中、重度创伤组相比,差异具有显著性意义(P<0.05);冲击点伤、对冲伤以及混合伤患者之间MQ相比,差异具有显著性意义(P<0.01),冲击点伤患者的MQ值最高(P<0.05);加速伤、减速伤、混合伤和切线伤患者之间MQ相比,差异亦有显著性意义(P<0.01)。结论颅脑创伤后混合伤和切线伤对患者记忆的影响最为明显。     

Non-credible language deficits following mild traumatic brain injury

Identification of non-credible memory and other cognitive symptoms has received widespread attention within the past two decades. However, minimal information is available regarding patterns of non-credible language symptoms. We present the case of a 36-year-old female civil litigant who displayed delayed onset, severe, relatively focal speech and language symptoms, including difficulties with articulation, dysfluent speech, expressive language impairments with minor receptive difficulties, and lack of prosody, subsequent to a minor head trauma. On neuropsychological evaluation 3 years post injury, the patient presented with the same speech/language characteristics, but additionally exhibited a vague “foreign accent.” Cognitive scores generally were normal with the exception of poor performance on many language tasks and processing/motor speed. The patient showed passing performance on most measures of response bias, but she failed effort indicators requiring rapid letter discrimination (b Test), rapid verbal repetition (timed forward digit span), and sensory function (finger agnosia errors) while passing effort indicators falling within the domains of memory, math/number skills, visuo-constructional ability, and attention. Thus, the type of failed effort indicators predicted the categories of standard cognitive tests on which she underperformed. Personality testing revealed patterns generally consistent with hysterical personality orientation. Given her long-standing history of multiple unexplained medical symptoms, the patient was diagnosed with a somatization disorder, as well as a current conversion disorder involving language symptoms. However, given her compensation-seeking status, the possibility of additional conscious feigning of symptoms could not be ruled out. The need for validation of additional measures to detect feigned language impairment is recommended.      

A functional magnetic resonance imaging study of cognitive control and neurosensory deficits in mild traumatic brain injury

Mild traumatic brain injury patients (mTBI) frequently report symptoms of increased distractability and sensory disturbances during mutisensory stimulation. These common post‐concussive symptoms could putatively result from dysfunction within the cognitive control network (CCN; top‐down) or from unisensory cortex (bottom‐up) itself. Functional magnetic resonance imaging (fMRI) and high‐resolution structural data were therefore prospectively collected during a multisensory (audio‐visual) cognitive control task from 46 mTBI patients within 3 weeks of injury and 46 matched healthy controls (HC), with a subset of participants returning at 4 months. Multisensory stimuli were presented at two frequencies to manipulate cognitive and perceptual load. Patients self‐reported more cognitive, emotional, somatic, vestibular and visual symptoms relative to HC, which improved, but did not entirely resolve, over the 4 month follow‐up period. There were no group differences in behavior or functional activation during cognitive control (incongruent – congruent trials). In contrast, patients exhibited abnormal activation within different regions of visual cortex that depended on whether attention was focused on auditory or visual information streams. Patients also exhibited increased activation within bilateral inferior parietal lobules during higher cognitive/perceptual loads, suggesting a compensatory mechanism to achieve similar levels of behavioral performance. Functional abnormalities within the visual cortex and inferior parietal lobules were only partially resolved at 4 months post‐injury, suggesting that neural abnormalities may take longer to resolve than behavioral measures used in most clinical settings. In summary, current results indicate that abnormalities within unisensory cortex (particularly visual areas) following mTBI, which likely contribute to deficits commonly reported during multisensory stimulation. Hum Brain Mapp 36:4394–4406, 2015. © 2015 Wiley Periodicals, Inc.     

脑外伤患者恢复期的注意障碍

目的探索脑外伤恢复期患者注意的改变及其特征.方法对42例大型医院神经外科住院治疗的脑外伤恢复期患者和42名正常人进行"2,7"划消测验和Strop测验.结果脑外伤患者在标准情况、不相关分心情况和相关分心情况下的划消速度明显低于正常对照组,而精确率无明显差异.进一步比较相关分心情况下划消速度的下降率显示脑外伤患者显著大于正常对照组.Stroop测验显示脑外伤患者读单色字时间、读色块时间和读彩色字颜色时间较正常对照组显著延长,但两组之间错误数无显著性差异.比较两组读彩色字颜色时间的延长率和读彩色字文字时间的延长率,脑外伤患者均显著大于对照组.结论脑外伤后患者的注意力下降.注意的分配受损,抗干扰能力下降,而选择注意相对完整.     

Hand movement span after mild traumatic brain injury: a longitudinal study.

This study examined whether memory span was impaired during the acute and post-acute phases following mild traumatic brain injury (mTBI). Twenty-two adults with mTBI were compared with 22 controls on computerized tasks of immediate memory for verbal, spatial, and hand movement sequences under no interference (baseline) and articulatory suppression conditions. Groups were assessed within a month and followed up 3-12 months post-injury. In the acute phase, there were no group differences across tasks under either condition. At follow-up, all spatial and verbal span scores and associated practice effects were equivalent across groups. Yet for the hand movement task, baseline movement span was worse for the mTBI group suggesting that they failed to benefit from practice to the same extent as controls. Furthermore, the fact that this group difference in span scores disappeared when articulatory suppression was imposed indicates that successful hand movement task performance involves verbal recoding.     

Lactate administration attenuates cognitive deficits following traumatic brain injury

Moderately head injured patients often suffer long term neurological sequelae. There is no therapy for brain trauma and current treatments aim only to minimize secondary damage. These secondary effects are often triggered by the inability to re-establish ionic homeostasis after injury, due to large energy demands. Recent reports have demonstrated that neurons are capable of utilizing lactate as an energy source, thus this report examines the usefulness of lactate administration in the attenuation of behavioural deficits following a moderate brain injury. Lactate infusion (i.v.) was started 30 min after lateral fluid percussion injury and continued for 3 h. Cognitive deficits were determined using the Morris water maze. Lactate infused injured animals demonstrated significantly less cognitive deficits than saline infused injured animals. Thus, lactate infusion attenuated the cognitive deficits normally observed in this model, and therefore may provide moderately head injured patients with a treatment to help ameliorate the sequelae.     

Electro-oculographic measures in patients with chronic whiplash and healthy subjects: a comparative study

BACKGROUND: Despite their high incidence, costs, and long lasting disability, whiplash associated disorders (WAD) lack an identifiable objective pathology that explains their acute or chronic symptoms. OBJECTIVE: In view of previous suggestions of a possible effect of neck torsion on several electro-oculography (EOG) parameters, the main objective of this study was to examine their applicability in differentiating patients from uninvolved subjects. METHODS: Smooth pursuit and saccadic eye movements were assessed in 26 patients with chronic WAD and 23 healthy subjects. All tests were executed in three neck positions: neutral and rotations to left and right. RESULTS: Neck torsion did not influence eye movement performance of either the WAD or healthy groups. However, compared with the healthy group, patients with WAD had significantly lower smooth pursuit velocity gain (SPVG) (p = 0.01) and prolonged saccadic latency (p = 0.001), irrespective of neck position. CONCLUSIONS: Despite scattered differences that reached significance, the electro-oculographic measures used in this study do not seem to offer a clinically relevant method for differentiating between patients with WAD and normal subjects.     

Neuropsychological and information processing deficits following mild traumatic brain injury.

Neuroradiological and neuropathological investigations have found evidence of diffuse brain damage in the frontal and temporal lobes, corpus callosum, and fornices in patients who have sustained a mild traumatic brain injury (TBI). However, neuropsychological assessments of these patients do not typically target many of the subtle information processing deficits that may arise from diffuse damage involving the frontotemporal regions of the brain as well as white matter pathology, including the corpus callosum. Consequently, we have a limited understanding of the deficits that may be attributable to temporary or permanent disruptions to these functional pathways. This study assessed a group of mild TBI patients (N = 40) and a matched control group (N = 40) on a number of standard neuropsychological tests of selective and sustained attention, verbal and non-verbal fluency, and verbal memory. In addition, reaction time (RT) tasks, requiring both the inter- and intra-hemispheric processing of visual and tactile information, were used to assess the functional integrity of the tracts that are likely to be affected by diffuse damage. In the 1st month after sustaining their injury, the mild TBI group demonstrated deficits in attention, non-verbal fluency, and verbal memory. They also demonstrated slower visual and tactile RTs, with the visual RTs of mild TBI patients being more affected by increased task difficulty and the need to transfer information across the corpus callosum, than did their matched controls.     

Emotional and cognitive sequelae to mild traumatic brain injury.

This study compared the emotional functioning and cognitive abilities (i.e., verbal fluency, executive functioning, memory, and attention) of 27 patients with mild traumatic brain injury (MTBI) to that of 27 controls. With the exception of verbal fluency, the cognitive abilities of the MTBI group appeared to be intact. Emotional functioning was assessed using the Neuropsychology Behavior and Affect Profile (NBAP), a revised version of the Neurobehavioural Rating Scale and the Headley Court Psychosocial Rating Scale. The NBAP demonstrated good internal reliability, criterion validity, and construct validity. The MTBI group showed significantly higher levels of post injury depression than controls on the NBAP. Pre injury levels of depression in the MTBI group were also higher than the controls but both the patient reports and those of family members confirmed an increase in depression following MTBI.     

Performance monitoring and cognitive control in individuals with mild traumatic brain injury

Literature suggests that individuals with mild traumatic brain injury (mTBI) show subtle abnormalities in the cognitive control process of performance monitoring. The neural bases of performance monitoring can be measured using the error-related negaitivity (ERN) and post-error positivity (Pe) components of the scalp-recorded event-related potential (ERP). Thirty-six individuals with mTBI and 46 demographically similar controls completed a modified color-naming Stroop task while ERPs were recorded. Separate repeated-measures analyses of variance were used to examine the behavioral (response times [RT] and error rates) and ERP (ERN and Pe amplitudes) indices of performance monitoring. Both groups showed slower RTs and increased error rates on incongruent trials relative to congruent trials. Likewise, both groups showed more negative ERN and more positive Pe amplitude to error trials relative to correct trials. Notably, there were no significant main effects or interactions of group for behavioral and ERP measures. Subgroup and correlational analyses with post-concussive symptoms and indices of injury severity were also not significant. Findings suggest comparable performance to non-injured individuals in some aspects of cognitive control in this sample. Neuropsychological implications and comparison with other cognitive control component processes in individuals with TBI are provided.     

多奈哌齐治疗颅脑创伤后记忆和智能障碍的临床观察

目的 观察多奈哌齐治疗96 例颅脑创伤后记忆和智能障碍的疗效.方法 颅脑创伤后记忆和智能障碍患者96例,治疗组给予多奈哌齐片5mg,1次/d, 晚上睡前口服;对照组给予尼莫地平片常规治疗.治疗期为1个月.结果 治疗组患者记忆功能、认知功能改善较为明显, 与对照组比较有明显差异(P ＜ 0.05).结论 多奈哌齐对颅脑创伤后记忆和智能障碍患者早期治疗效果好, 安全性高, 不良反应少, 服用方便.     

轻度颅脑损伤患者执行功能障碍研究

目的探讨轻度颅脑损伤(mild traumatic brain injury,m TBI)患者伤后执行功能(executive function,EF)的动态变化特点。方法对63例m TBI患者(研究组)在伤后1周、1个月、3个月和6个月进行执行功能测查,并与60例健康受试者(对照组)比较。测查工具采用连线测验(trail making test,TMTA)、霍普金斯词语学习测验修订版(Hopkins verbal learning test-revised,HVLT-R)、简易视觉记忆测验—修订版(brief visuospatial memory test-revised,BVMT-R)、Stroop色词测验、持续操作测验(continuous performance test,CPT)。结果伤后1周与对照组比较,TMTA、HVLT-R、BVMT-R、Stroop和CPT-IP分值差异有统计学意义(P0.05);与伤后1周相比,伤后1个月、3个月和6个月时的TMTA分值下降,HVLT-R、BVMT-R、Stroop和CPT-IP分值增加(P0.05)。组内两两比较,伤后1个月与伤后1周比较,TMTA分值下降,BVMT-R、Stroop分值增加(P0.05);伤后3个月与伤后1个月比较,Stroop、BVMT-R和CPT-IP分值增加(P0.05);伤后6个月与伤后3个月比较,Stroop和CPTIP分值增加(P0.05)。结论m TBI患者在注意能力/警觉性、学习与工作记忆、信息处理速度及执行功能上都可能存在一定的损害,伤后不同时间点恢复速度并不一致。