Intactness of inhibitory attentional mechanisms following severe closed-head injury.

Attentional problems are a common sequelae of closed-head injury (CHI). Research in the area of selective attention has pointed to the role of inhibitory mechanisms in the suppression of irrelevant information. In the current study, a negative priming paradigm was used to assess the inhibitory mechanisms of individuals suffering from a severe CHI. Twenty participants with severe CHIs (greater than 1 year postinjury) and 20 matched controls completed a negative priming task, as well as several other standardized tests of cognitive functioning. Within the negative priming task, 2 conditions were used to elicit information regarding facilitation by attended and ignored information and 1 condition was used to elicit inhibition of ignored information, as compared with a neutral control condition. Despite poorer performances on several tests of attention, there were no significant differences in the amount of inhibition displayed by the CHI participants as compared with the controls. Findings suggest that inhibitory processing deficits may not underlie the selective attention difficulties commonly seen following a severe CHI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeling of knowing in episodic memory following moderate to severe closed-head injury.

The ability to accurately monitor one's memory is a metacognitive process that is important in everyday life. The authors examined episodic memory feeling-of-knowing (FOK) ratings in 21 moderate to severe closed-head injury (CHI) participants (more than 1 year postinjury) and 21 controls. Participants studied 36 critical cue-target word pairs. Following a brief delay, they were asked to recall the target that corresponded to a given cue. Confidence ratings were made for recalled words, and FOK judgments were made for nonrecalled words in terms of the likelihood of recognizing the target word on a subsequent recognition test. CHI participants demonstrated less accurate recall but accurate ability to judge their recall performance (retrospective memory monitoring). They also demonstrated intact FOK judgments when providing binary judgments but demonstrated difficulties making finer discriminations on an ordinal scale (prospective memory monitoring). These findings suggest that memory monitoring is not a unitary construct. It is proposed that CHI participants may display intact memory monitoring when predictions are based on familiarity assessment but not when continued probing for additional episodic information is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Costs of a predictable switch between simple cognitive tasks following severe closed-head injury.

The authors used a predictable, externally cued task-switching paradigm to investigate executive control in a severe closed-head injury (CHI) population. Eighteen individuals with severe CHI and 18 controls switched between classifying whether a digit was odd or even and whether a letter was a consonant or vowel on every 4th trial. The target stimuli appeared in a circle divided into 8 equivalent parts. Presentation of the stimuli rotated clockwise. Participants performed the switching task at both a short (200 ms) and a long (1,000 ms) preparatory interval. Although the participants with CHI exhibited slower response times and greater switch costs, similar to controls, additional preparatory time reduced the switch costs, and the switch costs were limited to the 1st trial in the run. These findings indicate that participants with severe CHI were able to take advantage of time to prepare for the task switch, and the executive control processes involved in the switch costs were completed before the 1st trial of the run ended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptually based implicit learning in severe closed-head injury patients.

This study suggests that perceptually based implicit learning may either be preserved following a severe closed-head injury (CHI) or recover within the 1st year. Nineteen severe CHI patients and 19 controls searched visual matrices and indicated the quadrant location of a target. Participants were exposed to the following covariation pattern: AAAABAAA. For Covariation A blocks, the matrices systematically co-occurred with a unique location of the target. This relationship was altered for the B block. Despite CHI participants' overall slower response times (RTs), both groups demonstrated the expected decline in RTs across the first 4 Covariation A blocks followed by an increase when the covariation changed. Both groups also exhibited retention of their learning after a 20-min delay. Explicit knowledge tests indicated that participants lacked awareness for the covariation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of divided attention on automatic and controlled components of memory after severe closed-head injury.

The relation between attention available at encoding and automatic and consciously controlled aspects of memory was investigated using the process-dissociation procedure. Twenty-four severely closed-head injured (CHI) participants (> 1 year postinjury) and 24 matched controls studied word lists in full- and divided-attention conditions. Recall cued with word stems was tested. In contrast to consciously controlled memory, the CHI group did not perform more poorly than the controls in estimates of automatic memory. Furthermore, for both groups, the divided-attention manipulation reduced the controlled estimates of memory, whereas automatic influences remained invariant. These results suggest that automatic memory processes may remain partially immune to the deleterious effects of severe CHI or show recovery by 1 year postinjury. They also indicate that automatic memory processes do not require additional attentional resources following severe CHI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Abstract thinking following severe traumatic brain injury

Abstract abilities were studied in a sample of 34 individuals with severe TBI and a control group. The results indicate that TBI interferes with performance on tests requiring individuals to process information into new categories. There appears to be a dissociation between verbal abstract abilities and visual-perceptual abstract abilities. There is evidence that Goldstein and Sheerer's [1] postulate of a general 'abstract attitude' was at least partially correct. This attitude does not appear to be related to a general verbal ideational process, as dysphasic subjects were only deficient on a purely verbal abstract task.     

Overreporting of closed-head injury symptoms on the MMPI-2.

Minnesota Multiphasic Personality Inventory (MMPI-2) validity scales were compared in 4 groups: nonclinical participants answering under standard instructions (n?=?20), nonclinical participants instructed to fake closed-head injury (CHI) symptoms (n?=?18), non-compensation-seeking CHI patients (n?=?31), and compensation-seeking CHI patients (n?=?30). The highest scores on MMPI-2 overreporting scales were obtained by nonclinical participants faking CHI, and significantly higher scores on these scales were obtained by compensation-seeking relative to non-compensation-seeking CHI patients. These results suggest that MMPI-2 overreporting scales are sensitive to fabrication of CHI complaints, and possibly to exaggeration of CHI complaints, although further research is necessary to evaluate the latter hypothesis fully. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Automatic process development following severe closed head injury.

Automatic process development was investigated in a closed head injury (CHI) population. Ten severe CHI participants (>1 year postinjury) and 10 matched controls completed consistent mapping (CM) and varied mapping (VM) semantic-category memory search tasks. In VM search, despite a similar pattern of serial memory search, the CHI participants responded slower than controls and exhibited slower memory search rates throughout practice (1,800 trials). In CM search, after extensive practice (1,800 trials) both groups showed the performance characteristics indicative of automatic process development, that is, near-zero slopes and large reductions in response times. However, the CHI participants were slower to automatize the task. These results indicate that for memory-based search tasks the effects of a CHI may slow down the speed with which automatic processes develop but that CHI participants can acquire and use automatic processes in task performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Delayed and progressive brain injury in closed-head trauma: radiological demonstration

The importance of delayed or secondary brain insults in the eventual outcome of closed-head trauma has been documented in experimental models. To understand this phenomenon in the clinical setting, we studied a series of head-injured patients in whom multiple cranial computed tomographic (CT) scans were obtained. Patients whose follow-up CT studies revealed new intracranial lesions or worsening, compared with admission findings, were considered to have delayed cerebral injury. One hundred forty-nine (44.5%) of 337 consecutively studied patients developed delayed brain injury. There were highly significant associations (P < 0.001) between the appearance of delayed cerebral insults and the severity of the initial brain injury, the need for cardiopulmonary resuscitation in the field, the presence of coagulopathy at admission, and subdural hematoma on the initial CT scan. In addition, delayed injury was associated (P < 0.001) with higher mortality, slowed recovery, and poorer outcome at 6 months. Delayed brain injury was not significantly associated with patient age, sex, injury mechanism, associated injury, the need for endotracheal intubation in the field, early talking, CT abnormality other than intracranial hematoma, or type of residual neurological deficits. We used multiple regression analysis to explore the relationship between severity of injury, delayed insults, and outcome. As expected, the severity of the initial brain trauma contributed significantly to neurological outcome. The presence of delayed cerebral injury makes the outcome dramatically worse for each category of initial injury severity. The relationship between initial and secondary brain injury is discussed.     

Long-term psychosocial adjustment following very severe closed head injury.

Examined the cognitive, psychological, and social functioning of 18 community-dwelling male patients who had experienced a severe closed head injury (CHI) at least 18 mo previously and still required contact with rehabilitation services. Results from Ss with CHI were compared with those from 27 normal control Ss. Information on Ss' behavior was also obtained from their significant others. Results show that Ss with CHI exhibited deficits in their cognitive and social functioning but showed no signs of emotional or psychiatric disturbance. Attempts to find a relationship between the cognitive impairment and social functioning of Ss with CHI were partially successful. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Caregiver burden at 6 months following severe traumatic brain injury

We compared the performance of three computer based classification methods when applied to the problem of detecting microaneurysms on digitised angiographic images of the retina. An automated image processing system segmented 'candidate' objects (microaneurysms or spurious objects), and produced a list of features on each candidate for use by the classifiers. We compared an empirically derived rule based system with two automated methods, linear discriminant analysis and a learning vector quantiser artificial neural network, to classify the objects as microaneurysms or otherwise. ROC analysis shows that the rule based system gave a higher performance than the other methods (p = 0.92) although a much greater development time is required.     

Variables associated with employment following severe traumatic brain injury.

Results of a survey of employment outcome and their relationship to psychometric indices indicated that competitive employment following severe traumatic brain injury is an ambitious endeavor. While 98% of the 94 Ss sampled were either employed or in school premorbidly, 43% of them were unemployed postinjury. Psychometric variables were most highly related to employment outcome which suggested a useful role of neuropsychological testing in assisting in vocational rehabilitation planning. Furthermore, the psychometric test results indicated that many Ss who were unemployed may be capable of parttime employment. Future studies are needed to further examine those neuropsychological abilities which subsequently affect employability following severe traumatic brain injury. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The roles of macrophage in immune dysfunction following severe thermal injury

This experimental study in serious scald mice showed that the cytosolic free calcium ion concentration and the capacity of secreting TNF-alpha of macrophage (M phi) were obviously increased while the secretion of IL-1 was significantly decreased, and accompanied with simultaneous apparent rising of serum TNF-alpha in early postburn period. These indicate that M phi have been highly or even over activated after burn. But the ability of antigen presentation of M phi during this period was deeply suppressed rendering the obvious declination of activity and proliferation response of antigen pulsed lymphocytes. It might be concluded that the defective antigen presentation of M phi played a critical role in early immune dysfunction of severe scald mice, and the highly activated or even overactivated M phi by excessive secretion of TNF-alpha were the molecular basis of the alterations of M phi function.     

Mild closed-head injury in children and adolescents: behavior problems and academic outcomes

The issue of whether mild head injuries (HIs) in children cause behavior problems and poor scholastic performance is controversial. This study included 119 children (range = 8-16 years old) with HI, 114 with other injuries, and 106 with no injury (NI). Behavioral functioning was assessed with the Child Behavior Checklist; academic functioning, with school grades and standardized testing. Higher T scores were found for both injury groups versus NI participants on preinjury behavioral status. All 3 groups' behavioral scores decreased relative to baseline at 1 year. HI and NI groups did not differ in school grades or achievement testing either pre- or postinjury. These results are consistent with the conclusion that head injury of the mildest type does not increase the probability of new overt behavioral or academic problems.     

Mechanism of brain protection by nitroxide radicals in experimental model of closed-head injury

Reactive oxygen-derived species were previously implicated in mediation of post-traumatic brain damage; however, the efficacy of traditional antioxidants in preventing/reversing the damage is sometimes limited. The present work focused on the mechanisms underlying the neuroprotective activity of cell permeable, nontoxic, antioxidants, namely stable nitroxide radicals in an experimental model of rat closed-head injury. Brain damage was induced by the weight-drop method and the clinical status was evaluated according to a neurological severity score at 1 h and 24 h, where the difference between these scores reflects the extent of recovery. The metal chelator deferoxamine as well as three nitroxide derivatives, differing in hydrophilicity and charge, and one hydroxylamine (a reduced nitroxide) facilitated the clinical recovery and decreased the brain edema. The nitroxides, but neither the hydroxylamine nor deferoxamine, protected the integrity of the blood-brain barrier. Superoxide dismutase also improved the clinical recovery but did not affect brain edema or the blood-brain barrier. The results suggest that by switching back and forth between themselves, the nitroxide and hydroxylamine act catalytically as self-replenishing antioxidants, and protect brain tissue by terminating radical-chain reactions, oxidizing deleterious metal ions, and by removal of intracellular superoxide.     

Conversational discourse abilities following severe traumatic brain injury: a follow-up study

The major aim of this study was to describe the conversational abilities of a group of severely injured TBI speakers, at a minimum of 2 years post-injury. The association between conversational impairment and (a) selected measures of executive function and (b) psychosocial handicap was also examined. Twenty-four members of the group of 26 severely injured TBI speakers who had initially been assessed between 3 and 6 months post-injury were reviewed at a minimum of 2 years post-injury (mean = 2 years, 10 months). At initial assessment, TBI speakers were compared with non-TBI orthopaedic patients and with a group of university students. At follow-up, however, they were compared only with the orthopaedic patients. Conversational assessment was carried out using a modified form of Damico's Clinical Discourse Analysis. As a group, the TBI speakers' conversational abilities did not improve over time. There was, however, a subgroup (n = 8) of speakers who did improve, and these could be distinguished by greater initial severity of injury and a significantly longer period of speech-language pathology intervention than the speakers who either remained the same or worsened over time. Modest associations between conversational discourse skills and measures of executive function and a measure of psychosocial handicap were identified. These findings indicate that disruptions in conversation persist into the longer term. More assiduous efforts may need to be made to (a) identify subtle discourse changes in the early months after injury and (b) engage TBI speakers in speech-language pathology services. Such services are also required over a longer time frame, in community-based models of service provision.     

Recovery of time estimation following moderate to severe traumatic brain injury.

Objective: Accurate time estimation abilities are thought to play an important role in efficient performance of many daily activities. This study investigated the role of episodic memory in the recovery of time estimation abilities following moderate to severe traumatic brain injury (TBI). Method: Using a prospective verbal time estimation paradigm, TBI participants were tested in the early phase of recovery from TBI and then again approximately one year later. Verbal time estimations were made for filled intervals both within (i.e., 10 s, 25 s) and beyond (i.e., 45 s 60 s) the time frame of working memory. Results: At baseline, when compared to controls, the TBI group significantly underestimated time durations at the 25 s, 45 s and 60 s intervals, indicating that the TBI group perceived less time as having passed than actually had passed. At follow-up, despite the presence of continued episodic memory impairment and little recovery in episodic memory performance, the TBI group exhibited estimates of time passage that were similar to controls. Conclusion: The pattern of data was interpreted at suggesting that episodic memory performance did not play a noteworthy role in the recovery of temporal perception in TBI participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cognitive complaints in closed-head injury: relationship to memory test performance and emotional disturbance

Self-appraisal of cognitive difficulties by a sample of 63 male patients with closed-head injury (CHI) was examined in relation to their performance on the Wechsler Memory Scale - Revised (WMS-R; Wechsler, 1987), WAIS-R Digit Span (Wechsler, 1981), and to their scores on MMPI-2 (Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 1989) measures of anxiety and depression. In an initial step, the Cognitive Difficulties Scale (CDS; McNair & Kahn, 1983), consisting of 39 self-report items, was factor analyzed using a sample of 255 consecutive neuropsychological referrals with documented brain impairment. Seven orthogonal dimensions emerged: Attention and Concentration, Orientation and Memory, Praxis, Domestic Activities, Facial Recognition, Task Efficiency, and Errand and Name Recall. Within a sample subset consisting of 63 patients with CHI, subjective complaints on the CDS were predictive of WMS-R Logical Memory performance (r = -.51, p < .0005). In contrast, CDS scores were generally poor predictors of Digit Span and Visual Reproduction scores (rs < .31). Cognitive complaints were also associated with emotional distress on the MMPI-2. The CDS appears to be a useful measure of self-appraised cognitive difficulties in patients with CHI, and may assist in the assessment of their self-reflective insight.     

Correlation of computed tomography findings and serum brain damage markers following severe head injury

The objective of our study was to investigate the association between the initial levels of serum S-100B protein and neuron specific enolase and the severity of radiologically visible brain damage and outcome after severe head injury. Admission computed tomography (CT) scans of forty-four patients with severe head injury were analysed. Initial levels of S-100B protein and neuron specific enolase were compared between the different outcome groups at 6 month, the different categories of the Marshall classification, the presence of traumatic subarachnoid haemorrhage, the type of haematoma and the volume of contusion. Serum S-100B was significantly higher in patients with unfavourable outcome (1.1 micrograms/l versus 0.3 microgram/l, p < 0.005, Mann-Whitney U test). In diffuse injury, unfavourable outcome significantly increased with higher Marshall grades (p < 0.05). There was a significant correlation between the four grades of diffuse injury and initial serum S-100B protein (r = 0.48, p < 0.001). Patients with focal mass lesions and a favourable outcome after 6 month had significantly lower S-100B values than those who had an unfavourable outcome (0.51 microgram/l versus 1.3 micrograms/l, p < 0.05). A significant correlation was demonstrated between the volume of contusion visible on CT scans and serum S-100B (r = 0.58, p < 0.001). In our study, initial serum S-100B protein was a powerful predictor of outcome even within the same category of radiologically visible brain damage. Serum S-100B protein may provide independent information about the severity of primary brain damage after head injury.