Development of verbal selective learning

Using incentive-based auditory word recall we studied the efficiency of selective learning in children ages 6-18 years. We found effects of age for both selective learning efficiency and for total words recalled, which differed in developmental trajectory. The number of words recalled showed a nonlinear component, reflecting a negatively accelerated increase with age. In contrast, the measure of selective learning was linear with age. Overall, selective learning efficiency was not related to the total number of words recalled. The findings provide a framework for interpretation of studies of selective learning in clinical populations.

Correlates of persistent postconcussional disorder: DSM-IV criteria versus ICD-10

Controversy surrounding the causation of symptom complaints after mild traumatic brain injury (MTBI) is reflected by the existence of alternative diagnostic criteria for postconcussional syndrome (PCS) in the International Classification of Diseases (ICD) and postconcussional disorder (PCD) in the Diagnostic and Statistical Manual of Mental Disorders-4th edition (DSM-IV). Previous studies of persisting symptoms have employed various symptom checklists rather than uniform criteria-based diagnoses. This is the first prospective study of persisting symptom complaints using the formal diagnostic criteria for PCD and PCS and comparing these criteria sets in terms of prevalence, relationship to potential compensation, and emotional/functional status. In this prospective study, an unselected series of adults with uncomplicated MTBI (N = 139) was assessed at 6 months postinjury with a brief neuropsychological battery and measures of psychiatric symptoms/disorders, social support/community integration, health-related quality of life, and global outcome. In parallel analyses, participants with PCD/PCS were compared to those without the disorder. Potential compensation was an equally significant factor in both criteria sets. Persistent PCS criteria were met 3.1 times more frequently than persistent PCD criteria. Significant racial differences in fulfilling PCD/PCS criteria were found. No differences in emotional/functional status patterns or global outcome were found between the criteria sets except for minor dissimilarities in the social/community integration domain. The results demonstrate that despite large differences in the frequency of patients meeting the two diagnostic criteria sets, a clear basis for preferring either the PCD or PCS criteria remains to be determined.

Short and long-term motor and cognitive outcome of staged bilateral pallidotomy: a retrospective analysis

BACKGROUND

We investigated retrospectively the short and long-term motor and cognitive functioning of staged bilateral pallidotomy using motor testing and a comprehensive neuropsychological battery before and after each procedure.

METHODS

Fifteen patients with idiopathic Parkinson's disease were assessed at baseline and at least 3 months after each of their two staged surgeries. Motor and neuropsychological results were compared to 15 non-surgical Parkinson's disease patients matched for disease stage and mental status. In addition, nine bilateral pallidotomy patients were evaluated for long-term cognitive changes (>2 years).

FINDINGS

Bilateral pallidotomy patients demonstrated significant improvements in motor functioning in the "on" and "off" states and with dyskinesias after the first surgery, with an additional improvement reported for dyskinesias after the second procedure. On long-term follow-up, dyskinesia improvements were maintained. Bilateral pallidotomy patients did not show significant cognitive declines following both procedures on the short-term follow-up and when compared to the Parkinson's disease group. However, significant cognitive declines were found on the long-term follow-up evaluation.

CONCLUSIONS

Parkinson's disease patients received significant short- and long-term motor benefits, particularly reduced dyskinesias, following staged bilateral pallidotomy without significant short-term cognitive consequences. Two years following the second procedure, bilateral pallidotomy patients tended to show an increase in both motor and non-motor symptoms of Parkinson's disease, particularly cognitive decline.

Arthur L. Benton, Ph.D.: pioneer, colleague, mentor, and friend

Arthur Benton, 97, died in Glenview, IL on December 27, 2006. He was born October 16, 1909 in New York City. He received his B.A. and M.A. degrees from Oberlin College, where Raymond Stetson was his mentor, and his Ph.D. in Psychology from Columbia University in 1935 under the mentorship of Carney Landis of the New York State Psychiatric Institute. Benton completed his training as a psychologist at the Payne Whitney Psychiatric Clinic of New York Hospital. Early in 1941, he volunteered for service in the United States Navy and was commissioned as a lieutenant in the medical department. His active duty lasted until 1945, followed by many years of service in the United States Navy Reserve, retiring at the rank of Captain. During his assignment at the San Diego Naval Hospital, Benton worked closely with neurologist Morris Bender and examined servicemen who had sustained penetrating brain wounds during combat. The experience of assessing servicemen with brain injury and Bender's influence led Benton to develop the Visual Retention Test, which still bears his name and continues to be widely used in clinical neuropsychological assessment.

Assessing and inducing neuroplasticity with transcranial magnetic stimulation and robotics for motor function

OBJECTIVES

To describe 2 new ways of assessing and inducing neuroplasticity in the human brain--transcranial magnetic stimulation (TMS) and robotics--and to investigate and promote the recovery of motor function after brain damage.

DATA SOURCES

We identified recent articles and books directly bearing on TMS and robotics. Articles using these tools for purposes other than rehabilitation were excluded. From these studies, we emphasize the methodologic and technical details of these tools as applicable for assessing and inducing plasticity.

STUDY SELECTION

Because both tools have only recently been used for rehabilitation, the majority of the articles selected for this review have been published only within the last 10 years.

DATA EXTRACTION

We used the PubMed and Compendex databases to find relevant peer-reviewed studies for this review. The studies were required to be relevant to rehabilitation and to use TMS or robotics methodologies. Guidelines were applied via independent extraction by multiple observers.

DATA SYNTHESIS

Despite the limited amount of research using these procedures for assessing and inducing neuroplasticity, there is growing evidence that both TMS and robotics can be very effective, inexpensive, and convenient ways for assessing and inducing rehabilitation. Although TMS has primarily been used as an assessment tool for motor function, an increasing number of studies are using TMS as a tool to directly induce plasticity and improve motor function. Similarly, robotic devices have been used for rehabilitation because of their suitability for delivery of highly repeatable training. New directions in robotics-assisted rehabilitation are taking advantage of novel measurements that can be acquired via the devices, enabling unique methods of assessment of motor recovery.

CONCLUSIONS

As refinements in technology and advances in our knowledge continue, TMS and robotics should play an increasing role in assessing and promoting the recovery of function. Ongoing and future studies combining TMS and robotics within the same populations may prove fruitful for a more detailed and comprehensive assessment of the central and peripheral changes in the nervous system during precisely induced recovery.

Hippocampus, amygdala, and basal ganglia morphometrics in children after moderate-to-severe traumatic brain injury

While closed head injury frequently results in damage to the frontal and temporal lobes, damage to deep cortical structures, such as the hippocampus, amygdala, and basal ganglia, has also been reported. Five deep central structures (hippocampus, amygdala, globus pallidus, putamen, and caudate) were examined in 16 children (eight males, eight females; aged 9-16y), imaged 1 to 10 years after moderate-to-severe traumatic brain injury (TBI), and in 16 individually-matched uninjured children. Analysis revealed significant volume loss in the hippocampus, amydala, and globus pallidus of the TBI group. Investigation of relative volume loss between these structures and against five cortical areas (ventromedial frontal, superomedial frontal, lateral frontal, temporal, and parieto-occipital) revealed the hippocampus to be the most vulnerable structure following TBI (i.e. greatest relative difference between the groups). In a separate analysis excluding children with focal hippocampal abnormalities (e.g. lesions), group differences in hippocampal volume were still evident, suggesting that hippocampal damage may be diffuse rather than focal.

Working memory brain activation following severe traumatic brain injury

Functional magnetic resonance imaging (fMRI) has shown that brain activation during performance of working memory (WM) tasks under high memory loads is altered in adults with severe traumatic brain injury (TBI) relative to uninjured subjects (Perlstein et al., 2004; Scheibel et al., 2003). Our study attempted to equate TBI patients and orthopedically injured (OI) subjects on performance of an N-Back task that used faces as stimuli. To minimize confusion in TBI patients that was revealed in pilot work, we presented the memory conditions in two separate tasks, 0- versus 1-back and 0- versus 2-back. In the 0- versus 1-back task, OI subjects activated bilateral frontal areas more extensively than TBI patients, and TBI patients activated posterior regions more extensively than OI subjects. In the 0- versus 2-back task, there were no significant differences between the groups. Analysis of changes in activation over time on 1-back disclosed that OI subjects had decreases in bilateral anterior and posterior regions, while TBI patients showed activation increases in those and other areas over time. In the 2-back condition, both groups showed decreases over time in fusiform and parahippocampal gyri, although the OI group also showed increases over time in frontal, parietal, and temporal areas not seen in the TBI patients. The greatest group differences were found in the 1-back condition, which places low demand on WM. Although the extent of activation in the 2-back condition did not differ between the two groups, deactivation in the 2-back condition was seen in the OI patients only, and both groups' patterns of activation over time varied, suggesting a dissociation between the TBI and OI patients in recruitment of neural areas mediating WM.

Constraint-induced movement therapy during early stroke rehabilitation

BACKGROUND

Limited data are available about the effectiveness of early rehabilitation after stroke.

OBJECTIVE

This is the 1st randomized controlled trial of constraint-induced movement therapy (CIMT) in subacute stroke to investigate neurophysiologic mechanisms and long-term outcome.

METHODS

Within 2 weeks after stroke, 23 patients with upper extremity (UE) weakness were randomized to 2 weeks of CIMT or traditional therapy at an equal frequency of up to 3 h/day. Motor function of the affected UE was blindly assessed before treatment, after treatment, and 3 months after stroke. Transcranial magnetic stimulation (TMS) measured the cortical area evoking movement of the affected hand.

RESULTS

Long-term improvement in motor function of the affected UE did not differ significantly between patients who received CIMT versus intensive traditional therapy. All outcome comparisons showed trends favoring CIMT over intensive traditional therapy, but none was statistically significant except for improvements in the Fugl-Meyer (FM) UE motor scale immediately following treatment and in reported quality of hand function at 3 months. Improvement in UE motor function on the FM was associated with a greater number of sites on the affected cerebral hemisphere where responses of the affected hand were evoked by TMS.

CONCLUSIONS

Future trials of CIMT during early stroke rehabilitation need greater statistical power, more inclusive eligibility criteria, and improved experimental control over treatment intensity. The relationship between changes in motor function and in evoked motor responses suggests that motor recovery during the 1st 3 months after stroke is associated with increased motor excitability of the affected cerebral hemisphere.

cerebellar atrophy after moderate-to-severe pediatric traumatic brain injury

BACKGROUND AND PURPOSE

Although the cerebellum has not attracted the same degree of attention as cortical areas and the hippocampus in traumatic brain injury (TBI) literature, there is limited structural and functional imaging evidence that the cerebellum is also vulnerable to insult. The cerebellum is emerging as part of a frontocerebellar system that, when disrupted, results in significant cognitive and behavioral consequences. We hypothesized that cerebellar volume would be reduced in children following TBI and wished to examine the relation between the cerebellum and known sites of projection, including the prefrontal cortex, thalamus, and pons.

MATERIALS AND METHODS

Quantitative MR imaging was used to measure cerebellar white and gray matter and lesion volumes 1-10 years following TBI in 16 children 9-16 years of age and 16 demographically matched typically developing children 9-16 years of age. Cerebellar volumes were also compared with volumetric data from other brain regions to which the cerebellum projects.

RESULTS

A significant group difference was found in cerebellar white and gray matter volume, with children in the TBI group consistently exhibiting smaller volumes. Repeating the analysis after excluding children with focal cerebellar lesions revealed that significant group differences still remained for cerebellar white matter (WM). We also found a relation between the cerebellum and projection areas, including the dorsolateral prefrontal cortex, thalamus, and pons in 1 or both groups.

CONCLUSION

Our finding of reduced cerebellar WM volume in children with TBI is consistent with evidence from experimental studies suggesting that the cerebellum and its related projection areas are highly vulnerable to fiber degeneration following traumatic insult.

Brain activation during working memory after traumatic brain injury in children

Eight children with moderate to severe traumatic brain injury (TBI) and eight matched, uninjured control children underwent fMRI during an N-back task to test effects of TBI on working memory performance and brain activation. Two patterns in the TBI group were observed. Patients whose criterion performance was reached at lower memory loads than control children demonstrated less extensive frontal and extrafrontal brain activation than controls. Patients who performed the same, highest (3-back) memory load as controls demonstrated more frontal and extrafrontal activation than controls. Our findings of performance and brain activation changes in children after TBI await longitudinal investigation.

Memory, emotional and vocational impairments before and after anterior temporal lobectomy for complex partial seizures

PURPOSE

To assess the pre- and postsurgical frequency of memory, emotional, and vocational impairments in patients who underwent anterior temporal lobectomy (ATL), and to assess the relationship between emotional disturbance and memory abilities after ATL.

METHODS

Retrospective analysis of data was performed on 90 patients with medically intractable complex partial seizures who underwent ATL between 1981 and 2003. Patients were evaluated an average of 5 months before surgery and 11.3 months after surgery.

RESULTS

A moderate to high frequency of memory impairment (44.4%; verbal or nonverbal), emotional disturbance (38.9%) and unemployment (27.8%) existed in the same individuals both before and after surgery. There were small to moderate rates of new onset memory (18.9%), emotional (11.1%), and vocational (7.8%) difficulties after surgery often regardless of seizure control outcome. Patients who underwent left-ATL and had emotional disturbance after surgery had the lowest verbal memory test scores.

CONCLUSIONS

Results highlight the importance of taking into account emotional status when assessing memory abilities after ATL. Results replicate the finding of moderate to high frequencies of memory impairment, emotional disturbance, and unemployment both before and after ATL. Results provide support for the rationale that cognitive, psychiatric and vocational interventions are indicated to mitigate the problems that exist before and persist after ATL.

Diffusion tensor imaging in the corpus callosum in children after moderate to severe traumatic brain injury

Diffusion tensor imaging (DTI) is a recent imaging technique that assesses the microstructure of the cerebral white matter (WM) based on anisotropic diffusion (i.e., water molecules move faster in parallel to nerve fibers than perpendicular to them). Fractional anisotropy (FA), which ranges from 0 to 1.0, increases with myelination of WM tracts and is sensitive to diffuse axonal injury (DAI) in adults with traumatic brain injury (TBI). However, previous DTI studies of pediatric TBI were case reports without detailed outcome measures. Using mean FA derived from DTI fiber tractography, we compared DTI findings of the corpus callosum for 16 children who were at least 1 year (mean 3.1 years) post-severe TBI and individually matched, uninjured children. Interexaminer and intraexaminer reliability in measuring FA was satisfactory. FA was significantly lower in the patients for the genu, body, and splenium of the corpus callosum. Higher FA was related to increased cognitive processing speed and faster interference resolution on an inhibition task. In the TBI patients, higher FA was related to better functional outcome as measured by the dichotomized Glasgow Outcome Scale (GOS). FA also increased as a function of the area of specific regions of the corpus callosum such as the genu and splenium, and FA in the splenium was reduced with greater volume of lesions in this region. DTI may be useful in identifying biomarkers related to DAI and outcome of TBI in children.

Neuroplasticity and Brain Imaging Research: Implications for Rehabilitation

Advanced brain imaging technologies have been used recently to investigate neuroplasticity in relation to recovery and treatment of neurologic injury and disease. The contributors to this supplement present data and synthesize the extant literature on the use of functional magnetic resonance imaging, magnetic resonance spectroscopy, optical imaging, transcranial magnetic stimulation, and transcranial direct current stimulation to study remodeling of cortical representation of motor and cognitive abilities after stroke and other etiologies of neurologic impairment. In general, the collective findings of these studies support use-dependent neuroplasticity as a mechanism of recovery and response to training. Brain imaging findings support the role of training effects on increased activation of brain regions ipsilateral to unilateral vascular lesions in facilitating recovery from stroke. The articles in this supplement also report the potential therapeutic application of stimulation techniques to enhance reorganization of function.

Vulnerability of the anterior commissure in moderate to severe pediatric traumatic brain injury

In relation to the adult brain, the immature brain might be more vulnerable to damage during and following traumatic brain injury, particularly in white-matter tracts. Given well-established evidence of corpus callosum atrophy, we hypothesized that anterior commissure volume (using quantitative magnetic resonance imaging [MRI]) in this structure would be decreased in children with moderate to severe traumatic brain injury relative to typically developing children. Second, given the purported role of the anterior commissure in interhemispheric axon conveyance between temporal lobes, we hypothesized that temporal lobe white matter, temporal lesion volume, and injury severity (Glasgow Coma Scale score) would be predictive of decreased anterior commissure cross-sectional volume in patients with traumatic brain injury. Finally, we wished to establish the relationship between the anterior commissure and the temporal stem, a major white-matter tract into the temporal lobes, using diffusion tensor imaging fiber-tracking maps for each patient. We also hypothesized that children with traumatic brain injury would exhibit decreased fractional anisotropy in relation to typically developing children in a fiber system including the anterior commissure and the temporal lobes. Decreased anterior commissure cross-sectional volume was observed in patients with traumatic brain injury, and, as predicted, anterior commissure and temporal white-matter volumes were positively related to each other and to higher Glasgow Coma Scale scores. Lesion volume was not independently predictive of anterior commissure volume in the overall model. Diffusion tensor imaging fractional anisotropy values differed between the groups for the temporal stem-anterior commissure system, with the traumatic brain injury group exhibiting decreased fractional anisotropy. The anterior commissure, like the corpus callosum, appears to be highly vulnerable to white-matter degenerative changes resulting from mechanisms such as the direct impact of trauma, progressive axonal injury as tissue in other brain regions atrophies, or myelin degeneration. This is the first systematic examination of anterior commissure atrophy following traumatic brain injury using in vivo quantitative MRI and diffusion tensor imaging fiber tracking in pediatric subjects.

Decision-making after traumatic brain injury in children: a preliminary study

Decision-making under conditions of uncertainty was studied in 11 children with moderate to severe post-acute traumatic brain injury (TBI) using a modification of the Iowa Gambling Task (Bechara et al., 1994). We hypothesized that decision-making would be compromised in children with TBI. The results revealed that when divided into subgroups by lesion location, children with lesions in the amygdala (AM) were impaired on modified gambling task performance, but children with ventromedial (VM) lesions did not appear to be impaired on the task. These results are in contrast to studies of decision-making in adults with focal lesions of vascular etiology.

Evaluation of the errorless learning technique in children with traumatic brain injury

OBJECTIVE

To compare errorless learning with trial-and-error (T&E) learning of declarative facts in children with memory disorders secondary to traumatic brain injury (TBI).

DESIGN

Retrospective within-subjects concurrent treatment design.

SETTING

Participants' school or home.

PARTICIPANTS

Thirty-four children, ages 6 to 18 years, with mild, moderate, or severe postacute TBI who met criteria for memory impairment.

INTERVENTION

Conditions consisted of an errorless learning method and a T&E method. Within a session, half the items were taught with the errorless learning method and half with the T&E method. Each child received two 1-hour sessions a week for 7 weeks.

MAIN OUTCOME MEASURES

Relative effectiveness of errorless learning and T&E methods for (1) initial learning and (2) retention over time for learned items.

RESULTS

There was an advantage for T&E on initial learning. In children with mild, but not moderate or severe TBI, 2-day retention was better with the errorless learning technique; 7-day retention was better with errorless learning in young children with mild TBI. Seventy-seven-day retention revealed an advantage for errorless learning in younger children with severe TBI.

CONCLUSIONS

Findings did not support errorless learning as a generalized intervention for learning difficulties after TBI or identify specific age- or injury-severity groups that benefited from this technique.

Predictors of personality change due to traumatic brain injury in children and adolescents six to twenty-four months after injury

Phenomenology and predictive factors of personality change due to traumatic brain injury (TBI) 6 to 24 months after injury was investigated in children, ages 5 to 14 years, enrolled from consecutive admissions and followed prospectively for 2 years. Injury and preinjury psychosocial variables were assessed. Personality change occurred in 13% of participants between 6 and 12 months after injury and 12% in the second year after injury. Severity of injury consistently predicted personality change, and preinjury adaptive function predicted personality change only in the second year postinjury. Lesions of the superior frontal gyrus were associated with personality change between 6 and 12 months following injury, after controlling for severity of injury and the presence of other brain lesions. Only lesions in the frontal lobe white matter were significantly related to personality change in the second year after injury. After childhood TBI, neural correlates of personality change evolve between 6 and 12 months and 12 to 24 months after injury. The data implicate the dorsal prefrontal cortex and frontal lobe white matter in the emergence of personality change involving the effortful or conscious regulation of affective states.

Impaired discourse gist and working memory in children after brain injury

Emerging evidence suggests that a traumatic brain injury (TBI) in childhood may disrupt the ability to abstract the central meaning or gist-based memory from connected language (discourse). The current study adopts a novel approach to elucidate the role of immediate and working memory processes in producing a cohesive and coherent gist-based text in the form of a summary in children with mild and severe TBI as compared to typically developing children, ages 8-14 years at test. Both TBI groups showed decreased performance on a summary production task as well as retrieval of specific content from a long narrative. Working memory on n-back tasks was also impaired in children with severe TBI, whereas immediate memory performance for recall of a simple word list in both TBI groups was comparable to controls. Interestingly, working memory, but not simple immediate memory for a word list, was significantly correlated with summarization ability and ability to recall discourse content.

Functional reorganization and recovery after constraint-induced movement therapy in subacute stroke: case reports

Preliminary assessments of the feasibility, safety, and effects on neuronal reorganization measured with transcranial magnetic stimulation (TMS) from Constraint-Induced Movement Therapy (CIMT) of the upper extremity were made in eight cases of subacute stroke. Within fourteen days of their stroke, patients were randomly assigned to two weeks of CIMT or traditional therapy. Baseline motor performance and cortical/subcortical representation for movement with TMS were assessed before treatment. Post-treatment assessments were made at the end of treatment and at three months after the stroke. The TMS mapping showed a larger motor representation in the lesioned hemisphere of the CIMT patients as compared to the controls at the three-month follow-up assessment. The enlarged motor representation in the lesioned hemisphere for hand movement correlated with improved motor function of the affected hand, suggesting a link between movement representation size as measured with TMS and functionality. These results suggest that TMS can be safely and effectively used to assess brain function in subacute stroke and further suggest that CIMT may enhance cortical/subcortical motor reorganization and accelerate motor recovery when started within the first two weeks after stroke.

Diagnostic criteria for postconcussional syndrome after mild to moderate traumatic brain injury

This study evaluated the prevalence and specificity of diagnostic criteria for postconcussional syndrome (PCS) in 178 adults with mild to moderate traumatic brain injury (TBI) and 104 with extracranial trauma. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) and International Classification of Diseases (ICD-10) criteria for PCS were evaluated 3 months after injury. The results showed that prevalence of PCS was higher using ICD-10 (64%) than DSM-IV criteria (11%). Specificity to TBI was limited because PCS criteria were often fulfilled by patients with extracranial trauma. The authors conclude that further refinement of the DSM-IV and ICD-10 criteria for PCS is needed before these criteria are routinely employed.

Predictors of attention-deficit/hyperactivity disorder within 6 months after pediatric traumatic brain injury

OBJECTIVE

To assess the phenomenology and predictive factors of attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (SADHD).

METHOD

Children without preinjury ADHD 5-14 years old with TBI from consecutive admissions (n = 143) to five trauma centers were observed prospectively for 6 months (baseline and 6 months), with semistructured psychiatric interviews. Injury severity, lesion characteristics, and preinjury variables including psychiatric disorder, family psychiatric history, family psychiatric history of ADHD, family function, socioeconomic status, psychosocial adversity, and adaptive function were assessed with standardized instruments.

RESULTS

SADHD in the first 6 months after injury occurred in 18 of 115 (16%) of returning participants. All subtypes of ADHD occurred. Socioeconomic status (p = .041) and orbitofrontal gyrus lesions (p = .005) independently significantly predicted SADHD.

CONCLUSIONS

These findings are consistent with research on developmental ADHD that implicate psychosocial factors and prefrontal structural and functional differences between those with and without the disorder.

Predictors of secondary attention-deficit/hyperactivity disorder in children and adolescents 6 to 24 months after traumatic brain injury

OBJECTIVE

To assess the phenomenology and predictive factors of attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (SADHD).

METHOD

Children without preinjury ADHD 5-14 years old with TBI from consecutive admissions (n = 143) to five trauma centers were observed prospectively from 6 to 12 months (12-month assessment) and from 12 to 24 months (24-month assessment) postinjury with semistructured psychiatric interviews. Injury and preinjury psychosocial variables were assessed.

RESULTS

SADHD occurred in 15 of 103 (15%) of participants between 6 and 12 months after injury and 17 of 82 (21%) in the second year after injury. SADHD was significantly (p < .05) comorbid with personality change due to TBI and new-onset disruptive behavior disorders. Preinjury adaptive function was a consistent predictor of SADHD. Regression analyses revealed that preinjury psychosocial adversity was an independent predictor of SADHD in the second year after injury. Neither severity of injury nor lesion location predicted SADHD from 6 to 24 months postinjury.

CONCLUSIONS

Determination of preinjury psychosocial adversity and the child's preinjury functioning during the index hospitalization would improve identification of children at highest risk of development of SADHD.

Executive functions after traumatic brain injury in children

There is growing recognition that executive function, the superordinate, managerial capacity for directing more modular abilities, is frequently impaired by traumatic brain injury in children and mediates the neurobehavioral sequelae exhibited by these patients. This review encompasses the definition of specific executive functions, age-related changes in executive functions in typically developing children, and the effects of traumatic brain injury on executive functions. The neural substrate for executive functions is described, including relevant functional brain imaging studies that have implicated mediation by prefrontal and parietal cortex and their circuitry. The vulnerability of the neural substrate for executive function to the pathophysiology of traumatic brain injury is discussed, including focal lesions and diffuse axonal injury. Domains of executive functions covered in this review include the basic processes of working memory and inhibition and more complex processes such as decision making. Other domains of executive function, including motivation, self-regulation, and social cognition are discussed in terms of research methodology, clinical assessment, and findings in children with traumatic brain injury. Proposed approaches to the rehabilitation of executive functions are presented.

Postconcussional disorder: Are the DSM-IV criteria an improvement over the ICD-10?

Little is known about the characteristics and outcomes of patients diagnosed with postconcussional disorder (PCD) under the provisionally proposed criteria in the DSM-IV and how they differ from patients diagnosed with postconcussional syndrome (PCS) under the International Classification of Diseases, 10th edition clinical (ICD-10) criteria. This study investigated differences in outcome based on a diagnosis of PCD (DSM-IV) versus PCS (ICD-10 clinical criteria) as to which criteria set might be preferred for clinical practice. A consecutive series of adult patients with mild (N = 319) to moderate (N = 21) traumatic brain injury was assessed at 3 months postinjury with a brief neuropsychological battery and measures of specific outcome domains. In two separate series of analyses, patients with PCD were compared with those without PCD, and those with PCS were compared with those without PCS. Although the two criteria sets resulted in markedly different incidence rates, there was no substantial pattern of differences between the DSM-IV and ICD-10 in the outcome domains of psychiatric symptoms and disorders, social and community integration, health-related quality of life, or global outcome as measured by the Glasgow Outcome Scale-Extended. In spite of significant differences between the two diagnostic criteria sets and different incidence rates for PCD/PCS, outcome in all measured domains was very similar at 3 months postinjury. There is no compelling evidence, based on these outcome domains, to suggest which of the two diagnostic criteria sets should be clinically preferred.

Frontal and temporal morphometric findings on MRI in children after moderate to severe traumatic brain injury

In vivo MRI volumetric analysis enables investigators to evaluate the extent of tissue loss following traumatic brain injury (TBI). However, volumetric studies of pediatric TBI are sparse, and there have been no volumetric studies to date in children examining specific subregions of the prefrontal and temporal lobes. In this study, MRI volumetry was used to evaluate brain volume differences in the whole brain, and prefrontal, temporal, and posterior regions of children following moderate to severe TBI as compared to uninjured children of similar age and demographic characteristics. The TBI group had significantly reduced whole brain, and prefrontal and temporal regional tissue volumes as well as increased cerebrospinal fluid (CSF). Confidence interval testing further revealed group differences on gray matter (GM) and white matter (WM) in the superior medial and ventromedial prefrontal regions, WM in the lateral frontal region, and GM, WM, and CSF in the temporal region. Whole brain volume and total brain GM were reduced, and total ventricular volume, total CSF volume, and ventricle-to-brain ratio (VBR) were increased in the TBI group. Additional analyses comparing volumetric data from typically developing children and subgroups of TBI patients with and without regional focal lesions suggested that GM loss in the frontal areas was primarily attributable to focal injury, while WM loss in the frontal and temporal lobes was related to both diffuse and focal injury. Finally, volumetric measures of preserved frontotemporal tissue were related to functional recovery as measured by the Glasgow Outcome Scale (adapted for children) with greater tissue preservation predicting better recovery.

Predictors of personality change due to traumatic brain injury in children and adolescents in the first six months after injury

OBJECTIVE

To assess the phenomenology and predictive factors of personality change due to traumatic brain injury.

METHOD

Children (N = 177), aged 5 to 14 years with traumatic brain injury from consecutive admissions to five trauma centers, were followed prospectively at baseline and 6 months with semistructured psychiatric interviews. Injury severity, lesion characteristics, and preinjury variables including psychiatric disorder, family psychiatric history, family function, socioeconomic status, psychosocial adversity, and adaptive function were assessed with standardized instruments.

RESULTS

Personality change occurred in 22% of participants in the first 6 months after injury. Severity of injury predicted personality change, whereas none of the psychosocial variables predicted personality change. Lesions of the dorsal prefrontal cortex, specifically the superior frontal gyrus, were associated with personality change after controlling for severity of injury or the presence of other lesions.

CONCLUSIONS

These findings are consistent with models of affective dysregulation that implicate a dorsal prefrontal cortex system important for effortful regulation of affective states.

Predicting Depression Following Mild Traumatic Brain Injury

CONTEXT

Minimizing negative consequences of major depression following traumatic brain injury is an important public health objective. Identifying high-risk patients and referring them for treatment could reduce morbidity and loss of productivity.

OBJECTIVE

To develop a model for early screening of patients at risk for major depressive episode at 3 months after traumatic brain injury.

DESIGN

Prediction model using receiver operating characteristic curve.

SETTING

Level I trauma center in a major metropolitan area.

PARTICIPANTS

Prospective cohort of 129 adults with mild traumatic brain injury.

MAIN OUTCOME MEASURES

Center for Epidemiologic Studies Depression Scale score and current major depressive episode module of the Structured Clinical Interview for the DSM-IV.

RESULTS

A prediction model including higher 1-week Center for Epidemiologic Studies Depression Scale score, older age, and computed tomographic scans of intracranial lesions yielded 93% sensitivity and 62% specificity.

CONCLUSION

This study supports the feasibility of identifying patients with mild traumatic brain injury who are at high risk for developing major depressive episode by 3 months' postinjury, which could facilitate selective referral for potential treatment and reduction of negative outcomes.

Lost productive work time after mild to moderate traumatic brain injury with and without hospitalization

OBJECTIVE

Lost productivity after mild traumatic brain injury (TBI) is a large component of the economic costs of brain trauma in the United States. This is the first prospective study of employment after mild TBI to include patients not admitted to a hospital.

METHODS

Concurrent inception cohorts of 210 working-age adults with mild to moderate TBI and 122 patients who sustained general trauma not involving the brain were recruited at a trauma center and followed up to 6 months later. Outcomes were time from injury until first day worked and problems reported after resuming work.

RESULTS

Most patients who worked after their injury remained employed 6 months later in a similar capacity as before the injury. No consistent differences were demonstrated between employment outcomes of patients with mild TBI and those with general trauma. The majority of nonhospitalized patients with mild TBI did not work for at least 1 month and did not begin working until 1 to 3 months after injury. Most patients with moderate TBI remained unemployed at 6 months postinjury. Patients with lower preinjury occupational status tended to have longer work absences.

CONCLUSION

Lost productive work time after nonhospitalized TBI may cause significant economic costs because these injuries are frequent. Contrary to the theory that brain injury is more disabling to patients in cognitively demanding occupations, patients with higher job status tended to begin work earlier. A technique is needed to screen patients with mild TBI for risk of employment problems. Rehabilitation after moderate TBI may help to minimize lost productivity.

Late proton MR spectroscopy in children after traumatic brain injury: correlation with cognitive outcomes

BACKGROUND AND PURPOSE

Proton MR spectroscopy has demonstrated reduced levels of N-acetylaspartate (NAA) in normal-appearing occipital and frontal regions of patients with acute nonpenetrating traumatic brain injury (TBI). We studied the relationship of frontoparietal NAA, choline (Cho), and creatine (Cr) to test the hypothesis that reduction in NAA is predictive of cognitive outcome.

METHODS

Proton spectra were collected by using conventional 2D chemical shift imaging in five healthy children and seven children (6 weeks to 3 years) with severe (n=4), moderate (n=2), or mild (n=1) TBI. Spectra in the anterior and posterior regions of the left and right frontoparietal areas were averaged for analysis by using LCModel, with a phantom-established basis function, for quantification of NAA, Cho, and Cr concentrations. Intellectual function, expressive language, and arithmetic capability were measured within 4 months of imaging.

RESULTS

NAA/Cho concentration was lower in TBI patients than in control subjects, but no group differences were present for Cho or Cr. Hemispheric levels for NAA, Cho, and Cr were higher on the left than on the right, but we found no effect of region and no interactions. Cognition was lower in the TBI group than the control group and correlated with NAA levels. Left frontal Cho was also correlated with arithmetic scores, whereas Cr was not significantly correlated.

CONCLUSION

NAA levels remain low after TBI and are related to cognitive function. Neurometabolite values are greater in the left frontoparietal region than in the right, and the left frontal Cho level is related to arithmetic ability.

Perception of health and quality of life in minorities after mild-to-moderate traumatic brain injury

Much has been reported of the influence of age, affective symptoms, and satisfaction on self-ratings of health functioning, but little is known about the extent that race-based perceptions may have on influencing behavior or adjustment after a mild-to-moderate traumatic brain injury (MTBI). We investigated differences in perception of health functioning by race for mental and physical functioning using a global measure of health functioning. MTBI (n = 135) and general trauma (GT, n = 83) patients recruited from an area Level-1 trauma center at 3 months after injury were administered the Medical Outcomes Study: Short Form (SF-36), Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994), Community Integration Questionnaire, Social Support Questionnaire (SSQ), Center for Epidemiological Studies-Depression, and the Visual Analogue Scale of Depression. A significant interaction for Race Group (p < .01) was found on the Physical Component Scale (PCS) of the SF-36. In the MTBI group, African Americans reported worse functioning (p < .04) on the PCS scale; they perceived functioning on subscales General Health Perception (p < .02) and Physical Functioning (p < .04) to be more limited. On the SSQ, Hispanic MTBI patients reported having fewer social supports available to them (p < .05), although the race groups were comparable for satisfaction with their support. Rate of depression across groups was comparable, although subjective reporting by minority MTBI patients indicated greater depressed feelings. Differences in perception of health functioning may be related to the unique interaction created between sustaining an MTBI and variations in cultural expression of disability. Manifestations of physical difficulties may be better accepted for some cultures than having mental illness.

[The neurobehavioral rating scale-revised: assessment of concurrent validity]

Cognitive and behavioral impairment are a major source of disability in daily living of patients with traumatic brain injury (TBI). The Neurobehavioral Rating Scale-Revised (NRS-R) is a short, easy-to administer interview tool developed to improve assessment by clinicians. Data are available on its criterion validity and reliability, but the concurrent validity of the French NRS-R was not yet documented.

OBJECTIVE

To assess the concurrent validity of the NRS-R with current psychometric tests.

METHOD

One hundred and four patients with TBI enrolled in a community adjustment program underwent concurrent examination with the NRS-R, cognitive tests assessing memory, attention, and executive functions, and scales of anxiety (STAI) and depressive mood (CES-D). Intercorrelations were undertaken between these variables and the five factors of the NRS-R: F1, intentional behavior; F2, lowered emotional state; F3, survival-oriented behaviour/hightened emotional state; F4, arousal state; and F5, language. Patients were 82 men and 22 women, the mean age was 28.5 years, and 70% had severe TBI (Glasgow coma score [GCS] below 8 on admission). They were assessed 52 months on average after their injury.

RESULTS

Factor F1 was correlated with results on the GCS (P<0.05), the Tower of London test (TL, P<0.01), the Trail Making Test (TMT, P<0.01), divided attention (DA) and inhibition (IN) subscales of the Zimmermann and Fimm's Attention battery (TEA) (P<0.01) and reverse digit span (DS, P<0.05). Factor F2 was positively related to age at injury, time since injury (TSI) (P<0.05) and CESD and STAI scores (P<0.001). Factor F3 was related to DA (P<0.01) TL scores and TSI (P<0.05). Factor F4 was related to TL, TMT, DA, flexibility, DS (P<0.05), TSI, duration of post-traumatic amnesia, CES-D score (P<0.05) and STAI scores (P<0.01). Factor F5 was related to GCS, DA (P<0.05), and reaction time on the subscales IN and Go/nogo (GO) of the TEA battery (P<0.01). The NRS-R total score was related to CESD, STAI scores, TMT score, DA (P<0.01) and TL score, IN and GO scores and TSI (P<0.05).

DISCUSSION

As McCauley et al found with the English version of the NRS-R, significant relationships were found between NRS-R factor scores, cognitive tests and emotional scales. Relationships were also found between factor scores and indicators of injury severity and time since injury. These data suggest fair concurrent validity of the NRS-R.

Selective impairment of inhibition after TBI in children

Inhibition was studied in 12 children who had had sustained as severe traumatic brain injury (TBI) at least 1 year earlier and in 15 control children. On the flanker task, which involved pressing a button corresponding to the direction of an arrow, the TBI group performed less accurately than controls under interference (flankers were incongruent with arrow) and go-no-go (adjacent stimulus signaled child to withhold response) conditions, but not neutral or facilitation (flankers were congruent) conditions. Response latency was related to age and task condition, but not group. Severe TBI in children may disrupt development of distributed networks mediating inhibition.

Psychosocial outcome of TBI in children with unilateral frontal lesions

To evaluate effects of unilateral frontal lesions on psychosocial and global outcome of traumatic brain injury (TBI) in children, Study 1 compared matched groups of 22 school aged children who had sustained TBI either with or without unilateral frontal lesions. Study 2 evaluated effects of unilateral extrafrontal lesions in 18 TBI patients as compared with 18 nonlesional TBI patients. Communication, Daily Living, and Socialization domains and the Maladaptive Behavior Scale of the Vineland Adaptive Behavior Scales (VABS) were used to assess psychosocial outcome, and the Glasgow Outcome Scale (GOS) measured global outcome. All patients underwent magnetic resonance imaging at least 3 months post injury. Children with frontal lesions had worse scores on the Daily Living and Socialization domains and a higher frequency of maladaptive behavior than those without frontal lesions, but there was no difference in cognitive function. Disability was twice as common in the frontal lesion group relative to children without frontal lesions. Volume of frontal lesion was related to the Socialization domain. Side of lesion had no effect, nor did presence of an extrafrontal lesion (Study 2). Unilateral frontal lesions adversely affect late psychosocial outcome of TBI in children.

Modeling of longitudinal academic achievement scores after pediatric traumatic brain injury

In a prospective longitudinal study, academic achievement scores were obtained from youth 5 to 15 years of age who sustained mild-moderate (n = 34) or severe (n = 43) traumatic brain injuries (TBI). Achievement scores were collected from baseline to 5 years following TBI and were subjected to individual growth curve analysis. The models fitted age at injury, years since injury, duration of impaired consciousness, and interaction effects to Reading Decoding, Reading Comprehension, Spelling, and Arithmetic standard scores. Although scores improved significantly over the follow-up relative to normative data from the standardization sample of the tests, children with severe TBI showed persistent deficits on all achievement scores in comparison to children with mild-moderate TBI. Interactions of the slope and age parameters for the Arithmetic and Reading Decoding scores indicated greater increases over time in achievement scores of the children injured at an older age, but deceleration in growth curves for the younger children with both mild-moderate and severe TBI. These results are compatible with the hypothesis that early brain injuries disrupt the acquisition of some academic skills. Hierarchical regression models revealed that indexes of academic achievement obtained 2 years following TBI had weak relations with the duration of impaired consciousness and socioeconomic status. In contrast, concurrent cognitive variables such as phonological processing and verbal memory accounted for more variability in academic scores. Given the significant and persistent decrement in basic academic skills in youth with severe TBI, it is clear that head-injured youth require intensive, long-term remediation and intervention not only of the academic skills themselves, but also of those cognitive abilities that support the development and maintenance of reading and math.

Prospective memory in pediatric traumatic brain injury: a preliminary study

Prospective memory (PM) performance was investigated in a preliminary study of children and adolescents ages 10-19 in 3 groups: individuals with orthopedic injuries (not involving the head) requiring hospitalization (Ortho, N = 15), mild traumatic brain injury (TBI, N = 17), and severe TBI (N = 15). All participants with TBI were at least 5 years postinjury and participants in the Ortho group were at least 3 years postinjury. The PM task involved reporting words presented in blue during a category decision task in which words were presented in several different colors and participants were to determine which of two categories the word belonged. Participants were asked to make their choices as quickly as possible. After a 10- to 15-min intervening computer task in which all words were presented in black letters, a large proportion of participants with mild or severe TBI failed to indicate any blue words when they appeared. After a reminder to perform the PM task was given to all at the same point in the task, PM performance increased in the Ortho and Mild TBI groups, but remained comparably impaired in the Severe TBI group. Reaction time (RT) data indicated that mean RT was slower with increasing TBI severity. Further, there was a significant cost in RT for performing the PM task during the ongoing category decision task for all groups. The cost in terms of slowed RT increased with greater TBI severity.

Attention Deficit Hyperactivity Disorder Symptoms and Response Inhibition After Closed Head Injury in Children: Do Preinjury Behavior and Injury Severity Predict Outcome?

We examined the effect of closed head injury (CHI) on the development of symptoms of secondary attention deficit hyperactivity disorder (SADHD), emotional disturbance, and impaired response inhibition. We also investigated the relation of developmental and recovery variables to SADHD symptoms and inhibition. Participants were 200 children aged 5-17 years, 137 children who had CHI, and 63 children with no history of CHI served as controls. We assessed preinjury behavior problems, head injury variables (severity, age at time of injury, time since injury), postinjury SADHD, and anxiety symptoms at least 2 years following the head injury. Response inhibition was measured with the stop-signal task. CHI predicted the development of SADHD symptoms and anxiety with more severe injury predicting more severe outcomes. Only the combination of severe CHI and a high level of SADHD symptoms predicted poor response inhibition. Postinjury anxiety was not associated with poor inhibition. The consequences of CHI did not vary with age at injury or time since injury, but poorer outcome was predicted by preinjury behavior problems. CHI in children leads to SADHD symptoms and anxiety even after taking preinjury disturbance into account. Poor response inhibition is a consequence of CHI but only when the CHI is severe and the child manifests high levels of SADHD symptoms.

Childhood Head Injury and Metacognitive Processes in Language and Memory

We studied the metacognitive functioning of children with severe and mild traumatic brain injury (TBI) and typically developing children. To test metacognition for memory, children were tested on a modified Judgment of Learning task. We found that children with severe TBI were impaired in their ability to predict recall of specific items prior to study-recall trials, but were unimpaired in predicting recall on a delayed test when the judgment was made after study-recall trials. Metacognitive knowledge impairment for memorial abilities was also demonstrated in children with severe TBI by poor estimation of memory span and exaggerated overconfidence in performance. To test metacognition within the language domain, we gave children a sentence anomaly detection and repair task in which spoken sentences were monitored for semantic anomalies. Children with severe TBI were impaired on the detection of semantic anomalies, especially under conditions of high memory load. However, metalinguistic knowledge in the form of adequate repairs of anomalous sentences, was preserved. Results are discussed in terms of effects of age at test and injury severity.

Components of Executive Function in Typically Developing and Head-Injured Children

To identify the key components of executive functions (EFs) in children following traumatic brain injury (TBI), data from a series of EF tests administered to 286 pediatric TBI patients at least 3 years postinjury were subjected to an exploratory factor analysis. A 5-factor model included discourse, EFs (e.g., problem solving, planning), processing speed (e.g., coding), declarative memory, and motor speed. Confirmatory factor analysis based on data obtained from 265 pediatric TBI patients at 3 months postinjury disclosed that the 5-factor model provided a good fit to the data. A second exploratory analysis of the 3-month postinjury data disclosed a 4-factor model in which processing speed and motor speed measures loaded on a common factor. Severity of TBI and age at test had significant effects on all factors in both the 5- and 4-factor models. Adaptive functioning, as measured by the Vineland Adaptive Behavioral Scale-Revised, was moderately related to factor scores at 3 years or longer postinjury, but weakly related to factor scores obtained at 3 months postinjury. The factor scores could be used in clinical trials to facilitate data reduction and appear to have validity as indicators of TBI outcome.

Discourse Macrolevel Processing After Severe Pediatric Traumatic Brain Injury

The purpose of this study was to determine if discourse macrolevel processing abilities differed between children with severe traumatic brain injury (TBI) at least 2 years postinjury and typically developing children. Twenty-three children had sustained a severe TBI either before the age of 8 (n = 10) or after the age of 8 (n = 13). The remaining 32 children composed a control group of typically developing peers. The groups' summaries and interpretive lesson statements were analyzed according to reduction and transformation of narrative text information. Compared to the control group, the TBI group condensed the original text information to a similar extent. However, the TBI group produced significantly less transformed information during their summaries, especially those children who sustained early injuries. The TBI and control groups did not significantly differ in their production of interpretive lesson statements. In terms of related skills, discourse macrolevel summarization ability was significantly related to problem solving but not to lexical or sentence level language skills or memory. Children who sustain a severe TBI early in childhood are at an increased risk for persisting deficits in higher level discourse abilities, results that have implications for academic success and therapeutic practices.

Changes in Working Memory After Traumatic Brain Injury in Children

The impact of traumatic brain injury (TBI) on working memory (WM) was studied in 144 children (79 with mild, 23 with moderate, and 42 with severe injuries) who underwent magnetic resonance imaging (MRI) at 3 months and were tested at baseline and at 3, 6, 12, and 24 months postinjury. An n-back WM task for letter identity was administered with memory load ranging from 1- to 3-back and a 0-back condition. A TBI Severity x Quadratic Tune interaction showed that net percentage correct (correct detections of targets minus false alarms) was significantly lower in severe than in mild TBI groups. The Left Frontal Lesions x Age interaction approached significance. Mechanisms mediating late decline in WM and the effects of left frontal lesions are discussed.

Verbal selective learning after traumatic brain injury in children

Selective learning (SL), the ability to select items to learn from among other items, engages cognitive control, which is purportedly mediated by the frontal cortex and its circuitry. Using incentive-based auditory word recall and expository discourse tasks, we studied the efficiency of SL in children ages 6 to 16 years who had sustained severe traumatic brain injury (TBI) at least 1 year earlier. We hypothesized that SL would be compromised by severe TBI. Results indicated that children with severe TBI performed significantly worse than age-matched typically developing children on word- and discourse-level measures of SL efficiency with no significant group differences in number of items recalled from auditory word lists or declarative facts. We conclude that severe TBI disrupts incentive-based cognitive control processes, possibly due to involvement of frontal neural networks.

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.

Neuroplasticity following non-penetrating traumatic brain injury

The primary objective of this review is to examine the methodology and evidence for neuroplasticity operating in recovery from traumatic brain injury (TBI), as compared with previous findings in patients sustaining perinatal and infantile focal vascular lesions. The evidence to date indicates that the traditional view of enhanced reorganization of function after early focal brain lesions might apply to early focal brain lesions, but does not conform with studies of early severe diffuse brain injury. In contrast to early focal vascular lesions, young age confers no advantage in the outcome of severe diffuse brain injury. Disruption of myelination could potentially alter connectivity, a suggestion which could be confirmed through diffusion tensor imaging (DTI). Initial reports of DTI in TBI patients support the possibility that this technique can demonstrate alterations in white matter connections which are not seen on conventional magnetic resonance imaging (MRI) and might change over time or with interventions. Preliminary functional MRI studies of TBI patients indicate alterations in the pattern of brain activation, suggesting recruitment of more extensive cortical regions to perform tasks which stress computational resources. Functional MRI, coupled with DTI and possibly other imaging modalities holds the promise of elucidating mechanisms of neuroplasticity and repair following TBI.

Seizure control and cognitive outcome after temporal lobectomy: a comparison of classic Ammon's horn sclerosis, atypical mesial temporal sclerosis, and tumoral pathologies

PURPOSE

Neuropathologic examination of resected tissue after anterior temporal lobectomy (ATL) for treatment of complex partial seizures revealed several distinct histologic substrates. Our study examined the relation between neuropathology, seizure control, and cognition in ATL patients and described preliminary profiles to aid in the prediction of outcome.

METHODS

Of the 149 patients who underwent ATL from 1980 to 1999, long-term follow-up was available for 145. Specimens from 124 of the 145 patients had histologic findings consistent with one of three diagnoses: classic Ammon's horn sclerosis (cAHS; n = 75), atypical mesial sclerosis (Atypical; n = 21), or low-grade tumor (Tumor; n = 28). The other 20 patients had diverse pathologies that were insufficient for analysis. ATL patients underwent a complete preoperative and 68 underwent a postoperative neuropsychological evaluation.

RESULTS

Of the 145 patients, 84% of cAHS, 57% of Tumor, and 29% of Atypical patients had a > or =95% reduction in seizure frequency. Neuropsychological testing suggested that cAHS patients demonstrate more generalized preoperative cognitive impairment than do the Atypical or Tumor patients. The Atypical group recalled significantly less nonverbal material after surgery than did the cAHS or Tumor groups. Stratification by both pathology and surgery side revealed that the right Atypical patients declined more on information processing and set shifting.

CONCLUSIONS

Patients with cAHS or Tumor demonstrated better seizure control and fewer declines in cognitive functioning after ATL than did the Atypical patients, highlighting the need to investigate this group as a distinct entity.

Clustering and switching in phonemic fluency following pallidotomy for the treatment of Parkinson's disease

Phonemic fluency impairments have been reported as one of the most consistent cognitive declines following pallidotomy for the treatment of Parkinson's disease. In 39 pallidotomy patients, we evaluated two dissociable processes involved in phonemic fluency: (1) clustering, the ability to generate words within clusters or subcategories, which has been related to intact temporal lobe functioning; and (2) switching, the ability to shift between clusters, which has been related to frontostriatal integrity. We also correlated the location of the lesion in the pallidum and adjacent structures with the effect on phonemic fluency. Pallidotomy patients generated significantly fewer words on phonemic fluency for up to a year following surgery, with a decline in the total number of switches made, rather than a decline in the number of clusters generated. Patients whose lesions on postoperative neuroimaging fell entirely or mostly within the GPi performed worse on switching than patients whose lesions fell half outside of the GPi, either within the GPe or the internal capsule. However, no significant differences were found for lesion location 6 months following surgery. The findings support the hypothesis that the GPi plays a role in cognitive functioning.

Working memory after traumatic brain injury in children

To investigate the effects of traumatic brain injury on working memory in children, we administered semantic (letter identity) and phonological (letter rhyme) N-back tasks to children who were on average 5 years post-mild (n = 54) or -severe (n = 26) traumatic brain injury and 44 typically developing children who were comparable in age. The correct detection of targets and false alarms were measured for each task. Memory load (which varied from 0 to 3 letters back) and age significantly affected the detection of targets and false alarms in both tasks. The severity of traumatic brain injury affected the correct detection of letters on the identity task and false alarms on the rhyme task. Traumatic brain injury severity also interacted with memory load in its effect on false alarms on the rhyme task. Traumatic brain injury results in impaired working memory and diminished inhibition in children. The N-back working memory task is feasible for administration to brain-injured children and potentially could be useful for studying brain activation associated with working memory and effects of drug therapy in this group of patients.

Selective learning in children after traumatic brain injury: a preliminary study

Selective learning (SL) is the ability to select items to learn from among other items. It requires the use of the executive processes of metacognitive control and working memory, which are considered to be mediated by the frontal cortex and its circuitry. We studied the efficiency with which verbal items of greater value are selectively learned from among items varying in value in 14 children ages 8-15 years who had sustained severe traumatic brain injury (TBI) and in 39 typically developing age-matched children. We hypothesized that children with TBI would be disproportionately compromised in selective learning efficiency in contrast to memory span when compared to normally developing children. The results supported our hypothesis, as children with TBI performed significantly worse than controls on a measure of selective learning efficiency, but the two groups performed similarly on a measure of word recall within the same task. Furthermore, the effect of TBI on performance was demonstrated to take place at the time of encoding, rather than at retrieval.

Fluid thresholds and outcome from severe brain injury

OBJECTIVE

To determine, by retrospective analysis, critical thresholds for intracranial pressure, mean arterial pressure, cerebral perfusion pressure, and fluid balance associated with poor outcome in patients with severe brain injury.

DESIGN

Retrospective review of patient data from the prospective, randomized, multicenter National Acute Brain Injury Study: Hypothermia, comparing outcome results at 6 months after injury with intracranial pressure, mean arterial pressure, cerebral perfusion pressure, and fluid balance measurements recorded during the 96-hr period after randomization.

SETTING

Emergency departments and intensive care units in 11 metropolitan tertiary care university hospitals.

PATIENTS

A total of 392 patients, aged 16-65 yrs, with severe, nonpenetrating brain injuries and a Glasgow Coma Scale score of 3-8 after resuscitation, who were enrolled in a study designed to determine the treatment effect of moderate hypothermia in patients with severe brain injury.

INTERVENTION

Standard brain injury treatment for 193 randomly assigned patients and standard treatment plus hypothermia for 48 hrs for 199 patients.

MEASUREMENTS AND MAIN RESULTS

Intracranial pressure levels of 20, 25, and 30 mm Hg, mean arterial pressure levels of 70 and 80 mm Hg, cerebral perfusion pressure levels of 50, 60, and 70 mm Hg, and fluid balance levels in quartiles were examined for their effect on outcome as measured by the Glasgow Outcome Scale at 6 months after injury. When considered separately, any of the following-intracranial pressure >25 mm Hg, mean arterial pressure <70 mm Hg, or cerebral perfusion pressure <60 mm Hg and fluid balance lower than -594 mL-was associated with an increased percentage of patients with poor outcome. When the variables were combined into a stepwise logistic regression model, Glasgow Coma Scale score at admission, age, mean arterial pressure <70 mm Hg, fluid balance lower than -594 mL, and intracranial pressure > 25 mm Hg, in that order, were the most powerful variables in determining outcome.

CONCLUSIONS

Exceeding thresholds of intracranial pressure, mean arterial pressure, cerebral perfusion pressure, and fluid volume may be detrimental to severe brain injury outcome. Fluid balance lower than -594 mL was associated with an adverse effect on outcome, independent of its relationship to intracranial pressure, mean arterial pressure, or cerebral perfusion pressure.