Memory and head injury severity

Longitudinal assessment of magnetization transfer ratio, brain volume, and cognitive functions in diffuse axonal injury

BACKGROUND

Diffuse axonal injury (DAI) is a frequent mechanism of traumatic brain injury (TBI) that triggers a sequence of parenchymal changes that progresses from focal axonal shear injuries up to inflammatory response and delayed axonal disconnection.

OBJECTIVE

The main purpose of this study is to evaluate changes in the axonal/myelinic content and the brain volume up to 12 months after TBI and to correlate these changes with neuropsychological results.

METHODS

Patients with DAI (n = 25) were scanned at three time points after trauma (2, 6, and 12 months), and the total brain volume (TBV), gray matter volume, and white matter volume (WMV) were calculated in each time point. The magnetization transfer ratio (MTR) for the total brain (TB MTR), gray matter (GM MTR), and white matter (WM MTR) was also quantified. In addition, Hopkins verbal learning test (HVLT), Trail Making Test (TMT), and Rey-Osterrieth Complex Figure test were performed at 6 and 12 months after the trauma.

RESULTS

There was a significant reduction in the mean TBV, WMV, TB MTR, GM MTR, and WM MTR between time points 1 and 3 (p < .05). There was also a significant difference in HVLT-immediate, TMT-A, and TMT-B scores between time points 2 and 3. The MTR decline correlated more with the cognitive dysfunction than the volume reduction.

CONCLUSION

A progressive axonal/myelinic rarefaction and volume loss were characterized, especially in the white matter (WM) up to 1 year after the trauma. Despite that, specific neuropsychological tests revealed that patients' episodic verbal memory, attention, and executive function improved during the study. The current findings may be valuable in developing long-term TBI rehabilitation management programs.

Duration of post-traumatic amnesia is uniquely associated with memory functioning in chronic moderate-to-severe traumatic brain injury

BACKGROUND

Disrupted memory circuitry may contribute to post-traumatic amnesia (PTA) after traumatic brain injury (TBI). It is unclear whether duration of PTA (doPTA) uniquely impacts memory functioning in the chronic post-injury stage.

OBJECTIVE

To examine the relationship between doPTA and memory functioning, independent of other cognitive abilities, in chronic moderate-to-severe TBI.

METHODS

Participants were 82 individuals (median chronicity = 10.5 years) with available doPTA estimates and neuropsychological data. Composite memory, processing speed (PS), and executive functioning (EF) performance scores, as well as data on subjective memory (SM) beliefs, were extracted. DoPTA-memory associations were evaluated via linear modeling of doPTA with memory performance and clinical memory status (impaired/unimpaired), controlling for PS, EF and demographic covariates. Interrelationships between doPTA, objective memory functioning, and SM were assessed.

RESULTS

DoPTA was significantly related to memory performance, even after covariate adjustment. Impairment in memory, but not PS or EF, was associated with a history of longer doPTA. SM was associated with memory performance, but unrelated to doPTA.

CONCLUSIONS

Findings suggest a specific association between doPTA-an acute injury phenomenon-and chronic memory deficits after TBI. Prospective studies are needed to understand how underlying mechanisms of PTA shape distinct outcome trajectories, particularly functional abilities related to memory processing.

Early chronic systemic inflammation and associations with cognitive performance after moderate to severe TBI

BACKGROUND

Cognitive dysfunction adversely effects multiple functional outcomes and social roles after TBI. We hypothesize that chronic systemic inflammation exacerbates cognitive deficits post-injury and diminishes functional cognition and quality of life (QOL). Yet few studies have examined relationships between inflammation and cognition after TBI. Associations between early chronic serum inflammatory biomarker levels, cognitive outcomes, and QOL 6-months and 12-months after moderate-to-severe TBI were identified using unweighted (uILS) and weighted (wILS) inflammatory load score (ILS) formation.

METHODS

Adults with moderate-to-severe TBI (n ​= ​157) completed neuropsychological testing, the Functional Impairment Measure Cognitive Subscale (FIM-Cog) and self-reported Percent Back to Normal scale 6 months (n ​= ​139) and 12 months (n ​= ​136) post-injury. Serial serum samples were collected 1-3 months post-TBI. Cognitive composite scores were created as equally weighted means of T-scores derived from a multidimensional neuropsychological test battery. Median inflammatory marker levels associated with 6-month and 12-month cognitive composite T-scores (p ​< ​0.10) were selected for ILS formation. Markers were quartiled, and quartile ranks were summed to generate an uILS. Marker-specific β-weights were derived using penalized ridge regression, multiplied by standardized marker levels, and summed to generate a wILS. ILS associations with cognitive composite scores were assessed using multivariable linear regression. Structural equation models assessed ILS influences on functional cognition and QOL using 12-month FIM-Cog and Percent Back to Normal scales.

RESULTS

ILS component markers included: IL-1β, TNF-α, sIL-4R, sIL-6R, RANTES, and MIP-1β. Increased sIL-4R levels were positively associated with overall cognitive composite T-scores in bivariate analyses, while remaining ILS markers were negatively associated with cognition. Multivariable receiver operator curves (ROC) showed uILS added 14.98% and 31.93% relative improvement in variance captured compared to the covariates only base model (age, sex, education, Glasgow Coma Scale score) when predicting cognitive composite scores at 6 and 12 months, respectively; wILS added 33.99% and 36.87% relative improvement in variance captured. Cognitive composite mediated wILS associations with FIM-Cog scores at 12 months, and both cognitive composite and FIM-Cog scores mediated wILS associations with QOL.

CONCLUSIONS

Early chronic inflammatory burden is associated with cognitive performance post-TBI. wILS explains greater variance in cognitive composite T-scores than uILS. Linking inflammatory burden associated with cognitive deficits to functional outcome post-TBI demonstrates the potential impact of immunotherapy interventions aimed at improving cognitive recovery post-TBI.

Optimizing Outcome Assessment in Multicenter TBI Trials: Perspectives From TRACK-TBI and the TBI Endpoints Development Initiative

Traumatic brain injury (TBI) is a global public health problem that affects the long-term cognitive, physical, and psychological health of patients, while also having a major impact on family and caregivers. In stark contrast to the effective trials that have been conducted in other neurological diseases, nearly 30 studies of interventions employed during acute hospital care for TBI have failed to identify treatments that improve outcome. Many factors may confound the ability to detect true and meaningful treatment effects. One promising area for improving the precision of intervention studies is to optimize the validity of the outcome assessment battery by using well-designed tools and data collection strategies to reduce variability in the outcome data. The Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) study, conducted at 18 sites across the United States, implemented a multidimensional outcome assessment battery with 22 measures aimed at characterizing TBI outcome up to 1 year postinjury. In parallel, through the TBI Endpoints Development (TED) Initiative, federal agencies and investigators have partnered to identify the most valid, reliable, and sensitive outcome assessments for TBI. Here, we present lessons learned from the TRACK-TBI and TED initiatives aimed at optimizing the validity of outcome assessment in TBI.

Inter-rater agreement of the Turkish version of the Neurobehavioral Rating Scale-Revised form

Objectives

This study aims to adapt the Neurobehavioral Rating Scale-revised form (NBRS-R) for Turkish traumatic brain injury (TBI) patients and to investigate the inter-rater agreement of the Turkish revised scale.

Patients and methods

A total of 45 patients (36 males, 9 females; mean age 31.1±13.0 years; range 18 to 60 years) with TBI were included in this study between September 2013 and August 2014. A semi-structured interview was set up for Turkish patients using a multidisciplinary approach (physiatrist, psychiatrist, neurologist and psychologist) with the participation of four rehabilitation centers. Questions were prepared for each of the 29 items, based on the recommendations of the original NBRS-R form. Four different interviewers from the four centers applied this form to a total of 45 TBI patients.

Results

The items evaluated by intra-class correlation coefficient showed satisfactory stability and the reliability of the items ranged from moderate to very good.

Conclusion

The NBRS-R form can be suggested to provide a reliable and easily reproducible evaluation method of neurobehavioral deficits in TBI patients who speak Turkish.

Visuospatial memory improvement in patients with diffuse axonal injury (DAI): a 1-year follow-up study

OBJECTIVE

Diffuse axonal injury (DAI) is prevalent in traumatic brain injury (TBI), and is often associated with poor outcomes and cognitive impairment, including memory deficits. Few studies have explored visual memory after TBI and its relationship to executive functioning. Executive functioning is crucial for remembering an object's location, operating devices, driving, and route finding. We compared visual memory performance via the Rey-Osterrieth Complex Figure (ROCF) test 6 and 12 months after DAI.

METHOD

In total, 40 patients (mean age 28.7 years; 87.5% male) with moderate-to-severe DAI following a road traffic accident completed the 1-year follow-up. There was a three-phase prospective assessment. In phase 1 (1-3 months after trauma), patients completed the Beck Depression Inventory (BDI) and State-Trait Anxiety Inventory (STAI). In phases 2 (6 months) and 3 (12 months), they completed the BDI, STAI, and a neuropsychological battery [ROCF copy and recall, digit span forward/backward, Grooved Pegboard test, intelligence quotient (IQ) by Wechsler Adult Intelligence Scale-III (WAIS-III)].

RESULTS

There was an improvement in ROCF recall over time (p=0.013), but not ROCF copy (p=0.657).There was no change in executive function (Savage scores) copy (p=0.230) or recall (p=0.155). Age, years of education, severity of the trauma, and IQ did not influence ROCF recall improvement.

CONCLUSION

There are time-dependent improvements in visual memory in patients with DAI. Neuroplasticity in the 1st months after trauma provides an opportunity for visuospatial memory learning. The present findings may be useful to formulate management plans for long-term TBI rehabilitation.

Mild Traumatic Brain Injury: Longitudinal Study of Cognition, Functional Status, and Post-Traumatic Symptoms

More than 75% of traumatic brain injuries (TBIs) seeking medical attention are mild, and outcome in that group is heterogeneous. Until sensitive and valid biomarkers are identified, methods are needed to classify mild TBI into more homogeneous subgroups. Four hundred twenty-one adults with mild TBI were divided into groups based on Glasgow Coma Scale (GCS) 13-15 without computed tomography (CT) abnormalities, GCS 15 with CT abnormalities, and GCS 13-14 with CT abnormalities, and were compared with 120 trauma controls on 1-month and 1-year outcomes. At 1 month post-injury, almost all neuropsychological variables differed significantly among the groups. Compared with trauma controls, the GCS 13-15 CT normal group showed no significant differences on any neuropsychological measure or Glasgow Outcome Scale (GOS). The GCS 15 CT abnormal group performed significantly worse on only a measure of episodic memory and learning (Selective Reminding Recall [SRCL]) and GOS, and the GCS 13-14 CT abnormal group performed significantly worse on most neuropsychological measures and GOS. At 1 year post-injury, except for an isolated difficulty on SRCL in the GCS 13-14 CT abnormal group, no differences were observed on any neuropsychological measures nor on GOS. Mean percent of total post-traumatic symptoms endorsed as new or worse and percent endorsing three or more symptoms differed significantly (p < 0.001), with each TBI subgroup reporting significantly more symptoms than the trauma controls at both 1 month and 1 year. In conclusion, this subgrouping improves granularity within mild TBI. While most neuropsychological and functional differences abate by 1 year, reporting three or more post-traumatic symptoms remain for about half of individuals.

Traumatic brain injury and cognition

Traumatic brain injury (TBI) is a major cause of death and disability, and therefore an important health and socioeconomic problem for our society. Individuals surviving from a moderate to severe TBI frequently suffer from long-lasting cognitive deficits. Such deficits include different aspects of cognition such as memory, attention, executive functions, and awareness of their deficits. This chapter presents a review of the main neuropsychological and neuroimaging studies of patients with TBI. These studies found that patients evolve differently according to the severity of the injury, the mechanism causing the injury, and the lesion location. Further research is necessary to develop rehabilitation methods that enhance brain plasticity and recovery after TBI. In this chapter, we summarize current knowledge and controversies, focusing on cognitive sequelae after TBI. Recommendations from the Common Data Elements are provided, with an emphasis on diagnosis, outcome measures, and studies organization to make data more comparable across studies. Final considerations on neuroimaging advances, rehabilitation approaches, and genetics are described in the final section of the chapter.

Dispositional optimism and outcome following traumatic brain injury

OBJECTIVE

Despite vast literature examining the predictors of patient outcome following traumatic brain injury (TBI), the complicated relationship between personality and psychological, cognitive and functional outcomes remains poorly understood. The present study examined the relationship between the personality trait of dispositional optimism (DO) and outcome after moderate and severe TBI in the context of a proposed theoretical model.

METHODS

Forty-five individuals who had sustained moderate-to-severe TBI were recruited through mailings and completed the Symptom Checklist Questionnaire-90 Revised (SCL-90-R), the Telephone Interview for Cognitive Status (TICS), the Craig Handicap Assessment Reporting Technique (CHART) and the Life Orientation Test-Revised (LOT-R). Analyses were conducted to test a model predicting the relationship between personality and patient outcome after TBI.

RESULTS

DO was significantly correlated with psychological distress, but did not predict functional outcome. In addition, two significant mediating relationships were demonstrated: (1) psychological distress was shown to mediate the relationship between dispositional optimism and cognitive ability and (2) cognitive ability mediated the relationship between psychological distress and functional outcome.

CONCLUSION

These findings illustrate that higher levels of DO in individuals sustaining moderate-to-severe TBI are related to better psychological functioning which in turn predicts improved cognitive and functional outcomes.

Cognitive outcome following traumatic brain injury

OBJECTIVE

To determine whether an association exists between traumatic brain injury (TBI) sustained in adulthood and cognitive impairment 6 months or longer after injury.

DESIGN

Systematic review of the published, peer-reviewed literature.

RESULTS

From 430 articles, we identified 11 primary and 22 secondary studies that examined cognitive impairment by using performance measures for adults who were at least 6 months post-TBI. There was clear evidence of an association between penetrating brain injury and impaired cognitive function. Factors that modified this association included preinjury intelligence, volume of brain tissue lost, and brain region injured. There was also suggestive evidence that penetrating brain injury may exacerbate the cognitive effects of normal aging. We found clear evidence for long-term cognitive deficits associated with severe TBI. There was suggestive evidence that moderately severe brain injuries are associated with cognitive impairments. There was inadequate/insufficient evidence to determine whether an association exists between a single, mild TBI and cognitive deficits 6 months or longer postinjury.

CONCLUSION

In adults, penetrating, moderate, and severe TBIs are associated with cognitive deficits 6 months or longer postinjury. There is insufficient evidence to determine whether mild TBI is associated with cognitive deficits 6 months or longer postinjury.

Neurodevelopmental outcomes of pediatric traumatic brain injury

Pediatric traumatic brain injury is a major cause for concern when considering both the number of children sustaining injuries and the large number of children incurring life-long difficulties that impact on quality of life. Research is continuing to investigate outcomes and predictors of recovery in both cognitive and behavioral domains. Findings have contributed to better identification of children at high risk for neurobehavioral difficulties. The challenge is to now develop intervention programs to prevent or lessen the impact of such difficulties.

A computerized test battery sensitive to mild and severe brain injury

OBJECTIVE

Computerized neurocognitive testing (CNT) appears to be suited to measure relatively mild degrees of neurocognitive impairment in circumstances where speed, efficiency, and low cost are important. Computerized tests are used in the evaluation and management of patients who have had mild brain injuries; the objective is to determine if computerized testing is equally reliable and valid in the evaluation of patients who have had more severe brain injuries.

DESIGN

A cross-sectional, naturalistic study of brain injury patients compared with normal controls.

SETTING

An outpatient neuropsychiatry clinic.

PARTICIPANTS

141 patients, aged 18-65 years, who had sustained traumatic brain injuries (TBIs): 13 patients with postconcussion syndrome; 15 who had recovered from mild brain injuries; 85 patients who had had severe brain injuries, but who had recovered, and were living independently; and 28 severe brain injury patients who were unable to live without assistance; compared with 145 normal controls.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

The CNS Vital Signs (CNS VS) battery is a PC-based system that includes tests of verbal and visual memory, psychomotor speed, complex attention, reaction time, and cognitive flexibility.

RESULTS

Performance on the CNS VS battery was related to severity of brain injury and degree of recovery. Tests of psychomotor speed and cognitive flexibility were the most relevant to TBI status. Patients who had recovered from mild brain injuries scored almost as well as normal controls. The Neurocognition Index (NCI), a summary score based on performance on all the tests in the battery, was 100 for normal controls and 98 for recovered mild brain injury patients. Postconcussive patients scored 82 on the MCI, and severe brain injury patients scored 66 on the NCI if they were living independently and 47 if they were not.

CONCLUSIONS

Computerized tests like CNS VS allow clinicians the advantage of precise neurocognitive measurement in the service of diagnosis and appropriate treatment. CNTs are never going to replace the flexibility or comprehensiveness of conventional neuropsychological testing, but they have a role to play in circumstances where a full test battery is not feasible, such as screening and serial assessment.

Recovery in Memory Function, and its Relationship to Academic Success, at 24 Months Following Pediatric TBI*

While a number of research papers have reported findings on memory deficits following traumatic brain injury (TBI), only limited studies have monitored the recovery of these skills over time. The present study examined memory ability and its effect on academic success in a group of children who had sustained a mild, moderate, or severe traumatic brain injury (TBI). Results showed that the severe TBI group exhibited greater deficits on memory tasks, irrespective of modality, in the acute, 6-, 12-, and 24-month postinjury stages, in comparison to mild and moderate TBI groups. Performance on academic measures was dependent on both injury severity and task demands. Preinjury academic ability and verbal memory indices best predicted academic success.

Response of the contralateral hippocampus to lateral fluid percussion brain injury

Traumatic brain injury is a leading cause of death and disability in the United States. Pathological examinations of humans and animal models after brain injury demonstrate hippocampal neuronal damage, which may contribute to cognitive impairments. Data from our laboratories have shown that, at 1 week after brain injury, mice possess significantly fewer neurons in all ipsilateral hippocampal subregions and a cognitive impairment. Since cognitive function is distributed across both cerebral hemispheres, the present paper explores the morphological and physiological response of the contralateral hippocampus to lateral brain injury. We analyzed the contralateral hippocampus using design-based stereology, Fluoro-Jade (FJ) histochemistry, and extracellular field recordings in mice at 7 and 30 days after lateral fluid percussion injury (FPI). At 7 days, all contralateral hippocampal subregions possess significantly fewer healthy neurons compared to sham-injured animals and demonstrate FJ-positive neuronal damage, but not at 30 days. Both the ipsilateral and contralateral dentate gyri demonstrate significantly increased excitability at 7 days post-injury, but only ipsilateral dentate gyrus hyperexcitability persists at 30 days compared to sham. In the contralateral hippocampus, the transient decrease in the number of healthy neurons, concomitant with FJ damage, and electrophysiological alterations establish a stunned period of cellular and circuit dysfunction. The return of healthy neuron number, absence of FJ damage, and sham level of excitability in the contralateral hippocampus suggest recovery of structure and function by 30 days after injury. The cognitive recovery observed after human traumatic brain injury may stem from a differential injury exposure and time course of recovery between homologous regions of the two hemispheres.

Genetic Factors in Outcome After Traumatic Brain Injury

It is becoming increasingly clear that genetic factors modify outcome after traumatic brain injury (TBI). The best known example of this is the association between the apolipoprotein E4 allele (APOE epsilon4) and poorer outcomes. However, our knowledge of the many other genes that might influence outcome is still in its infancy. This article will review the basic principles underlying recent advances in genetics, and then describe the current state of knowledge regarding the impact of genetic factors on TBI outcome. We conclude that although genetic advances have implications for prognosis, their biggest contribution will be to elucidate the pathophysiology of TBI, potentially leading to new treatments.

Memory function after resolution of post-traumatic amnesia

PRIMARY OBJECTIVES

The aims of this pilot study were (1) to examine neuropsychological, particularly memory functions immediately after post-traumatic amnesia (PTA) resolution according to the Galveston Orientation and Amnesia Test (GOAT), and (2) to provide a preliminary exploration of pattern of performance on GOAT items across PTA duration.

METHODS AND PROCEDURES

Thirty-seven head injured patients were administered the Recognition Memory Tests on the day that PTA resolved. Formal neuropsychological assessment was conducted on average 10 days after PTA resolution.

MAIN OUTCOMES AND RESULTS

All the patients in the series showed memory impairment which varied in severity but was typically characterized as global and severe. Deficits in executive and speed and attention functions were common. GOAT items relating to orientation were typically passed, while items concerning anterograde and retrograde recall were most commonly failed across all stages of PTA duration.

CONCLUSIONS

These findings suggest that reliance on memory performance as a measure of PTA is not ideal and highlight the need for further research of this issue.

Overview of traumatic brain injury patients at a tertiary trauma centre

OBJECTIVE

The goal of this study was to provide a general descriptive and cognitive portrait of a population with traumatic brain injury (TBI) at the time of their acute care stay.

MATERIAL AND METHODS

Three hundred and forty-eight TBI patients were assessed. The following data were collected for each patient: age, level of education, duration of post-traumatic amnesia, Galveston Orientation Amnesia Test score, Glasgow Coma Scale score, results of cerebral imaging, Neurobehavioral Rating Scale score, the Functional Independence Measure cognitive score and the Glasgow Outcome Scale score.

RESULTS

The clinical profile of the population revealed a mean age of 40.2 (+/-18.7) and a mean of 11.5 (+/-3.6) years of education. Most patients presented with frontal (57.6%) and temporal (40%) lesions. Sixty-two percent had post-traumatic amnesia of less than 24 hours. Seventy percent presented with mild TBI, 14% with moderate and 15% with severe TBI. The cognitive deficits most frequently observed on the Neurobehavioral Rating Scale were in the areas of attention, memory and mental flexibility as well as slowness and mental fatigability. Most patients had good cognitive outcome on the Functional Independence Measure and scores of 2 and 3 were frequent on the GOS. Forty-five percent of the patients returned home after discharge, 51.7% were referred to in or out patient rehabilitation and 3.2% were transferred to long-term care facilities.

CONCLUSION

Because of the specialized mandate of acute care institutions, the information provided here concerning characteristics of our TBI population is essential for more efficient decision-making and planning/programming with regards to care and service delivery.

Magnetization transfer and T2 quantitation in normal appearing cortical gray matter and white matter adjacent to focal abnormality in patients with traumatic brain injury

Traumatic brain injury (TBI) is one of the commonest causes of morbidity and mortality in the developed countries with posttraumatic epilepsy and functional disability being its major sequelae. The purpose of this study was to test the hypothesis whether the normal appearing adjacent gray and white matter regions on T2 and T1 weighted magnetization transfer (MT) weighted images show any abnormality on quantitative imaging in patients with TBI. A total of 51 patients with TBI and 10 normal subjects were included in this study. There were significant differences in T2 and MT ratio values of T2 weighted and T1 weighted MT normal appearing gray matter regions adjacent to focal image abnormality compared to normal gray matter regions in the normal individuals as corresponding contralateral regions of the TBI patient's group (p < 0.05). However the adjoining normal appearing white matter quantitative values did not show any significant change compared to the corresponding contralateral normal white matter values. We conclude that quantitative T2 and MT ratio values provide additional abnormality in patients with TBI that is not discernable on conventional T2 weighted and T1 weighted MT imaging especially in gray matter. This additional information may be of value in overall management of these patients with TBI.

The mediating effects of effort upon the relationship between head injury severity and cognitive functioning

PRIMARY OBJECTIVE

Given that poor effort may have a profound impact upon the results of neuropsychological assessment, it is of critical importance that assessment of effort is incorporated into the interpretation of a patient's neuropsychological profile. The current study examines the relationship between head injury severity (as measured by length of post-traumatic amnesia) and level of cognitive functioning in patients passing or failing a test of effort (Test of Malingered Memory).

RESEARCH DESIGN

A cross-sectional correlational design was employed in a consecutive cohort of 78 persons with ongoing compensation claims.

METHODS AND PROCEDURES

Head injury severity was assessed by duration of post-traumatic amnesia. All participants received a clinical interview followed by neuropsychological assessment.

MAIN OUTCOMES AND RESULTS

A systematic and interpretable negative correlation between head injury severity and intellectual and memory functioning was demonstrated in persons passing the test of effort. However, in persons failing the test of effort no such relationships were demonstrated.

CONCLUSIONS

The implications for the interpretation of neuropsychological test data are discussed. It is strongly recommend that valid interpretation of neuropsychological assessment data should include consideration of at least one test of effort.

Prediction of functional outcomes after traumatic brain injury: a comparison of 2 measures of duration of unconsciousness

OBJECTIVE

To compare the usefulness of time until motor localization occurs versus time until commands are followed in predicting outcome after traumatic brain injury (TBI).

DESIGN

A retrospective analysis of data from a prospective cohort study of subjects with severe TBI.

SETTING

Seventeen Traumatic Brain Injury Model System programs.

PARTICIPANTS

A total of 496 subjects, recruited through the TBI Model System programs, with loss of consciousness greater than 1 day, with no late neurosurgical complications, and complete data for all measures.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Time until Glasgow Coma Scale (GCS) motor score of 5 (time to motor localization) and time until GCS motor score of 6 (time until commands were followed) were abstracted from medical records. Functional outcomes were assessed at inpatient rehabilitation admission and discharge, along with acute and rehabilitation lengths of stay and charges.

RESULTS

Time until commands were followed was a better predictor of all of the outcomes assessed than time until motor localization occurred. In multiple regression models, time until motor localization did not add significantly to the prediction provided by time until commands were followed. The predictive power of time to command following was superior even in the subgroup with poor language comprehension as measured by the Token Test.

CONCLUSION

Despite the theoretical appeal of time to motor localization (eg, in persons with language comprehension problems), time to command following appears to be a more powerful predictor of outcome after severe brain injury.

Assessment of neuropsychologic impairments after head injury: interrater reliability and factorial and criterion validity of the Neurobehavioral Rating Scale-Revised

OBJECTIVE

To study interrater reliability and factorial and criterion validity of the Neurobehavioral Rating Scale-Revised (NRS-R).

DESIGN

Validity study on persons with traumatic brain injury (TBI) and test-retest reliability study on a randomly selected subset of patients. Factor analyses, kappa statistics, intraclass correlation coefficients, and Cronbach's alphas were used.

SETTING

Inpatients from 15 French hospitals, mainly rehabilitation units. Other recruitment sites included a neurology hospital unit and a psychiatry hospital specifically devoted to TBI rehabilitation.

PATIENTS

Two hundred eighty-six TBI patients ages 16 to 70 years (convenience sample).

RESULTS

For the reliability study, the average of percentages of agreement among the items was 74.3% and the average of kappa statistics was .40. Factor analyses disclosed a maximum likelihood extraction of 5 correlated factors (F), explaining 42.2% of total variance: (F1) deficits in intentional behavior and in memory, (F2) lowering of emotional state, (F3) emotional and behavioral hyperactivation, (F4) lowering of arousal state and of attention, and (F5) language and speech problems. Results support the criterion validity of the factors. Reliability of the factor scores and internal consistencies of factors were very good.

CONCLUSIONS

Results describe some important properties of the NRS-R and, through an understanding of its underlying structure and relationships with the patients' clinical characteristics, contribute to the conceptual framework of neuropsychologic impairments after TBI.

A review of outcome after moderate and severe closed head injury with an introduction to life care planning

Forensic consultation regarding moderate and severe closed head injury (CHI) generally focuses on determination of severity of residual deficits and the implications of these deficits for future health care needs, personal independence, and employment. This information can be used to develop a life care plan that describes the patient's needs for continued medical care, rehabilitation, and daily assistance or supervision and estimates the long-term costs for these services. This article provides brief reviews of CHI classification, epidemiology, residual deficits, expected outcomes, and factors predictive of outcome. An introduction to the process of developing a life care plan is presented.

Secondary hypoxia following moderate fluid percussion brain injury in rats exacerbates sensorimotor and cognitive deficits

Human head trauma is frequently associated with respiratory problems resulting in secondary hypoxic insult. To document the behavioral consequences of secondary hypoxia in an established model of traumatic brain injury (TBI), intubated anesthetized animals were subjected to fluid percussion (FP) injury (1.87-2.17 atm) followed by 30 min of either normoxic (TBI-NO, n = 10) or hypoxic (TBI-HY, n = 11; pO2 = 30-40 mm Hg) gas levels. Sham animals (n = 19) underwent all manipulations except for the actual trauma. Animals were tested on various sensorimotor tasks beginning 3 days after FP injury along with cognitive testing on days 22 through 29 posttrauma. The secondary hypoxic insult exacerbated the sensorimotor deficits on beam-walking compared to those animals only receiving trauma. Cognitive impairments were also observed in the TBI-HY group in the hidden platform task compared to FP injury alone. These data indicate that a secondary hypoxic insult exacerbates both sensorimotor and cognitive deficits after TBI. This study provides direct evidence that incidences of hypoxia after brain trauma may potentially result in an increase in neurological deficits for the subpopulation of head injured patients undergoing hypoxic conditions further warranting strict monitoring of these events.

One year outcome in mild to moderate head injury: the predictive value of acute injury characteristics related to complaints and return to work

OBJECTIVES

To determine the prognostic value of characteristics of acute injury and duration of post-traumatic amnesia (PTA) for long term outcome in patients with mild to moderate head injury in terms of complaints and return to work.

METHODS

Patients with a Glasgow coma score (GCS) on admission of 9-14 were included. Post-traumatic amnesia was assessed prospectively. Follow up was performed at 1, 3, 6, and 12 months after injury. Outcome was determined by the Glasgow outcome scale (GOS) 1 year after injury and compared with a more detailed outcome scale (DOS) comprising cognitive and neurobehavioural aspects.

RESULTS

Sixty seven patients were included, mean age 33.2 (SD 14.7) years and mean PTA 7.8 (SD 7.3) days. One year after injury, 73% of patients had resumed previous work although most (84%) still reported complaints. The most frequent complaints were headache (32%), irritability (34%), forgetfulness and poor concentration (42%), and fatigue (45%). According to the GOS good recovery (82%) or moderate disability (18%) was seen. Application of the DOS showed more cognitive (40%) and behavioural problems (48%), interfering with return to work. Correlation between the GOS and DOS was high (r=0.87, p<0.01). Outcome correlated with duration of PTA (r=-0.46) but not significantly with GCS on admission (r=0.19). In multiple regression analysis, PTA and the number of complaints 3 months after injury explained 49% of variance on outcome as assessed with the GOS, and 60% with the DOS.

CONCLUSIONS

In mild to moderate head injury outcome is determined by duration of PTA and not by GCS on admission. Most patients return to work despite having complaints. The application of a more detailed outcome scale will increase accuracy in predicting outcome in this category of patients with head injury.

Moderate head injury: a system of neurotrauma care

BACKGROUND

The aim of the present study was to determine those factors which contribute to a poor outcome and to propose a management plan that is complementary to trauma systems in common use.

METHODS

A prospective study of 110 consecutive patients with moderate head injury (post-resuscitation Glasgow Coma Scale (GCS) 9-13) was carried out.

RESULTS

A total of 75% of the patients sustained multisystem trauma, generally of minor or moderate grade according to the Abbreviated Injury Scale (AIS). However, the death rate increased with the severity of the injury as measured by the Injury Severity Score (ISS). The initial cranial computed tomography (CT) scan was abnormal in 61% and no patient with a normal scan developed a delayed intracranial haematoma or neurological worsening. Those patients who developed a delayed intracerebral haematoma had a worse outcome. Sixteen patients underwent craniotomy for haematoma. The intracranial pressure (ICP) was measured selectively in 20 patients and exceeded 20 mmHg in half, requiring treatment. Nine patients died, four as a result of head injury and all those had an intracranial haematoma. As a group, those who died were older and had a higher ISS.

CONCLUSIONS

A plan for care of patients with moderate head injury is proposed, complementary to the Early Management of Severe Trauma (EMST) protocol and the Neurosurgical Society of Australasia guidelines for neurotrauma management in rural and remote locations.

Severe head injuries: an outcome prediction and survival analysis

OBJECTIVE

To identify the predictors determined early after admission and associated with unfavorable outcome or early (within 48 h) death after severe head injury.

DESIGN

Prospective cohort study.

SETTING

A neurosurgical intensive care unit in a university hospital.

PATIENTS

198 consecutive comatose patients hospitalized from 1989 to 1992.

RESULTS

Logistic regression showed that a combination of age, best motor response score from the Glasgow Coma Scale, and hypoxia provided a good prediction model of unfavorable outcome (sensitivity = 0.93). The length of participation of survivors was 6 to 61 months (median 27.1). The Cox model demonstrated age, motor score less than 3, mydriasis, and hypoxia as poor prognosis factors.

CONCLUSIONS

Clinicians can determine the odds of a good outcome from the combination of three easily measurable factors using a simple diagram constructed from logistic regression. Survival analysis showed that motor score adjusted values greater than 3 had the same prognosis.

Minor head injury: attempts at clarifying the confusion

Traumatic brain injury (TBI) refers to a broad range of neurological, cognitive and emotional factors that result from the application of a mechanical force to the head. Mechanical force can be applied on a continuum from none to very severe, and the extent of brain injury is related to the severity of this force. A review of the literature reveals that, while considerable research has been done on minor head injury, there remain several major sources of confusion. First, one of the most noticeable problems relates to the fact that the mild head injury has lower limits which are vaguely defined. This leads to individuals being categorized as having sustained a mild TBI despite minimal or no neurological damage being present. A second source of confusion in the literature is related to the failure to differentiate between cognitive consequences of TBI and post-concussion symptoms (PCS). Since PCS can occur in the absence of head injury, and are often present beyond the period of cognitive recovery from mild TBI, the two clearly result from different factors. Researchers have often failed to separate these two factors when studying recovery of function, and this has led to varying findings on outcome. Finally, many pre-injury factors (age, education, emotional adjustment) and post-injury factors (pain, family support, stress) interact with cognitive functioning and significantly affect recovery from TBI. These problems are reviewed and discussed.

Classification and regression trees (CART) for prediction of function at 1 year following head trauma

A cohort of 514 hospitalized head-injury survivors was identified based on their injury and 448 (87%) of them were followed for 1 year. Comprehensive neurobehavioral testing was performed 1 month and 1 year after injury. The authors developed predictions of six neuropsychological and two psychosocial outcomes 1 year after head injury. Prediction trees are presented for verbal IQ, Halstead's Impairment Index, and work status at 1 year. Early predictors of neurobehavioral outcome in survivors are similar to previously reported predictors of mortality. Extent (both depth and length) of coma and age are the medical and demographic variables most predictive of late outcome. Adding 1-month scores substantially improves prediction of neuropsychological variables. The classification and regression tree is a useful technique for predicting long-term outcome in patients with head injury. The trees are simple enough to be used in a clinical setting and, especially with 1-month scores, predictions are accurate enough for clinical utility.

Psychosocial recovery after head injury

Psychosocial recovery after head injury was prospectively examined at 1 and 12 months postinjury in a group of 102 hospitalized adult head-injured patients representing a broad range of head injury severity. For comparison purposes, 102 friend controls were used. Outcome was assessed with a battery of psychosocial measures including the Sickness Impact Profile, the Head Injury Symptom Checklist, and the Modified Function Status Index. The results indicate that head-injury patients experience significant psychosocial problems (eg, ability to return to work, resume leisure activity, concentrate and remember information, feelings of irritability) at both 1 and 12 months postinjury but these difficulties improve over time. Whereas improvements occur in both psychosocial and physical areas of functioning, improvements are greater in the physical area. The nature and extent of difficulties seen vary as a function of head injury severity, and time from injury to observation. Finally, the results suggest that not all problems reported by head-injured patients are solely related to the injury (eg, irritability, anxiety, fatigue, or headaches).

Outcomes after cardiac arrest

The simplest, most easily determined, and most easily understood outcomes after cardiac arrest are survival and awakening. Awakening is defined by the patient's being able to follow commands or produce comprehensible speech. Both occur at specific times, thus lending themselves to life-table analyses. Unfortunately, these simple measures are not adequate to characterize the disability that may be present in those who survive and awaken after cardiac arrest. For such patients, measures of independence are needed. These measures often require longer follow-up, direct contact with patients, and a greater understanding of the instrument to be used than for the simple measures. Investigators must decide based on the goals of a particular study what outcomes are most appropriate and the amount of resources that they are willing to devote to outcome assessment. As initial steps in resuscitation research, there may be more to gain from studies of large numbers of patients evaluated with simple measures than small numbers of patients evaluated intensively with more detailed measures.

Head-injured subjects aged over 50 years: correlations between variables of trauma and neuropsychological follow-up

Neuropsychological follow-up was studied in 70 consecutive head-injured subjects aged over 50 years. Diffuse deterioration (28%), moderate deterioration (25%) and dementia (21%) were the most frequent sequelae. Analysis of correlations between neuropsychological sequelae and trauma variables showed that: (1) mild trauma did not necessarily imply good prognosis and could be followed by very severe consequences; (2) duration of post-traumatic amnesia was correlated with coma duration but not with neuropsychological outcome; (3) on the whole, no prognostic predictor of the outcome was found.

Quantified EEG and cortical evoked responses in patients with chronic traumatic frontal lesions

Eighteen frontal trauma patients and 17 age-matched control subjects had quantified EEGs and measurements of sensory (SEP) and auditory evoked potentials (P300) using a Biologic Brain Atlas III system. The findings were compared to the conventional paper EEG, and to the frontal lesion volumes, severity of head injury, and outcome variables. The quantified EEG confirmed the pathological findings detected by visual inspection, but some regional abnormalities were more easily detected by topographic mapping. The regional distribution of pathological slowing corresponded well with the morphological lesions in most patients. The modal frequency of EEG correlated both with lesion volume and injury severity and with the outcome variables. There were no pathological findings in the SEPs, and all but one patient had clearly distinguishable P300 responses. There was a significant reduction in P300 amplitude in the frontal patients at the anterior, but not at the posterior electrodes. The topographical distribution of the P300 changes corresponded well with the morphological lesions. Our findings indicate that the P300 potential is, in part, dependent upon the prefrontal cortical areas. The present study thus supports P300 investigations which have shown amplitude reduction in other disorders (e.g., schizophrenia) with a presumed prefrontal dysfunction.

The relationship between intelligence and memory following minor or mild closed head injury: greater impairment in memory than intelligence

This study investigated the performance of patients with minor or mild closed head injury and age/education-matched normal controls on the Wechsler Adult Intelligence Scale-Revised (WAIS-R) and the Wechsler Memory Scale-Revised (WMS-R). The results demonstrated that the control group had significantly higher scores than the patients with closed head injury on all WAIS-R and WMS-R index scores. Further analysis revealed that the patients with closed head injury showed a greater impairment in delayed memory when directly compared to intellectual performance that was not seen in the control group. These results are discussed in relation to findings in patients with more severe closed head injury, the construction of the WAIS-R and the WMS-R, and the performance patterns of the two groups.

The delayed neurobehavioural sequelae of traumatic brain injury

This is a comprehensive review of the late-occurring effects of traumatic brain injury (TBI). It appears that TBI increases the risk over basal rates for the general population, to this degree: for depression, by a factor of five or 10; for seizures, by two to five; for psychotic disorders, by the same factor; and for dementia, by four or five. Severe TBI, or injuries with special characteristics, may increase the risk of delayed sequelae even further. One is not able, at this point, to estimate the relative occurrence of a newly described entity--delayed amnesia. An initial TBI increases the risk for subsequent TBI, by a factor of two. A second TBI increases the risk of yet another TBI eightfold.

Neuropsychological recovery in patients with moderate to severe head injury: 2 year follow-up

Neuropsychological outcome and recovery of a group of 31 consecutive adult patients with moderate to severe head injuries were prospectively investigated over a 2-year period. A friend control group was used for comparison purposes. Based on the results we conclude: (1) there is marked impairment of a broad spectrum of neuropsychological functions at 1, 12, and 24 months postinjury; (2) coma length is significantly related to neuropsychological status at all three time periods, although the relationship is weaker at 12 and 24 months; (3) marked improvement in all functions occurs in the first year, while recovery in the second year appears more specific and may depend on the severity of the injury and type of function; (4) practice effects and variability over repeated measures cause difficulties in determining recovery and need to be addressed with larger samples.

Amnestic disorders. Pathophysiology and patterns of memory dysfunction

A wide variety of conditions seen in medical practice can produce memory impairment (amnesia). Normal aging, depression, and anxiety are commonly associated with memory difficulties, as are many neurologic conditions. Systemic illnesses can impair memory by injuring vulnerable limbic regions sensitive to hypoxia or hypoglycemia. Commonly used over-the-counter and prescription medications can likewise cause amnesia. These conditions disrupt memory in characteristic ways. Recent studies suggest that immediate, recent, and remote memory functions have different neuroanatomic substrates, as do the processes of registration, retention, and retrieval. New classifications have emerged to explain the evidence for multiple memory subsystems. The neuropharmacology of memory now includes several peptides in addition to cholinergic and noradrenergic pathways. Critical limbic regions have been discovered that mediate memory consolidation, and neuronal mechanisms such as long-term potentiation are being implicated in the unique capacity of these areas to permit new learning to take place.

Memory deficit after closed head injury

This paper reviews research concerning impairment of memory during the early and late stages of recovery from closed-head injury (CHI). Posttraumatic and retrograde amnesia are discussed, including direct measurement, rate of forgetting and evoked potential correlates. Studies of residual memory deficit in survivors of CHI are reviewed, including the effects of severity and chronicity of injury and features such as utilization of semantic features to guide recall. The evidence for relatively preserved motor and pattern analyzing skills after severe CHI is presented and the implications for rehabilitation are discussed.

The perilymph fistula syndrome defined in mild head trauma

Neurological and neuro-otological studies were carried out on 102 adults with mild cranio-cervical trauma productive of positional vertigo and perilymph fistula as confirmed by laboratory tests, and by the finding of perilymph fistula at tympanotomy in the surgically managed group. In this patient group, all other neurological and neuro-otological diagnoses were excluded, e.g. epilepsy, cerebral palsy, multiple sclerosis, retardation; and for the neuro-otological group those with a history of ototoxicity, labyrinthitis, Meniere's disease, chronic ear infections, or developmental or familial disorders. Emphasis in this study was on mild trauma: fewer than half of the sample had been rendered unconscious in the injury of record, and a third of the cases were of whiplash type, with no loss of consciousness (LOC) and no remembered headstrike. These concomitant lesions comprise the perilymph fistula syndrome (PLFS) with a unique profile of neurological, perceptual, and cognitive deficits resembling a post-concussion injury. A complete description of the clinical picture is given, including psychological, cognitive and diagnostic tests, and the outcome of bedrest vs. surgical management. PLFS can arise from minor trauma, fistula are frequently bilateral (71/102), a mild sensorineural hearing loss is of variable occurrence (53%), secondary hydrops is not uncommon, and women appear more vulnerable than men for developing the syndrome. As based upon combined laboratory techniques and clinical symptomology, fistula were correctly predicted in 61 of 65 laser-operated ears. The positional vertigo component of PLFS was in all cases managed according to a special physical therapy program utilizing exercises for vestibular symptom habituation. Even when diagnosed late, a good-to-excellent outcome was achieved in 70% of treated patients.