Callosal Interhemispheric Communication in Mild Traumatic Brain Injury: A Mediation Analysis on WM Microstructure Effects.

BACKGROUND AND PURPOSE: Because the corpus callosum connects the left and right hemispheres and a variety of WM bundles across the brain in complex ways, damage to the neighboring WM microstructure may specifically disrupt interhemispheric communication through the corpus callosum following mild traumatic brain injury. Here we use a mediation framework to investigate how callosal interhemispheric communication is affected by WM microstructure in mild traumatic brain injury. MATERIALS AND METHODS: Multishell diffusion MR imaging was performed on 23 patients with mild traumatic brain injury within 1 month of injury and 17 healthy controls, deriving 11 diffusion metrics, including DTI, diffusional kurtosis imaging, and compartment-specific standard model parameters. Interhemispheric processing speed was assessed using the interhemispheric speed of processing task (IHSPT) by measuring the latency between word presentation to the 2 hemivisual fields and oral word articulation. Mediation analysis was performed to assess the indirect effect of neighboring WM microstructures on the relationship between the corpus callosum and IHSPT performance. In addition, we conducted a univariate correlation analysis to investigate the direct association between callosal microstructures and IHSPT performance as well as a multivariate regression analysis to jointly evaluate both callosal and neighboring WM microstructures in association with IHSPT scores for each group. RESULTS: Several significant mediators in the relationships between callosal microstructure and IHSPT performance were found in healthy controls. However, patients with mild traumatic brain injury appeared to lose such normal associations when microstructural changes occurred compared with healthy controls. CONCLUSIONS: This study investigates the effects of neighboring WM microstructure on callosal interhemispheric communication in healthy controls and patients with mild traumatic brain injury, highlighting that neighboring noncallosal WM microstructures are involved in callosal interhemispheric communication and information transfer. Further longitudinal studies may provide insight into the temporal dynamics of interhemispheric recovery following mild traumatic brain injury.

Veteran Beliefs About the Causes of Gulf War Illness and Expectations for Improvement.

BACKGROUND: Individuals' beliefs about the etiology of persistent physical symptoms (PPS) are linked to differences in coping style. However, it is unclear which attributions are related to greater expectations for improvement. METHOD AND RESULTS: A cross-sectional regression analysis (N = 262) indicated that Veterans with Gulf War Illness (GWI) who attributed their GWI to behavior, (e.g., diet and exercise), had greater expectations for improvement (p = .001) than those who attributed their GWI to deployment, physical, or psychological causes (p values > .05). CONCLUSIONS: Findings support the possible clinical utility of exploring perceived contributing factors of PPS, which may increase perceptions that improvement of PPS is possible. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02161133.

Inflammatory Bowel Disease: A Concise Review.

Inflammatory bowel disease is a term describing a group of diseases, Crohn's disease and ulcerative colitis, that cause chronic inflammation in the gastrointestinal tract. Both conditions tend to have episodic flares of diarrhea, abdominal pain, fatigue, and unintentional weight loss. This analysis will discuss the etiology, pathophysiology, epidemiology, clinical and histologic features, treatment, and complications of Crohn's disease and ulcerative colitis. Though there are many similarities between these two conditions it is important to recognize their differences for accurate diagnosis, treatment, and surveillance for potential long-term complications.

Comparison of Informational and Educational Resource Provision for Individuals Living With Traumatic Brain Injury Based on Language, Nativity, and Neighborhood.

OBJECTIVE: To examine a resource provision program for individuals living with moderate-to-severe traumatic brain injury (TBI), using a comparison of the resources provided across social differences of language, nativity, and neighborhood. SETTING: The Rusk Rehabilitation TBI Model System (RRTBIMS) collects data longitudinally on individuals from their associated private and public hospitals, located in New York City. PARTICIPANTS: A total of 143 individuals with TBI or their family members. DESIGN: An observational study of relative frequency of resource provision across variables of language, nativity, and neighborhood, using related-samples nonparametric analyses via Cochran's Q test. MAIN MEASURES: Variables examined were language, place of birth, residence classification as medically underserved area/population (MUA), and resource categories. RESULTS: Results indicate that US-born persons with TBI and those living in medically underserved communities are provided more resources than those who are born outside the United States or reside in communities identified as adequately medically served. Language was not found to be a factor. CONCLUSION: Lessons learned from this research support the development of this resource provision program, as well as guide future programs addressing the gaps in health information resources for groups negatively impacted by social determinants of health (SDoH). An approach with immigrant participants should take steps to elicit questions and requests, or offer resources explicitly. We recommend research looking at what interpreter strategies are most effective and research on SDoH in relation to the dynamic interaction of variables in the neighborhood setting.

Effect of Problem-solving Treatment on Self-reported Disability Among Veterans With Gulf War Illness: A Randomized Clinical Trial.

Importance: Few evidence-based treatments are available for Gulf War illness (GWI). Behavioral treatments that target factors known to maintain the disability from GWI, such as problem-solving impairment, may be beneficial. Problem-solving treatment (PST) targets problem-solving impairment and is an evidence-based treatment for other conditions. Objective: To examine the efficacy of PST to reduce disability, problem-solving impairment, and physical symptoms in GWI. Design, Setting, and Participants: This multicenter randomized clinical trial conducted in the US Department of Veterans Affairs compared PST with health education in a volunteer sample of 511 Gulf War veterans with GWI and disability (January 1, 2015, to September 1, 2019); outcomes were assessed at 12 weeks and 6 months. Statistical analysis was conducted between January 1, 2019, and December 31, 2020. Interventions: Problem-solving treatment taught skills to improve problem-solving. Health education provided didactic health information. Both were delivered by telephone weekly for 12 weeks. Main Outcomes and Measures: The primary outcome was reduction from baseline to 12 weeks in self-report of disability (World Health Organization Disability Assessment Schedule). Secondary outcomes were reductions in self-report of problem-solving impairment and objective problem-solving. Exploratory outcomes were reductions in pain, pain disability, and fatigue. Results: A total of 268 veterans (mean [SD] age, 52.9 [7.3] years; 88.4% male; 66.8% White) were randomized to PST (n = 135) or health education (n = 133). Most participants completed all 12 sessions of PST (114 of 135 [84.4%]) and health education (120 of 133 [90.2%]). No difference was found between groups in reductions in disability at the end of treatment. Results suggested that PST reduced problem-solving impairment (moderate effect, 0.42; P = .01) and disability at 6 months (moderate effect, 0.39; P = .06) compared with health education. Conclusions and Relevance: In this randomized clinical trial of the efficacy of PST for GWI, no difference was found between groups in reduction in disability at 12 weeks. Problem-solving treatment had high adherence and reduced problem-solving impairment and potentially reduced disability at 6 months compared with health education. These findings should be confirmed in future studies. Trial Registration: ClinicalTrials.gov Identifier: NCT02161133.

Development of an MMPI reference group for outpatients with persisting symptoms following mild TBI.

OBJECTIVE: To develop an MMPI-2-RF reference group for persistently symptomatic patients with mTBI in order to aid interpretation and better evaluate atypical scale elevations. METHOD: Using the Q Local MMPI-2-RF Comparison Group Generator (CGG), 200 valid MMPI-2-RF profiles were aggregated for mTBI outpatients with persisting symptoms 2-24 months post injury. RESULTS: Compared to established MMPI general population norms, individuals with persisting symptoms demonstrated elevations on several scales, primarily in cognitive and somatic domains. T scores > 60 and standard deviations > 10 were observed for the F-r (Infrequent Responses), Fs (Infrequent Somatic Responses), FBS-r (Symptom Validity), RBS (Response Bias Scale), RC1 (Somatic Complaints), MLS (Malaise), HPC (Head Pain Complaints), NUC (Neurological Complaints), and COG (Cognitive Complaints) scales. All other scales were consistent with established norms for the general population. CONCLUSION: This study is the first to establish an empirically derived MMPI reference group for individuals with persisting symptoms following mTBI. By comparing MMPI profiles of patients with mTBI against this reference group, clinicians may be better able to identify abnormal symptomatology. Evaluating profiles within this context may allow for more accurate case conceptualization and targeted treatment recommendations for those patients who demonstrate disproportionate symptomatology outside the range of the mTBI reference group.

The effects of plasticity-based cognitive rehabilitation on resting-state functional connectivity in chronic traumatic brain injury: A pilot study.

BACKGROUND: Traumatic brain injury (TBI) often results in chronic impairments to cognitive function, and these may be related to disrupted functional connectivity (FC) of the brain at rest. OBJECTIVE: To investigate changes in default mode network (DMN) FC in adults with chronic TBI following 40 hours of auditory processing speed training. METHODS: Eleven adults with chronic TBI underwent 40-hours of auditory processing speed training over 13-weeks and seven adults with chronic TBI were assigned to a non-intervention control group. For all participants, resting-state FC and cognitive and self-reported function were measured at baseline and at a follow-up visit 13-weeks later. RESULTS: No significant group differences in cognitive function or resting-state FC were observed at baseline. Following training, the intervention group demonstrated objective and subjective improvements on cognitive measures with moderate-to-large effect sizes. Repeated measures ANCOVAs revealed significant (p < 0.001) group×time interactions, suggesting training-related changes in DMN FC, and semipartial correlations demonstrated that these were associated with changes in cognitive functioning. CONCLUSIONS: Changes in the FC between the DMN and other resting-state networks involved in the maintenance and manipulation of internal information, attention, and sensorimotor functioning may be facilitated through consistent participation in plasticity-based auditory processing speed training in adults with chronic TBI.

Cognitive Dependence in Physically Independent Patients at Discharge From Acute Traumatic Brain Injury Rehabilitation.

OBJECTIVE: To determine the incidence of cognitive dependence in adults who are physically independent at discharge from acute traumatic brain injury (TBI) rehabilitation. DESIGN: Analysis of historical clinical and demographic data obtained from inpatient stay. SETTING: Inpatient rehabilitation unit in a large, metropolitan university hospital. PARTICIPANTS: Adult inpatients with moderate to severe TBI (N=226) who were physically independent at discharge from acute rehabilitation. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: FIM Motor and Cognitive subscales, discharge destination, and care plan. RESULTS: Approximately 69% (n=155) of the physically independent inpatients were cognitively dependent at discharge from acute rehabilitation, with the highest proportions of dependence found in the domains of problem solving and memory. Most (82.6%; n=128) of these physically independent, yet cognitively dependent, patients were discharged home. Of those discharged home, 82% (n=105) were discharged to the care of family members, and 11% (n=15) were discharged home alone. Patients from racial and ethnic minority backgrounds were significantly more likely than White patients to be discharged while cognitively dependent. CONCLUSIONS: The majority of physically independent patients with TBI were cognitively dependent at the time of discharge from acute inpatient rehabilitation. Further research is needed to understand the effect of cognitive dependence on caregiver stress and strain and the disproportionate burden on racial and ethnic minority patients and families. Given the potential functional and safety limitations imposed by cognitive deficits, health care policy and practice should facilitate delivery of cognitive rehabilitation services in acute TBI rehabilitation.

The effects of neuroplasticity-based auditory information processing remediation in adults with chronic traumatic brain injury.

BACKGROUND: Adults with chronic traumatic brain injury (TBI) may experience long-term deficits in multiple cognitive domains. Higher-order functions, such as verbal memory, are impacted by deficits in the ability to acquire verbal information. OBJECTIVE: This study investigated the effects of a neuroplasticity-based computerized cognitive remediation program for auditory information processing in adults with a chronic TBI. METHODS: Forty-eight adults with TBI were randomly assigned to an intervention or control group. Both groups underwent a neuropsychological assessment at baseline and post-training. The Intervention group received 40 one-hour cognitive training sessions with the Brain Fitness Program. RESULTS: The intervention group improved in performance on measures of the Woodcock-Johnson-III Understanding Directions subtest and Trail Making Test Part-A. They also reported improvement on the cognitive domain of the Cognitive Self-Report Questionnaire. CONCLUSIONS: The present study demonstrated that a neuroplasticity-based computerized cognitive remediation program may improve objective and subjective cognitive function in adults with TBI several years post-injury.

Veterans with Gulf War Illness perceptions of management strategies.

AIMS: Gulf War Illness (GWI) is a prevalent and disabling condition characterized by persistent physical symptoms. Clinical practice guidelines recommend self-management to reduce the disability from GWI. This study evaluated which GWI self-management strategies patients currently utilize and view as most effective and ineffective. MATERIALS AND METHODS: Data were collected from 267 Veterans during the baseline assessment of a randomized clinical trial for GWI. Respondents answered 3 open-ended questions regarding which self-management strategies they use, view as effective, and view as ineffective. Response themes were coded, and code frequencies were analyzed. KEY FINDINGS: Response frequencies varied across questions (in-use: n = 578; effective: n = 470; ineffective: n = 297). Healthcare use was the most commonly used management strategy (38.6% of 578), followed by lifestyle changes (28.5% of 578), positive coping (13% of 578), and avoidance (13.7% of 578). When asked about effective strategies, healthcare use (25.9% of 470), lifestyle change (35.7% of 470), and positive coping (17.4% of 470) were identified. Avoidance was frequently identified as ineffective (20.2% of 297 codes), as was invalidating experiences (14.1% of 297) and negative coping (10.4% of 297). SIGNIFICANCE: Patients with GWI use a variety of self-management strategies, many of which are consistent with clinical practice guidelines for treating GWI, including lifestyle change and non-pharmacological strategies. This suggests opportunities for providers to encourage effective self-management approaches that patients want to use.

Coping with Medically Unexplained Physical Symptoms: the Role of Illness Beliefs and Behaviors.

BACKGROUND: Medically unexplained syndromes (MUS) are both prevalent and disabling. While illness beliefs and behaviors are thought to maintain MUS-related disability, little is known about which specific behavioral responses to MUS are related to disability or the way in which beliefs and behaviors interact to impact functioning. The purpose of the present study was to examine the relationship between illness beliefs and disability among patients with MUS, and assess the extent to which behaviors mediate this relationship. METHODS: The study examined data from the baseline assessment of a multi-site randomized controlled trial (RCT). Participants were 248 veterans with MUS. Illness beliefs, behavioral responses to illness, and disability were assessed through self-report questionnaire. Data were analyzed using mediation analysis. RESULTS: Threat-related beliefs predicted greater disability through decreased activity and increased practical support seeking. Protective beliefs predicted less disability through reductions in all-or-nothing behavior and limiting behavior. CONCLUSIONS: These outcomes suggest that all-or-nothing behavior, limiting behavior, and practical support seeking are important in the perpetuation of disability among those with MUS. This has implications for improving MUS treatment by highlighting potential treatment targets. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02161133.

MTBI Identification From Diffusion MR Images Using Bag of Adversarial Visual Features.

In this paper, we propose bag of adversarial features (BAFs) for identifying mild traumatic brain injury (MTBI) patients from their diffusion magnetic resonance images (MRIs) (obtained within one month of injury) by incorporating unsupervised feature learning techniques. MTBI is a growing public health problem with an estimated incidence of over 1.7 million people annually in USA. Diagnosis is based on clinical history and symptoms, and accurate, concrete measures of injury are lacking. Unlike most of the previous works, which use hand-crafted features extracted from different parts of brain for MTBI classification, we employ feature learning algorithms to learn more discriminative representation for this task. A major challenge in this field thus far is the relatively small number of subjects available for training. This makes it difficult to use an end-to-end convolutional neural network to directly classify a subject from MRIs. To overcome this challenge, we first apply an adversarial auto-encoder (with convolutional structure) to learn patch-level features, from overlapping image patches extracted from different brain regions. We then aggregate these features through a bag-of-words approach. We perform an extensive experimental study on a dataset of 227 subjects (including 109 MTBI patients, and 118 age and sex-matched healthy controls) and compare the bag-of-deep-features with several previous approaches. Our experimental results show that the BAF significantly outperforms earlier works relying on the mean values of MR metrics in selected brain regions.

Impact of racial-ethnic minority status and systemic vulnerabilities on time to acute TBI rehabilitation admission in an urban public hospital setting.

PURPOSE/OBJECTIVE: Racial/ethnic minorities and other vulnerable social groups experience health care disparities. There is a lack of research exploring how time to acute rehabilitation admission is impacted by race/ethnicity and other marginalizing systemic vulnerabilities. The purpose of this study is to investigate whether race/ethnicity and other sociodemographic vulnerabilities impact expediency of acute rehabilitation admission following traumatic brain injury (TBI). Research Method/Design: This study is a secondary analysis of an existing dataset of 111 patients admitted for acute TBI rehabilitation at an urban public hospital. Patient groups were defined by race/ethnicity (People of color or White) and vulnerable group status (high or low vulnerable group membership [VGM]). RESULTS: White patients are admitted to acute TBI rehabilitation significantly faster than people of color. After taking vulnerabilities into account, high VGM people of color experience the most severe injuries and take the longest to receive acute TBI rehabilitation. Despite small differences in injury severity, low VGM people of color take longer to be admitted to acute TBI rehabilitation than White patients. High VGM White patients have less severe injuries yet take longer to be admitted to acute rehabilitation than low VGM White patients. Finally, notable differences exist between White patients and patients of color on rater-based injury severity scales that are discordant with severity as measured by more objective markers. CONCLUSIONS/IMPLICATIONS: Overall, findings indicate that sociodemographic factors including race/ethnicity and systemic vulnerabilities impact injury severity and time to acute TBI rehabilitation admission. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Training adults with acquired brain injury how to help-seek when wayfinding: an understudied critical life skill.

The objective of this study was to investigate the efficacy of a group treatment protocol called NICE (Noticing you have a problem, Identifying the information you need for help, Compensatory strategies, Evaluating progress) to train help-seeking when wayfinding for individuals with acquired brain injury (ABI). Seven participants completed the NICE group treatment in an outpatient rehabilitation department at a university medical centre. A single subject multiple baseline design was employed to evaluate the efficacy of the NICE group treatment. The Social Behaviour Rating Scale and the Executive Function Route-Finding Task- Revised were repeated measures used to evaluate potential changes in help-seeking and wayfinding. Secondary outcome measures included pre- and post-treatment evaluation of social problem solving and social cognition. Results revealed that all participants improved on measures of help-seeking and wayfinding. Patterns of improvement and implications for rehabilitation are discussed. This is the first experimental study to evaluate the treatment of help-seeking behaviours and discuss its application to wayfinding in adults with ABI. Preliminary evidence supports further investigation of the NICE group treatment protocol.

A Deep Unsupervised Learning Approach Toward MTBI Identification Using Diffusion MRI.

Mild traumatic brain injury is a growing public health problem with an estimated incidence of over 1.7 million people annually in US. Diagnosis is based on clinical history and symptoms, and accurate, concrete measures of injury are lacking. This work aims to directly use diffusion MR images obtained within one month of trauma to detect injury, by incorporating deep learning techniques. To overcome the challenge due to limited training data, we describe each brain region using the bag of word representation, which specifies the distribution of representative patch patterns. We apply a convolutional auto-encoder to learn the patch-level features, from overlapping image patches extracted from the MR images, to learn features from diffusion MR images of brain using an unsupervised approach. Our experimental results show that the bag of word representation using patch level features learnt by the auto encoder provides similar performance as that using the raw patch patterns, both significantly outperform earlier work relying on the mean values of MR metrics in selected brain regions.

Traumatic brain injury results in altered physiologic, but not subjective responses to emotional stimuli.

BACKGROUND: While the cognitive sequelae of traumatic brain injury (TBI) are well known, emotional impairments after TBI are suboptimally characterized. Lack of awareness of emotional difficulties can make self-report unreliable. However, individuals with TBI demonstrate involuntary changes in heart rate variability which may enable objective quantification of emotional dysfunction. METHODS: Sixteen subjects with chronic TBI and 10 age-matched controls were tested on an emotional function battery during which they watched a series of film clips normed to elicit specific positively and negatively valenced emotions: amusement, sexual amusement, sadness, fear and disgust. Subjective responses to the emotional stimuli were also obtained. Additionally, surface electrodes measured cardiac and respiratory signals to compute heart rate variability (HRV), from which measures of parasympathetic activity, the respiratory frequency area (RFA) and sympathetic activity, the low frequency area (LFA), of the HRV frequency spectrum were derived. The Neurobehavioral Rating Scale-Revised (NRS-R) and the King-Devick (KD) test were administered to assess neurobehavioral dysfunction. RESULTS: The two groups showed no differences in subjective ratings of emotional intensity. Subjects with TBI showed significantly decreased sympathetic activity when viewing amusing stimuli and significantly increased sympathetic activity when viewing sad stimuli compared to controls. Most of the subjects did not show agitation, anxiety, depression, blunted affect, emotional withdrawal, decreased motivation or mental fatiguability on the NRS-R. However, 13/16 subjects with TBI demonstrated attention difficulty on the NRS-R which was positively correlated with the increased sympathetic activity during sad stimuli. Both attention difficulty and abnormal autonomic responses to sad stimuli were correlated with the timing on the KD test, which reflected difficulty with visual attention shifting. CONCLUSIONS: The HRV spectrum may be useful to identify subclinical emotional dysfunction in individuals with TBI. Attention difficulites, specifically impairment in visual attention shifting, may contribute to abnormal reactivity to sad stimuli that may be detected and potentially treated to improve emotional function.

Problem solving, biofeedback, and severe brain injury: The moderating role of positive affect.

OBJECTIVE: To examine how positive affect influences ability to benefit from heart rate variability (HRV) biofeedback treatment for individuals with severe brain injury. METHOD: Secondary data analysis of a nonrandomized experimental study that assessed the efficacy of biofeedback treatment for executive dysfunction in 13 individuals with chronic severe brain injury. RESULTS: Bivariate correlations between the predictors (levels of HRV and positive affect) and the outcome (change in Category Test errors) showed large effect sizes for higher levels of HRV coherence (r = -.495, p = .085) but not for positive affect (r = .069, p = .824). Although positive affect had a negligible effect on Category Test improvements by itself, positive affect played a moderating role that complemented the effect of HRV coherence. HRV coherence had a stronger effect on Category Test performance among those participants who demonstrated higher positive affect. A regression model was fit that included main effects for HRV coherence and positive affect, as well as their interaction. The interaction term was significant in a 1-tailed test (b = -3.902, SE = 1.914, p = .072). CONCLUSIONS: Participants who had the most positive emotions made the most gains in the HRV biofeedback training and performed better posttreatment on a test designed to measure problem-solving ability. Results indicate that positive affect can improve cognition, specifically mental flexibility and abstract thinking. Addressing factors that shape negative affect such as irrational beliefs and self-doubt is an important target for therapeutic intervention even in those with severe, chronic deficits. (PsycINFO Database Record

Working Memory And Brain Tissue Microstructure: White Matter Tract Integrity Based On Multi-Shell Diffusion MRI.

Working memory is a complex cognitive process at the intersection of sensory processing, learning, and short-term memory and also has a general executive attention component. Impaired working memory is associated with a range of neurological and psychiatric disorders, but very little is known about how working memory relates to underlying white matter (WM) microstructure. In this study, we investigate the association between WM microstructure and performance on working memory tasks in healthy adults (right-handed, native English speakers). We combine compartment specific WM tract integrity (WMTI) metrics derived from multi-shell diffusion MRI as well as diffusion tensor/kurtosis imaging (DTI/DKI) metrics with Wechsler Adult Intelligence Scale-Fourth Edition (WAIS-IV) subtests tapping auditory working memory. WMTI is a novel tool that helps us describe the microstructural characteristics in both the intra- and extra-axonal environments of WM such as axonal water fraction (AWF), intra-axonal diffusivity, extra-axonal axial and radial diffusivities, allowing a more biophysical interpretation of WM changes. We demonstrate significant positive correlations between AWF and letter-number sequencing (LNS), suggesting that higher AWF with better performance on complex, more demanding auditory working memory tasks goes along with greater axonal volume and greater myelination in specific regions, causing efficient and faster information process.

Cluster Analysis of Vulnerable Groups in Acute Traumatic Brain Injury Rehabilitation.

OBJECTIVE: To analyze the complex relation between various social indicators that contribute to socioeconomic status and health care barriers. DESIGN: Cluster analysis of historical patient data obtained from inpatient visits. SETTING: Inpatient rehabilitation unit in a large urban university hospital. PARTICIPANTS: Adult patients (N=148) receiving acute inpatient care, predominantly for closed head injury. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: We examined the membership of patients with traumatic brain injury in various "vulnerable group" clusters (eg, homeless, unemployed, racial/ethnic minority) and characterized the rehabilitation outcomes of patients (eg, duration of stay, changes in FIM scores between admission to inpatient stay and discharge). RESULTS: The cluster analysis revealed 4 major clusters (ie, clusters A-D) separated by vulnerable group memberships, with distinct durations of stay and FIM gains during their stay. Cluster B, the largest cluster and also consisting of mostly racial/ethnic minorities, had the shortest duration of hospital stay and one of the lowest FIM improvements among the 4 clusters despite higher FIM scores at admission. In cluster C, also consisting of mostly ethnic minorities with multiple socioeconomic status vulnerabilities, patients were characterized by low cognitive FIM scores at admission and the longest duration of stay, and they showed good improvement in FIM scores. CONCLUSIONS: Application of clustering techniques to inpatient data identified distinct clusters of patients who may experience differences in their rehabilitation outcome due to their membership in various "at-risk" groups. The results identified patients (ie, cluster B, with minority patients; and cluster D, with elderly patients) who attain below-average gains in brain injury rehabilitation. The results also suggested that systemic (eg, duration of stay) or clinical service improvements (eg, staff's language skills, ability to offer substance abuse therapy, provide appropriate referrals, liaise with intensive social work services, or plan subacute rehabilitation phase) could be beneficial for acute settings. Stronger recruitment, training, and retention initiatives for bilingual and multiethnic professionals may also be considered to optimize gains from acute inpatient rehabilitation after traumatic brain injury.

White Matter Tract Integrity: An Indicator of Axonal Pathology after Mild Traumatic Brain Injury.

We seek to elucidate the underlying pathophysiology of injury sustained after mild traumatic brain injury (mTBI) using multi-shell diffusion magnetic resonance imaging, deriving compartment-specific white matter tract integrity (WMTI) metrics. WMTI allows a more biophysical interpretation of white matter (WM) changes by describing microstructural characteristics in both intra- and extra-axonal environments. Thirty-two patients with mTBI within 30 days of injury and 21 age- and sex-matched controls were imaged on a 3 Tesla magnetic resonance scanner. Multi-shell diffusion acquisition was performed with five b-values (250-2500 sec/mm2) along 6-60 diffusion encoding directions. Tract-based spatial statistics (TBSS) was used with family-wise error (FWE) correction for multiple comparisons. TBSS results demonstrated focally lower intra-axonal diffusivity (Daxon) in mTBI patients in the splenium of the corpus callosum (sCC; p < 0.05, FWE-corrected). The area under the curve value for Daxon was 0.76 with a low sensitivity of 46.9% but 100% specificity. These results indicate that Daxon may be a useful imaging biomarker highly specific for mTBI-related WM injury. The observed decrease in Daxon suggests restriction of the diffusion along the axons occurring shortly after injury.