Exploring the kynurenine pathway in mild traumatic brain injury: A longitudinal study

A potential source of novel biomarkers for mTBI is the kynurenine pathway (KP), a metabolic pathway of tryptophan (Trp), that is up-regulated by neuroinflammation and stress. Considering that metabolites of the KP (kynurenines) are implicated in various neuropsychiatric diseases, exploration of this pathway could potentially bridge the gap between physiological and psychological factors in the recovery process after mTBI. This study, therefore, set out to characterize the KP after mTBI and to examine associations with long-term outcome. Patients were prospectively recruited at the emergency department (ED), and blood samples were obtained in the acute phase (<24 h; N = 256) and at 1-month follow-up (N = 146). A comparison group of healthy controls (HC; N = 32) was studied at both timepoints. Trp, kynurenines, and interleukin (IL)-6 and IL-10 were quantified in plasma. Clinical outcome was measured at six months post-injury. Trp, xanthurenic acid (XA), and picolinic acid (PA) were significantly reduced in patients with mTBI relative to HC, corrected for age and sex. For Trp (d = -0.57 vs. d = -0.29) and XA (d = -0.98 vs. d = -0.32), larger effects sizes were observed during the acute phase compared to one-month follow-up, while for PA (d = -0.49 vs. d = -0.52) effect sizes remained consistent. Findings for other kynurenines (e.g., kynurenine, kynurenic acid, and quinolinic acid) were non-significant after correction for multiple testing. Within the mTBI group, lower acute Trp levels were significantly related to incomplete functional recovery and higher depression scores at 6 months post-injury. No significant relationships were found for Trp, XA, and PA with IL-6 or IL-10 concentrations. In conclusion, our findings indicate that perturbations of the plasma KP in the hyperacute phase of mTBI and 1 month later are limited to the precursor Trp, and glutamate system modulating kynurenines XA and PA. Correlations between acute reductions of Trp and unfavorable outcomes may suggest a potential substrate for pharmacological intervention.

Good Health-Related Quality of Life in Older Patients One Year after mTBI despite Incomplete Recovery: An Indication of the Disability Paradox?

Background: Older adults (OAs) with mild traumatic brain injury (OA-mTBI) are a growing population, but studies on long-term outcomes and quality of life are scarce. Our aim was to determine the health-related quality of life (HRQoL) in OA-mTBI one year after injury and to assess the early predictors of HRQoL. Methods: Data from a prospective follow-up study of 164 older (≥60 years) and 289 younger mTBI patients (<60 years) admitted to the emergency department were analyzed. Post-traumatic complaints, emotional distress and coping were evaluated 2 weeks post-injury using standardized questionnaires. At 12 months post-injury, HRQoL and functional recovery were determined with the abbreviated version of the World Health Organization Quality of Life scale and Glasgow Outcome Scale Extended (GOSE), respectively. Results: One year post-injury, 80% (n = 131) of the OA-mTBI rated their HRQoL as "good" or "very good", which was comparable to younger patients (79% (n = 226), p = 0.72). Incomplete recovery (GOSE <8) was present in 43% (n = 69) of OA-mTBI, with 67% (n = 46) reporting good HRQoL. Two weeks post-injury, fewer OA-mTBI had (≥2) post-traumatic complaints compared to younger patients (68% vs. 80%, p = 0.01). In the multivariable analyses, only depression-related symptoms (OR = 1.20 for each symptom, 95% CI = 1.01-1.34, p < 0.01) were predictors of poor HRQoL in OA-mTBI. Conclusions: Similar to younger patients, most OA-mTBI rated their HRQoL as good at one year after injury, although a considerable proportion showed incomplete recovery according to the GOSE, suggesting a disability paradox. Depression-related symptoms emerged as a significant predictor for poor HRQoL and can be identified as an early target for treatment after mTBI.

Primary central nervous system lymphoma

Primary central nervous system lymphoma (PCNSL) is a rare type of non-Hodgkin lymphoma (NHL) manifesting in the brain, spinal cord, cerebrospinal fluid and/or eyes, in the absence of systemic manifestations. With an increasing incidence and a 30% 5-year overall survival if promptly treated, timely diagnosis and subsequent treatment is paramount. The typical MRI appearance for PCNSL is a solitary or multiple T2-hypointense, homogeneous gadolinium-enhancing lesion with restricted diffusion. Dexamethasone treatment might compromise and delay the diagnosis. Hallmark of treatment is induction with intravenous high-dose methotrexate consisting polychemotherapy followed by consolidation treatment. Consolidation treatment consists of either whole brain radiotherapy (WBRT) or autologous stem cell transplantation (ASCT). Given the (cognitive) side effects of WBRT, ASCT is increasingly being used as the first choice of treatment.

An exploratory study on the association between blood-based biomarkers and subacute neurometabolic changes following mild traumatic brain injury

BACKGROUND AND OBJECTIVES

Blood-based biomarkers and advanced neuroimaging modalities such as magnetic resonance spectroscopy (MRS) or diffusion tensor imaging (DTI) have enhanced our understanding of the pathophysiology of mild traumatic brain injury (mTBI). However, there is limited published data on how blood biomarkers relate to neuroimaging biomarkers post-mTBI.

METHODS

To investigate this, 30 patients with mTBI and 21 healthy controls were enrolled. Data was collected at two timepoints postinjury: acute, < 24 h, (blood) and subacute, four-to-six weeks, (blood and imaging). Interleukin (IL) 6 and 10 (inflammation), free thiols (systemic oxidative stress) and neurofilament light (NF-L) (axonal injury) were quantified in plasma. The neurometabolites total N-acetyl aspartate (tNAA) (neuronal energetics), Myo-Inositol (Ins) and total Choline (tCh) (inflammation) and, Glutathione (GSH, oxidative stress) were quantified using MRS.

RESULTS

Concentrations of IL-6 and IL-10 were significantly elevated in the acute phase post-mTBI, while NF-L was elevated only in the subacute phase. Total NAA was lowered in patients with mTBI, although this difference was only nominally significant (uncorrected P < 0.05). Within the patient group, acute IL-6 and subacute tNAA levels were negatively associated (r =  - 0.46, uncorrected-P = 0.01), albeit not at a threshold corrected for multiple testing (corrected-P = 0.17). When age was added as a covariate a significant increase in correlation magnitude was observed (ρ =  - 0.54, corrected-P = 0.03).

CONCLUSION

This study demonstrates potential associations between the intensity of the inflammatory response in the acute phase post-mTBI and neurometabolic perturbations in the subacute phase. Future studies should assess the longitudinal dynamics of blood-based and imaging biomarkers after injury.

Evaluation of Glial Fibrillary Acidic Protein and Ubiquitin C-Terminal Hydrolase-L1 Using a Rapid Point of Care Test for Predicting Head Computed Tomography Lesions After Mild Traumatic Brain Injury in a Dutch Multi-Center Cohort

Mild traumatic brain injury (mTBI) is a common condition seen in emergency departments worldwide. Blood-based biomarkers glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1) are recently U.S. Food and Drug Administration-approved for the prediction of intracranial lesions on head computed tomography (CT) scans in mTBI. We evaluated the diagnostic performance of GFAP and UCH-L1 in a Dutch cohort using the i-STAT TBI assay. In a multi-center observational study, we enrolled 253 mTBI patients. Head CT scans were scored using the Marshall classification system. Logistic regression models were used to assess the contribution of biomarkers and clinical parameters to diagnostic performance. Detection of UCH-L1 and GFAP resulted in a sensitivity of 97% and specificity of 19% for CT positivity in mTBI patients, along with a negative predictive value of 95% (88-100%) and a positive predictive value of 27% (21-33%). Combining biomarker testing with loss of consciousness and time to sample increased specificity to 46%. Combined testing of UCH-L1 and GFAP testing resulted in possibly more unnecessary CT scans compared with GFAP testing alone, with only limited increase in sensitivity. This study confirmed high sensitivity of GFAP and UCH-L1 for CT abnormalities in mTBI patients using the i-STAT TBI test. The results support the potential use of GFAP and UCH-L1 as tools for determining the indication for CT scanning in mTBI patients, possibly offering a cost- and time-effective approach to management of patients with mTBI. Prospective studies in larger cohorts are warranted to validate our findings.

Identification of At-Risk Patients That Need More Intensive Treatment Following mTBI: Post-Hoc Insights From the UPFRONT-Study

OBJECTIVE

To investigate which factors within an at-risk group make patients less likely to benefit from preventive treatment following mild traumatic brain injury (mTBI).

SETTING

Inclusion in 3 level I trauma centers in the Netherlands. Data collection through surveys as outpatients.

PARTICIPANTS

mTBI patients (18-66 years), reporting 3 or more complaints 2 weeks postinjury (at-risk status). Eighty-four patients included and randomized (39 patients cognitive behavioral therapy, 45 patients telephonic counseling). Eighty patients filled out the questionnaires 12 months postinjury. Post hoc analysis investigating 80 patients as 1 at-risk group receiving psychological treatment.

DESIGN

Post hoc study of a randomized controlled trial (RCT). Binomial logistic regression performed determining which variables 2 weeks postinjury contributed strongly to unsuccessful return to work/study (RTW) and unfavorable outcome at 12 months.

MAIN MEASURES

RTW and functional outcome as measured with the Glasgow Outcome Scale-Extended (GOSE) at 12 months postinjury.

RESULTS

Out of 80 patients, 43 (53.8%) showed a favorable functional outcome at 12 months, and 56 (70%) patients had a full RTW. Patients with unfavorable outcome had a higher age and higher reports of anxiety, depression at 2 weeks and 12 months postinjury. Patients with an unsuccessful RTW had a higher age and higher reports of depression, and posttraumatic stress disorder at 2 weeks and 12 months postinjury. A logistic regression model for functional outcome (GOSE) was statistically significant (χ²7 = 40.30, P < .0001). Of 6 predictor variables, 3 were significant: anxiety, depression, and treatment condition. For RTW, logistic regression was also statistically significant (χ²7 = 19.15, P = .008), with only 1 out of 6 predictor variables (ie, age) being significant.

CONCLUSION

Main findings comprise differences in demographic and psychological measures between patients with favorable and unfavorable outcomes and patients with RTW versus no RTW. Prediction models of outcome and RTW showed several psychological measures at 2 weeks greatly determining patients' likelihood benefitting from the preventive treatment. Results suggest that from the beginning there are some patients for whom a short preventive treatment is not sufficient. Selection and treatment of at-risk patients might be better based on psychological symptoms instead of posttraumatic complaints.

Neurophysiological signatures of mild traumatic brain injury in the acute and subacute phase

BACKGROUND

Mild traumatic brain injury (mTBI) affects 48 million people annually, with up to 30% experiencing long-term complaints such as fatigue, blurred vision, and poor concentration. Assessing neurophysiological features related to visual attention and outcome measures aids in understanding clinical symptoms and prognostication.

METHODS

We recorded EEG and eye movements in mTBI patients during a computerized task performed in the acute (< 24 h, TBI-A) and subacute phase (4-6 weeks thereafter). We estimated the posterior dominant rhythm, reaction times (RTs), fixation duration, and event-related potentials (ERPs). Clinical outcome measures were assessed using the Head Injury Symptom Checklist (HISC) and the Extended Glasgow Outcome Scale (GOSE) at 6 months post-injury. Similar analyses were performed in an age-matched control group (measured once). Linear mixed effect modeling was used to examine group differences and temporal changes within the mTBI group.

RESULTS

Twenty-nine patients were included in the acute phase, 30 in the subacute phase, and 19 controls. RTs and fixation duration were longer in mTBI patients compared to controls (p < 0.05), but not between TBI-A and TBI-S (p < 0.05). The frequency of the posterior dominant rhythm was significantly slower in TBI-A (0.6 Hz, p < 0.05) than TBI-S. ERP mean amplitude was significantly lower in mTBI patients than in controls. Neurophysiological features did not significantly relate to clinical outcome measures.

CONCLUSION

mTBI patients demonstrate impaired processing speed and stimulus evaluation compared to controls, persisting up to 6 weeks after injury. Neurophysiological features in mTBI can assist in determining the extent and temporal progression of recovery.

Dynamic phase-locking states and personality in sub-acute mild traumatic brain injury: An exploratory study

Research has shown that maladaptive personality characteristics, such as Neuroticism, are associated with poor outcome after mild traumatic brain injury (mTBI). The current exploratory study investigated the neural underpinnings of this process using dynamic functional network connectivity (dFNC) analyses of resting-state (rs) fMRI, and diffusion MRI (dMRI). Twenty-seven mTBI patients and 21 healthy controls (HC) were included. After measuring the Big Five personality dimensions, principal component analysis (PCA) was used to obtain a superordinate factor representing emotional instability, consisting of high Neuroticism, moderate Openness, and low Extraversion, Agreeableness, and Conscientiousness. Persistent symptoms were measured using the head injury symptom checklist at six months post-injury; symptom severity (i.e., sum of all items) was used for further analyses. For patients, brain MRI was performed in the sub-acute phase (~1 month) post-injury. Following parcellation of rs-fMRI using independent component analysis, leading eigenvector dynamic analysis (LEiDA) was performed to compute dynamic phase-locking brain states. Main patterns of brain diffusion were computed using tract-based spatial statistics followed by PCA. No differences in phase-locking state measures were found between patients and HC. Regarding dMRI, a trend significant decrease in fractional anisotropy was found in patients relative to HC, particularly in the fornix, genu of the corpus callosum, anterior and posterior corona radiata. Visiting one specific phase-locking state was associated with lower symptom severity after mTBI. This state was characterized by two clearly delineated communities (each community consisting of areas with synchronized phases): one representing an executive/saliency system, with a strong contribution of the insulae and basal ganglia; the other representing the canonical default mode network. In patients who scored high on emotional instability, this relationship was even more pronounced. Dynamic phase-locking states were not related to findings on dMRI. Altogether, our results provide preliminary evidence for the coupling between personality and dFNC in the development of long-term symptoms after mTBI.

Trajectories of Fatigue, Psychological Distress, and Coping Styles After Mild Traumatic Brain Injury: A 6-Month Prospective Cohort Study

OBJECTIVE

To analyze fatigue after mild traumatic brain injury (TBI) with latent class growth analysis (LCGA) to determine distinct recovery trajectories and investigate influencing factors, including emotional distress and coping styles.

DESIGN

An observational cohort study design with validated questionnaires assessing fatigue, anxiety, depression, posttraumatic stress, and coping at 2 weeks and 3 and 6 months postinjury.

SETTING

Three level 1 trauma centers.

PARTICIPANTS

Patients with mild TBI (N=456).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Fatigue was measured with the fatigue severity subscale of the Checklist Individual Strength, including 8 items (sum score, 8-56). Subsequently, 3 clinical categories were created: high (score, 40-56), moderate (score, 26-38), and low (score, 8-25).

RESULTS

From the entire mild TBI group, 4 patient clusters with distinct patterns for fatigue, emotional distress, and coping styles were found with LCGA. Clusters 1 and 2 showed favorable recovery from fatigue over time, with low emotional distress and the predominant use of active coping in cluster 1 (30%) and low emotional distress and decreasing passive coping in cluster 2 (25%). Clusters 3 and 4 showed unfavorable recovery, with persistent high fatigue and increasing passive coping together with low emotional distress in cluster 3 (27%) and high emotional distress in cluster 4 (18%). Patients with adverse trajectories were more often women and more often experiencing sleep disturbances and pain.

CONCLUSIONS

The prognosis for recovery from posttraumatic fatigue is favorable for 55% of mild TBI patients. Patients at risk for chronic fatigue can be signaled in the acute phase postinjury based on the presence of high fatigue, high passive coping, and, for a subgroup of patients, high emotional distress. LCGA proved to be a highly valuable and multipurpose statistical method to map distinct courses of disease-related processes over time.

Coping with stress before and after mild traumatic brain injury: a pilot hair cortisol study

Background: Cortisol is a crucial hormone for adaptation to challenging and stressful situations. Hair cortisol measurement is used to determine chronic stress; the growth rate of hair allows to determine averaged cortisol levels for a longer period. Objective: Pre- and post-injury measures of hair cortisol were compared in patients with mild traumatic brain injury (mTBI), and related to their coping styles.Methods: For 46 patients with mTBI, 3 cm scalp hair samples were collected 4-6 weeks post-injury, resulting in two 1 cm segments, pre- and post-injury. Hair samples were also collected for 11 healthy controls. Hair cortisol was quantified using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Complaints, anxiety, depression and coping style were measured two weeks post-injury and long term (six-twelve months), added with measures for post-traumatic stress and functional outcome.Results: There were no differences between patients' pre- and post-injury cortisol levels, nor between cortisol levels of patients and controls. However, pre- and post-injury cortisol levels of patients were negatively correlated with both passive and an avoidant coping style.Conclusions: Our findings suggest that mTBI has no separate impact on chronic long-term cortisol levels, possibility indicating that variability in cortisol levels reflects individuals' premorbid characteristics determining coping with stress in general.

Patients with mild traumatic brain injury and acute neck pain at the emergency department are a distinct category within the mTBI spectrum: a prospective multicentre cohort study

BACKGROUND

Acute neck pain (ANP) has recently been demonstrated to be a predictor of persistent posttraumatic complaints after mild traumatic brain injury (mTBI). The aim of this study was to determine specific characteristics of patients with ANP following mTBI, their posttraumatic complaints and relationship with functional outcome.

METHODS

Data from a prospective follow-up study of 922 mTBI patients admitted to the emergency department (ED) in three level-one trauma centres were analysed. Patients were divided into two groups: 156 ANP patients and 766 no acute neck pain (nANP) patients. Posttraumatic complaints were evaluated 2 weeks and 6 months post-injury using standardized questionnaires and functional outcome was evaluated at 6 months with the Glasgow Outcome Scale Extended (GOSE).

RESULTS

ANP patients were more often female (p < 0.01), younger (38 vs. 47 years, p < 0.01) with more associated acute symptoms at the ED (p < 0.05) compared to nANP patients. More motor vehicle accidents (12% vs. 6%, p = 0.01) and less head wounds (58% vs. 73%, p < 0.01) in ANP patients indicated 'high-energy low-impact' trauma mechanisms. ANP patients showed more posttraumatic complaints 2 weeks and 6 months post-injury (p < 0.05) and more often incomplete recovery (GOSE < 8) was present after 6 months (56% vs. 40%, p = 0.01).

CONCLUSIONS

MTBI patients with acute neck pain at the ED constitute a distinct group within the mTBI spectrum with specific injury and demographic characteristics. Early identification of this at risk group already at the ED might allow specific and timely treatment to avoid development of incomplete recovery.

Prediction of work resumption and sustainability up to 1 year after mild traumatic brain injury

Objective:

To study return to work (RTW) after mild traumatic brain injury (mTBI) at several intervals after injury and to predict RTW on the basis of occupational factors in addition to demographic, personality, and injury-related factors at 6 and 12 months after injury.

Methods:

This was a prospective cohort study (UPFRONT study, n = 1,151) of patients with mTBI admitted to the emergency department. Patients received questionnaires at 2 weeks and 3, 6, and 12 months after injury. RTW was divided into 3 levels: complete (cRTW), partial (pRTW), and no RTW.

Results:

Rates of cRTW increased from 34% at 2 weeks to 77% at 12 months after injury, pRTW varied from 8% to 16% throughout the year. Logistic regression (complete vs incomplete RTW) demonstrated that apart from previously identified predictors such as demographics (e.g., age and education) and injury characteristics (e.g., cause and severity of injury) and indicators of psychological distress, occupational factors were of influence on work resumption after 6 months (area under the curve [AUC] = 0.82), At 12 months, however, the model was based solely on the presence of extracranial injuries and indicators of maladaptation after injury (AUC = 0.81).

Conclusions:

RTW after mTBI is a gradual process, with varying levels of RTW throughout the first year after injury. Different predictors were relevant for short- vs long-term work resumption, with occupational factors influencing short-term RTW. However, for both short- and long-term RTW, posttraumatic complaints and signs of psychological distress early after injury were relevant predictors, allowing early identification of patients at risk for problematic work resumption.

Graph Analysis of Functional Brain Networks in Patients with Mild Traumatic Brain Injury

Mild traumatic brain injury (mTBI) is one of the most common neurological disorders worldwide. Posttraumatic complaints are frequently reported, interfering with outcome. However, a consistent neural substrate has not yet been found. We used graph analysis to further unravel the complex interactions between functional brain networks, complaints, anxiety and depression in the sub-acute stage after mTBI. This study included 54 patients with uncomplicated mTBI and 20 matched healthy controls. Posttraumatic complaints, anxiety and depression were measured at two weeks post-injury. Patients were selected based on presence (n = 34) or absence (n = 20) of complaints. Resting-state fMRI scans were made approximately four weeks post-injury. High order independent component analysis resulted in 89 neural components that were included in subsequent graph analyses. No differences in graph measures were found between patients with mTBI and healthy controls. Regarding the two patient subgroups, degree, strength, local efficiency and eigenvector centrality of the bilateral posterior cingulate/precuneus and bilateral parahippocampal gyrus were higher, and eigenvector centrality of the frontal pole/ bilateral middle & superior frontal gyrus was lower in patients with complaints compared to patients without complaints. In patients with mTBI, higher degree, strength and eigenvector centrality of default mode network components were related to higher depression scores, and higher degree and eigenvector centrality of executive network components were related to lower depression scores. In patients without complaints, one extra module was found compared to patients with complaints and healthy controls, consisting of the cingulate areas. In conclusion, this research extends the knowledge of functional network connectivity after mTBI. Specifically, our results suggest that an imbalance in the function of the default mode- and executive network plays a central role in the interaction between emotion regulation and the persistence of posttraumatic complaints.

Brain network dysregulation, emotion, and complaints after mild traumatic brain injury

OBJECTIVES

To assess the role of brain networks in emotion regulation and post-traumatic complaints in the sub-acute phase after non-complicated mild traumatic brain injury (mTBI).

EXPERIMENTAL DESIGN

Fifty-four patients with mTBI (34 with and 20 without complaints) and 20 healthy controls (group-matched for age, sex, education, and handedness) were included. Resting-state fMRI was performed at four weeks post-injury. Static and dynamic functional connectivity were studied within and between the default mode, executive (frontoparietal and bilateral frontal network), and salience network. The hospital anxiety and depression scale (HADS) was used to measure anxiety (HADS-A) and depression (HADS-D).

PRINCIPAL OBSERVATIONS

Regarding within-network functional connectivity, none of the selected brain networks were different between groups. Regarding between-network interactions, patients with complaints exhibited lower functional connectivity between the bilateral frontal and salience network compared to patients without complaints. In the total patient group, higher HADS-D scores were related to lower functional connectivity between the bilateral frontal network and both the right frontoparietal and salience network, and to higher connectivity between the right frontoparietal and salience network. Furthermore, whereas higher HADS-D scores were associated with lower connectivity within the parietal midline areas of the bilateral frontal network, higher HADS-A scores were related to lower connectivity within medial prefrontal areas of the bilateral frontal network.

CONCLUSIONS

Functional interactions of the executive and salience networks were related to emotion regulation and complaints after mTBI, with a key role for the bilateral frontal network. These findings may have implications for future studies on the effect of psychological interventions.

Pathways of care the first year after moderate and severe traumatic brain injury-discharge destinations and outpatient follow-up

PRIMARY OBJECTIVE

To determine the pathways of care within the first year after traumatic brain injury (TBI) and to explore whether provided care is related to residual impairments.

RESEARCH DESIGN

Retrospective study of 343 patients with moderate and severe TBI admitted to a Level-1 trauma centre.

METHODS AND PROCEDURES

Discharge destinations from hospital to home and frequency of outpatient visits were determined. Outcome was defined 1 year after injury by the Extended Glasgow Outcome Scale and Return to Work.

RESULTS

Most (94%) patients had returned home 1-year after injury despite cognitive (76%), behavioural (67%) and physical (55%) impairments. One in four patients was severely disabled and 32% had resumed work on a previous level. Two-thirds of all patients went home as secondary discharge destination and 50% needed inpatient rehabilitation. Almost half of patients needed outpatient care, mostly for behavioural and cognitive impairments. One in 10 patients consulted a psychiatrist, with 55% unfavourable outcome. Of those patients initially discharged to home without follow-up, eventually 10% needed outpatient rehabilitation.

CONCLUSIONS

One-year after injury most patients had returned home with residual impairments and frequent medical consultations. This finding warrants further investigation to define appropriate aftercare by various medical specialists aimed at long-term community integration.