Untargeted blood serum proteomics identifies novel proteins related to neurological recovery after human spinal cord injury.

BACKGROUND: The discovery of new prognostic biomarkers following spinal cord injury (SCI) is a rapidly growing field that could help uncover the underlying pathological mechanisms of SCI and aid in the development of new therapies. To date, this search has largely focused on the initial days after the lesion. However, during the subacute stage of SCI (weeks to months after the injury), there remains potential for sensorimotor recovery, and numerous secondary events develop in various organs. Additionally, the confounding effects of early interventions after the injury are less likely to interfere with the results. METHODS: In this study, we conducted an untargeted proteomics analysis to identify biomarkers of recovery in blood serum samples during the subacute phase of SCI patients, comparing those with strong recovery to those with no recovery between 30 and 120 days. We analyzed the fraction of serum that is depleted of the most abundant proteins to unmask proteins that would otherwise go undetected. Linear models were used to identify peptides and proteins related to neurological recovery and we validated changes in some of these proteins using Enzyme-linked Immunosorbent Assay (ELISA). RESULTS: Our findings reveal that differences in subacute recovery after SCI (from 30 to 120 days) are associated with an enrichment in proteins involved in inflammation, coagulation, and lipid metabolism. Technical validation using commercial ELISAs further confirms that high levels of SERPINE1 and ARHGAP35 are associated with strong neurological recovery, while high levels of CD300a and DEFA1 are associated with a lack of recovery. CONCLUSIONS: Our study identifies new candidates for biomarkers of neurological recovery and for novel therapeutic targets after SCI.

International surveillance study in acute spinal cord injury confirms viability of multinational clinical trials.

BACKGROUND: The epidemiological international landscape of traumatic spinal cord injury (SCI) has evolved over the last decades along with given inherent differences in acute care and rehabilitation across countries and jurisdictions. However, to what extent these differences may influence neurological and functional recovery as well as the integrity of international trials is unclear. The latter also relates to historical clinical data that are exploited to inform clinical trial design and as potential comparative data. METHODS: Epidemiological and clinical data of individuals with traumatic and ischemic SCI enrolled in the European Multi-Center Study about Spinal Cord Injury (EMSCI) were analyzed. Mixed-effect models were employed to account for the longitudinal nature of the data, efficiently handle missing data, and adjust for covariates. The primary outcomes comprised demographics/injury characteristics and standard scores to quantify neurological (i.e., motor and sensory scores examined according to the International Standards for the Neurological Classification of Spinal Cord Injury) and functional recovery (walking function). We externally validated our findings leveraging data from a completed North American landmark clinical trial. RESULTS: A total of 4601 patients with acute SCI were included. Over the course of 20 years, the ratio of male to female patients remained stable at 3:1, while the distribution of age at injury significantly shifted from unimodal (2001/02) to bimodal distribution (2019). The proportional distribution of injury severities and levels remained stable with the largest percentages of motor complete injuries. Both, the rate and pattern of neurological and functional recovery, remained unchanged throughout the surveillance period despite the increasing age at injury. The findings related to recovery profiles were confirmed by an external validation cohort (n=791). Lastly, we built an open-access and online surveillance platform ("Neurosurveillance") to interactively exploit the study results and beyond. CONCLUSIONS: Despite some epidemiological changes and considerable advances in clinical management and rehabilitation, the neurological and functional recovery following SCI has remained stable over the last two decades. Our study, including a newly created open-access and online surveillance tool, constitutes an unparalleled resource to inform clinical practice and implementation of forthcoming clinical trials targeting neural repair and plasticity in acute spinal cord injury.

[Germany-wide, Web-based ParaReg Registry for Lifelong Monitoring of People with Spinal Cord Injury: Data Model, Ethico-legal Prerequisites and Technical Implementation]. / Das deutschlandweite, webbasierte ParaReg-Register zur lebenslangen Dokumentation von Querschnittgelähmten ­ Datenmodell, rechtlich-ethische Voraussetzungen und technische Implementierung.

OBJECTIVE: In Germany, treatment paths for patients with acute spinal cord injury (SCI) differ considerably depending on intrinsic, disease-specific and extrinsic factors. Which of these factors are associated with improved outcome with fewer subsequent complications and inpatient re-admissions is not clear. The German-wide, patient-centered, web-based ParaReg registry will be implemented to improve the long-term quality of patient care and the planning of treatment paths with increased cost-effectiveness. METHODS: In the 2017-18 conceptualization phase, the data model of the registry was developed in an iterative process of the ParaReg steering committee together with the extended DMGP board and patient representatives. In ParaReg, routine social and medical data as well as internationally established neurological, functional and participation scores will be documented. The assignment of a unique patient ID allows a lifelong, cross-center documentation of inpatient stays in one of the 27 SCI centers organized in the German-speaking Medical Society for SCI (DMGP). The ParaReg data protection concept and patient information/consent are based on the Open Source Registry for Rare Diseases (OSSE) which were extended by GDPR-relevant aspects. RESULTS: In the realization phase, which started in 2019, the information technology infrastructure was implemented according to the clinical ID management module of the Technology and Methods Platform for Networked Medical Research (TMF). In parallel, the legal and ethical prerequisites for registry operation under the patronage of the DMGP were created. Recommendations of the working group data protection of the TMF were integrated into ParaReg's data protection concept. Based on the feedback from the alpha test phase with documentation of the hospitalization data of 40 patients, the ergonomics of the electronic case report forms were improved in particular for data entry on mobile devices. CONCLUSION: After completion of the monocentric alpha test phase, the multicenter data acquisition was started in 5 DMGP-SCI centers. The sustainability of ParaReg is ensured by the structural and financial support of the DMGP after expiry of the funding by the German Federal Ministry of Education and Research (BMBF).

Severe pressure ulcers requiring surgery impair the functional outcome after acute spinal cord injury.

STUDY DESIGN: Retrospective matched cohort study. OBJECTIVES: Assessing the influence of surgically managed grade 3 and 4 pressure ulcers (PU) in the acute phase after spinal cord injury (SCI) on the neurological and functional outcome after 1 year. SETTING: Specialized SCI-unit within a level 1 trauma center in Murnau, Germany. METHODS: We performed a retrospective matched cohort study. For every patient with acute SCI and a PU requiring surgery, we identified matched controls within our database in a 1:3 ratio. Matching criteria were: AIS-grade (American Spinal Injury Association Impairment Scale), neurological level and age. The scores of the SCIM-III (Spinal Cord Independence Measure) and the ISNCSCI (International Standards for Neurological Classification of Spinal Cord Injury) as well as the total length of stay (LOS) at the hospital were used as outcome parameters. We applied a stratified analysis using a conditional logistic regression to test for group differences in each outcome parameter of the study. RESULTS: In a 6-year period (2010-2015) 28 patients required flap surgery due to 3-4° PU in the acute phase after SCI. Of these patients, 15 had complete data sets according to the EMSCI (European Multicenter Study about Spinal Cord Injury) protocol. Patients with severe PUs during the acute SCI phase had a significantly impaired functional outcome. After 1 year the improvement of the SCIM score was significantly lower in the PU group compared to the control group (17.4 versus 30.5; p < 0.006). However, the change in AIS grade after 1 year was not significantly affected. The LOS was prolonged by a mean of 48 days in the PU group (p < 0.006). CONCLUSIONS: Severe PUs requiring surgery in the acute phase after SCI impair the functional outcome and increase LOS. Preventive measures should be applied to all acute SCI patients. Patients should be transferred to specialized SCI-centers as soon as possible.

Comparison of outcomes between people with and without central cord syndrome.

STUDY DESIGN: Retrospective analysis of prospectively collected data. OBJECTIVE: Central cord syndrome (CCS) is reported to have better outcomes than other cervical lesions, especially for ambulation and bladder recovery. However, a formal comparison between patients with CCS and other incomplete cervical spinal cord injuries (iCSCI) is lacking. Aim of the study is to investigate the neurological and functional outcomes in patients with or without CCS. SETTING: European Multicenter Study. METHODS: Data following SCI were derived from the European Multicenter Study about Spinal Cord Injury Database. CCS was diagnosed based on a difference of at least ten points of motor score in favour of the lower extremities. Patients were evaluated at 30 days, 6 months and 1 year from injury. The neurological and functional data were collected at each time point based on the International Standards for Neurological Classification of Spinal Cord injury (ISNSCI) and Spinal Cord Independence Measure (SCIM). Patients were selected with a matching procedure based on lesion severity, neurological level of injury (NLI) and age. Evaluation of the outcomes was performed by means of two-way Anova for repeated measures. RESULTS: The matching produced 110 comparable dyads. At all time points, upper extremity motor scores remained lower than lower extremity motor scores in CCS compared with iCSCI. With regard to daily life independence, both cohorts achieved comparable improvements in self-care sub-scores between T0 and T2 (6.6 ± 6.5 in CCS vs 8.2 ± 6.9 in iCSCI, p = 0.15) but this sub-score was significantly lower in CCS compared with iCSCI (3.6 ± 5.2 in CCS vs 7.3 ± 7.0 in iCSCI at T0, 13.7 ± 6.2 vs 16.5 ± 5.7 at T2), while the other sub-scores were comparable. CONCLUSIONS: In contrast to previous reports, people with CCS have poorer outcomes of self-care ability compared with iCSCI.

Recovery after traumatic thoracic- and lumbar spinal cord injury: the neurological level of injury matters.

STUDY DESIGN: Multicenter prospective cohort. OBJECTIVE: To discern neurological- and functional recovery in patients with a traumatic thoracic spinal cord injury (TSCI), conus medullaris syndrome (CMS), and cauda equina syndrome (CES). SETTING: Specialized spinal cord injury centers in Europe. METHOD: Lower extremity motor score (LEMS) and spinal cord independent measure (SCIM) scores from patients with traumatic TSCI, CMS, and CES were extracted from the EMSCI database. Scores from admittance and during rehabilitation at 1, 3, 6, and 12 months were compared. Linear mixed models were used to statistically analyse differences in outcome, which were corrected for the ASIA Impairment Scale (AIS) in the acute phase. RESULTS: Data from 1573 individuals were analysed. Except for the LEMS in patients with a CES AIS A, LEMS, and SCIM significantly improved over time for patients with a TSCI, CMS, and CES. Irrespectively of the AIS score, recovery in 12 months after trauma as measured by the LEMS showed a statistically significant difference between patients with a TSCI, CMS, and CES. Analysis of SCIM score showed no difference between patients with TSCI, CMS, or CES. CONCLUSION: Difference in recovery between patients with a traumatic paraplegia is based on neurological (motor) recovery. Regardless the ceiling effect in CES patients, patients with a mixed upper and lower motor neuron syndrome (CMS) showed a better recovery compared with patients with a upper motor neuron syndrome (TSCI). These findings enable stratifications of patients with paraplegia according to the level and severity of SCI.

Increased intrathecal pressure after traumatic spinal cord injury: an illustrative case presentation and a review of the literature.

PURPOSE: Early surgical management after traumatic spinal cord injury (SCI) is nowadays recommended. Since posttraumatic ischemia is an important sequel after SCI, maintenance of an adequate mean arterial pressure (MAP) within the first week remains crucial in order to warrant sufficient spinal cord perfusion. However, the contribution of raised intraparenchymal and consecutively increased intrathecal pressure has not been implemented in treatment strategies. METHODS: Case report and review of the literature. RESULTS: Here we report a case of a 54-year old man who experienced a thoracic spinal cord injury after a fall. CT-examination revealed complex fractures of the thoracic spine. The patient underwent prompt surgical intervention. Intraoperatively, fractured parts of the ascending Th5 facet joint were displaced into the spinal cord itself. Upon removal, excessive protruding of medullary tissue was observed over several minutes. This demonstrates the clinical relevance of increased intrathecal pressure in some patients. CONCLUSION: Monitoring and counteracting raised intrathecal pressure should guide clinical decision-making in the future in order to ensure optimal spinal cord perfusion pressure for every affected individual.

Prediction of Bladder Outcomes after Traumatic Spinal Cord Injury: A Longitudinal Cohort Study.

BACKGROUND: Neurogenic bladder dysfunction represents one of the most common and devastating sequelae of traumatic spinal cord injury (SCI). As early prediction of bladder outcomes is essential to counsel patients and to plan neurourological management, we aimed to develop and validate a model to predict urinary continence and complete bladder emptying 1 y after traumatic SCI. METHODS AND FINDINGS: Using multivariate logistic regression analysis from the data of 1,250 patients with traumatic SCI included in the European Multicenter Spinal Cord Injury study, we developed two prediction models of urinary continence and complete bladder emptying 1 y after traumatic SCI and performed an external validation in 111 patients. As predictors, we evaluated age, gender, and all variables of the International Standards for Neurological Classification of Spinal Cord Injury (ISNCSCI) and of the Spinal Cord Independence Measure (SCIM). Urinary continence and complete bladder emptying 1 y after SCI were assessed through item 6 of SCIM. The full model relies on lower extremity motor score (LEMS), light-touch sensation in the S3 dermatome of ISNCSI, and SCIM subscale respiration and sphincter management: the area under the receiver operating characteristics curve (aROC) was 0.936 (95% confidence interval [CI]: 0.922-0.951). The simplified model is based on LEMS only: the aROC was 0.912 (95% CI: 0.895-0.930). External validation of the full and simplified models confirmed the excellent predictive power: the aROCs were 0.965 (95% CI: 0.934-0.996) and 0.972 (95% CI 0.943-0.999), respectively. This study is limited by the substantial number of patients with a missing 1-y outcome and by differences between derivation and validation cohort. CONCLUSIONS: Our study provides two simple and reliable models to predict urinary continence and complete bladder emptying 1 y after traumatic SCI. Early prediction of bladder function might optimize counselling and patient-tailored rehabilitative interventions and improve patient stratification in future clinical trials.

Depression, posttraumatic stress, and risk factors following spinal cord injury.

BACKGROUND: Chronic depression and posttraumatic stress have been frequently observed in populations of accident victims with spinal cord injuries. Studies suggest that various risk factors contribute to the development and maintenance of these symptoms. PURPOSE: This study assessed psychopathology around 4 years post-discharge in a German sample of 102 participants with spinal cord injuries. METHODS: A wide range of sociodemographic, clinical, and psychological variables was investigated with regard to their association with psychopathology. RESULTS: Approximately half of the patients (46.1 %) retrospectively reported clinically relevant depressive symptoms immediately post-discharge and 12.7 % exhibited scores indicative of a present depressive disorder. In addition, 8.8 % retrospectively reported clinically relevant symptoms of posttraumatic stress disorder (PTSD) after discharge from the hospital and 2 % were currently identified with chronic PTSD symptomatology. Time since injury and negative trauma-related appraisals of the self were strongly related to current psychopathology. CONCLUSION: Depressive reactions and posttraumatic distress may commonly occur after spinal injuries but will usually improve over time. It might be useful to routinely arrange follow-up contacts post-discharge in order to timely identify patients who are at risk of developing chronic psychopathology and require intervention.

Exploring the potential of routine serological markers in predicting neurological outcomes in spinal cord injury.

Spinal cord injury (SCI) is a rare condition with a heterogeneous presentation, making the prediction of recovery challenging. However, serological markers have been shown to be associated with severity and long-term recovery following SCI. Therefore, our investigation aimed to assess the feasibility of translating this association into a prediction of the lower extremity motor scores (LEMS) at chronic stage (52 weeks after initial injury) in patients with SCI using routine serological markers. Serological markers, assessed within the initial seven days post-injury in the observational cohort study from the Trauma Hospital Murnau underwent diverse feature engineering approaches. These involved arithmetic measurements such as mean, median, minimum, maximum, and range, as well as considerations of the frequency of marker testing and whether values fell within the normal range. To predict LEMS scores at the chronic stage, eight different regression models (including linear, tree-based, and ensemble models) were used to quantify the predictive value of serological markers relative to a baseline model that relied on the very acute LEMS score and patient age alone. The inclusion of serological markers did not improve the performance of the prediction model. The best-performing approach including serological markers achieved a mean absolute error (MAE) of 6.59 (2.14), which was equivalent to the performance of the baseline model. As an alternative approach, we trained separate models based on the LEMS observed at the very acute stage after injury. Specifically, we considered individuals with an LEMS of 0 or an LEMS exceeding zero separately. This strategy led to a mean improvement in MAE across all cohorts and models, of 1.20 (2.13). We conclude that, in our study, routine serological markers hold limited power for prediction of LEMS. However, the implementation of model stratification by the very acute LEMS markedly enhanced prediction performance. This observation supports the inclusion of clinical knowledge in the modeling of prediction tasks for SCI recovery. Additionally, it lays the path for future research to consider stratified analyses when investigating the predictive power of potential biomarkers.

Extent of Traumatic Spinal Cord Injury Is Lesion Level Dependent and Predictive of Recovery: A Multicenter Neuroimaging Study.

Assessing the extent of the intramedullary lesion after spinal cord injury (SCI) might help to improve prognostication. However, because the neurological level of injury impacts the recovery potential of SCI patients, the question arises whether lesion size parameters and predictive models based on those parameters are affected as well. In this retrospective observational study, the extent of the intramedullary lesion between individuals who sustained cervical and thoracolumbar SCI was compared, and its relation to clinical recovery was assessed. In total, 154 patients with subacute SCI (89 individuals with cervical lesions and 65 individuals with thoracolumbar lesions) underwent conventional clinical magnetic resonance imaging 1 month after injury and clinical examination at 1 and 12 months. The morphology of the focal lesion within the spinal cord was manually assessed on the midsagittal slice of T2-weighted magnetic resonance images and compared between cervical and thoracolumbar SCI patients, as well as between patients who improved at least one American Spinal Injury Association Impairment Scale (AIS) grade (converters) and patients without AIS grade improvement (nonconverters). The predictive value of lesion parameters including lesion length, lesion width, and preserved tissue bridges for predicting AIS grade conversion was assessed using regression models (conditional inference tree analysis). Lesion length was two times longer in thoracolumbar compared with cervical SCI patients (F = 39.48, p < 0.0001), whereas lesion width and tissue bridges width did not differ. When comparing AIS grade converters and nonconverters, converters showed a smaller lesion length (F = 5.46, p = 0.021), a smaller lesion width (F = 13.75, p = 0.0003), and greater tissue bridges (F = 12.87, p = 0.0005). Using regression models, tissue bridges allowed more refined subgrouping of patients in AIS groups B, C, and D according to individual recovery profiles between 1 month and 12 months after SCI, whereas lesion length added no additional information for further subgrouping. This study characterizes differences in the anteroposterior and craniocaudal lesion extents after SCI. The two times greater lesion length in thoracolumbar compared with cervical SCI might be related to differences in the anatomy, biomechanics, and perfusion between the cervical and thoracic spines. Preserved tissue bridges were less influenced by the lesion level while closely related to the clinical impairment. These results highlight the robustness and utility of tissue bridges as a neuroimaging biomarker for predicting the clinical outcome after SCI in heterogeneous patient populations and for patient stratification in clinical trials.

Prognostic value of tissue bridges in cervical spinal cord injury: a longitudinal, multicentre, retrospective cohort study.

BACKGROUND: The accuracy of prognostication in patients with cervical spinal cord injury (SCI) needs to be improved. We aimed to explore the prognostic value of preserved spinal tissue bridges-injury-spared neural tissue adjacent to the lesion-for prediction of sensorimotor recovery in a large, multicentre cohort of people with SCI. METHODS: For this longitudinal study, we included patients with acute cervical SCI (vertebrae C1-C7) admitted to one of three trauma or rehabilitation centres: Murnau, Germany (March 18, 2010-March 1, 2021); Zurich, Switzerland (May 12, 2002-March 2, 2019); and Denver, CO, USA (Jan 12, 2010-Feb 16, 2017). Patients were clinically assessed at admission (baseline), at discharge (3 months), and at 12 months post SCI. Midsagittal tissue bridges were quantified from T2-weighted images assessed at 3-4 weeks post SCI. Fractional regression and unbiased recursive partitioning models, adjusted for age, sex, centre, and neurological level of injury, were used to assess associations between tissue bridge width and baseline-adjusted total motor score, pinprick score, and light touch scores at 3 months and 12 months. Patients were stratified into subgroups according to whether they showed better or worse predicted recovery. FINDINGS: The cohort included 227 patients: 93 patients from Murnau (22 [24%] female); 43 patients from Zurich (four [9%] female); and 91 patients from Denver (14 [15%] female). 136 of these participants (from Murnau and Zurich) were followed up for up to 12 months. At 3 months, per preserved 1 mm of tissue bridge at baseline, patients recovered a mean of 9·3% (SD 0·9) of maximal total motor score (95% CI 7·5-11.2), 8·6% (0·8) of maximal pinprick score (7·0-10·1), and 10·9% (0·8) of maximal light touch score (9·4-12·5). At 12 months post SCI, per preserved 1 mm of tissue bridge at baseline, patients recovered a mean of 10·9% (1·3) of maximal total motor score (8·4-13·4), 5·7% (1·3) of maximal pinprick score (3·3-8·2), and 6·9% (1·4) of maximal light touch score (4·1-9·7). Partitioning models identified a tissue bridge cutoff width of 2·0 mm to be indicative of higher or lower 3-month total motor, pinprick, and light touch scores, and a cutoff of 4·0 mm to be indicative of higher and lower 12-month scores. Compared with models that contained clinical predictors only, models additionally including tissue bridges had significantly improved prediction accuracy across all three centres. INTERPRETATION: Tissue bridges, measured in the first few weeks after SCI, are associated with short-term and long-term clinical improvement. Thus, tissue bridges could potentially be used to guide rehabilitation decision making and to stratify patients into more homogeneous subgroups of recovery in regenerative and neuroprotective clinical trials. FUNDING: Wings for Life, International Foundation for Research in Paraplegia, EU project Horizon 2020 (NISCI grant), and ERA-NET NEURON.

Prediction of segmental motor outcomes in traumatic spinal cord injury: Advances beyond sum scores.

BACKGROUND AND OBJECTIVES: Neurological and functional recovery after traumatic spinal cord injury (SCI) is highly challenged by the level of the lesion and the high heterogeneity in severity (different degrees of in/complete SCI) and spinal cord syndromes (hemi-, ant-, central-, and posterior cord). So far outcome predictions in clinical trials are limited in targeting sum motor scores of the upper (UEMS) and lower limb (LEMS) while neglecting that the distribution of motor function is essential for functional outcomes. The development of data-driven prediction models of detailed segmental motor recovery for all spinal segments from the level of lesion towards the lowest motor segments will improve the design of rehabilitation programs and the sensitivity of clinical trials. METHODS: This study used acute-phase International Standards for Neurological Classification of SCI exams to forecast 6-month recovery of segmental motor scores as the primary evaluation endpoint. Secondary endpoints included severity grade improvement, independent walking, and self-care ability. Different similarity metrics were explored for k-nearest neighbor (kNN) matching within 1267 patients from the European Multicenter Study about Spinal Cord Injury before validation in 411 patients from the Sygen trial. The kNN performance was compared to linear and logistic regression models. RESULTS: We obtained a population-wide root-mean-squared error (RMSE) in motor score sequence of 0.76(0.14, 2.77) and competitive functional score predictions (AUCwalker = 0.92, AUCself-carer = 0.83) for the kNN algorithm, improving beyond the linear regression task (RMSElinear = 0.98(0.22, 2.57)). The validation cohort showed comparable results (RMSE = 0.75(0.13, 2.57), AUCwalker = 0.92). We deploy the final historic control model as a web tool for easy user interaction (https://hicsci.ethz.ch/). DISCUSSION: Our approach is the first to provide predictions across all motor segments independent of the level and severity of SCI. We provide a machine learning concept that is highly interpretable, i.e. the prediction formation process is transparent, that has been validated across European and American data sets, and provides reliable and validated algorithms to incorporate external control data to increase sensitivity and feasibility of multinational clinical trials.

[Movement analysis in spinal cord injuries : Assistance in clinical decision making]. / Bewegungsanalyse bei Querschnittverletzungen : Hilfestellung in der klinischen Entscheidungsfindung.

For motor incomplete spinal cord injured patients, improvement of walking function is an important aim in the rehabilitation program. In specialized treatment centers, the 6­minute walking test, the 10-meter walking test or the timed-up-and-go test are used as an assessment tool to determine walking ability, but these tests are not able to assess the quality of gait. Marker-based movement analysis can be used as a reliable method to evaluate the gait pattern. This allows an objective assessment of gait quality over time or can be used to support therapy planning. The benefit of such an analysis is presented by means of two case studies.

Trajectory of Serum Levels of Glial Fibrillary Acidic Protein Within Four Weeks Post-Injury Is Related to Neurological Recovery During the Transition from Acute to Chronic Spinal Cord Injury.

The use of biomarkers in spinal cord injury (SCI) research has evolved rapidly in recent years whereby most studies focused on the acute post-injury phase. Since SCI is characterized by persisting neurological impairments, the question arises whether blood biomarkers remain altered during the subacute post-injury time. Sample collection in the subacute phase might provide a better insight in the ongoing SCI specific molecular mechanism with fewer confounding factors compared with the acute phase where, amongst other complications, individuals receive a substantial amount of medication. This study aimed to determine if the temporal dynamics of serum biomarkers of neurodegeneration differ between individuals depending on their extent of neurological recovery in the transition phase between acute and chronic SCI. We performed a secondary analysis of biomarkers in patients with SCI (n = 41) who were treated at a level I trauma center in Germany. Patients with cervical or thoracic SCI regardless of injury severity were included. Blood samples were collected in the acute phase (1-4 days post-injury), and after 30 and 120 days post-injury. Serum protein levels of glial fibrillary acidic protein (GFAP) and neurofilament light protein (NfL) were determined for each time-point of sample collection using R-Plex Assays (Meso Scale Discovery). Linear mixed models were used to evaluate the trajectory of GFAP and NfL over time. Fixed effects of time, neurological recovery, and injury severity, along with the recovery-by-time interaction, were included in models with random slopes and intercepts. GFAP levels increase during the first days after SCI and decrease in subacute to chronic stages. Notably, the trajectory of GFAP over time is significantly associated with the extent of neurological recovery during the transition from acute to chronic SCI with a steeper decline in individuals who recovered better. Serum levels of NfL continue to rise significantly until Day 30 followed by a decrease afterwards, independent of neurological recovery. The trajectory of serum GFAP levels qualifies as a prognostic biomarker for neurological recovery, and facilitates monitoring of disease progression in the sub-acute post-injury phase.

Segmental motor recovery after cervical spinal cord injury relates to density and integrity of corticospinal tract projections.

Cervical spinal cord injury (SCI) causes extensive impairments for individuals which may include dextrous hand function. Although prior work has focused on the recovery at the person-level, the factors determining the recovery of individual muscles are poorly understood. Here, we investigate the muscle-specific recovery after cervical spinal cord injury in a retrospective analysis of 748 individuals from the European Multicenter Study about Spinal Cord Injury (NCT01571531). We show associations between corticospinal tract (CST) sparing and upper extremity recovery in SCI, which improves the prediction of hand muscle strength recovery. Our findings suggest that assessment strategies for muscle-specific motor recovery in acute spinal cord injury are improved by accounting for CST sparing, and complement person-level predictions.

A Predictive Model to Identify Treatment-related Risk Factors for Odontoid Fracture Nonunion Using Machine Learning.

STUDY DESIGN: Multicenter retrospective analysis of routinely collected data. OBJECTIVE: The underlying aim of this study was to identify potential treatment-related risk factors for odontoid fracture nonunion while accounting for known patient- and injury-related risk factors. SUMMARY OF BACKGROUND DATA: Type II and III odontoid fractures represent the most common cervical spine fracture in elderly patients and are associated with a relatively high nonunion rate. The management of odontoid fractures is controversial and treatment strategies range from conservative treatment to extensive surgical stabilization and fusion. METHODS: A total of 415 individuals who sustained odontoid fracture and were treated in either of four tertiary referral centers in Austria and Germany were included in the study. We included the following potential contributing factors for fracture nonunion in cross-validated extreme gradient boosted (XGBoost) and binary logistic regression models: age, gender, fracture displacement, mechanism of injury (high vs. low energy), fracture classification (Anderson II vs. III), presence of comorbidities (Charlson comorbidity index), and treatment (conservative, anterior screw fixation with one or two screws, posterior C1/C2 spondylodesis, cervico-occipital C0-C4 fusion). RESULTS: In our cohort, 187 (45%) had radiologically confirmed odontoid nonunion six months postinjury. The odds for nonunion increase significantly with age, and are lower in type III compared to type II fractures. Also, odds for nonunion are significantly lower in posterior C1/C2 spondylodesis, and C0-C4 fusion compared to conservative treatment. Importantly, odds are not statistically significantly lower in the group treated with anterior screw fixation compared to conservative treatment. The factors gender, fracture displacement, mechanism of injury, and the presence of comorbidities did not produce significant odds. CONCLUSION: Higher age, type II fractures, and conservative treatment are the main risk factors for odontoid nonunion. Anterior screw fixation did not differ significantly from conservative treatment in terms of fracture union. LEVEL OF EVIDENCE: 3.

Walking Outcome After Traumatic Paraplegic Spinal Cord Injury: The Function of Which Myotomes Makes a Difference?

BACKGROUND: Accurate prediction of walking function after a traumatic spinal cord injury (SCI) is crucial for an appropriate tailoring and application of therapeutical interventions. Long-term outcome of ambulation is strongly related to residual muscle function acutely after injury and its recovery potential. The identification of the underlying determinants of ambulation, however, remains a challenging task in SCI, a neurological disorder presented with heterogeneous clinical manifestations and recovery trajectories. OBJECTIVES: Stratification of walking function and determination of its most relevant underlying muscle functions based on stratified homogeneous patient subgroups. METHODS: Data from individuals with paraplegic SCI were used to develop a prediction-based stratification model, applying unbiased recursive partitioning conditional inference tree (URP-CTREE). The primary outcome was the 6-minute walk test at 6 months after injury. Standardized neurological assessments ≤15 days after injury were chosen as predictors. Resulting subgroups were incorporated into a subsequent node-specific analysis to attribute the role of individual lower extremity myotomes for the prognosis of walking function. RESULTS: Using URP-CTREE, the study group of 361 SCI patients was divided into 8 homogeneous subgroups. The node specific analysis uncovered that proximal myotomes L2 and L3 were driving factors for the differentiation between walkers and non-walkers. Distal myotomes L4-S1 were revealed to be responsible for the prognostic distinction of indoor and outdoor walkers (with and without aids). CONCLUSION: Stratification of a heterogeneous population with paraplegic SCI into more homogeneous subgroups, combined with the identification of underlying muscle functions prospectively determining the walking outcome, enable potential benefit for application in clinical trials and practice.

Immobility-associated thromboprotection is conserved across mammalian species from bear to human.

Venous thromboembolism (VTE) comprising deep venous thrombosis and pulmonary embolism is a major cause of morbidity and mortality. Short-term immobility-related conditions are a major risk factor for the development of VTE. Paradoxically, long-term immobilized free-ranging hibernating brown bears and paralyzed spinal cord injury (SCI) patients are protected from VTE. We aimed to identify mechanisms of immobility-associated VTE protection in a cross-species approach. Mass spectrometry-based proteomics revealed an antithrombotic signature in platelets of hibernating brown bears with heat shock protein 47 (HSP47) as the most substantially reduced protein. HSP47 down-regulation or ablation attenuated immune cell activation and neutrophil extracellular trap formation, contributing to thromboprotection in bears, SCI patients, and mice. This cross-species conserved platelet signature may give rise to antithrombotic therapeutics and prognostic markers beyond immobility-associated VTE.