Somatosensory cortical atrophy after spinal cord injury: a voxel-based morphometry study

A novel imaging marker of cortical "cellularity" in multiple sclerosis patients

Pathological data showed focal inflammation and regions of diffuse neuronal loss in the cortex of people with multiple sclerosis (MS). In this work, we applied a novel model ("soma and neurite density imaging (SANDI)") to multishell diffusion-weighted MRI data acquired in healthy subjects and people with multiple sclerosis (pwMS), in order to investigate inflammation and degeneration-related changes in the cortical tissue of pwMS. We aimed to (i) establish whether SANDI is applicable in vivo clinical data; (ii) investigate inflammatory and degenerative changes using SANDI soma fraction (fsoma)-a marker of cellularity-in both cortical lesions and in the normal-appearing-cortex and (iii) correlate SANDI fsoma with clinical and biological measures in pwMS. We applied a simplified version of SANDI to a clinical scanners. We then provided evidence that pwMS exhibited an overall decrease in cortical SANDI fsoma compared to healthy subjects, suggesting global degenerative processes compatible with neuronal loss. On the other hand, we have found that progressive pwMS showed a higher SANDI fsoma in the outer part of the cortex compared to relapsing-remitting pwMS, possibly supporting current pathological knowledge of increased innate inflammatory cells in these regions. A similar finding was obtained in subpial lesions in relapsing-remitting patients, reflecting existing pathological data in these lesion types. A significant correlation was found between SANDI fsoma and serum neurofilament light chain-a biomarker of inflammatory axonal damage-suggesting a relationship between SANDI soma fraction and inflammatory processes in pwMS again. Overall, our data show that SANDI fsoma is a promising biomarker to monitor changes in cellularity compatible with neurodegeneration and neuroinflammation in the cortex of MS patients.

Beyond the aging spine - a systematic review of functional changes in the human brain in cervical spondylotic myelopathy

Cervical Spondylotic Myelopathy (CSM) is a degenerative condition that leads to loss of cervical spinal cord integrity, typically affecting the aged population. Emerging fMRI-based evidence suggests that the brain is also affected by CSM. This systematic review aimed to understand the usefulness of brain fMRI in CSM. A comprehensive literature search was conducted until March 2023 according to PRISMA guidelines. The inclusion criteria included original research articles in English, primarily studying the human brain's functional changes in CSM using fMRI with at least 5 participants. The extracted data from each study included demographics, disease severity, MRI machine characteristics, affected brain areas, functional changes, and clinical utilities. A total of 30 studies met the inclusion criteria. Among the fMRI methods, resting-state fMRI was the most widely used experimental paradigm, followed by motor tasks. The brain areas associated with motor control were most affected in CSM, followed by the superior frontal gyrus and occipital cortex. Functional changes in the brain were correlated to clinical metrics showing clinical utility. However, the evidence that a specific fMRI metric correlating with a clinical metric was "very low" to "insufficient" due to a low number of studies and negative results. In conclusion, fMRI can potentially facilitate the diagnosis of CSM by quantitatively interrogating the functional changes of the brain, particularly areas of the brain associated with motor control. However, this field is in its early stages, and more studies are needed to establish the usefulness of brain fMRI in CSM.

Predicting and coding sound into action translation in spinal cord injured people

Motor activation in response to perception of action-related stimuli may depend on a resonance mechanism subserving action understanding. The extent to which this mechanism is innate or learned from sensorimotor experience is still unclear. Here, we recorded EEG while people with paraplegia or tetraplegia consequent to spinal cord injury (SCI) and healthy control participants were presented with action sounds produced by body parts (mouth, hands or feet) that were or were not affected by SCI. Non-action sounds were used as further control. We observed reduced brain activation in subjects affected by SCI at both pre- and post-stimulus latencies specifically for those actions whose effector was disconnected by the spinal lesion (i.e., hand sound for tetraplegia and leg sound for both paraplegia and tetraplegia). Correlation analyses showed that these modulations were functionally linked with the chronicity of the lesion, indicating that the longer the time the lesion- EEG data acquisition interval and/or the more the lesion occurred at a young age, the weaker was the cortical activity in response to these action sounds. Tellingly, source estimations confirmed that these modulations originated from a deficit in the motor resonance mechanism, by showing diminished activity in premotor (during prediction and perception) and near the primary motor (during perception) areas. Such dissociation along the cortical hierarchy is consistent with both previous reports in healthy subjects and with hierarchical predictive coding accounts. Overall, these data expand on the notion that sensorimotor experience maintains the cortical representations relevant to anticipate and perceive action-related stimuli.

Microstructural alterations of major thalamic nuclei in the chronic pediatric spinal cord injured population

Background

The brain undergoes reorganization following spinal cord injury (SCI), but little is known about how the thalamus is affected in pediatric SCIs.

Purpose

To characterize microstructural alterations in the thalamus after SCI with diffusion tensor imaging (DTI) metrics.

Methods

18 pediatric participants with chronic SCI (8-20 years) were stratified using the American Spinal Injury Association Impairment Scale (AIS) into groups: A, B, and C/D. DTI of the brain used a 3 T Siemens Verio MRI using the parameters: 20 directions, number of averages = 3, b = 1000 s/mm2, voxel size = 1.8 mm × 1.8 mm, slice thickness = 5 mm, TE = 95 ms, TR = 4300 ms, 30 slices, FOV = 230 × 230 mm2, matrix = 128 × 128, acquisition time = 4:45 min. Diffusion data was processed to generate DTI metrics FA, MD, AD, and RD.

Data analysis

DTI metrics were acquired by superimposing the AAL3 thalamic atlas onto participant diffusion images registered to MNI152 space. We utilized a multiple Mann-Whitney U-test to compare between AIS groups, considering values of p ≤ 0.05 as significant.

Results

FA, AD, RD, and MD significantly differed in thalamic nuclei between AIS groups A vs B and B vs C/D. Significant nuclei include the right ventral anterior, left intralaminar, bilateral lateral pulvinar, and right lateral geniculate.

Conclusion

Our findings suggest the presence of microstructural alterations based on SCI severity in pediatric patients. These results are encouraging and warrant further study.

Rehabilitation Training after Spinal Cord Injury Affects Brain Structure and Function: From Mechanisms to Methods

Spinal cord injury (SCI) is a serious neurological insult that disrupts the ascending and descending neural pathways between the peripheral nerves and the brain, leading to not only functional deficits in the injured area and below the level of the lesion but also morphological, structural, and functional reorganization of the brain. These changes introduce new challenges and uncertainties into the treatment of SCI. Rehabilitation training, a clinical intervention designed to promote functional recovery after spinal cord and brain injuries, has been reported to promote activation and functional reorganization of the cerebral cortex through multiple physiological mechanisms. In this review, we evaluate the potential mechanisms of exercise that affect the brain structure and function, as well as the rehabilitation training process for the brain after SCI. Additionally, we compare and discuss the principles, effects, and future directions of several rehabilitation training methods that facilitate cerebral cortex activation and recovery after SCI. Understanding the regulatory role of rehabilitation training at the supraspinal center is of great significance for clinicians to develop SCI treatment strategies and optimize rehabilitation plans.

A shift of brain network hub after spinal cord injury

Background

Spinal cord injury (SCI) causes severe sequelae and significant social loss, depending on the extent of the damage. Most previous studies have focused on the pathology of the spinal cord to develop treatments for SCI. However, it is now known that the brain, which is not directly damaged, also undergoes morphological changes after spinal cord injury, which could affect natural recovery and treatment. In recent years, magnetic resonance imaging (MRI) has been developed to analyze functional changes in the brain. Resting-state functional MRI (rsfMRI), which captures brain activity at rest, can calculate functional connections between brain areas and identify central hubs by network analysis.

Purpose

We aim to investigate functional connectivity in the brain using rsfMRI after SCI and to determine how brain-network main hubs change over time.

Methods

We evaluated rsfMRI in 10 mice of the contusional SCI model and calculated connectivity using graph theory. We evaluated "centrality," a representative parameter of network analysis. The subtype of centrality was degree centrality, which indicates the hub function of a single area. The five times of rsfMRI were performed in each individual mouse: before injury and at 1, 3, 7, and 14 weeks post-injury.

Results

Before the injury, the degree centralities of the primary and secondary motor cortex were high, suggesting that these motor cortices served as main hubs for motor function. After SCI, the hub function of the motor cortices decreased by 14 weeks. In contrast, hub function in the external capsule and the putamen comparatively increased with time after injury, suggesting that the extrapyramidal/subcortical system, which runs the ventral side of the spinal cord and remains after injury in this model, becomes dominant.

Conclusion

We demonstrated the shift of the brain network hub after SCI. The results of this study provide basic information for understanding brain network changes after SCI and would be useful for treatment selection and evaluation of its efficacy in SCI patients.

The gray matter atrophy and related network changes occur in the higher cognitive region rather than the primary sensorimotor cortex after spinal cord injury

Objective

This study used functional magnetic resonance imaging (fMRI) to explore brain structural and related network changes in patients with spinal cord injury (SCI).

Methods

Thirty-one right-handed SCI patients and 31 gender- and age-matched healthy controls (HC) were included. The gray matter volume (GMV) changes in SCI patients were observed using voxel-based morphometry (VBM). Then, these altered gray matter clusters were used as the regions of interest (ROIs) for whole-brain functional connectivity (FC) analysis to detect related functional changes. The potential association between GMV and FC values with the visual analog scale (VAS), the American Spinal Injury Association (ASIA) score, and the course of injuries was investigated through partial correlation analysis.

Results

GMV of the frontal, temporal, and insular cortices was lower in the SCI group than in the HC group. No GMV changes were found in the primary sensorimotor area in the SCI group. Besides, the altered FC regions were not in the primary sensorimotor area but in the cingulate gyrus, supplementary motor area, precuneus, frontal lobe, and insular. Additionally, some of these altered GMV and FC regions were correlated with ASIA motor scores, indicating that higher cognitive regions can affect motor function in SCI patients.

Conclusions

This study demonstrated that gray matter and related network reorganization in patients with SCI occurred in higher cognitive regions. Future rehabilitation strategies should focus more on cognitive functions.

Cognitive and physical impairment in spinal cord injury: A scoping review and call for new understanding

Study Design: Scoping review.Objective: To examine potential underlying mechanisms of cognitive and physical impairment in patients with spinal cord injury and identify current research gaps.Methods: A scoping review of the literature was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) extension for scoping reviews to identify primary studies that explored mechanisms of cognitive and/or physical impairment after spinal cord injury. The databases searched were PubMed/MEDLINE, EMBASE (OVID), Cumulative Index to Nursing and Allied Health Literature (CINAHL; EBSCO), Web of Science, Scopus, and PsycInfo. These databases were searched from inception through December 20, 2021.Results: Accumulating research suggests that neuroinflammation and neurodegeneration after a traumatic event may be possible mechanisms for cognitive impairment among patients with SCI. In addition, lack of physical activity due to impaired mobility is associated with an increased risk of cognitive impairment.Conclusion: While the results establish a foundation for understanding how cognitive impairment, mental health, and physical function independently affect patients with SCI, further research is warranted to understand how these factors systemically impact the patient and discover refined targets for future rehabilitation therapies. Studies should also explore potential predisposing factors for the relationship between cognitive and physical impairment among patients with SCI.

Visual Dysfunction in Posterior Cortical Atrophy: A Masquerade

Posterior cortical atrophy, considered an atypical dementia, is a syndrome characterised by dysfunction of posterior cortical regions with prominent visuospatial and visuoperceptual impairment at presentation. We report the case of posterior cortical atrophy, which was diagnosed six years after the onset of visual symptoms. The patient is a 67-year-old married gentleman, with six years history of visual impairment, characterised by difficulty in locating and manipulating door handles, overreaching objects and difficulty in depth perception. He had a history of repeated visits to ophthalmologists and underwent multiple unsuccessful changes in eyeglasses and a cataract surgery to correct acuity. The patient also developed recent memory deficits about two years back, insidious in onset and gradually progressed and symptoms of visual and auditory hallucinations about six months back. Cognitive and functional assessments, and imaging findings were consistent with a diagnosis of posterior cortical atrophy, possible Alzheimer's disease. The patient was started on cognitive enhancers and low dose antipsychotics. He was engaged in meaningful and cognitively stimulating activities. Environmental manipulations and home safety recommendations for visual impairment were conveyed to the family. In the early stages of posterior cortical atrophy, visual symptoms predominate, while episodic memory, executive functioning, language, and insight are substantially retained. Better identification, prognosis, and treatment of posterior cortical atrophy will result from increased knowledge and understanding of the condition among neurologists, psychiatrists, general doctors, ophthalmologists, and optometrists.

Brain morphology changes after spinal cord injury: A voxel-based meta-analysis

Objectives

Spinal cord injury (SCI) remodels the brain structure and alters brain function. To identify specific changes in brain gray matter volume (GMV) and white matter volume (WMV) following SCI, we conducted a voxel-based meta-analysis of whole-brain voxel-based morphometry (VBM) studies.

Methods

We performed a comprehensive literature search on VBM studies that compared SCI patients and healthy controls in PubMed, Web of Science and the China National Knowledge Infrastructure from 1980 to April 2022. Then, we conducted a voxel-based meta-analysis using seed-based d mapping with permutation of subject images (SDM-PSI). Meta-regression analysis was performed to identify the effects of clinical characteristics.

Results

Our study collected 20 studies with 22 GMV datasets and 15 WMV datasets, including 410 patients and 406 healthy controls. Compared with healthy controls, SCI patients showed significant GMV loss in the left insula and bilateral thalamus and significant WMV loss in the bilateral corticospinal tract (CST). Additionally, a higher motor score and pinprick score were positively related to greater GMV in the right postcentral gyrus, whereas a positive relationship was observed between the light touch score and the bilateral postcentral gyrus.

Conclusion

Atrophy in the thalamus and bilateral CST suggest that SCI may trigger neurodegeneration changes in the sensory and motor pathways. Furthermore, atrophy of the left insula may indicate depression and neuropathic pain in SCI patients. These indicators of structural abnormalities could serve as neuroimaging biomarkers for evaluating the prognosis and treatment effect, as well as for monitoring disease progression. The application of neuroimaging biomarkers in the brain for SCI may also lead to personalized treatment strategies.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42021279716, identifier: CRD42021279716.

Cerebellum regulating cerebral functional cortex through multiple pathways in complete thoracolumbar spinal cord injury

The previous studies have found significant brain structural and functional changes in cerebral regions after spinal cord injury (SCI), but few studies have explored the cerebellar–cerebral circuit changes in SCI. This study aims to study the brain structural changes of cerebellar subregions and its functional connectivity (FC) changes with cerebrum in complete thoracolumbar SCI (CTSCI), and screen out the regions that play relatively important roles in affecting sensorimotor function. Eighteen CTSCI patients and 18 age- and gender-matched healthy controls (HCs) were recruited. Voxel-based morphometry (VBM) was used to characterize the brain structural changes of cerebellar subregions [from the Anatomical Automatic Labeling (AAL116)], seed-based FC was used to evaluate the cerebellar–cerebral FC changes and support vector machine (SVM) analysis was used to search for sensitive imaging indicators. CTSCI patients showed slightly structural atrophy in vermis_3 (p = 0.046) and significantly decreased FC between cerebellum and cerebral sensorimotor-, visual-, cognitive-, and auditory-related regions (cluster-level FWE correction with p < 0.05). Additionally, SVM weight analysis showed that FC values between vermis_10 and right fusiform gyrus had the greatest weight in functional changes of CTSCI. In conclusion, different degrees of structural and functional changes occurred in each subregion of cerebellum following CTSCI, and FC change between vermis_10 and right fusiform gyrus plays the most important role in dysfunction and may become an important neural network index of rehabilitation therapy.

Traumatic spinal cord injury and the contributions of the post-injury microbiome

Spinal cord injuries are an enormous burden on injured individuals and their caregivers. The pathophysiological effects of injury are not limited to the spine and limb function, but affect numerous body systems. Growing observations in human studies and experimental models suggest that the gut microbiome is altered following spinal cord injury. Given the importance of signals derived from the gut microbiome for host physiology, it is possible that injury-triggered dysbiosis subsequently affects aspects of recovery. Here, we review emerging literature on the role of the microbiome following spinal cord injury. Specifically, we highlight findings from both human and experimental studies that correlate taxonomic changes to aspects of injury recovery. Examination of both observational and emerging interventional studies supports the notion that future therapeutic avenues for spinal cord injury pathologies may lie at the interface of the host and indigenous microbes.

18F-FDG positron emission tomography imaging of cortical reorganization in spinal trauma

Objective:

Spinal cord injury (SCI) extensively impacts the sensorimotor reorganization in the brain. The effects can be both anatomical and functional. To date, not many studies using 18F-Fluoro-2-Deoxyglucose positron emission tomography (18F-FDG PET) to evaluate metabolic changes in the brain are done. Understanding such changes is crucial for developing clinical management and evidence-based rehabilitation strategies for these patients.

Subjects and Methods:

In this study, we compared 18F-FDG PET imaging of 6 SCI patients with complete paraplegia and 19 controls. Statistical parametric mapping software was utilized to compare the images on a voxel to voxel basis (significance level P < 0.05 and clusters having >50 voxels).

Results:

The study showed raised metabolism in supplementary motor areas, comprehension centers, some areas in the parietal and temporal lobe, putamen and cerebellum while reduced metabolic uptake in areas like anterior cingulate gyrus, hippocampus and sensory cortical areas when SCI patients were compared against healthy controls. The frontal lobe showed varied results where certain regions showed higher metabolism while the others showed lower in patients compared with controls.

Conclusion:

Cerebral deafferentation or disuse atrophy can be linked with reduced metabolism while raised uptake can be associated with initiation and planning of movement and cognitive changes in the brain posttrauma.

Anatomical Increased/Decreased Changes in the Brain Area Following Individuals with Chronic Traumatic Complete Thoracic Spinal Cord Injury

OBJECTIVES

This study aimed to investigate anatomical changes in the brain following chronic complete traumatic thoracic spinal cord injury (ThSCI) using voxel-based morphometry (VBM). That is, it attempted to examine dynamic physical change following thoracic injury and the presence or absence of regions with decreased and increased changes in whole brain volume associated with change in the manner of how activities of daily living are performed.

METHODS

Twelve individuals with chronic traumatic complete ThSCI (age; 21-63 years, American Spinal Injury Association Impairment Scale; grade C-D) participated in this study. VBM was used to investigate the regions with increased volume and decreased volume in the brain in comparison with healthy control individuals.

RESULTS

Decreases in volume were noted in areas associated with motor and somatosensory functions, including the right paracentral lobule (PCL)-the primary motor sensory area for lower limbs, left dorsal premotor cortex, and left superior parietal lobule (SPL). Furthermore, increased gray matter volume was noted in the primary sensorimotor area for fingers and arms, as well as in higher sensory areas.

CONCLUSIONS

Following SCI both regions with increased volume and regions with decreased volume were present in the brain in accordance with changes in physical function. Using longitudinal observation, anatomical changes in the brain may be used to determine the rehabilitation effect by comparing present cases with cases with cervical SCI or cases with incomplete palsy.

Supraspinal nociceptive networks in neuropathic pain after spinal cord injury

Neuropathic pain following spinal cord injury involves plastic changes along the whole neuroaxis. Current neuroimaging studies have identified grey matter volume (GMV) and resting-state functional connectivity changes of pain processing regions related to neuropathic pain intensity in spinal cord injury subjects. However, the relationship between the underlying neural processes and pain extent, a complementary characteristic of neuropathic pain, is unknown. We therefore aimed to reveal the neural markers of widespread neuropathic pain in spinal cord injury subjects and hypothesized that those with greater pain extent will show higher GMV and stronger connectivity within pain related regions. Thus, 29 chronic paraplegic subjects and 25 healthy controls underwent clinical and electrophysiological examinations combined with neuroimaging. Paraplegics were demarcated based on neuropathic pain and were thoroughly matched demographically. Our findings indicate that (a) spinal cord injury subjects with neuropathic pain display stronger connectivity between prefrontal cortices and regions involved with sensory integration and multimodal processing, (b) greater neuropathic pain extent, is associated with stronger connectivity between the posterior insular cortex and thalamic sub-regions which partake in the lateral pain system and (c) greater intensity of neuropathic pain is related to stronger connectivity of regions involved with multimodal integration and the affective-motivational component of pain. Overall, this study provides neuroimaging evidence that the pain phenotype of spinal cord injury subjects is related to the underlying function of their resting brain.

Cerebral white matter alterations revealed by multiple diffusion metrics in cervical spondylotic patients with pain: A TBSS study

OBJECTIVE

The aims of the present study were to investigate white matter alterations and their associations with the clinical variables in cervical spondylotic (CS) patients with pain.

DESIGN

Cross-sectional study.

SETTING

Chinese community.

SUBJECTS

Forty-two CS patients with pain and 42 matched healthy participants were ultimately recruited from August 2018 to September 2019.

METHODS

Tract-based spatial statistics (TBSS) analysis was performed to investigate the differences of DTI-derived indices (fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD), and axial diffusivity (AD)) between the patients and healthy controls throughout brain white matter. The relationship of the severity of cervical pain and affective disturbance to aberrant DTI indices in the patients was also examined using spearman correlation analyses.

RESULTS

The CS patients with pain showed decreased FA in the genu, body, and splenium portions of corpus callosum (CC), and increased MD and RD along with decreased FA in anterior corona radiata (ACR) compared with healthy controls, whereas no significant difference of AD was observed between groups. Additionally, lower FA of the genu part of CC together with higher MD of the left ACR were statistically correlated with the pain severity in the patient group.

CONCLUSIONS

Decreased FA coupled with increased MD and RD was detected in multiple white matter regions, and several DTI metrics in certain white matter tracts had moderate relationships with the pain severity in the CS patients with pain. These observations may provide alternative imaging clues for the evaluation of the pathophysiological characteristics of CS pain.

In chronic complete spinal cord injury supraspinal changes detected by quantitative MRI are confined to volume reduction in the caudal brainstem

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Cervical spinal cord and medulla oblongata atrophy correlate in chronic SCI.

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The most likely underlying mechanism is Wallerian degeneration of ascending tracts.

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No other structural MRI brain changes were evident in our cohort of chronic SCI.

There is much controversy about the potential impact of spinal cord injury (SCI) on brain anatomy and function, which is mirrored in the substantial divergence of findings between animal models and human imaging studies. Given recent advances in quantitative magnetic resonance imaging (MRI) we sought to tackle the unresolved question about the link between the presumed injury associated volume differences and underlying brain tissue property changes in a cohort of chronic complete SCI patients. Using the established computational anatomy methods of voxel-based morphometry (VBM) and voxel-based quantification (VBQ), we performed statistical analyses on grey and white matter volumes as well as on parameter maps indicative for myelin, iron, and free tissue water content in the brain of complete SCI patients (n = 14) and healthy individuals (n = 14). Our regionally unbiased white matter analysis showed a significant volume reduction of the dorsal aspect at the junction between the most rostral part of the spinal cord and the medulla oblongata consistent with Wallerian degeneration of proprioceptive axons in the dorsal column tracts in SCI subjects. This observation strongly correlated with spinal cord atrophy assessed by quantification of the spinal cord cross-sectional area at the cervical level C2/3. These findings suggest that Wallerian degeneration of the dorsal column tracts represents a main contributor to the observed spinal cord atrophy, which is highly consistent with preclinical histological evidence of remote changes in the central nervous system secondary to SCI. Structural changes in other brain regions representing remote changes in the course of chronic SCI could neither be confirmed by conventional VBM nor by VBQ analysis. Whether and how MRI based brain morphometry and brain tissue property analysis will inform clinical decision making and clinical trial outcomes in spinal cord medicine remains to be determined.

Cortical morphometric changes associated with completeness, level, and duration of spinal cord injury in humans: A case-control study

OBJECTIVE

This study investigated how the injury completeness, level, and duration of spinal cord injury (SCI) affect cortical morphometric changes in humans.

METHODS

T1-weighted images were acquired from 59 SCI patients and 37 healthy controls. Voxel-based morphometry analyses of the gray matter volume (GMV) were performed between SCI patients and healthy controls, complete SCI and incomplete SCI, and tetraplegia and paraplegia. Correlation analyses were performed to explore the associations between GMV and clinical variables in SCI patients.

RESULTS

Compared to healthy controls, SCI patients showed decreased GMV in bilateral middle frontal gyrus, left superior frontal gyrus (SFG), left medial frontal gyrus in the whole-brain analysis, while increased GMV in right supplementary motor area and right pallidum in ROI analysis. The complete SCI had lower GMV in left primary somatosensory cortex (S1) and higher GMV in left primary motor cortex compared with incomplete SCI. Lower GMV was identified in left thalamus and SFG in tetraplegia than that in paraplegia. Moreover, time since injury was positive with the GMV in right pallidum, positive correlations were observed between the GMV in bilateral S1 and total motor and sensory scores, whereas the GMV in left cuneus was negatively correlated with total motor and sensory scores in SCI patients.

CONCLUSIONS

The study provided imaging evidence for identifying cerebral structural abnormalities in SCI patients and significant differences in complete/incomplete and paraplegia/tetraplegia subgroups. These results suggested brain structural changes occur after SCI and these changes may depend on the injury completeness, level, and duration.

Inconsistency between cortical reorganization and functional connectivity alteration in the sensorimotor cortex following incomplete cervical spinal cord injury

The aim of this study was to explore whether there will be any alterations in sensorimotor-related cortex and the possible causes of sensorimotor dysfunction after incomplete cervical spinal cord injury (ICSCI). Structural and resting-state functional magnetic resonance imaging (rs-fMRI) of nineteen ICSCI patients and nineteen healthy controls (HCs) was acquired. Voxel based morphometry (VBM) and tract-based spatial statistics were performed to assess differences in gray matter volume (GMV) and white matter integrity between ICSCI patients and HCs. Whole brain functional connectivity (FC) was analyzed using the results of VBM as seeds. Associations between the clinical variables and the brain changes were studied. Compared with HCs, ICSCI patients demonstrated reduced GMV in the right fusiform gyrus (FG) and left orbitofrontal cortex (OFC) but no changes in areas directly related to sensorimotor function. There were no significant differences in brain white matter. Additionally, the FC in the left primary sensorimotor cortex and cerebellum decreased when the FG and OFC, respectively, were used as seeds. Subsequent relevance analysis suggests a weak positive correlation between the left OFC's GMV and visual analog scale (VAS) scores. In conclusion, brain structural changes following ICSCI occur mainly in certain higher cognitive regions, such as the FG and OFC, rather than in the brain areas directly related to sensation or motor control. The functional areas of the brain that are related to cognitive processing may play an important role in sensorimotor dysfunction through the decreased FC with sensorimotor areas after ICSCI. Therefore, cognition-related functional training may play an important role in rehabilitation of sensorimotor function after ICSCI.

A Review on Cellular and Molecular Mechanisms Linked to the Development of Diabetes Complications

Modern lifestyle, changing eating habits and reduced physical work have been known to culminate into making diabetes a global pandemic. Hyperglycemia during the course of diabetes is an important causative factor for the development of both microvascular (retinopathy, nephropathy and neuropathy) and macrovascular (coronary artery disease, stroke and peripheral artery disease) complications. In this article, we summarize several mechanisms accountable for the development of both microvascular and macrovascular complications of diabetes. Several metabolic and cellular events are linked to the augmentation of oxidative stress like the activation of advanced glycation end products (AGE) pathway, polyol pathway, Protein Kinase C (PKC) pathway, Poly-ADP Ribose Polymerase (PARP) and hexosamine pathway. Oxidative stress also leads to the production of reactive oxygen species (ROS) like hydroxyl radical, superoxide anion and peroxides. Enhanced levels of ROS rescind the anti-oxidant defence mechanisms associated with superoxide dismutase, glutathione and ascorbic acid. Moreover, ROS triggers oxidative damages at the level of DNA, protein and lipids, which eventually cause cell necrosis or apoptosis. These physiological insults may be related to the microvascular complications of diabetes by negatively impacting the eyes, kidneys and the brain. While underlying pathomechanism of the macrovascular complications is quite complex, hyperglycemia associated atherosclerotic abnormalities like changes in the coagulation system, thrombin formation, fibrinolysis, platelet and endothelial function and vascular smooth muscle are well proven. Since hyperglycemia also modulates the vascular inflammation, cytokines, macrophage activation and gene expression of growth factors, elevated blood glucose level may play a central role in the development of macrovascular complications of diabetes. Taken collectively, chronic hyperglycemia and increased production of ROS are the miscreants for the development of microvascular and macrovascular complications of diabetes.

Synaptic remodeling in mouse motor cortex after spinal cord injury

Spinal cord injury dramatically blocks information exchange between the central nervous system and the peripheral nervous system. The resulting fate of synapses in the motor cortex has not been well studied. To explore synaptic reorganization in the motor cortex after spinal cord injury, we established mouse models of T12 spinal cord hemi-section and then monitored the postsynaptic dendritic spines and presynaptic axonal boutons of pyramidal neurons in the hindlimb area of the motor cortex in vivo. Our results showed that spinal cord hemi-section led to the remodeling of dendritic spines bilaterally in the motor cortex and the main remodeling regions changed over time. It made previously stable spines unstable and eliminated spines more unlikely to be re-emerged. There was a significant increase in new spines in the contralateral motor cortex. However, the low survival rate of the new spines demonstrated that new spines were still fragile. Observation of presynaptic axonal boutons found no significant change. These results suggest the existence of synapse remodeling in motor cortex after spinal cord hemi-section and that spinal cord hemi-section affected postsynaptic dendritic spines rather than presynaptic axonal boutons. This study was approved by the Ethics Committee of Chinese PLA General Hospital, China (approval No. 201504168S) on April 16, 2015.

Intravenous delivery of microRNA-133b along with Argonaute-2 enhances spinal cord recovery following cervical contusion in mice

BACKGROUND CONTEXT

Acute spinal cord injury (SCI) is a devastating condition for which spine decompression and stabilization of injury remains the only therapy available in the clinical setup. However, fibrous scar formation during the healing process significantly impairs full recovery. MicroRNAs (miRs) are small noncoding RNAs that regulate gene expression by binding to target mRNA(s) and initiating translational repression or mRNA degradation. It has been reported that microRNA-133b (miR133b) is highly expressed in regenerating neurons following a SCI in zebrafish, and lentiviral delivery of miR133b at the time of SCI in mice resulted in improved functional recovery.

PURPOSE

The aim of this study was to investigate whether intravenous delivery of miR133b enhances spinal cord recovery when administered 24 hours following a cervical contusion injury in mice.

STUDY DESIGN

This is an experimental animal study of acute SCI, investigating the effect of miR133b on spinal cord recovery by targeting scar lesion formation. The approach involved setting an acute SCI in mice, which was followed 24 hours later by intravenous co-delivery of miR133b and Argonaute 2 (Ago2), a protein involved in miRNA stabilization. Readouts of the impact of this intervention included analysis of RNA and protein expression at the lesion site, in particular with regard to markers of scar tissue formation, and determination of motor function recovery by the grip strength meter task.

METHODS

C57BL6 female mice between 6 and 8 weeks of age were tested. The injury model employed was a unilateral moderate contusion at the cervical fifth level. Twenty-four hours following the injury, the authors co-delivered miR133b, or scrambled miRNA as negative control, along with Ago2 for 3 consecutive days, one dose per day via tail-vein injection. They first investigated the level of miR133b in the spinal cord and in spinal cord lesion after a single dose of injection. Next, they determined the efficacy of miR133b and/or Ago2 delivery in regulating gene and protein expression at the lesion site. Finally, they established the role of miR133b and/or Ago2 in enhancing forelimb gripping recovery as assessed by the grip strength meter task for 8 weeks post-SCI.

RESULTS

Intravenous delivery of miR133b and/or Ago2 targeted the microenvironment at the lesion site and prevented the increased expression of certain extracellular matrix proteins (ECM), in particular collagen type 1 alpha 1 and tenascin N, which are known to have a key role in scar formation. It also reduced microglia and/or macrophage recruitment to the lesion site. Functional recovery in mice treated with miR133b and/or Ago2 started around 2 weeks postinjury and continued to improve over time, whereas mice in the control group displayed significantly poorer recovery.

CONCLUSIONS

Our data indicate therapeutic activity of intravenous miR133b and/or Ago2 treatment, possibly via decreasing ECM protein expression and macrophage recruitment at the lesion site, thereby minimizing detrimental fibrous scar formation.

CLINICAL SIGNIFICANCE

There is an urgent medical need for better treatments of SCIs. Based on our findings in a preclinical model, the miR133b and/or Ago2 system specifically targets fibrous scar formation, a barrier in neuronal regrowth, by remodeling ECM molecules at the injury site. Prevention of scar formation is critical to improved outcomes of treatment. Of note, delivery of miR133b and/or Ago2 was initiated 24 hours after traumatic impact, thus indicating a fairly long window of opportunity providing more time and flexibility for therapeutic intervention. Intravenous miR133b may become a beneficial therapeutic strategy to treat patients with acute SCI.

Regional estimates of cortical thickness in brain areas involved in control of surgically restored limb movement in patients with tetraplegia

Context/Objective: Spinal cord injury (SCI) causes atrophy of brain regions linked to motor function. We aimed to estimate cortical thickness in brain regions that control surgically restored limb movement in individuals with tetraplegia. Design: Cross-sectional study. Setting: Sahlgrenska University hospital, Gothenburg, Sweden. Participants: Six individuals with tetraplegia who had undergone surgical restoration of grip function by surgical transfer of one elbow flexor (brachioradialis), to the paralyzed thumb flexor (flexor pollicis longus). All subjects were males, with a SCI at the C6 or C7 level, and a mean age of 40 years (range = 31-48). The average number of years elapsed since the SCI was 13 (range = 6-26). Outcome measures: We used structural magnetic resonance imaging (MRI) to estimate the thickness of selected motor cortices and compared these measurements to those of six matched control subjects. The pinch grip control area was defined in a previous functional MRI study. Results: Compared to controls, the cortical thickness in the functionally defined pinch grip control area was not significantly reduced (P = 0.591), and thickness showed a non-significant but positive correlation with years since surgery in the individuals with tetraplegia. In contrast, the anatomically defined primary motor cortex as a whole exhibited substantial atrophy (P = 0.013), with a weak negative correlation with years since surgery. Conclusion: Individuals with tetraplegia do not seem to have reduced cortical thickness in brain regions involved in control of surgically restored limb movement. However, the studied sample is very small and further studies with larger samples are required to establish these findings.

Dementia, Depression, and Associated Brain Inflammatory Mechanisms after Spinal Cord Injury

Evaluation of the chronic effects of spinal cord injury (SCI) has long focused on sensorimotor deficits, neuropathic pain, bladder/bowel dysfunction, loss of sexual function, and emotional distress. Although not well appreciated clinically, SCI can cause cognitive impairment including deficits in learning and memory, executive function, attention, and processing speed; it also commonly leads to depression. Recent large-scale longitudinal population-based studies indicate that patients with isolated SCI (without concurrent brain injury) are at a high risk of dementia associated with substantial cognitive impairments. Yet, little basic research has addressed potential mechanisms for cognitive impairment and depression after injury. In addition to contributing to disability in their own right, these changes can adversely affect rehabilitation and recovery and reduce quality of life. Here, we review clinical and experimental work on the complex and varied responses in the brain following SCI. We also discuss potential mechanisms responsible for these less well-examined, important SCI consequences. In addition, we outline the existing and developing therapeutic options aimed at reducing SCI-induced brain neuroinflammation and post-injury cognitive and emotional impairments.

Heritability of cervical spinal cord structure

OBJECTIVE

Measures of spinal cord structure can be a useful phenotype to track disease severity and development; this observational study measures the hereditability of cervical spinal cord anatomy and its correlates in healthy human beings.

METHODS

Twin data from the Human Connectome Project were analyzed with semiautomated spinal cord segmentation, evaluating test-retest reliability and broad-sense heritability with an AE model. Relationships between spinal cord metrics, general physical measures, regional brain structural measures, and motor function were assessed.

RESULTS

We found that the spinal cord C2 cross-sectional area (CSA), left-right width (LRW), and anterior-posterior width (APW) are highly heritable (85%-91%). All measures were highly correlated with the brain volume, and CSA only was positively correlated with thalamic volumes (p = 0.005) but negatively correlated with the occipital cortex area (p = 0.001). LRW was correlated with the participant's height (p = 0.00027). The subjects' sex significantly influenced these metrics. Analyses of a test-retest data set confirmed validity of the approach.

CONCLUSIONS

This study provides the evidence of genetic influence on spinal cord structure. MRI metrics of cervical spinal cord anatomy are robust and not easily influenced by nonpathological environmental factors, providing a useful metric for monitoring normal development and progression of neurodegenerative disorders affecting the spinal cord, including-but not limited to-spinal cord injury and MS.

Disentangling the Effects of Spinal Cord Injury and Related Neuropathic Pain on Supraspinal Neuroplasticity: A Systematic Review on Neuroimaging

Background: Spinal cord injury (SCI) and its accompanying changes of brain structure and function have been widely studied and reviewed. Debilitating chronic neuropathic pain (NP) is reported in 53% of SCI patients, and brain changes have been shown to be involved with the presence of this secondary complication. However, there is yet a synthesis of current studies that investigated brain structure, resting connectivity, and metabolite changes that accompanies this condition.

Methods: In this review, a systematic search was performed using Medical Subject Headings heading search terms in PubMed and SCOPUS to gather the appropriate published studies. Neuroimaging studies that investigated supraspinal structural, resting-state connectivity, and metabolite changes in SCI subjects with NP were included. To this end, voxel-based morphometry, diffusion tensor imaging, resting-state functional MRI, magnetic resonance spectroscopy, and PET studies were summarized and reviewed. Further inclusion and exclusion criteria allowed delineation of appropriate studies that included SCI subgroups with and without NP.

Results: A total of 12 studies were eligible for qualitative synthesis. Overall, current studies that investigated NP-associated changes within the SCI cohort show primarily metabolite concentration alterations in sensory-pain processing regions, alongside bidirectional changes of brain structure. Moreover, in comparison to healthy controls, there remains limited evidence of structural and connectivity changes but a range of alterations in metabolite concentrations in SCI subjects with NP.

Conclusions: There is some evidence suggesting that the magnitude and presence of NP following SCI results in both adaptive and maladaptive structural plasticity of sensorimotor regions, alongside altered metabolism of brain areas involved with descending pain modulation, pain perception (i.e., anterior cingulate cortex) and sensory integration (i.e., thalamus). However, based on the fact that only a few studies investigated structural and glucose metabolic changes in chronic SCI subjects with NP, the underlying mechanisms that accompany this condition remains to be further elucidated. Future cross-sectional or longitudinal studies that aim to disentangle NP related to SCI may benefit from stricter constraints in subject cohorts, controlled subgroups, improved pain phenotyping, and implementation of multimodal approaches to discover sensitive biomarkers that profile pain and optimize treatment in SCI subjects with NP.

Spinal cord lesions

A spinal cord injury (SCI) may result in impairments of motor, sensory, and autonomous functions below the injury level. Worldwide, the prevalence of SCI is 1:1000 and the incidence is between 4 and 9 new cases per 100,000 people per year. Most common causes for traumatic SCI are traffic accidents, falls, and violence. Nowadays, the proportion of patients with tetraplegia and paraplegia is equal. In industrialized countries, the percentage of nontraumatic injuries increases together with age. Most patients with initially preserved motor functions below the injury level show a substantial functional recovery, while three quarters of patients with initially complete SCI remain that way. In SCI, brain-computer interfaces (BCIs) may be used in the subacute phase as part of a restorative therapy program and, later, for control of assistive devices most needed by individuals with high cervical lesions. Research on structural and functional reorganization of the deefferented and deafferented brain after SCI is inconclusive mainly because of varying methods of analysis and the heterogeneity of the investigated populations. A better characterization of study participants with SCI together with documentation of confounding factors such as antispasticity medication or neuropathic pain is indicated.

Alterations in Cortical Thickness and Subcortical Volume are Associated With Neurological Symptoms and Neck Pain in Patients With Cervical Spondylosis

BACKGROUND

Advanced cervical spondylosis (CS) can cause structural damage to the spinal cord resulting in long-term neurological impairment including neck pain and motor weakness. We hypothesized long-term structural reorganization within the brain in patients with CS.

OBJECTIVE

To explore the associations between cortical thickness, subcortical volumes, neurological symptoms, and pain severity in CS patients with or without myelopathy and healthy controls (HCs).

METHODS

High-resolution T1-weighted structural magnetic resonance imaging (MRI) scans from 26 CS patients and 45 HCs were acquired. Cortical thickness and subcortical volumes were computed and compared to the modified Japanese Orthopedic Association (mJOA) and the Neck Disability Index (NDI) scores.

RESULTS

Cortical thinning within the superior frontal gyrus, anterior cingulate, precuneus, and reduction in putamen volume were associated with worsening neurological and pain symptoms. Among the strongest associations were cortical thickness within the left precuneus (R2 = 0.34) and left and right putamen (R2 = 0.43, 0.47, respectively) vs mJOA, and the left precuneus (R2 = 0.55), insula (R2 = 0.57), and right putamen (R2 = 0.54) vs NDI (P ≤ .0001 for all). Cortical thickness along Brodmann areas 3a, 4a, and 4p were also moderately associated with mJOA. Preliminary evidence also suggests that patients with CS may undergo cortical atrophy at a faster rate than HCs.

CONCLUSION

Patients with CS appear to exhibit cortical thinning and atrophy with worsening neurological and pain symptoms in specific brain regions associated with sensorimotor and pain processing.

Specific Brain Morphometric Changes in Spinal Cord Injury: A Voxel-Based Meta-Analysis of White and Gray Matter Volume

The objective of the study was to investigate degenerative changes of white matter volume (WMV) and gray matter volume (GMV) in individuals after a spinal cord injury (SCI). Published studies of whole-brain voxel-based morphometry (VBM) published between January 1, 2006 and March 1, 2018 comparing SCI patients with controls were collected by searching PubMed, Web of Science, and EMBASE databases. Voxel-wise meta-analyses of GMV and WMV differences between SCI patients and controls were performed separately using seed-based d mapping. Twelve studies with 12 GMV data sets and 9 WMV data sets yielded a total of 466 individuals (190 SCI patients and 276 controls) who were included in this meta-analysis. Compared with controls, SCI patients showed GMV atrophy in sensorimotor system regions including the bilateral sensorimotor cortex (S1 and M1), the supplementary motor area (SMA), paracentral gyrus, thalamus, and basal ganglia, as well as WMV loss in the corticospinal tract.GMV aberrancies were also demonstrated in brain regions responsible for cognition and emotion, such as the orbitofrontal cortex (OFC) and the left insula. Additionally, GMV in both the bilateral S1 and the left SMA was positively correlated with the time span after the injury. In conclusion, anatomical atrophy in cortical-thalamic-spinal pathways suggested that SCIs may result in degenerative changes of the sensorimotor system. Further, OFC and insula GMV abnormalities may explain symptoms such as neuropathic pain and potential cognitive-emotional impairments in chronic SCI patients. These findings indicate that anatomical brain magnetic resonance imaging (MRI) protocols could be neuroimaging biomarkers for interventional studies and treatments.

Differences in Cortical Gray Matter Atrophy of Paraplegia and Tetraplegia after Complete Spinal Cord Injury

Anatomical studies of spinal cord injury (SCI) using magnetic resonance imaging (MRI) report diverging observations, from "no changes" to "tissue atrophy in motor and non-motor regions." These discrepancies among studies can be attributed to heterogeneity in extent, level, and post-injury duration observed within the SCI population. But, no studies have investigated structural changes associated with different levels of injury (paraplegia vs. tetraplegia). High-resolution MRI images were processed using a voxel-based morphometry technique to compare regional gray matter volume (GMV) between 16 complete paraplegia and 7 complete tetraplegia SCI subjects scanned within 2 years of injury when compared to 22 age-matched healthy controls using one-way analysis of covariance (ANCOVA). A post-hoc analysis using a region of interest-based approach was utilized to quantify GMV differences between healthy controls and subgroups of SCI. A voxel-wise one-sample t-test was also performed to evaluate the mean effect of post-injury duration on GMV of the SCI group. ANCOVA resulted in altered GMV in inferior frontal gyrus, bilateral mid orbital gyrus extending to rectal gyrus, and anterior cingulate cortex. Post-hoc analysis, in general, indicated GM atrophy after SCI, but tetraplegia showed a greater decrease in GMV when compared to paraplegia and healthy controls. Further, the GMV of the middle frontal gyrus, superior frontal gyrus, inferior frontal gyrus, insula, mid-orbital gyrus, and middle temporal gyrus was positively correlated with post-injury duration in both paraplegia and tetraplegia groups. GM atrophy after SCI is affected by level of cord injury, with higher levels of injury resulting in greater loss of GMV. Magnitude of GMV loss in the frontal cortex after SCI also appears to be dynamic within the first 2 years of injury. Understanding the effect of injury level and injury duration on structural changes after SCI can help to better understand the mechanisms leading to positive and negative clinical outcome in SCI patients.

Reorganization of the somatosensory pathway after subacute incomplete cervical cord injury

Objective

The main purpose of the present study was to investigate the possible somatosensory-related brain functional reorganization after traumatic spinal cord injury (SCI).

Methods

Thirteen patients with subacute incomplete cervical cord injury (ICCI) and thirteen age- and sex-matched healthy controls (HCs) were recruited. Eleven patients and all the HCs underwent both sensory task-related brain functional scanning and whole brain structural scanning on a 3.0 Tesla MRI system, and two patients underwent only structural scanning; the process of structural scanning was completed on thirteen patients, while functional scanning was only applied to eleven patients. We performed sensory task-related functional MRI (fMRI) to investigate the functional changes in the brain. In addition, voxel-based morphometry (VBM) was applied to explore whether any sensory-related brain structural changes occur in the whole brain after SCI.

Results

Compared with HCs, ICCI patients exhibited decreased activation in the left postcentral gyrus (postCG), the brainstem (midbrain and right pons) and the right cerebellar lobules IV-VI. Moreover, a significant positive association was found between the activation in the left PostCG and the activation in both the brainstem and the right cerebellar lobules IV-VI. Additionally, the decrease in gray matter volume (GMV) was detected in the left superior parietal lobule (SPL). The decrease of white matter volume (WMV) was observed in the right temporal lobe, the right occipital lobe, and the right calcarine gyrus. No structural change in the primary sensory cortex (S1), the secondary somatosensory cortex (S2) or the thalamus was detected.

Conclusion

These functional and structural findings may demonstrate the existence of an alternative pathway in the impairment of somatosensory function after SCI, which consists of the ipsilateral cerebellum, the brainstem and the contralateral postCG. It provides a new theoretical basis for the mechanism of sensory-related brain alteration in SCI patients and the rehabilitation therapy based on this pathway in the future.

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We found that sensory-related brain reorganization may not occur in the thalamus in patients with ICCI.

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We found that brain structural reorganization did not occur in the S1 or the S2 in patients with ICCI.

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We observed that SCI can cause brain structural reorganization in non-sensory-related areas.

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We observed that an alternative pathway may exist in the impairment of somatosensory function after SCI.

Whether Visual-related Structural and Functional Changes Occur in Brain of Patients with Acute Incomplete Cervical Cord Injury: A Multimodal Based MRI Study

Visual-related cortex plays an important role in the process of movement. It is of great importance to clarify whether traumatic spinal cord injury (SCI), which is a typical disease that results in sensorimotor dysfunction, leads to the alteration of visual-related brain structure and function area. To address this issue, multimodality MRI was applied on eleven patients with acute incomplete cervical cord injury (ICCI) and eleven healthy controls (HCs) to explore possible structural and functional changes of the brain. Voxel-based morphometry (VBM) analysis was performed to investigate the changes in brain structure of ICCI patients. The fractional amplitude of low-frequency fluctuations (fALFF) was used to characterize changes in regional neural activities, and independent component analysis (ICA) was carried out to explore alterations in the resting-state networks (RSNs) after ICCI. We also investigated correlations among brain imaging metrics and between the metrics and clinical variables. Compared with HCs, ICCI patients exhibited significant gray matter atrophy in the left hippocampus and parahippocampal gyrus, right superior frontal gyrus (SFG), and middle frontal gyrus (MFG) and also a decrease in fALFF in the left orbitofrontal cortex (OFC). Moreover, ICCI patients exhibited decreased intra-network functional connectivity (FC) in the medial vision network (mVN). The mean fALFF value was correlated with clinical motor scores of the left extremities and the total motor scores. Our findings proved that ICCI can not only cause structural changes in visual-related brain regions, but also result in visual-related brain functional alterations, revealing the possible mechanism of the effects of visual feedback training in motor function rehabilitation of SCI patients.

Nutritional Health Considerations for Persons with Spinal Cord Injury

Chronic spinal cord injury (SCI) often results in morbidity and mortality due to all-cause cardiovascular disease (CVD) and comorbid endocrine disorders. Several component risk factors for CVD, described as the cardiometabolic syndrome (CMS), are prevalent in SCI, with the individual risks of obesity and insulin resistance known to advance the disease prognosis to a greater extent than other established risks. Notably, adiposity and insulin resistance are attributed in large part to a commonly observed maladaptive dietary/nutritional profile. Although there are no evidence-based nutritional guidelines to address the CMS risk in SCI, contemporary treatment strategies advocate more comprehensive lifestyle management that includes sustained nutritional guidance as a necessary component for overall health management. This monograph describes factors in SCI that contribute to CMS risks, the current nutritional profile and its contribution to CMS risks, and effective treatment strategies including the adaptability of the Diabetes Prevention Program (DPP) to SCI. Establishing appropriate nutritional guidelines and recommendations will play an important role in addressing the CMS risks in SCI and preserving optimal long-term health.

Reactivating the Dormant Motor Cortex After Spinal Cord Injury With EEG Neurofeedback: A Case Study With a Chronic, Complete C4 Patient

Chronic spinal cord injury (SCI) patients present poor motor cortex activation during movement attempts. The reactivation of this brain region can be beneficial for them, for instance, allowing them to use brain-machine interfaces for motor rehabilitation or restoration. These brain-machine interfacess generally use electroencephalography (EEG) to measure the cortical activation during the attempts of movement, quantifying it as the event-related desynchronization (ERD) of the alpha/mu rhythm. Based on previous evidence showing that higher tonic EEG alpha power is associated with higher ERD, we hypothesized that artificially increasing the alpha power over the motor cortex of these patients could enhance their ERD (ie, motor cortical activation) during movement attempts. We used EEG neurofeedback (NF) to enhance the tonic EEG alpha power, providing real-time visual feedback of the alpha oscillations measured over the motor cortex. This approach was evaluated in a C4, ASIA A, SCI patient (9 months after the injury) who did not present ERD during the movement attempts of his paralyzed hands. The patient performed 4 NF sessions (in 4 consecutive days) and screenings of his EEG activity before and after each session. After the intervention, the patient presented a significant increase in the alpha power over the motor cortex, and a significant enhancement of the mu ERD in the contralateral motor cortex when he attempted to close the assessed right hand. As a proof of concept investigation, this article shows how a short NF intervention might be used to enhance the motor cortical activation in patients with chronic tetraplegia.

Traumatic Brain Injury in Spinal Cord Injury: Frequency and Risk Factors

BACKGROUND

The frequency of traumatic brain injury (TBI) co-occurring with traumatic spinal cord injury (tSCI) is unclear despite a number of past studies; as well, limited research has examined predictors of co-morbid TBI in tSCI patients.

OBJECTIVES

(1a) To summarize past literature on comorbid diagnosis of TBI in tSCI in order to reexamine the frequency of dual diagnosis in a study designed to obviate past methodological limitations; (1b) to compare dual-diagnosis frequency with vs without the inclusion of diagnostically ambiguous cases; and (2) to measure risk factors for tSCI and comorbid TBI.

METHODS

Ninety-one of 135 eligible adults with tSCI, 3 to 6 months postinjury, were prospectively recruited from a tertiary inpatient tSCI rehabilitation program. TBI diagnosis was based on comprehensive, validated clinical neurological and neuroimaging measures.

RESULTS

Objective 1: 39.6% of the tSCI patients sustained a concomitant TBI, but when ambiguous cases were removed from analysis, frequency rose to 58.1%. Objective 2: Motor vehicle collisions were most likely to yield a comorbid TBI diagnosis, but 31.6% of falls also resulted in TBI. Patients with cervical and thoracic injuries showed a very similar frequency of comorbid TBI.

CONCLUSIONS

Varied methodological approaches, particularly the decision to include/exclude ambiguous cases, likely explain disparate past estimates of TBI in tSCI. However, even this study's lower frequency estimate, at nearly 40%, is clinically important. The prevailing assumption that dual diagnosis is less common in thoracic than cervical spine injuries was not supported. Finally, while comorbid TBI most frequently occurred in motor vehicle collisions, nearly a third of tSCIs sustained in falls resulted in comorbid TBI in our sample.

Pain and somatic sensation are transiently normalized by illusory body ownership in a patient with spinal cord injury

PURPOSE

Spinal cord injury (SCI), a profound impairment of sensorimotor functions, is often associated with pain related phenomena, including mechanical allodynia, a condition in which non-painful tactile sensation is perceived as pain. Pain and somatic sensation are undeniable markers of normal bodily awareness. However, the mechanism by which they are integrated into a coherent sense of the bodily self remains largely unclear. In this study, we investigated the effect of high-level multisensory manipulation on subjective experiences of pain, touch, and body-ownership.

METHODS

We administered visuo-tactile stimulation based on the rubber hand illusion. In a longitudinal study, we compared the strength of the illusion in a male with SCI, who initially had lost somatosensation in all his fingers, but a few months later reported signs of tactile allodynia restricted to the left C6-dermatome.

RESULTS

After the restoration of some somatosensation, even if it were painful, synchronous but not asynchronous visuo-tactile stimulation induced body illusion. Previously painful stimuli were temporarily perceived as less painful, and the patient further regained tactile sensations in adjacent numb areas.

CONCLUSIONS

The sensations of touch and pain are mutually influenced and inextricably linked to a coherent representation of one's own body. Multisensory manipulations affecting the perception and representation of the body might thus offer a powerful opportunity to mitigate nociceptive and somatic abnormalities.

Factors Affecting Volume Changes of the Somatosensory Cortex in Patients with Spinal Cord Injury: To Be Considered for Future Neuroprosthetic Design

Spinal cord injury (SCI) leads to severe chronic disability, but also to secondary adaptive changes upstream to the injury in the brain which are most likely induced due to the lack of afferent information. These neuroplastic changes are a potential target for innovative therapies such as neuroprostheses, e.g., by stimulation in order to evoke sensation or in order to suppress phantom limb pain. Diverging results on gray matter atrophy have been reported in patients with SCI. Detectability of atrophy seems to depend on the selection of the regions of interest, while whole-brain approaches are not sensitive enough. In this study, we discussed previous research approaches and analyzed differential atrophic changes in incomplete SCI using manual segmentation of the somatosensory cortex. Patients with incomplete SCI (ASIA C-D), with cervical (N = 5) and thoracic (N = 6) injury were included. Time since injury was ≤12 months in 7 patients, and 144, 152, 216, and 312 months in the other patients. Age at the injury was ≤26 years in 4 patients and ≥50 years in 7 patients. A sample of 12 healthy controls was included in the study. In contrast to all previous studies that used voxel-based morphometry, we performed manual segmentation of the somatosensory cortex in the postcentral gyrus from structural magnetic resonance images and normalized the calculated volumes against the sum of volumes of an automated whole-head segmentation. Volumes were smaller in patients than in controls (p = 0.011), and as a tendency, female patients had smaller volumes than male patients (p = 0.017, uncorrected). No effects of duration (subacute vs. chronic), level of lesion (cervical vs. thoracic), region (left vs. right S1), and age at onset (≤26 vs. ≥50 years) was found. Our results demonstrate volume loss of S1 in incomplete SCI and encourage further research with larger sample sizes on volumetric changes in the acute and chronic stage of SCI, in order to document the moderating effect of type and location of injury on neuroplastic changes. A better understanding of neuroplastic changes in the sensorimotor cortex after SCI and its interaction with sex is needed in order to develop efficient rehabilitative interventions and neuroprosthetic technologies.

Cortical morphometric changes after spinal cord injury

Neuroimaging studies suggest that spinal cord injury (SCI) may lead to significant anatomical alterations in the human sensorimotor system. In particular, voxel-based morphometry (VBM) of cortical volume has revealed a significant gray and white matter atrophy bilaterally in the primary sensory cortex (S1). By contrast, some structural studies failed to detect changes in gray matter volume (GMV) in the primary motor cortex (M1) following SCI, whereas others have reported a substantial decrease of GMV also in M1. In addition to direct degeneration of the sensorimotor cortex, SCI can also lead to atrophy of the non-sensorimotor cortex, such as anterior cingulate cortex, insular cortex, middle frontal gyrus and supplementary motor area. These findings suggest that SCI can cause remote atrophy of brain gray matter in the salient network. Furthermore, pain-related remodelling may occur in SCI. In fact, structural changes in SCI are also related to the presence and degree of below-level pain. We performed a systematic review of the neuroimaging studies showing morphometric cortical changes and subsequent functional reorganization in humans with SCI. Literature search was conducted using PubMed and Embase. We identified 12 articles matching the inclusion criteria and 195 patients were included in these studies. The wide range of disease duration, rehabilitation training, drug intervention, and different research methodology, especially the identification of region of interest and the statistical approach to correct for multiple comparisons, may have contributed to some inconsistencies between the reviewed studies. Nevertheless, neuroimaging biomarkers can assess the extent of neural damage, elucidate the mechanisms of neural repair, and predict clinical outcome. A better understanding of the structural and functional changes that occur at cortical level following SCI may be useful in tracking potential treatment induced changes and identifying potential therapeutic targets, thus developing evidence-based rehabilitation therapies.

Large-Scale Network Analysis of Whole-Brain Resting-State Functional Connectivity in Spinal Cord Injury: A Comparative Study

Network analysis based on graph theory depicts the brain as a complex network that allows inspection of overall brain connectivity pattern and calculation of quantifiable network metrics. To date, large-scale network analysis has not been applied to resting-state functional networks in complete spinal cord injury (SCI) patients. To characterize modular reorganization of whole brain into constituent nodes and compare network metrics between SCI and control subjects, fifteen subjects with chronic complete cervical SCI and 15 neurologically intact controls were scanned. The data were preprocessed followed by parcellation of the brain into 116 regions of interest (ROI). Correlation analysis was performed between every ROI pair to construct connectivity matrices and ROIs were categorized into distinct modules. Subsequently, local efficiency (LE) and global efficiency (GE) network metrics were calculated at incremental cost thresholds. The application of a modularity algorithm organized the whole-brain resting-state functional network of the SCI and the control subjects into nine and seven modules, respectively. The individual modules differed across groups in terms of the number and the composition of constituent nodes. LE demonstrated statistically significant decrease at multiple cost levels in SCI subjects. GE did not differ significantly between the two groups. The demonstration of modular architecture in both groups highlights the applicability of large-scale network analysis in studying complex brain networks. Comparing modules across groups revealed differences in number and membership of constituent nodes, indicating modular reorganization due to neural plasticity.

Brain Gray Matter Atrophy after Spinal Cord Injury: A Voxel-Based Morphometry Study

The aim of this study was to explore possible changes in whole brain gray matter volume (GMV) after spinal cord injury (SCI) using voxel-based morphometry (VBM), and to study their associations with the injury duration, severity, and clinical variables. In total, 21 patients with SCI (10 with complete and 11 with incomplete SCI) and 21 age- and sex-matched healthy controls (HCs) were recruited. The 3D high-resolution T1-weighted structural images of all subjects were obtained using a 3.0 Tesla MRI system. Disease duration and American Spinal Injury Association (ASIA) Scale scores were also obtained from each patient. Voxel-based morphometry analysis was carried out to investigate the differences in GMV between patients with SCI and HCs, and between the SCI sub-groups. Associations between GMV and clinical variables were also analyzed. Compared with HCs, patients with SCI showed significant GMV decrease in the dorsal anterior cingulate cortex, bilateral anterior insular cortex, bilateral orbital frontal cortex (OFC), and right superior temporal gyrus. No significant difference in GMV in these areas was found either between the complete and incomplete SCI sub-groups, or between the sub-acute (duration <1 year) and chronic (duration >1 year) sub-groups. Finally, the GMV of the right OFC was correlated with the clinical motor scores of left extremities in not only all SCI patients, but especially the CSCI subgroup. In the sub-acute subgroup, we found a significant positive correlation between the dACC GMV and the total clinical motor scores, and a significant negative correlation between right OFC GMV and the injury duration. These findings indicate that SCI can cause remote atrophy of brain gray matter, especially in the salient network. In general, the duration and severity of SCI may be not associated with the degree of brain atrophy in total SCI patients, but there may be associations between them in subgroups.

Functional cortical reorganization in cases of cervical spondylotic myelopathy and changes associated with surgery

OBJECTIVE The physiological mechanisms underlying the recovery of motor function after cervical spondylotic myelopathy (CSM) surgery are poorly understood. Neuronal plasticity allows neurons to compensate for injury and disease and to adjust their activities in response to new situations or changes in their environment. Cortical reorganization as well as improvement in corticospinal conduction happens during motor recovery after stroke and spinal cord injury. In this study the authors aimed to understand the cortical changes that occur due to CSM and following CSM surgery and to correlate these changes with functional recovery by using blood oxygen level-dependent (BOLD) functional MRI (fMRI). METHODS Twenty-two patients having symptoms related to cervical cord compression due to spondylotic changes along with 12 age- and sex-matched healthy controls were included in this study. Patients underwent cervical spine MRI and BOLD fMRI at 1 month before surgery (baseline) and 6 months after surgery. RESULTS Five patients were excluded from analysis because of technical problems; thus, 17 patients made up the study cohort. The mean overall modified Japanese Orthopaedic Association score improved in patients following surgery. Mean upper-extremity, lower-extremity, and sensory scores improved significantly. In the preoperative patient group the volume of activation (VOA) was significantly higher than that in controls. The VOA after surgery was reduced as compared with that before surgery, although it remained higher than that in the control group. In the preoperative patient group, activations were noted only in the left precentral gyrus (PrCG). In the postoperative group, activations were seen in the left postcentral gyrus (PoCG), as well as the PrCG and premotor and supplementary motor cortices. In postoperative group, the VOA was higher in both the PrCG and PoCG as compared with those in the control group. CONCLUSIONS There is over-recruitment of sensorimotor cortices during nondexterous relative to dexterous movements before surgery. After surgery, there was recruitment of other cortical areas such as the PoCG and premotor and supplementary motor cortices, which correlated with improvement in dexterity, but activation in these areas was greater than that found in controls. The results show that improvement in dexterity and finer movements of the upper limbs is associated with recruitment areas other than the premotor cortex to compensate for the damage in the cervical spinal cord.

Brain White Matter Impairment in Patients with Spinal Cord Injury

It remains unknown whether spinal cord injury (SCI) could indirectly impair or reshape the white matter (WM) of human brain and whether these changes are correlated with injury severity, duration, or clinical performance. We choose tract-based spatial statistics (TBSS) to investigate the possible changes in whole-brain white matter integrity and their associations with clinical variables in fifteen patients with SCI. Compared with the healthy controls, the patients exhibited significant decreases in WM fractional anisotropy (FA) in the left angular gyrus (AG), right cerebellum (CB), left precentral gyrus (PreCG), left lateral occipital region (LOC), left superior longitudinal fasciculus (SLF), left supramarginal gyrus (SMG), and left postcentral gyrus (PostCG) (p < 0.01, TFCE corrected). No significant differences were found in all diffusion indices between the complete and incomplete SCI. However, significantly negative correlation was shown between the increased radial diffusivity (RD) of left AG and total motor scores (uncorrected p < 0.05). Our findings provide evidence that SCI can cause not only direct degeneration but also transneuronal degeneration of brain WM, and these changes may be irrespective of the injury severity. The affection of left AG on rehabilitation therapies need to be further researched in the future.

Spinal cord injury drives chronic brain changes

Only a few studies have considered changes in brain structures other than sensory and motor cortex after spinal cord injury, although cognitive impairments have been reported in these patients. Spinal cord injury results in chronic brain neuroinflammation with consequent neurodegeneration and cognitive decline in rodents. Regarding the hippocampus, neurogenesis is reduced and reactive gliosis increased. These long-term abnormalities could explain behavioral impairments exhibited in humans patients suffering from spinal cord trauma.

The corticomotor projection to liminally-contractable forearm muscles in chronic spinal cord injury: a transcranial magnetic stimulation study

STUDY DESIGN

A cross-sectional study in chronic spinal cord injury with cervical lesions (cSCI).

OBJECTIVE

To determine the corticomotor projection and motor cortex organization of paralyzed forearm muscles that presented only liminal voluntary activation.

SETTING

Burke Medical Research Institute, White Plains, NY, USA.

METHODS

We identified ten people with chronic SCI who had a wrist flexor or extensor muscle with a motor power (MP) of 1 over 5. We recorded motor evoked potentials (MEPs) to transcranial magnetic stimulation (TMS) over the primary motor cortex of the hemisphere contralateral to the target muscle. We measured resting motor threshold (RMT), corticomotor latency (LTY), MEP amplitude (AMP) and performed cortical motor mapping to determine the optimal site (OPT) and map area (AREA). Results were compared with the data from 18 controls.

RESULTS

A MEP in the target muscle was observed for all cSCI cases. LTY was normal, while corticomotor excitability (as determined by RMT and AMP) was reduced in about half of the group. The OPT site of the motor maps was within control range for all cSCI cases, while AREA was reduced in three cases.

CONCLUSIONS

Corticomotor conduction and cortical topography were appreciably normal despite only liminal activation of the target muscle with voluntary effort. Muscles with these characteristics may benefit from a targeted rehabilitation program even in the chronic phase after SCI.

Combined nonlinear metrics to evaluate spontaneous EEG recordings from chronic spinal cord injury in a rat model: a pilot study

Spinal cord injury (SCI) is a high-cost disability and may cause permanent loss of movement and sensation below the injury location. The chance of cure in human after SCI is extremely limited. Instead, neural regeneration could have been seen in animals after SCI, and such regeneration could be retarded by blocking neural plasticity pathways, showing the importance of neural plasticity in functional recovery. As an indicator of nonlinear dynamics in the brain, sample entropy was used here in combination with detrended fluctuation analysis (DFA) and Kolmogorov complexity to quantify functional plasticity changes in spontaneous EEG recordings of rats before and after SCI. The results showed that the sample entropy values were decreased at the first day following injury then gradually increased during recovery. DFA and Kolmogorov complexity results were in consistent with sample entropy, showing the complexity of the EEG time series was lost after injury and partially regained in 1 week. The tendency to regain complexity is in line with the observation of behavioral rehabilitation. A critical time point was found during the recovery process after SCI. Our preliminary results suggested that the combined use of these nonlinear dynamical metrics could provide a quantitative and predictive way to assess the change of neural plasticity in a spinal cord injury rat model.

Alterations in Cortical Sensorimotor Connectivity following Complete Cervical Spinal Cord Injury: A Prospective Resting-State fMRI Study

Functional magnetic resonance imaging (fMRI) studies have demonstrated alterations during task-induced brain activation in spinal cord injury (SCI) patients. The interruption to structural integrity of the spinal cord and the resultant disrupted flow of bidirectional communication between the brain and the spinal cord might contribute to the observed dynamic reorganization (neural plasticity). However, the effect of SCI on brain resting-state connectivity patterns remains unclear. We undertook a prospective resting-state fMRI (rs-fMRI) study to explore changes to cortical activation patterns following SCI. With institutional review board approval, rs-fMRI data was obtained in eleven patients with complete cervical SCI (>2 years post injury) and nine age-matched controls. The data was processed using the Analysis of Functional Neuroimages software. Region of interest (ROI) based analysis was performed to study changes in the sensorimotor network using pre- and post-central gyri as seed regions. Two-sampled t-test was carried out to check for significant differences between the two groups. SCI patients showed decreased functional connectivity in motor and sensory cortical regions when compared to controls. The decrease was noted in ipsilateral, contralateral, and interhemispheric regions for left and right precentral ROIs. Additionally, the left postcentral ROI demonstrated increased connectivity with the thalamus bilaterally in SCI patients. Our results suggest that cortical activation patterns in the sensorimotor network undergo dynamic reorganization following SCI. The presence of these changes in chronic spinal cord injury patients is suggestive of the inherent neural plasticity within the central nervous system.

Motor recovery at 6 months after admission is related to structural and functional reorganization of the spine and brain in patients with spinal cord injury

This study aimed to explore structural and functional reorganization of the brain in the early stages of spinal cord injury (SCI) and identify brain areas that contribute to motor recovery. We studied 25 patients with SCI, including 10 with good motor recovery and 15 with poor motor recovery, along with 25 matched healthy controls. The mean period post-SCI was 9.2 ± 3.5 weeks in good recoverers and 8.8 ± 2.6 weeks in poor recoverers. All participants underwent structural and functional MRI on a 3-T magnetic resonance system. We evaluated differences in cross-sectional spinal cord area at the C2/C3 level, brain cortical thickness, white matter microstructure, and functional connectivity during the resting state among the three groups. We also evaluated associations between structural and functional reorganization and the rate of motor recovery. After SCI, compared with good recoverers, poor recoverers had a significantly decreased cross-sectional spinal cord area, cortical thickness in the right supplementary motor area and premotor cortex, and fractional anisotropy (FA) in the right primary motor cortex and posterior limb of the internal capsule. Meanwhile, poor recoverers showed decreased functional connectivity between the primary motor cortex and higher order motor areas (supplementary motor area and premotor cortex), while good recoverers showed increased functional connectivity among these regions. The structural and functional reorganization of the spine and brain was associated with motor recovery rate in all SCI patients. In conclusion, structural and functional reorganization of the spine and brain directly affected the motor recovery of SCI. Less structural atrophy and enhanced functional connectivity are associated with good motor recovery in patients with SCI. Multimodal imaging has the potential to predict motor recovery in the early stage of SCI. Hum Brain Mapp 37:2195-2209, 2016. © 2016 Wiley Periodicals, Inc.

Short-latency afferent inhibition in chronic spinal cord injury

Background

Short-latency afferent inhibition (SAI) results when somatosensory afferent input inhibits the corticospinal output from primary motor cortex (M1). The present study examined SAI in the flexor carpi radialis (FCR) muscle in individuals with spinal cord injury (SCI) and uninjured controls.

Methods

Short-latency afferent inhibition (SAI) was evoked by stimulating the median nerve at the elbow at intervals of 15, 20 and 25 ms in advance of a transcranial magnetic stimulation (TMS) pulse over M1. SAI was tested with the FCR at rest and also during ~20% of maximum voluntary contraction. Corticospinal output was assessed through measuring both motor thresholds and motor evoked potential (MEP) recruitment curves. The afferent volley was assessed via the N20–P25 amplitude of the somatosensory evoked potential (SEP) and the amplitude of sensory nerve action potentials (SNAP) recorded over the median nerve at the elbow.

Results

SAI is reduced in SCI in both the contracted and non-contracted FCR muscle. MEP recruitment curves and thresholds were decreased in SCI only in the active state and not the resting state. N20–P25 amplitude was similar between groups in both the resting and active states although SNAP was significantly reduced in SCI at rest.

Conclusions

We conclude that reduced SAI in SCI is likely attributed to neuroplasticity altering the intrinsic M1 circuitry mediating SAI and/or reduced afferent input traversing a direct thalamocortical route to M1. These data provide a new avenue of research aimed at identifying therapeutic approaches to alter SAI to improve upper limb function in individuals with SCI.