Spinal cord compression is associated with brain plasticity in degenerative cervical myelopathy

Patterns of cortical thickness alterations in degenerative cervical myelopathy: associations with dexterity and gait dysfunctions

Degenerative cervical myelopathy (DCM) can lead to significant brain structural reorganization. The association between the cortical changes and specific motor symptoms in DCM has yet to be fully elucidated. We investigated the associations between cortical thickness changes with neurological symptoms, such as dexterity and gait abnormalities, in patients with DCM in a case-control study. A 3 Tesla MRI scanner was used to acquire high-resolution T1-weighted structural scans from 30 right-handed patients with DCM and 22 age-matched healthy controls. Pronounced cortical thinning was observed in DCM patients relative to healthy controls, particularly in the bilateral precentral and prefrontal gyri, left pars triangularis, left postcentral gyrus, right transverse temporal and visual cortices (P ≤ 0.04). Notably, cortical thickness in these regions showed strong correlations with objective motor deficits (P < 0.0001). Specifically, the prefrontal cortex, premotor area and supplementary motor area exhibited significant thickness reductions correlating with diminished dexterity (R2 = 0.33, P < 0.0007; R2 = 0.34, P = 0.005, respectively). Similarly, declines in gait function were associated with reduced cortical thickness in the visual motor and frontal eye field cortices (R2 = 0.39, P = 0.029, R2 = 0.33, P = 0.04, respectively). Interestingly, only the contralateral precuneus thickness was associated with the overall modified Japanese Orthopaedic Association (mJOA) scores (R2 = 0.29, P = 0.003). However, the upper extremity subscore of mJOA indicated an association with the visual cortex and the anterior prefrontal (R2 = 0.48, P = 0.002, R2 = 0.33, P = 0.0034, respectively). In conclusion, our findings reveal patterns of cortical changes correlating with motor deficits, highlighting the significance of combining objective clinical and brain imaging assessments for understanding motor network dysfunction in DCM.

Modular organization of functional brain networks in patients with degenerative cervical myelopathy

Previous studies have indicated that brain functional plasticity and reorganization in patients with degenerative cervical myelopathy (DCM). However, the effects of cervical cord compression on the functional integration and separation between and/or within modules remain unclear. This study aimed to address these questions using graph theory. Functional MRI was conducted on 46 DCM patients and 35 healthy controls (HCs). The intra- and inter-modular connectivity properties of the whole-brain functional network and nodal topological properties were then calculated using theoretical graph analysis. The difference in categorical variables between groups was compared using a chi-squared test, while that between continuous variables was evaluated using a two-sample t-test. Correlation analysis was conducted between modular connectivity properties and clinical parameters. Modules interaction analyses showed that the DCM group had significantly greater inter-module connections than the HCs group (DMN-FPN: t = 2.38, p = 0.02); inversely, the DCM group had significantly lower intra-module connections than the HCs group (SMN: t = - 2.13, p = 0.036). Compared to HCs, DCM patients exhibited higher nodal topological properties in the default-mode network and frontal-parietal network. In contrast, DCM patients exhibited lower nodal topological properties in the sensorimotor network. The Japanese Orthopedic Association (JOA) score was positively correlated with inter-module connections (r = 0.330, FDR p = 0.029) but not correlated with intra-module connections. This study reported alterations in modular connections and nodal centralities in DCM patients. Decreased nodal topological properties and intra-modular connection in the sensory-motor regions may indicate sensory-motor dysfunction. Additionally, increased nodal topological properties and inter-modular connection in the default mode network and frontal-parietal network may serve as a compensatory mechanism for sensory-motor dysfunction in DCM patients. This could provide an implicative neural basis to better understand alterations in brain networks and the patterns of changes in brain plasticity in DCM 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.

The efficacy of virtual reality technology for the postoperative rehabilitation of patients with cervical spondylotic myelopathy (CSM): a study protocol for a randomized controlled trial

BACKGROUND

Patients with cervical spondylosis myelopathy (CSM) may experience severe neurological dysfunction due to untimely spinal cord compression after surgery. These disorders may lead to sensory and motion disorders, causing considerable psychological distress. Recent studies found that virtual reality (VR) technology can be an effective tool for treating spinal cord injuries. Owing to this discovery, we developed an exploratory research project to investigate the impact of this intervention on the postoperative recovery of patients with CSM.

METHODS

The purpose of this randomized controlled trial was to evaluate the efficacy of combining VR technology with conventional rehabilitation strategies for the postoperative rehabilitation of patients with CSM. A total of 78 patients will be recruited and randomized to either the conventional rehabilitation group or the group subjected to VR technology combined with conventional rehabilitation strategies. The Japanese Orthopaedic Association (JOA) scale will be the main tool used, and secondary outcomes will be measured via the visual analogue scale (VAS), neck disability index (NDI), and functional MRI (fMRI). The data analysis will identify differences between the intervention and control groups as well as any relationship between the intragroup changes in the functional area of the brain and the subjective scale scores after the intervention.

DISCUSSION

The aim of this trial is to investigate the effect of VR training on the postoperative rehabilitation of patients with CSM after 12 intervention treatments. Positive and negative outcomes will help us better understand the effectiveness of the intervention and its neural impact. If effective, this study could provide new options for the postoperative rehabilitation of patients with CSM.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2300071544). Registered 17 May 2023, https://www.chictr.org.cn/ .

Brain MRI changes in degenerative cervical myelopathy: a systematic review

BACKGROUND

Degenerative cervical myelopathy (DCM) is the most common cause of adult spinal cord dysfunction globally. Associated neurological symptoms and signs have historically been explained by pathobiology within the cervical spine. However, recent advances in imaging have shed light on numerous brain changes in patients with DCM, and it is hypothesised that these changes contribute to DCM pathogenesis. The aetiology, significance, and distribution of these supraspinal changes is currently unknown. The objective was therefore to synthesise all current evidence on brain changes in DCM.

METHODS

A systematic review was performed. Cross-sectional and longitudinal studies with magnetic resonance imaging on a cohort of patients with DCM were eligible. PRISMA guidelines were followed. MEDLINE and Embase were searched to 28th August 2023. Duplicate title/abstract screening, data extraction and risk of bias assessments were conducted. A qualitative synthesis of the literature is presented as per the Synthesis Without Meta-Analysis (SWiM) reporting guideline. The review was registered with PROSPERO (ID: CRD42022298538).

FINDINGS

Of the 2014 studies that were screened, 47 studies were identified that used MRI to investigate brain changes in DCM. In total, 1500 patients with DCM were included in the synthesis, with a mean age of 53 years. Brain alterations on MRI were associated with DCM both before and after surgery, particularly within the sensorimotor network, visual network, default mode network, thalamus and cerebellum. Associations were commonly reported between brain MRI alterations and clinical measures, particularly the Japanese orthopaedic association (JOA) score. Risk of bias of included studies was low to moderate.

INTERPRETATION

The rapidly expanding literature provides mounting evidence for brain changes in DCM. We have identified key structures and pathways that are altered, although there remains uncertainty regarding the directionality and clinical significance of these changes. Future studies with greater sample sizes, more detailed phenotyping and longer follow-up are now needed.

FUNDING

ODM is supported by an Academic Clinical Fellowship at the University of Cambridge. BMD is supported by an NIHR Clinical Doctoral Fellowship at the University of Cambridge (NIHR300696). VFJN is supported by an NIHR Rosetrees Trust Advanced Fellowship (NIHR302544). This project was supported by an award from the Rosetrees Foundation with the Storygate Trust (A2844).

Brainstem and subcortical regions volume loss in patients with degenerative cervical myelopathy and its association with spinal cord compression severity

BACKGROUND

In recent years, structural and functional reorganization of the brain and changes in brainstem structural connectivity have been shown in patients with degenerative cervical myelopathy (DCM). We hypothesized that volume loss in the basal ganglia, thalami, and brainstem structures exists and is associated with spinal cord compression severity in patients with DCM.

METHODS

Forty-seven patients with DCM and 25 patients with cervical radiculopathy were evaluated using cervical spinal cord and brain magnetic resonance imaging (MRI). Brainstem structures, basal ganglia, and thalami volumes were evaluated with FreeSurfer and compared between groups with correction for individual intracranial volume, as well as patient age and sex. Additionally, spinal cord MRI data were analysed with the Spinal Cord Toolbox, and cross-sectional area (CSA) and fractional anisotropy (FA) values were calculated. Correlations between MR-morphometry data and spinal cord structural changes, as well as disease duration, were also evaluated in patients with DCM.

RESULTS

A statistically significant reduction in the volume of the whole brainstem was revealed in the DCM group compared to the radiculopathy group (p < 0.01, FDR-corrected). Additionally, reductions in medulla oblongata, pons and midbrain volumes were found in patients with DCM (p < 0.01, p < 0.01 and p < 0.05, respectively, FDR-corrected). Additionally, a trend in the loss of volume of the left putamen was found (p = 0.087, FDR-corrected). Furthermore, medulla oblongata volume was correlated with spinal cord compression severity (R = 0.54, adjusted p < 0.001) and white matter damage (R = 0.46, adjusted p < 0.05) in patients with DCM. Negative correlations between the duration of the disease and the severity of spinal cord compression (R = -0.42, adjusted p < 0.05) and white matter damage (R = -0.49, adjusted p < 0.05) were also revealed, as well as a trend toward a negative association between the duration of the disease and the volume of the medulla oblongata (R = -0.35; adjusted p < 0.1).

CONCLUSIONS

We revealed a reduction in the volume of brainstem structures in patients with DCM compared to patients with radiculopathy. Moreover, we found that these changes are associated with cord compression severity.

Quantitative MR Markers in Non-Myelopathic Spinal Cord Compression: A Narrative Review

Degenerative spinal cord compression is a frequent pathological condition with increasing prevalence throughout aging. Initial non-myelopathic cervical spinal cord compression (NMDC) might progress over time into potentially irreversible degenerative cervical myelopathy (DCM). While quantitative MRI (qMRI) techniques demonstrated the ability to depict intrinsic tissue properties, longitudinal in-vivo biomarkers to identify NMDC patients who will eventually develop DCM are still missing. Thus, we aim to review the ability of qMRI techniques (such as diffusion MRI, diffusion tensor imaging (DTI), magnetization transfer (MT) imaging, and magnetic resonance spectroscopy (1H-MRS)) to serve as prognostic markers in NMDC. While DTI in NMDC patients consistently detected lower fractional anisotropy and higher mean diffusivity at compressed levels, caused by demyelination and axonal injury, MT and 1H-MRS, along with advanced and tract-specific diffusion MRI, recently revealed microstructural alterations, also rostrally pointing to Wallerian degeneration. Recent studies also disclosed a significant relationship between microstructural damage and functional deficits, as assessed by qMRI and electrophysiology, respectively. Thus, tract-specific qMRI, in combination with electrophysiology, critically extends our understanding of the underlying pathophysiology of degenerative spinal cord compression and may provide predictive markers of DCM development for accurate patient management. However, the prognostic value must be validated in longitudinal studies.