Molecular mechanisms of spinal cord dysfunction and cell death in the spinal hyperostotic mouse: implications for the pathophysiology of human cervical spondylotic myelopathy

Spinal cord perfusion is associated with microstructural damage in cervical spondylotic myelopathy patients who underwent cervical laminoplasty

OBJECTIVES

To investigate the association between spinal cord perfusion and microstructural damage in CSM patients who underwent cervical laminoplasty using MR dynamic susceptibility contrast (DSC), diffusion tensor imaging (DTI), and neurite orientation dispersion and density imaging (NODDI) techniques.

METHODS

A follow-up cohort study was conducted with 53 consecutively recruited CSM patients who had undergone cervical laminoplasty 12-14 months after the surgery from April 2016 to December 2016. Twenty-one aged-matched healthy volunteers were recruited as controls. For each patient, decompressed spinal cord levels were imaged on a 3.0-T MRI scanner by diffusion and DSC sequences to quantify the degrees of microstructural damage and perfusion conditions, respectively. The diffusion data were analyzed by DTI and NODDI models to produce diffusion metrics. Classic indicator dilution model was used to quantify the DSC metrics. Mann-Whitney U test was performed for comparison of diffusion metrics between patients and healthy controls. Pearson correlation was used to explore the associations between the metrics of spinal cord perfusion and microstructural damage.

RESULTS

DTI metrics, neurite density, and isotropic volume fraction had significant differences between postoperative patients and healthy controls. Pearson correlation test showed that SCBV was significantly positively correlated with RD, MD, and ODI, and negatively correlated with FA and NDI. SCBF was found to be significantly positively correlated with RD and MD, and negatively correlated with FA.

CONCLUSIONS

Increased spinal cord perfusion quantified by DSC is associated with microstructural damage assessed by diffusion MRI in CSM patients who underwent cervical laminoplasty.

CLINICAL RELEVANCE STATEMENT

This study found that the spinal cord perfusion is associated with microstructural damage in postoperative cervical spondylotic myelopathy patients, indicating that high perfusion may play a role in the pathophysiological process of cervical spondylotic myelopathy and deserves more attention.

KEY POINTS

• Spinal cord microstructural damage can be persistent despite the compression had been relieved 12-14 months after the cervical laminoplasty in cervical spondylotic myelopathy (CSM) patients. • Spinal cord perfusion is associated with microstructural damage in CSM patients after the cervical laminoplasty. • Inflammation in the decompressed spinal cord may be a cause of increased perfusion and is associated with microstructural damage during the recovery period of CSM.

Impaired communication at the neuromotor axis during Degenerative Cervical Myelopathy

Degenerative Cervical Myelopathy (DCM) is a progressive neurological condition characterized by structural alterations in the cervical spine, resulting in compression of the spinal cord. While clinical manifestations of DCM are well-documented, numerous unanswered questions persist at the molecular and cellular levels. In this study, we sought to investigate the neuromotor axis during DCM. We use a clinically relevant mouse model, where after 3 months of DCM induction, the sensorimotor tests revealed a significant reduction in both locomotor activity and muscle strength compared to the control group. Immunohistochemical analyses showed alterations in the gross anatomy of the cervical spinal cord segment after DCM. These changes were concomitant with the loss of motoneurons and a decrease in the number of excitatory synaptic inputs within the spinal cord. Additionally, the DCM group exhibited a reduction in the endplate surface, which correlated with diminished presynaptic axon endings in the supraspinous muscles. Furthermore, the biceps brachii (BB) muscle exhibited signs of atrophy and impaired regenerative capacity, which inversely correlated with the transversal area of remnants of muscle fibers. Additionally, metabolic assessments in BB muscle indicated an increased proportion of oxidative skeletal muscle fibers. In line with the link between neuromotor disorders and gut alterations, DCM mice displayed smaller mucin granules in the mucosa layer without damage to the epithelial barrier in the colon. Notably, a shift in the abundance of microbiota phylum profiles reveals an elevated Firmicutes-to-Bacteroidetes ratio-a consistent hallmark of dysbiosis that correlates with alterations in gut microbiota-derived metabolites. Additionally, treatment with short-chain fatty acids stimulated the differentiation of the motoneuron-like NSC34 cell line. These findings shed light on the multifaceted nature of DCM, resembling a synaptopathy that disrupts cellular communication within the neuromotor axis while concurrently exerting influence on other systems. Notably, the colon emerges as a focal point, experiencing substantial perturbations in both mucosal barrier integrity and the delicate balance of intestinal microbiota.

Increased blood flow of spinal cord lesion after decompression improves neurological recovery of degenerative cervical myelopathy: an intraoperative ultrasonography-based prospective cohort study

INTRODUCTION

Surgical decompression is a highly effective therapy for degenerative cervical myelopathy (DCM), but the mechanisms of neurological recovery following decompression remain unclear. This study aimed to evaluate the spinal cord blood flow status after sufficient decompression by intraoperative contrast-enhanced ultrasonography (CEUS) and to analyze the correlation between neurological recovery and postdecompressive spinal cord blood perfusion in DCM.

MATERIALS AND METHODS

Patients with multilevel DCM were treated by ultrasound-guided modified French-door laminoplasty using a self-developed rongeur. Neurological function was evaluated using the modified Japanese Orthopaedic Association (mJOA) score preoperatively and at 12 months postoperatively. Spinal cord compression and cervical canal enlargement before and after surgery were assessed by magnetic resonance imaging and computerized tomography. The decompression status was evaluated in real time by intraoperative ultrasonography, while the spinal cord blood flow after sufficient decompression was assessed by CEUS. Patients were categorized as favourable (≥50%) or unfavourable (<50%) recovery according to the recovery rate of the mJOA score at 12 months postoperatively.

RESULTS

Twenty-nine patients were included in the study. The mJOA scores were significantly improved in all patients from 11.2±2.1 preoperatively to 15.0±1.1 at 12 months postoperatively, with an average recovery rate of 64.9±16.2%. Computerized tomography and intraoperative ultrasonography confirmed adequate enlargement of the cervical canal and sufficient decompression of the spinal cord, respectively. CEUS revealed that patients with favourable neurological recovery had a greater increased blood flow signal in the compressive spinal cord segment after decompression.

CONCLUSIONS

In DCM, intraoperative CEUS can clearly reflect spinal cord blood flow. Patients with increased blood perfusion of the spinal cord lesion immediately after surgical decompression tended to achieve greater neurological recovery.

Zonisamide improves Fas/FasL-mediated apoptosis and inflammation in a degenerative cervical myelopathy rat model

Degenerative cervical myelopathy (DCM) is a severe condition of the spinal cord caused by chronic compression. However, no studies to date have examined the effects of zonisamide (ZNS) on DCM via the Fas/FasL-mediated pathway. The aim of this study was to investigate the effects of ZNS on a DCM rat model and to explore the potential mechanisms. First, 40 adult Sprague-Dawley rats were used to establish the DCM rat model and were individually divided into four groups: the Sham group, DCM model group (DCM), ZNS group (DCM model rats treated with ZNS, 30 mg/kg/day), and ZNS + CD95 group (DCM model rats treated with ZNS and CD95). Histopathology injury and cell apoptosis, Fas and Fas ligand (FasL) expression and Fas/FasL relative protein levels were detected by hematoxylin and eosin staining, TUNEL assay, and immunofluorescence and western blotting, respectively. The results of our study demonstrated that ZNS could promote motor recovery while reversing histopathological injury and cell apoptosis in DCM rats. Moreover, Iba-1, Fas and FasL expression in DCM rats was decreased, accompanied by a decrease in cleaved caspase-3/caspase-3, cleaved caspase-8/caspase-8, cleaved caspase-9/caspase-9, cleaved caspase-10/caspase-10 and B-cell lymphoma-2 (Bcl-2)/Bcl-2 associated X (Bax) levels. All these results revealed that ZNS attenuates DCM injury in a rat model via the regulation of Fas and FasL signaling. Our study indicated that ZNS had beneficial effects on DCM and thus provided a novel theoretical approach for subsequent academic and clinical research on DCM injury.

Neurovascular Unit Compensation from Adjacent Level May Contribute to Spontaneous Functional Recovery in Experimental Cervical Spondylotic Myelopathy

The progression and remission of cervical spondylotic myelopathy (CSM) are quite unpredictable due to the ambiguous pathomechanisms. Spontaneous functional recovery (SFR) has been commonly implicated in the natural course of incomplete acute spinal cord injury (SCI), while the evidence and underlying pathomechanisms of neurovascular unit (NVU) compensation involved in SFR remains poorly understood in CSM. In this study, we investigate whether compensatory change of NVU, in particular in the adjacent level of the compressive epicenter, is involved in the natural course of SFR, using an established experimental CSM model. Chronic compression was created by an expandable water-absorbing polyurethane polymer at C5 level. Neurological function was dynamically assessed by BBB scoring and somatosensory evoked potential (SEP) up to 2 months. (Ultra)pathological features of NVUs were presented by histopathological and TEM examination. Quantitative analysis of regional vascular profile area/number (RVPA/RVPN) and neuroglial cells numbers were based on the specific EBA immunoreactivity and neuroglial biomarkers, respectively. Functional integrity of blood spinal cord barrier (BSCB) was detected by Evan blue extravasation test. Although destruction of the NVU, including disruption of the BSCB, neuronal degeneration and axon demyelination, as well as dramatic neuroglia reaction, were found in the compressive epicenter and spontaneous locomotor and sensory function recovery were verified in the modeling rats. In particular, restoration of BSCB permeability and an evident increase in RVPA with wrapping proliferated astrocytic endfeet in gray matter and neuron survival and synaptic plasticity were confirmed in the adjacent level. TEM findings also proved ultrastructural restoration of the NVU. Thus, NVU compensation changes in the adjacent level may be one of the essential pathomechanisms of SFR in CSM, which could be a promising endogenous target for neurorestoration.

Rodent Models of Spinal Cord Injury: From Pathology to Application

Spinal cord injury (SCI) often has devastating consequences for the patient's physical, mental and occupational health. At present, there is no effective treatment for SCI, and appropriate animal models are very important for studying the pathological manifestations, injury mechanisms, and corresponding treatment. However, the pathological changes in each injury model are different, which creates difficulties in selecting appropriate models for different research purposes. In this article, we analyze various SCI models and introduce their pathological features, including inflammation, glial scar formation, axon regeneration, ischemia-reperfusion injury, and oxidative stress, and evaluate the advantages and disadvantages of each model, which is convenient for selecting suitable models for different injury mechanisms to study therapeutic methods.

Utility of Diffusion Basis Spectrum Imaging in Quantifying Baseline Disease Severity and Prognosis of Cervical Spondylotic Myelopathy

STUDY DESIGN

Prospective cohort study.

OBJECTIVE

The aim was to assess the association between diffusion tensor imaging (DTI) and diffusion basis spectrum imaging (DBSI) measures and cervical spondylotic myelopathy (CSM) clinical assessments at baseline and two-year follow-up.

SUMMARY OF BACKGROUND DATA

Despite advancements in diffusion-weighted imaging, few studies have examined associations between diffusion magnetic resonance imaging (MRI) markers and CSM-specific clinical domains at baseline and long-term follow-up.

MATERIALS AND METHODS

A single-center prospective cohort study enrolled 50 CSM patients who underwent surgical decompression and 20 controls from 2018 to 2020. At initial evaluation, all patients underwent diffusion-weighted MRI acquisition, followed by DTI and DBSI analyses. Diffusion-weighted MRI metrics assessed white matter integrity by fractional anisotropy, axial diffusivity, radial diffusivity, and fiber fraction. To improve estimations of intra-axonal anisotropic diffusion, DBSI measures intra-/extra-axonal fraction and intra-axonal axial diffusivity. DBSI also evaluates extra-axonal isotropic diffusion by restricted and nonrestricted fraction. Clinical assessments were performed at baseline and two-year follow-up and included the modified Japanese Orthopedic Association (mJOA); 36-Item Short Form Survey physical component summary (SF-36 PCS); SF-36 mental component summary; neck disability index; myelopathy disability index; and disability of the arm, shoulder, and hand. Pearson correlation coefficients were computed to compare associations between DTI/DBSI and clinical measures. A False Discovery Rate correction was applied for multiple comparisons testing.

RESULTS

At baseline presentation, of 36 correlations analyzed between DTI metrics and CSM clinical measures, only DTI fractional anisotropy showed a positive correlation with SF-36 PCS ( r =0.36, P =0.02). In comparison, there were 30/81 (37%) significant correlations among DBSI and clinical measures. Increased DBSI axial diffusivity, intra-axonal axial diffusivity, intra-axonal fraction, restricted fraction, and extra-axonal anisotropic fraction were associated with worse clinical presentation (decreased mJOA; SF-36 PCS/mental component summary; and increased neck disability index; myelopathy disability index; disability of the arm, shoulder, and hand). At latest follow-up, increased preoperative DBSI intra-axonal axial diffusivity and extra-axonal anisotropic fraction were significantly correlated with improved mJOA.

CONCLUSIONS

This findings demonstrate that DBSI measures may reflect baseline disease burden and long-term prognosis of CSM as compared with DTI. With further validation, DBSI may serve as a noninvasive biomarker following decompressive surgery.

LEVEL OF EVIDENCE

3.

Ultrastructural destruction of neurovascular unit in experimental cervical spondylotic myelopathy

Background and purpose

The pathogenesis of cervical spondylotic myelopathy (CSM) remains unclear. This study aimed to explore the ultrastructural pathology of neurovascular unit (NVU) during natural development of CSM.

Methods

A total of 24 rats were randomly allocated to the control group and the CSM group. Basso-Beattie-Bresnahan (BBB) scoring and somatosensory evoked potentials (SEP) were used as functional assessments. Hematoxylin-eosin (HE), toluidine blue (TB), and Luxol fast blue (LFB) stains were used for general structure observation. Transmission electron microscopy (TEM) was applied for investigating ultrastructural characteristics.

Results

The evident compression caused significant neurological dysfunction, which was confirmed by the decrease in BBB score and SEP amplitude, as well as the prolongation of SEP latency (P < 0.05). The histopathological findings verified a significant decrease in the amount of Nissl body and myelin area and an increase in vacuolation compared with the control group (P < 0.05). The TEM results revealed ultrastructural destruction of NVU in several forms, including: neuronal degeneration and apoptosis; disruption of axonal cytoskeleton (neurofilaments) and myelin sheath and dystrophy of axonal terminal with dysfunction mitochondria; degenerative oligodendrocyte, astrocyte, and microglial cell inclusions with degenerating axon and dystrophic dendrite; swollen microvascular endothelium and loss of tight junction integrity; corroded basement membrane and collapsed microvascular wall; and proliferated pericyte and perivascular astrocytic endfeet. In the CSM group, reduction was observed in the amount of mitochondria with normal appearance and the number of cristae per mitochondria (P < 0.05), while no substantial drop of synaptic vesicle number was seen (P > 0.05). Significant narrowing of microvascular lumen size was also observed, accompanied by growth in the vascular wall area, endothelial area, basement membrane thickness, astrocytic endfeet area, and pericyte coverage area (rate) (P < 0.05).

Conclusion

Altogether, the findings of this study demonstrated ultrastructural destruction of NVU in an experimental CSM model with dorsal-lateral compression, revealing one of the crucial pathophysiological mechanisms of CSM.

The influence of carotid atherosclerosis on surgical outcomes of patients with cervical spondylotic myelopathy: A retrospective study

The appearance of atherosclerosis in the carotid artery may be suggest the possibility of atherosclerosis in the spinal cord artery, which can cause spinal cord ischemia and further lead to neural element damage.According to the inclusion and exclude standard, there are 137 patients with cervical spondylotic myelopathy (CSM) incorporating retrospective analysis. These patients were consecutively admitted into The Second Hospital- Cheeloo College of Medicine-Shandong University from January 2016 to December 2018 and have accepted surgical treatment. All patients were examined by color Doppler ultrasound to detect carotid atherosclerosis before surgery. All patients were divided into 2 groups according to the presence or absence of carotid atherosclerosis: carotid atherosclerosis group (n = 88) and noncarotid atherosclerosis group (n = 49). All patients were followed up for at least 12 months after surgery. Demographic and surgery-related data were collected and analyzed to identify potential factors that affect the surgical outcomes in CSM.The average age of carotid atherosclerosis group (51 males and 37 females), and noncarotid atherosclerosis group (24 males and 25 females) were 62.02 ± 10.34 years (range, 38-85 years) and 49.61 ± 10.28 years (range, 26-67 years), respectively.In carotid atherosclerosis group: pre and postoperative modify Japanese Orthopedic Association Scores (mJOA score) were 11.58 ± 1.82 and 14.36 ± 1.64; the recovery rate of mJOA score was 45.57% ± 13.28%. In noncarotid atherosclerosis group: pre and postoperative mJOA score were 12.00 ± 2.11 and 15.04 ± 1.70; the recovery rate of mJOA score was 53.90% ± 13.22%. Univariate logistic regression analysis demonstrated that gender (P = .004), age ≥65 years (P = .001), duration of symptoms ≥12 months (P = .040), smoking history (P < .001), preoperative mJOA score ≤11 (P = .007) and carotid atherosclerosis (P = .004) were related to poor surgical outcomes. Multivariate logistic regression analysis showed significant correlations between poor surgical outcomes and age ≥65 years (P = .047), smoking history (P = .010), preoperative mJOA score ≤11 (P = .008) or carotid atherosclerosis (P = .047).Carotid atherosclerosis may be a risk factor for poor surgical outcomes in CSM.

Extent of cord pathology in the lumbosacral enlargement in non-traumatic versus traumatic spinal cord injury

This study compares remote neurodegenerative changes caudal to a cervical injury in degenerative cervical myelopathy (DCM) (i.e., non-traumatic) and incomplete traumatic spinal cord injury (tSCI) patients, using MRI-based tissue area measurements and diffusion tensor imaging (DTI). Eighteen mild to moderate DCM patients with sensory impairments (mJOA score: 16.2±1.9), 14 incomplete tetraplegic tSCI patients (AIS C&D), and 20 healthy controls were recruited. All participants received DTI and T2*-weighted scans in the lumbosacral enlargement (caudal to injury) and at C2/C3 (rostral to injury). MRI readouts included DTI metrics in the white matter (WM) columns and cross-sectional WM and gray matter area. One-way ANOVA with Tukey's post-hoc comparison (p<0.05) was used to assess group differences. In the lumbosacral enlargement, compared to DCM, tSCI patients exhibited decreased fractional anisotropy in the lateral (tSCI vs. DCM, -11.9%, p=0.007) and ventral WM column (-8.0%, p=0.021), and showed trend toward lower values in the dorsal column (-8.9%, p=0.068). At C2/C3, compared to controls, fractional anisotropy was lower in both groups in the dorsal (DCM vs. controls, -7.9%, p=0.024; tSCI vs. controls, -10.0%, p=0.007) and in the lateral column (DCM: -6.2%, p=0.039; tSCI: -13.3%, p<0.001), while tSCI patients had lower fractional anisotropy than DCM patients in the lateral column (-7.6%, p=0.029). WM areas were not different between patient groups but were lower compared to controls in the lumbosacral enlargement (DCM: -16.9%, p<0.001; tSCI, -10.5%, p=0.043) and at C2/C3 (DCM: -16.0%, p<0.001; tSCI: -18.1%, p<0.001). In conclusion, mild to moderate DCM and incomplete tSCI lead to similar degree of degeneration of the dorsal and lateral columns at C2/C3, but tSCI results in more widespread white matter damage in the lumbosacral enlargement. These remote changes are likely to contribute to the patients' impairment and recovery. DTI is a sensitive tool to assess remote pathological changes in DCM and tSCI patients.

Risk factors for the development of degenerative cervical myelopathy: a review of the literature

Degenerative cervical myelopathy (DCM) encompasses various pathological conditions causing spinal cord (SC) impairment, including spondylosis (multiple level degeneration), degenerative disc disease (DDD), ossification of the posterior longitudinal ligament (OPLL), and ossification of the ligamentum flavum (OLF). It is considered the most common cause of SC dysfunction among the adult population. The degenerative phenomena of DDD, spondylosis, OPLL and OLF, is likely due to both inter-related and distinct factors. Age, cervical alignment, and range of motion, as well as congenital factors such as cervical cord-canal mismatch due to congenital stenosis, Klippel-Feil, Ehler-Danlos, and Down syndromes have been previously reported as potential factors of risk for DCM. The correlation between some comorbidities, such as rheumatoid arthritis and movement disorders (Parkinson disease and cervical dystonia) and DCM, has also been reported; however, the literature remains scare. Other patient-specific factors including smoking, participation in contact sports, regular heavy load carrying on the head, and occupation (e.g. astronauts) have also been suggested as potential risk of myelopathy development. Most of the identified DCM risk factors remain poorly studied however. Further researches will be necessary to strengthen the current knowledge on the subject, especially concerning physical labors in order to identify patients at risk and to develop an effective treatment strategy for preventing this increasing prevalent disorder.

Inhibition of CDK1 attenuates neuronal apoptosis and autophagy and confers neuroprotection after chronic spinal cord injury in vivo

Chronic spinal cord injury (CSCI) results from progressive compression of the spinal cord over time. A variety of factors cause CSCI, and its exact pathogenesis is unknown. Cyclin-dependent kinase 1 (CDK1) is closely related to the apoptosis pathway, but no CSCI-related studies on CDK1 have been conducted. In this study, the role of CDK1 in CSCI was explored in a rat model. The CSCI model was established by screw compression using the cervical anterior approach for twelve weeks. The neurological function of the rats was evaluated using the neurological severity scores (NSS) and motor evoked potentials (MEPs). Pathological changes in spinal cord tissue were observed by hematoxylin-eosin (HE) staining, and Nissl staining was performed to assess the survival of motor neurons in the anterior horn of the spinal cord. Changes in autophagy and apoptosis in anterior horn of spinal cord tissue were detected using transmission electron microscopy and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, respectively. The expression levels of glial fibrillary acidic protein (GFAP), ionized calcium-binding adaptor (IBA) and choline acetyltransferase (CHAT) in the anterior horn were determined using immunohistochemistry assays to investigate astrocytes, microglia and motor neurons, respectively, in the anterior horn. Western blot assays were used to detect the expression levels of CDK1, Bcl-2, Bax, Caspase 3, LC3 and Beclin1. Changes in the expression of CDK1, LC3 and Beclin1 were also observed using immunohistochemistry. The results indicated that CSCI resulted in neuronal injury and a decrease in the NSS. In the CSCI model group, anterior horn astrocytes and microglia were activated, and motor neurons were decreased. Neuronal apoptosis was promoted, and the number of autophagic vacuoles was elevated. Rats treated with the CDK1 shRNA lentivirus exhibited better NSS, more surviving motor neurons, and fewer apoptotic neurons than the model rats. The occurrence of autophagy and the expression of proapoptotic and autophagy-related proteins were lower in the CDK1 shRNA group than the model group. In conclusion, CDK1 downregulation suppressed the activation of anterior horn astrocytes and microglia, promoted motor neuron repair, and inhibited neurons apoptosis and autophagy to promote the recovery of motor function after spinal cord injury.

Degenerative Cervical Myelopathy: Towards a Personalized Approach

Degenerative cervical myelopathy (DCM) is a recently coined term encompassing a variety of age-related and genetically associated pathologies, including cervical spondylotic myelopathy, degenerative disc disease, and ligamentous aberrations such as ossification of the posterior longitudinal ligament. All of these pathologies produce chronic compression of the spinal cord causing a clinical syndrome characterized by decreased hand dexterity, gait imbalance, and potential genitourinary or sensorimotor disturbances. Substantial variability in the underlying etiology of DCM and its natural history has generated heterogeneity in practice patterns. Ongoing debates in DCM management most commonly center around clinical decision-making, timing of intervention, and the ideal surgical approach. Pivotal basic science studies during the past two decades have deepened our understanding of the pathophysiologic mechanisms surrounding DCM. Growing knowledge of the key pathophysiologic processes will help us tailor personalized approaches in an increasingly heterogeneous patient population. This article focuses on summarizing the most exciting approaches in personalizing DCM patient treatments including biomarkers, factors affecting clinical decision-making, and choice of the optimal surgical approach. Throughout we provide a concise review on the conditions encompassing DCM and discuss the underlying pathophysiology of chronic spinal cord compression. We also provide an overview on clinical-radiologic diagnostic modalities as well as operative and nonoperative treatment strategies, thereby addressing knowledge gaps and controversies in the field of DCM.

Pathophysiological Changes and the Role of Notch-1 Activation After Decompression in a Compressive Spinal Cord Injury Rat Model

Surgical decompression is the primary treatment for cervical spondylotic myelopathy (CSM) patients with compressive spinal cord injury (CSCI). However, the prognosis of patients with CSCI varies, and the pathophysiological changes following decompression remain poor. This study aimed to investigate the pathophysiological changes and the role of Notch-1 activation after decompression in a rat CSCI model. Surgical decompression was conducted at 1 week post-injury (wpi). DAPT was intraperitoneally injected to down-regulate Notch-1 expression. Basso, Beattie, and Bresnahan scores and an inclined plane test were used to evaluate the motor function recovery. Hematoxylin and eosin staining was performed to assess pathophysiological changes, while hypoxia-inducible factor 1 alpha, vascular endothelial growth factor (VEGF), von Willebrand factor (vWF), matrix metalloproteinase (MMP)-9, MMP-2, Notch-1, and Hes-1 expression in the spinal cord were examined by immunohistochemical analysis or quantitative PCR. The results show that early decompression can partially promote motor function recovery. Improvements in structural and cellular damage and hypoxic levels were also observed in the decompressed spinal cord. Moreover, decompression resulted in increased VEGF and vWF expression, but decreased MMP-9 and MMP-2 expression at 3 wpi. Expression levels of Notch-1 and its downstream gene Hes-1 were increased after decompression, and the inhibition of Notch-1 significantly reduced the decompression-induced motor function recovery. This exploratory study revealed preliminary pathophysiological changes in the compressed and decompressed rat spinal cord. Furthermore, we confirmed that early surgical decompression partially promotes motor function recovery may via activation of the Notch-1 signaling pathway after CSCI. These results could provide new insights for the development of drug therapy to enhance recovery following surgery.

Clinical outcomes of epidural and intradural decompression for treatment of degenerative cervical myelopathy

Objective

This study was performed to examine the clinical outcomes of epidural and intradural decompression for degenerative cervical myelopathy.

Methods

The data for 13 patients who underwent epidural and intradural decompression for treatment of degenerative cervical myelopathy (study group) and 20 patients who underwent only cervical laminoplasty, fusion, and epidural decompression (historical control group) were retrospectively reviewed. The preoperative and postoperative neurological status was evaluated using the Japanese Orthopaedic Association (JOA) score.

Results

All patients’ neurological symptoms were significantly improved at the final follow-up. In the study group, the patients’ mean preoperative JOA score was 8.07 ± 1.80, and the final score improved by 70.88% ± 21.18%. The blood loss and operation time were significantly greater in the study group than control group. The recovery time was shorter in the study group than control group. The improvement rate was not significantly different between the two groups.

Conclusions

A pia mater incision with separation of the arachnoid adhesion can significantly improve the cerebrospinal fluid flow and spinal blood flow in degenerative cervical myelopathy. Arachnoid adhesion can lead to intradural spinal scar compression. The surgical intervention described herein can achieve satisfactory neurological outcomes and shorten the recovery time.

Echinacoside attenuates inflammatory response in a rat model of cervical spondylotic myelopathy via inhibition of excessive mitochondrial fission

Cervical spondylotic myelopathy (CSM) is a leading cause of spinal cord dysfunction with few treatment options. Although mitochondrial dynamics are linked to a wide range of pathological changes in neurodegenerative diseases, a connection between aberrant mitochondrial dynamics and CSM remains to be illuminated. In addition, mechanisms underlying the emerging anti-inflammatory and neuroprotective effects of echinacoside (ECH), the main active ingredient of Cistanche salsa, are poorly understood. We hypothesized that excessive mitochondrial fission plays a critical role in regulating inflammatory responses in CSM, and ECH might alleviate such responses by regulating mitochondrial dynamics. To this end, we assessed the effects of ECH and Mdivi-1, a selective inhibitor of dynamin-related protein (Drp1), in a rat model of chronic cervical cord compression and activated BV2 cells. Our results showed that rats with Mdivi-1 intervention had improved motor function compared with vehicle-treated rats. Indeed, Mdivi-1 treatment attenuated pro-inflammatory cytokine expression, as well as activation of the nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome, nuclear transcription factor-κB (NF-κB), and Drp1 in lesions. Compared with vehicle-treated rats, compression sites of Mdivi-1-treated animals exhibited elongated mitochondrial morphologies and reduced reactive oxygen species (ROS). Similarly, ECH-treated rats exhibited neurological recovery and suppression of inflammatory response or related signals in the lesion area after treatment. Interestingly, ECH treatment partly reversed aberrant mitochondrial fragmentation and oxidative stress within the lesion area. In vitro data suggested that ECH suppressed activated microglia by modulating activation of the NLRP3 inflammasome and NF-κB signaling. Furthermore, we observed that ECH markedly inhibited Drp1 translocation onto mitochondria, whereby it regulated mitochondrial dynamics and ROS production, which act as regulators of NLRP3 inflammasome activation and NF-κB signaling. Thus, our findings reveal that mitochondrial dynamics modulate inflammatory responses during CSM. Moreover, ECH may attenuate neuroinflammation in rats subjected to chronic cervical cord compression by regulating Drp1-dependent mitochondrial fission and activation of downstream signaling.

The Pathophysiology of Degenerative Cervical Myelopathy and the Physiology of Recovery Following Decompression

Background: Degenerative cervical myelopathy (DCM), also known as cervical spondylotic myelopathy is the leading cause of spinal cord compression in adults. The mainstay of treatment is surgical decompression, which leads to partial recovery of symptoms, however, long term prognosis of the condition remains poor. Despite advances in treatment methods, the underlying pathobiology is not well-known. A better understanding of the disease is therefore required for the development of treatments to improve outcomes following surgery. Objective: To systematically evaluate the pathophysiology of DCM and the mechanism underlying recovery following decompression. Methods: A total of 13,808 published articles were identified in our systematic search of electronic databases (PUBMED, WEB OF SCIENCE). A total of 51 studies investigating the secondary injury mechanisms of DCM or physiology of recovery in animal models of disease underwent comprehensive review. Results: Forty-seven studies addressed the pathophysiology of DCM. Majority of the studies demonstrated evidence of neuronal loss following spinal cord compression. A number of studies provided further details of structural changes in neurons such as myelin damage and axon degeneration. The mechanisms of injury to cells included direct apoptosis and increased inflammation. Only four papers investigated the pathobiological changes that occur in spinal cords following decompression. One study demonstrated evidence of axonal plasticity following decompressive surgery. Another study demonstrated ischaemic-reperfusion injury following decompression, however this phenomenon was worse when decompression was delayed. Conclusions: In preclinical studies, the pathophysiology of DCM has been poorly studied and a number of questions remain unanswered. The physiological changes seen in the decompressed spinal cord has not been widely investigated and it is paramount that researchers investigate the decompressed spinal cord further to enable the development of therapeutic tools, to enhance recovery following surgery.

Muscone suppresses inflammatory responses and neuronal damage in a rat model of cervical spondylotic myelopathy by regulating Drp1-dependent mitochondrial fission

Cervical spondylotic myelopathy (CSM) is a common cause of disability with few treatments. Aberrant mitochondrial dynamics play a crucial role in the pathogenesis of various neurodegenerative diseases. Thus, regulation of mitochondrial dynamics may offer therapeutic benefit for the treatment of CSM. Muscone, the active ingredient of an odoriferous animal product, exhibits anti-inflammatory and neuroprotective effects for which the underlying mechanisms remain obscure. We hypothesized that muscone might ameliorate inflammatory responses and neuronal damage by regulating mitochondrial dynamics. To this end, the effects of muscone on a rat model of chronic cervical cord compression, as well as activated BV2 cells and injured neurons, were assessed. The results showed that muscone intervention improved motor function compared with vehicle-treated rats. Indeed, muscone attenuated pro-inflammatory cytokine expression, neuronal-apoptosis indicators in the lesion area, and activation of the nod-like receptor family pyrin domain-containing 3 inflammasome, nuclear transcription factor-κB, and dynamin-related protein 1 in Iba1- and βIII-tubulin-labeled cells. Compared with vehicle-treated rats, compression sites of muscone-treated animals exhibited elongated mitochondrial morphologies in individual cell types and reduced reactive oxygen species. In vitro results indicated that muscone suppressed microglial activation and neuronal damage by regulating related-inflammatory or apoptotic molecules. Moreover, muscone inhibited dynamin-related protein 1 activation in activated BV2 cells and injured neurons, whereby it rescued mitochondrial fragmentation and reactive oxygen species production, which regulate a wide range of inflammatory and apoptotic molecules. Our findings reveal that muscone attenuates neuroinflammation and neuronal damage in rats with chronic cervical cord compression by regulating mitochondrial fission events, suggesting its promise for CSM therapy.

Degenerative cervical myelopathy - update and future directions

Degenerative cervical myelopathy (DCM) is the leading cause of spinal cord dysfunction in adults worldwide. DCM encompasses various acquired (age-related) and congenital pathologies related to degeneration of the cervical spinal column, including hypertrophy and/or calcification of the ligaments, intervertebral discs and osseous tissues. These pathologies narrow the spinal canal, leading to chronic spinal cord compression and disability. Owing to the ageing population, rates of DCM are increasing. Expeditious diagnosis and treatment of DCM are needed to avoid permanent disability. Over the past 10 years, advances in basic science and in translational and clinical research have improved our understanding of the pathophysiology of DCM and helped delineate evidence-based practices for diagnosis and treatment. Surgical decompression is recommended for moderate and severe DCM; the best strategy for mild myelopathy remains unclear. Next-generation quantitative microstructural MRI and neurophysiological recordings promise to enable quantification of spinal cord tissue damage and help predict clinical outcomes. Here, we provide a comprehensive, evidence-based review of DCM, including its definition, epidemiology, pathophysiology, clinical presentation, diagnosis and differential diagnosis, and non-operative and operative management. With this Review, we aim to equip physicians across broad disciplines with the knowledge necessary to make a timely diagnosis of DCM, recognize the clinical features that influence management and identify when urgent surgical intervention is warranted.

Traumatic and nontraumatic spinal cord injury: pathological insights from neuroimaging

Pathophysiological changes in the spinal cord white and grey matter resulting from injury can be observed with MRI techniques. These techniques provide sensitive markers of macrostructural and microstructural tissue integrity, which correlate with histological findings. Spinal cord MRI findings in traumatic spinal cord injury (tSCI) and nontraumatic spinal cord injury - the most common form of which is degenerative cervical myelopathy (DCM) - have provided important insights into the pathophysiological processes taking place not just at the focal injury site but also rostral and caudal to the spinal injury. Although tSCI and DCM have different aetiologies, they show similar degrees of spinal cord pathology remote from the injury site, suggesting the involvement of similar secondary degenerative mechanisms. Advanced quantitative MRI protocols that are sensitive to spinal cord pathology have the potential to improve diagnosis and, more importantly, predict outcomes in patients with tSCI or nontraumatic spinal cord injury. This Review describes the insights into tSCI and DCM that have been revealed by neuroimaging and outlines current activities and future directions for the field.

Role of macrophages and activated microglia in neuropathic pain associated with chronic progressive spinal cord compression

Neuropathic pain (NeP) is commonly encountered in patients with diseases associated with spinal cord damage (e.g., spinal cord injury (SCI) and compressive myelopathy). Recent studies described persistent glial activation and neuronal hyperactivity in SCI, but the pathomechanisms of NeP in chronic compression of the spinal cord remains elusive. The purpose of the present study was to determine the roles of microglia and infiltrating macrophages in NeP. The study was conducted in chimeric spinal hyperostotic mice (ttw/ttw), characterized by chronic progressive compression of the spinal cord as a suitable model of human compressive myelopathy. The severity of spinal cord compression correlated with proportion of activated microglia and hematogenous macrophages. Spinal cord compression was associated with overexpression of mitogen-activated protein kinases (MAPKs) in infiltrating macrophages and reversible blood-spinal cord barrier (BSCB) disruption in the dorsal horns. Our results suggested that chronic neuropathic pain in long-term spinal cord compression correlates with infiltrating macrophages, activated microglial cells and the associated damage of BSCB, together with overexpression of p-38 MAPK and p-ERK1/2 in these cells. Our findings are potentially useful for the design of new therapies to alleviate chronic neuropathic pain associated with compressive myelopathy.

Microarray analysis of apoptosis gene expression in liver injury induced by chronic exposure to arsenic and high-fat diet in male mice

Rapid growth in the incidence of liver disease is largely attributable to lifestyle and environmental contaminants, which are often overlooked as the leading causes of this problem. Thus, the possible contribution of arsenic (As) to high-fat diet (HFD)-induced liver damage was examined via microarray analysis. To perform this experiment, a total number of 40 healthy adult male NMRI mice (22-30 g) were used. To this end, these animals were randomly assigned to four groups of 10. Oxidative stress and histopathological parameters were also evaluated in the liver of the mice exposed to a minimally cytotoxic concentration of As (50 ppm) in drinking water while being fed with a HFD for 20 weeks. Subsequently, apoptosis gene expression profiling was utilized via real-time (RT) PCR array analysis. The results showed that As had increased the amount of HFD-induced liver damage and consequently amplified changes in oxidative stress factors, histopathological parameters, as well as apoptosis pathway genes. Investigating the expression profile of apoptosis pathway genes similarly revealed that caspase-8, as a main upstream contributor to the apoptosis pathway, might play an important role in the induction of apoptosis generated by As and HFD. Ultimately, this study highlighted that As in drinking water could increase sensitivity in mice to HFD-induced liver disease through strengthening apoptosis pathway.

Degenerative Cervical Myelopathy; A Review of the Latest Advances and Future Directions in Management

The assessment, diagnosis, operative and nonoperative management of degenerative cervical myelopathy (DCM) have evolved rapidly over the last 20 years. A clearer understanding of the pathobiology of DCM has led to attempts to develop objective measurements of the severity of myelopathy, including technology such as multiparametric magnetic resonance imaging, biomarkers, and ancillary clinical testing. New pharmacological treatments have the potential to alter the course of surgical outcomes, and greater innovation in surgical techniques have made surgery safer, more effective and less invasive. Future developments for the treatment of DCM will seek to improve the diagnostic accuracy of imaging, improve the objectivity of clinical assessment, and increase the use of surgical technology to ensure the best outcome is achieved for each individual patient.

Multilevel critical stenosis with minimal functional deficits: a case of cervical spondylotic myelopathy

Introduction

We present a case of a previously asymptomatic and highly functional individual whose critical degenerative stenosis was exacerbated by recent trauma (motor vehicle accident), resulting in cervical spondylotic myelopathy.

Case presentation

A 57-year-old African-American man with no significant past medical history presented to the Orthopaedic Surgery outpatient clinic with mild neck discomfort, stiffness, and bilateral hand numbness 4 days after being involved in a motor vehicle accident. He ambulated without assistive devices and displayed a tandem gait pattern with normal cadence. He was minimally tender to palpation at the posterior cervical midline and paraspinal musculature with motor and sensory function intact bilaterally. Reflexes were hypoactive at C5, C6, C7, L4, and S1 bilaterally with positive Babinski signs bilaterally. Imaging revealed degenerative changes, spinal stenosis, and cord compression. The patient eventually underwent posterior cervical decompression and fusion from the C3 to the C6 level, with the only reported complication being transient loss of somatosensory evoked potential (SSEP) signals intra-operatively. In the postoperative period, the patient complained of stiffness in his left shoulder, elbow, and hand, as well as left hand palmar numbness and an inability to make a full fist. His complaints were managed with medication and physical therapy.

Discussion

This case report highlights the point that stenosis that occurs slowly over time is often well compensated, and patients are commonly asymptomatic at first glance. Often times, acute events tip patients from being asymptomatic to symptomatic, generally warranting invasive intervention to prevent further insults from causing permanent damage.

Cervical spondylotic myelopathy patients with prior cerebral infarction: Clinical characteristics, surgical outcomes and prognostic value of "prior cerebral infarction"

OBJECTIVE

To investigate the clinical characteristics and surgical outcomes of patients with cervical spondylotic myelopathy (CSM) and prior cerebral infarction (CI); to identify whether "prior CI" correlates with poor surgical outcomes.

PATIENTS AND METHODS

Twenty-two patients with CSM and prior CI were retrospectively reviewed and included as the CI group while 100 CSM patients without CI were included as the control group (matched for gender, age, symptom duration and surgical approach). Extensive demographic and surgery-related data for patients in both groups were collected and compared. Multivariate logistic regression analysis was performed to assess all potential factors affecting surgical outcomes.

RESULTS

Compared to the control group, the CI group had the following: significantly higher percentages of hypertension, "progressive myelopathy", "rapid progressive myelopathy" and "intramedullary T2-weighted hyperintensity on MRI"; lower mean "preoperative mJOA score" and "postoperative mJOA score"; higher percentages of "preoperative mJOA score ≤11″ and "recovery rate of mJOA score <50%". In the CI group, 14 patients had CI within 6 months before CSM, and their percentage of "rapid progressive myelopathy" was higher than that of patients who had CI over 6 months before CSM. Logistic regression analysis showed that smoking, "symptom duration ≥12 months", "T2-weighted hyperintensity" and "prior CI" correlated with poor surgical outcome.

CONCLUSION

Rapid progressive myelopathy with advanced neurological impairment and "intramedullary T2-weighted hyperintensity" are common in patients with CSM and prior CI. Surgical outcomes in these patients are poorer than those of ordinary CSM patients. "Prior CI" is a risk factor for predicting poor surgical outcomes.

Trends, Challenges, and Opportunities Regarding Research in Non-traumatic Spinal Cord Dysfunction

Background: Spinal cord dysfunction (SCDys) is caused by heterogeneous health conditions, and the incidence is increasing. Despite the growing interest in rehabilitation research for SCDys, research into SCDys faces many challenges. Objective: The objective of this project was to perform a clinical review of changes in SCDys research over the last 4 decades; identify challenges to conducting research in SCDys; and propose opportunities for improving research in SCDys. Methods: A triangulation approach was used for obtaining evidence: literature search (January 2017) using MEDLINE and Embase databases for publications in English (1974-2016) regarding SCDys; workshop discussions at the International Spinal Cord Society annual meeting, September 16, 2016, Vienna, Austria; and our collective expertise in SCDys clinical rehabilitation research. Results: There has been a substantial increase in publications on SCDys over the 4 decades, from 1,825 in 1974-1983 to 11,887 in the decade 2004-2013, along with an improvement in research methodology. Numerous challenges to research in SCDys rehabilitation were grouped into the following themes: (a) identification of cases; (b) study design and data collection; and (c) funding, preclinical, and international research. Opportunities for addressing these were identified. Conclusions: The increase in scientific publications on SCDys highlights the importance of this heterogeneous group among the research community. The overall lack of good quality epidemiological studies regarding incidence, prevalence, and survival in these patients serves as a benchmark for guiding improvements to inform evidence-based care and policy.

Methylprednisolone treatment enhances early recovery following surgical decompression for degenerative cervical myelopathy without compromise to the systemic immune system

Background

Degenerative cervical myelopathy (DCM) is caused by degenerative or congenital changes to the discs and soft tissues of the cervical spine, which leads to chronic compression of the spinal cord. The current treatment for moderate to severe DCM consists of surgical decompression, which, while effective in most cases, can result in neuroinflammation and spinal cord reperfusion injury, leading to perioperative neurological complications and suboptimal neurological recovery. The primary objective of this study was to assess, in a translationally relevant animal model of DCM, the efficacy of perioperative methylprednisolone (MP) in enhancing neurological recovery and to evaluate its effect on the inflammatory response following decompression.

Methods

DCM was induced in C57BL/6 mice. Briefly, an aromatic polyether material was implanted underneath the C5-C6 laminae to cause progressive compression of the cervical spinal cord due to focal ossification. Decompressive surgery was undertaken at 12 weeks post initial biomaterial implantation. Animals received one dose of MP (30 mg/kg) or vehicle 30 min before decompression and at 2 weeks after decompression. Acute analysis of secreted cytokines and spinal cord microvasculature was complemented with immunohistochemistry for glial and neuronal cell markers. Locomotor outcomes were measured using the CatWalk system. The composition of circulating white blood cells was analyzed by flow cytometry.

Results

A single dose of MP before decompression significantly sped locomotor recovery (*p < 0.05) and reduced the incidence of perioperative motor complications, without affecting the composition of circulating white blood cells. Histological assessment of the spinal cord showed significant neuronal preservation and a modest reduction in parenchymal inflammation.

Conclusions

Our data suggest that MP reduces perioperative neurological complications following decompressive surgery for DCM by protecting neurons from inflammation, without compromising the composition of circulating immune cells. We propose that MP, which is commonly used for neurological disorders including spinal cord injury, be considered as a perioperative adjunct to decompressive surgery to attenuate neurological complications.

Pathobiology of Degenerative Cervical Myelopathy

Degenerative cervical myelopathy (DCM) is a common spinal cord disease caused by chronic mechanical compression of the spinal cord. The mechanism by which mechanical stress results in spinal cord injury is poorly understood. The most common mechanisms involved in the pathobiology of DCM include apoptosis, inflammation, and vascular changes leading to loss of neurons, axonal degeneration, and myelin changes. However, the exact pathophysiologic mechanisms of DCM are unclear. A better understanding of the pathogenesis of DCM is required for the development of treatments to improve outcomes. This review highlights the mechanisms of injury and pathology in DCM.

ASK1 in neurodegeneration

Neurodegenerative diseases (NDDs) such as glaucoma, multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and Huntington's disease (HD) are characterized by the progressive loss of neurons, causing irreversible damage to patients. Longer lifespans may be leading to an increase in the number of people affected by NDDs worldwide. Among the pathways strongly impacting the pathogenesis of NDDs, oxidative stress, a condition that occurs because of an imbalance in oxidant and antioxidant levels, has been known to play a vital role in the pathophysiology of NDDs. One of the molecules activated by oxidative stress is apoptosis signal-regulating kinase 1 (ASK1), which has been shown to play a role in NDDs. ASK1 activation is regulated by multiple steps, including oligomerization, phosphorylation, and protein-protein interactions. In the oxidative stress state, reactive oxygen species (ROS) induce the dissociation of thioredoxin, a protein regulating cellular reduction and oxidation (redox), from the N-terminal region of ASK1, and ASK1 is subsequently activated by the oligomerization and phosphorylation of a critical threonine residue, leading to cell death. Here, we review experimental evidence that links ASK1 signaling with the pathogenesis of several NDDs. We propose that ASK1 may be a new point of therapeutic intervention to prevent or treat NDDs.

In vivo diffusion tensor imaging of chronic spinal cord compression : a rat model with special attention to the conus medullaris

Background Few studies have focused on diffusion tensor imaging (DTI) parameters of the conus medullaris after chronic compression in the cervical spinal cord. Purpose To discuss the correlation of DTI parameters between the chronically compressed cervical spinal cord and the conus medullaris in a rat model at different time points. Material and Methods Fifty female Sprague-Dawley rats were randomized into five groups: control group (group A), sham group (group B), and test groups C, D, and E (1, 2, and 3 weeks after compression, respectively). Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of the cervical spinal cord and conus medullaris were compared among different groups. Correlations of ADC and FA values of the cervical spinal cord with those of the conus medullaris were performed in all groups. Results The ADC values at the cervical spinal cord and conus medullaris in all test groups were higher than those of group A and B, while the FA values were lower. The ADC value of the cervical spinal cord was linearly correlated with that of the conus medullaris only in group D. There were no linear correlations of FA values between the cervical spinal cord and the conus medullaris in all test groups. Conclusion After compression of the cervical spinal cord, ADC values of the cervical spinal cord and conus medullaris in test group were significantly increased, while FA values were significantly decreased. The ADC value of the cervical spinal cord was linearly correlated with that of the conus medullaris at 2 weeks after compression.

Voxel-based analysis of grey and white matter degeneration in cervical spondylotic myelopathy

In this prospective study, we made an unbiased voxel-based analysis to investigate above-stenosis spinal degeneration and its relation to impairment in patients with cervical spondylotic myelopathy (CSM). Twenty patients and 18 controls were assessed with high-resolution MRI protocols above the level of stenosis. Cross-sectional areas of grey matter (GM), white matter (WM), and posterior columns (PC) were measured to determine atrophy. Diffusion indices assessed tract-specific integrity of PC and lateral corticospinal tracts (CST). Regression analysis was used to reveal relationships between MRI measures and clinical impairment. Patients showed mainly sensory impairment. Atrophy was prominent within the cervical WM (13.9%, p = 0.004), GM (7.2%, p = 0.043), and PC (16.1%, p = 0.005). Fractional anisotropy (FA) was reduced in the PC (−11.98%, p = 0.006) and lateral CST (−12.96%, p = 0.014). In addition, radial (+28.47%, p = 0.014), axial (+14.72%, p = 0.005), and mean (+16.50%, p = 0.001) diffusivities were increased in the PC. Light-touch score was associated with atrophy (R² = 0.3559, p = 0.020) and FA (z score 3.74, p = 0.003) in the PC, as was functional independence and FA in the lateral CST (z score 3.68, p = 0.020). This study demonstrates voxel-based degeneration far above the stenosis at a level not directly affected by the compression and provides unbiased readouts of tract-specific changes that relate to impairment.

Degenerative Cervical Myelopathy: Epidemiology, Genetics, and Pathogenesis

STUDY DESIGN

Review.

OBJECTIVE

To formally introduce "degenerative cervical myelopathy" (DCM) as the overarching term to describe the various degenerative conditions of the cervical spine that cause myelopathy. Herein, the epidemiology, pathogenesis, and genetics of conditions falling under this hypernym are carefully described.

SUMMARY OF BACKGROUND DATA

Nontraumatic, degenerative forms of cervical myelopathy represent the commonest cause of spinal cord impairment in adults and include cervical spondylotic myelopathy, ossification of the posterior longitudinal ligament, ossification of the ligamentum flavum, and degenerative disc disease. Unfortunately, there is neither a specific term nor a specific diagnostic International Classification of Diseases, Tenth Revision code to describe this collection of clinical entities. This has resulted in the inconsistent use of diagnostic terms when referring to patients with myelopathy due to degenerative disease of the cervical spine.

METHODS

Narrative review.

RESULTS

The incidence and prevalence of myelopathy due to degeneration of the spine are estimated at a minimum of 41 and 605 per million in North America, respectively. Incidence of cervical spondylotic myelopathy-related hospitalizations has been estimated at 4.04/100,000 person-years, and surgical rates seem to be rising. Pathophysiologically, myelopathy results from static compression, spinal malalignment leading to altered cord tension and vascular supply, and dynamic injury mechanisms. Occupational hazards, including transportation of goods by weight bearing on top of the head, and other risk factors may accelerate DCM development. Potential genetic factors include those related to MMP-2 and collagen IX for degenerative disc disease, and collagen VI and XI for ossification of the posterior longitudinal ligament. In addition, congenital anomalies including spinal stenosis, Down syndrome, and Klippel-Feil syndrome may predispose to the development of DCM.

CONCLUSION

Although DCMs can present as separate diagnostic entities, they are highly interrelated, frequently manifest concomitantly, present similarly from a clinical standpoint, and seem to be in part a response to compensate and improve stability due to progressive age and wear of the cervical spine. The use of the term "degenerative cervical myelopathy" is advocated.

LEVEL OF EVIDENCE

5.

Posterior surgical treatment of cervical spondylotic myelopathy: review article

BACKGROUND

Cervical spondylosis is now recognised as the leading cause of myelopathy and spinal cord dysfunction worldwide. Chronic spinal cord compression results in chronic inflammation, cellular apoptosis, and microvacular insufficiency, which are thought to the biologic basis for cervical spondylotic myelopathy (CSM).

QUESTIONS/PURPOSES

Our purpose was to address the key principles of CSM, including natural history and presentation, pathogenesis, optimal surgical approach, results and complication rates of posterior surgical approaches for CSM so that the rationale for addressing CSM by a posterior approach can be fully understood.

METHODS

We conducted a systematic search of PubMed/MEDLINE and the Cochrane Collaboration Library for literature published through February 2014 to identify articles that evaluated CSM and its management. Reasons for exclusion included patients with ossification of the posterior longitudinal ligament (OPLL), patients with degenerative disc disease without CSM, and patients with spine tumor, trauma and infection. Meeting abstracts/proceedings, white articles and editorials were additionally excluded.

RESULTS

The search strategy yielded 1,292 articles, which was reduced to 52 articles, after our exclusion criteria were introduced. CSM is considered to be a surgical disorder due to its progressive nature. There is currently no consensus in the literature whether multilevel spondylotic compression is best treated via an anterior or posterior surgical approach.

CONCLUSION

Multilevel CSM may be safely and effectively treated using a posterior approach, either by laminoplasty or with a laminectomy and fusion technique.

Application of magnetic resonance imaging in cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is the most common cause of spinal cord dysfunction and is caused by static or dynamic repeated compression of the spinal cord resulting from degenerative arthritis of the cervical spine and some biological injuries to the cervical spine. The T2 signal change on conventional magnetic resonance imaging (MRI) is most commonly associated with neurological deficits. Diffusion tensor imaging and MR spectroscopy show altered microstructure and biochemistry that reflect patient-specific pathogenesis and can be used to predict neurological outcome and response to intervention. Functional MRI can help to assess the neurological functional recovery after decompression surgery for CSM.

Alteration in chondroitin sulfate proteoglycan expression at the epicenter of spinal cord is associated with the loss of behavioral function in Tiptoe walking Yoshimura mice

The objective of this study was to explore the correlation between the alteration in chondroitin sulfate proteoglycan (CSPG) expression at the epicenter of spinal cord and the loss of behavioral function in tiptoe walking Yoshimura mice. The tiptoe walking Yoshimura mice (twy) and Institute of Cancer Research (ICR) mice, aged 20 and 26 weeks, were used in the present study. The behavior assessment, micro-computed tomography and immunofluorescent staining were performed. The compressed spinal cord was histologically analyzed. The results showed that the expression of CSPG was statistically higher at the compressed spinal cord for twy mice compared with that at the normal spinal cord for ICR mice. At the 26th week, a large ossification block at the posterior longitudinal ligament of C1-3 was obviously observed at the micro-CT image We observed the BMS Score was significantly correlated with the expression of glial fibrillary acidic protein, CSPG and hyaluronan (P < 0.05). These findings suggest that compression injury induces the higher CSPG expression at the compressed spinal cord in the twy mice. Furthermore, the alteration in CSPG expression at the epicenter of spinal cord is associated with the loss of behavioral function in twy mice.

Cytokine concentrations in the cerebrospinal fluid of great danes with cervical spondylomyelopathy

Background

Chronic inflammation is involved in the pathogenesis of human cervical spondylotic myelopathy and could also play a role in cervical spondylomyelopathy (CSM) in dogs.

Hypothesis/Objectives

That cerebrospinal fluid (CSF) cytokine concentrations would differ between clinically normal (control) and CSM‐affected Great Danes (GDs), with affected GDs showing higher levels of inflammatory cytokines, such as interleukin (IL)‐6 and monocyte chemoattractant protein‐1/chemokine ligand 2 (MCP‐1/CCL2).

Animals

Client‐owned GDs: 15 control, 15 CSM‐affected.

Methods

Prospective study. Dogs underwent cervical vertebral column magnetic resonance imaging and collection of CSF from the cerebellomedullary cistern. Cytokine concentrations were measured using a commercially available canine multiplex immunoassay. Cytokine concentrations were compared between groups. Associations with the administration of anti‐inflammatory medications, disease duration and severity, severity of spinal cord (SC) compression, and SC signal changes were investigated in affected GDs.

Results

Affected GDs had significantly lower MCP‐1/CCL2 (mean 138.03 pg/mL, 95% confidence interval [CI] = 114.85–161.20) than control GDs (212.89 pg/mL, 95% CI = 165.68–260.11, P = .028). In affected GDs, MCP‐1/CCL2 concentrations correlated inversely with the severity of SC compression. There were no associations with administration of anti‐inflammatory medications, disease duration, or disease severity. IL‐6 concentrations were significantly higher (2.20 pg/mL, 95% CI = 1.92–2.47, P < .001) in GDs with SC signal changes.

Conclusions and Clinical Importance

Lower MCP‐1/CCL2 in CSM‐affected GDs might compromise clearance of axonal and myelin debris, delay axon regeneration, and affect recovery. Higher IL‐6 in CSM‐affected GDs with SC signal changes suggests more severe inflammation in this group.

Enhanced p62 expression triggers concomitant autophagy and apoptosis in a rat chronic spinal cord compression model

Chronic spinal cord compression is the result of mechanical pressure on the spinal cord, which in contrast to traumatic spinal cord injury, leads to slowly progressing nerve degeneration. These two types of spinal cord injuries may trigger similar mechanisms, including motoric nerve cell apoptosis and autophagy, however, depending on differences in the underlying injury severity, nerve reactions may predominantly involve the conservation of function or the initiation of functions for the removal of irreversibly damaged cells. p62 is a multidomain adapter protein, which is involved in apoptosis and cell survival as well as autophagy, and is a common component of protein aggregations in neurodegenerative diseases. In the present study, a rat chronic spinal cord compression model was used, in which the spinal cord was progressively compressed for six weeks and then constantly compressed for another 10 weeks. As a result Basso, Beattie and Bresnahan locomotor scaling revealed a gradual score decrease until the 6th week followed by constant recovery until the 16th week after spinal cord compression was initiated. During the first eight weeks of the experiment, p62 and nuclear factor-κB (NF-κB) were increasingly expressed up to a constant plateau at 12-16 weeks, whereas caspase 3 exhibited a marginally enhanced expression at 8 weeks, however, reached a constant maximum peak 12-16 weeks after the beginning of spinal cord compression. It was hypothesized that, in the initial phase of spinal cord compression, enhanced p62 expression triggered NF-κB activity, directing the cell responses mainly to cell survival and autophagy, whereas following eight weeks of spinal cord compression, caspase 3 was additionally activated indicating cumulative elimination of irreversibly damaged nerve cells with highly activated autophagy.

Inflammatory cascades mediate synapse elimination in spinal cord compression

Background

Cervical compressive myelopathy (CCM) is caused by chronic spinal cord compression due to spondylosis, a degenerative disc disease, and ossification of the ligaments. Tip-toe walking Yoshimura (twy) mice are reported to be an ideal animal model for CCM-related neuronal dysfunction, because they develop spontaneous spinal cord compression without any artificial manipulation. Previous histological studies showed that neurons are lost due to apoptosis in CCM, but the mechanism underlying this neurodegeneration was not fully elucidated. The purpose of this study was to investigate the pathophysiology of CCM by evaluating the global gene expression of the compressed spinal cord and comparing the transcriptome analysis with the physical and histological findings in twy mice.

Methods

Twenty-week-old twy mice were divided into two groups according to the magnetic resonance imaging (MRI) findings: a severe compression (S) group and a mild compression (M) group. The transcriptome was analyzed by microarray and RT-PCR. The cellular pathophysiology was examined by immunohistological analysis and immuno-electron microscopy. Motor function was assessed by Rotarod treadmill latency and stride-length tests.

Results

Severe cervical calcification caused spinal canal stenosis and low functional capacity in twy mice. The microarray analysis revealed 215 genes that showed significantly different expression levels between the S and the M groups. Pathway analysis revealed that genes expressed at higher levels in the S group were enriched for terms related to the regulation of inflammation in the compressed spinal cord. M1 macrophage-dominant inflammation was present in the S group, and cysteine-rich protein 61 (Cyr61), an inducer of M1 macrophages, was markedly upregulated in these spinal cords. Furthermore, C1q, which initiates the classical complement cascade, was more upregulated in the S group than in the M group. The confocal and electron microscopy observations indicated that classically activated microglia/macrophages had migrated to the compressed spinal cord and eliminated synaptic terminals.

Conclusions

We revealed the detailed pathophysiology of the inflammatory response in an animal model of chronic spinal cord compression. Our findings suggest that complement-mediated synapse elimination is a central mechanism underlying the neurodegeneration in CCM.

Characterization of a cervical spinal cord hemicontusion injury in mice using the infinite horizon impactor

The majority of clinical spinal cord injuries (SCIs) are contusive and occur at the cervical level of the spinal cord. Most scientists and clinicians agree that the preclinical evaluation of novel candidate treatments should include testing in a cervical SCI contusion model. Because mice are increasingly used because of the availability of genetically engineered lines, we characterized a novel cervical hemicontusion injury in mice using the Infinite Horizon Spinal Cord Impactor (Precisions Systems & Instrumentation, Lexington, KY). In the current study, C57BL/6 mice received a hemicontusion injury of 75 kilodynes with or without dwell time in an attempt to elicit a sustained moderate-to-severe motor deficit. Hemicontusion injuries without dwell time resulted in sustained deficits of the affected forepaw, as revealed by a 3-fold decrease in usage during rearing, a ∼50% reduction in grooming scores, and retrieval of significantly fewer pellets on the Montoya staircase test. Only minor transient deficits were observed in grasping force. CatWalk analysis revealed reduced paw-print size and swing speed of the affected forelimb. Added dwell time of 15 or 30 sec significantly worsened behavioral outcome, and mice demonstrated minimal ability of grasping, paw usage, and overground locomotion. Besides worsening of behavioral deficits, added dwell time also reduced residual white and gray matter at the epicenter and rostral-caudal to the injury, including on the contralateral side of the spinal cord. Taken together, we developed and characterized a new hemicontusion SCI model in mice that produces sufficient and sustained impairments in gross and skilled forelimb function and produced primarily unilateral functional deficits.

Pathophysiology and natural history of cervical spondylotic myelopathy

STUDY DESIGN

This study is a combination of narrative and systematic review.

OBJECTIVE

Clinicians who deal with cervical spondylotic myelopathy (CSM) should be up-to-date with the emerging knowledge related to the cascade of pathobiological secondary events that take place under chronic cervical spinal cord compression. Moreover, by performing a systematic review, we aim to (1) describe the natural history and (2) determine potential risk factors that affect the progression of CSM.

SUMMARY OF BACKGROUND DATA

The pathophysiology, natural history, as well as the factors associated with clinical deterioration have not been fully described in CSM.

METHODS

For the first part of the study, a literature review was performed. To answer key questions 1 and 2 of the second goal, a systematic search was conducted in PubMed and the Cochrane Collaboration Library for articles published between January 1, 1956, and November 7, 2012. We included all articles that described the progression and outcomes of CSM for which no surgical intervention was given.

RESULTS

By performing a narrative literature review, we found that the assumption that acute traumatic spinal cord injury and CSM share a similar series of cellular and molecular secondary injury events was made in the past. However, recent advances in basic research have shown that the chronic mechanical compression results in secondary injury mechanisms that have distinct characteristics regarding the nature and the temporal profile compared with those of spinal cord injury. For the purpose of the systematic review, 10 studies yielding 16 publications met inclusion criteria for key questions 2 and 3. Moderate-strength evidence related to the natural history of CSM suggests that 20% to 60% of patients will deteriorate neurologically over time without surgical intervention. Finally, there is low-strength evidence indicating that the area of circumferential compression is associated with deteriorating neurological symptoms.

CONCLUSION

CSM has unique pathobiological mechanisms that mainly remain unexplored. Although the natural history of CSM can be mixed, surgical intervention eliminates the chances of the neurological deterioration. EVIDENCE-BASED CLINICAL RECOMMENDATIONS:

RECOMMENDATION

Evidence concerning the natural history of CSM suggests that 20% to 60% of patients will deteriorate neurologically over time without surgical intervention. Therefore, we recommend that patients with mild CSM be counseled regarding the natural history of CSM and have the option of surgical decompression explained.

OVERALL STRENGTH OF EVIDENCE

Moderate.

STRENGTH OF RECOMMENDATION

Strong. SUMMARY STATEMENTS: Chronic compression of the spinal cord results in progressive neural cell loss related to secondary mechanisms including apoptosis, neuroinflammation, and vascular disruption.

Advances in MR imaging for cervical spondylotic myelopathy

PURPOSE

To outline the pathogenesis of cervical spondylotic myelopathy (CSM), the correlative abnormalities observed on standard magnetic resonance imaging (MRI), the biological implications and current status of diffusion tensor imaging (DTI), and MR spectroscopy (MRS) as clinical tools, and future directions of MR technology in the management of CSM patients.

METHODS

A systematic review of the pathogenesis and current state-of-the-art in MR imaging technology for CSM was performed.

RESULTS

CSM is caused by progressive, degenerative, vertebral column abnormalities that result in spinal cord damage related to both primary mechanical and secondary biological injuries. The T2 signal change on conventional MRI is most commonly associated with neurological deficits, but tends not to be a sensitive predictor of recovery of function. DTI and MRS show altered microstructure and biochemistry that reflect patient-specific pathogenesis.

CONCLUSION

Advanced imaging techniques, including DTI and MRS, show higher sensitivity to microstructural and biochemical changes within the cord, and may aid in management of CSM patients.

The prevalence and phenotype of activated microglia/macrophages within the spinal cord of the hyperostotic mouse (twy/twy) changes in response to chronic progressive spinal cord compression: implications for human cervical compressive myelopathy

Background

Cervical compressive myelopathy, e.g. due to spondylosis or ossification of the posterior longitudinal ligament is a common cause of spinal cord dysfunction. Although human pathological studies have reported neuronal loss and demyelination in the chronically compressed spinal cord, little is known about the mechanisms involved. In particular, the neuroinflammatory processes that are thought to underlie the condition are poorly understood. The present study assessed the localized prevalence of activated M1 and M2 microglia/macrophages in twy/twy mice that develop spontaneous cervical spinal cord compression, as a model of human disease.

Methods

Inflammatory cells and cytokines were assessed in compressed lesions of the spinal cords in 12-, 18- and 24-weeks old twy/twy mice by immunohistochemical, immunoblot and flow cytometric analysis. Computed tomography and standard histology confirmed a progressive spinal cord compression through the spontaneously development of an impinging calcified mass.

Results

The prevalence of CD11b-positive cells, in the compressed spinal cord increased over time with a concurrent decrease in neurons. The CD11b-positive cell population was initially formed of arginase-1- and CD206-positive M2 microglia/macrophages, which later shifted towards iNOS- and CD16/32-positive M1 microglia/macrophages. There was a transient increase in levels of T helper 2 (Th2) cytokines at 18 weeks, whereas levels of Th1 cytokines as well as brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF) and macrophage antigen (Mac) −2 progressively increased.

Conclusions

Spinal cord compression was associated with a temporal M2 microglia/macrophage response, which may act as a possible repair or neuroprotective mechanism. However, the persistence of the neural insult also associated with persistent expression of Th1 cytokines and increased prevalence of activated M1 microglia/macrophages, which may lead to neuronal loss and demyelination despite the presence of neurotrophic factors. This understanding of the aetiopathology of chronic spinal cord compression is of importance in the development of new treatment targets in human disease.

A novel experimental model of cervical spondylotic myelopathy (CSM) to facilitate translational research

Cervical spondylotic myelopathy (CSM) is the most common form of spinal cord impairment in adults. However critical gaps in our knowledge of the pathobiology of this disease have limited therapeutic advances. To facilitate progress in the field of regenerative medicine for CSM, we have developed a unique, clinically relevant model of CSM in rats. To model CSM, a piece of synthetic aromatic polyether, to promote local calcification, was implanted microsurgically under the C6 lamina in rats. We included a sham group in which the material was removed 30s after the implantation. MRI confirmed postero-anterior cervical spinal cord compression at the C6 level. Rats modeling CSM demonstrated insidious development of a broad-based, ataxic, spastic gait, forelimb weakness and sensory changes. No neurological deficits were noted in the sham group during the course of the study. Spasticity of the lower extremities was confirmed by a significantly greater H/M ratio in CSM rats in H reflex recordings compared to sham. Rats in the compression group experienced significant gray and white matter loss, astrogliosis, anterior horn cell loss and degeneration of the corticospinal tract. Moreover, chronic progressive posterior compression of the cervical spinal cord resulted in compromise of the spinal cord microvasculature, blood-spinal cord barrier disruption, inflammation and activation of apoptotic signaling pathways in neurons and oligodendrocytes. Finally, CSM rats were successfully subjected to decompressive surgery as confirmed by MRI. In summary, this novel rat CSM model reproduces the chronic and progressive nature of human CSM, produces neurological deficits and neuropathological features accurately mimicking the human condition, is MRI compatible and importantly, allows for surgical decompression.

In vivo tracing of neural tracts in tiptoe walking Yoshimura mice by diffusion tensor tractography

STUDY DESIGN

Basic imaging experiment.

OBJECTIVE

To determine whether in vivo diffusion tensor tractography (DTT) can be used to evaluate the axonal disruption of the chronically compressed spinal cord in tiptoe walking Yoshimura (twy) mice.

SUMMARY OF BACKGROUND DATA

In cervical ossification of the posterior longitudinal ligament, axonal disruption results in motor and sensory functional impairment. Twy mice develop spontaneous calcification in the cervical ligaments, which causes chronic compression of the spinal cord. DTT is emerging as a powerful tool for tracing axonal fibers in vivo.

METHODS

Five twy mice were subjected to DTT at 6, 15, and 20 weeks of age. Magnetic resonance imaging was performed using a 7.0-Tesla magnet (Biospec 70/16; Billerica, MA) with a CryoProbe. Diffusion tensor images were analyzed using TrackVis (Massachusetts General Hospital, MA). Motor performance was evaluated by Rotarod treadmill test and Digigait analysis. Histological analysis was performed by hematoxylin-eosin staining and immunostaining for RT-97 and SMI-31.

RESULTS

High resolution DTT of twy mice in vivo was successful. A lower number of RT-97- or SMI-31-positive fibers were associated with more severe spinal cord compression, which was determined by observing the ligamentous calcification at the C2-C3 level in each twy mouse. The severity of canal stenosis based on magnetic resonance images was strongly correlated with the axial area of the spinal cord. The tract fiber (TF) ratio (the number of TFs at the C2-C3 level/the number of TFs at the C0-C1 level) was strongly correlated with the RT-97/SMI-31-positive area and with motor function (rotarod latency, stride length). Furthermore, a two-part linear regression analysis showed that canal stenosis around 50% to 60% caused a sharp decrease in the TF ratio before the deterioration of motor function.

CONCLUSION

We conclude that DTT could be useful for detecting the early changes associated with the compressed spinal cord in cervical ossification of the posterior longitudinal ligament.

Cervical spondylotic myelopathy: the clinical phenomenon and the current pathobiology of an increasingly prevalent and devastating disorder

Cervical spondylotic myelopathy (CSM) is a common disorder involving chronic progressive compression of the cervical spinal cord due to degenerative disc disease, spondylosis, or other degenerative pathology. CSM is the most common form of spinal cord impairment and causes functional decline leading to reduced independence and quality of life. Despite a sound understanding of the disease process, clinical presentation and management, a universal definition of CSM and a standardized index of severity are not currently used universally. Work is required to develop a definition and establish clinical predictors of progression to improve management of CSM. Despite advances in decompressive and reconstructive surgery, patients are often left with residual disability. Gaps in knowledge of the pathobiology of CSM have limited therapeutic advances to complement surgery. Although the histopathologic and pathophysiologic similarities between CSM and traumatic spinal cord injury have long been acknowledged, the unique pathomechanisms of CSM remain unexplored. Increased efforts to elucidate CSM pathobiology could lead to the discovery of novel therapeutic targets for human CSM and other spinal cord diseases. Here, the natural history of CSM, epidemiology, clinical presentation, and current methods of clinical management are reported, along with the current state of basic scientific research in the field.

Role of apoptosis in disease

Since the initial description of apoptosis, a number of different forms of cell death have been described. In this review we will focus on classic caspase-dependent apoptosis and its variations that contribute to diseases. Over fifty years of research have clarified molecular mechanisms involved in apoptotic signaling as well and shown that alterations of these pathways lead to human diseases. Indeed both reduced and increased apoptosis can result in pathology. More recently these findings have led to the development of therapeutic approaches based on regulation of apoptosis, some of which are in clinical trials or have entered medical practice.