Genetics of Degenerative Cervical Myelopathy: A Systematic Review and Meta-Analysis of Candidate Gene Studies

APOE4 and prevalence of degenerative cervical myelopathy: A genetic case-control study in the UK Biobank cohort

INTRODUCTION

APOE ε4 expression mediates a pro-inflammatory response that has been associated with poorer outcomes in patients with degenerative cervical myelopathy (DCM). However, no study has yet assessed the association between APOE genotype and prevalence of DCM on a population level which may be useful for screening and treatment purposes.

METHODS

ICD-10 codes were used to ascertain DCM cases and positive control outcomes for which APOE ε4 is known to increase the odds (dementia, hypercholesterolemia and ischemic heart disease) and one negative control with no known association with APOE (diaphragmatic hernia). Multivariate logistic regression was performed of DCM or positive/negative control status against each APOE genotype (vs ε3ε3), adjusting for age, sex, array-type, assessment centre and measurement batch. Sensitivity analyses assessed the association between ε4 allele dosage (homozygous vs. heterozygous/ε4-negative) and DCM severity, indicated by cervical spine surgery history, short-term postoperative outcomes, number of hospital admissions, and critical care utilization within 6 months of DCM diagnosis.

RESULTS

Overall, 929 DCM cases were identified. The most prevalent APOE genotype was ε3ε3 (57.6%), followed by ε3ε4 (24.3%), ε2ε3 (12.2%), ε2ε4 (2.5%) and ε4ε4 (2.4%). In logistic regression, the ε4ε4 genotype was associated with increased odds of having DCM (OR 1.48, 95% CI 1.03-2.11). APOE genotypes showed the expected associations with positive and negative control disease outcomes. Sensitivity analyses revealed associations between ε4 and indicators of increased DCM severity, but these results did not reach statistical significance after accounting for multiple testing.

CONCLUSIONS

We found a strong positive association between APOE genotype and DCM status. The APOE ε4 variant may serve as a novel biomarker for screening high-risk individuals and as a personalized therapeutic target in DCM.

Transcriptomic imputation identifies tissue-specific genes associated with cervical myelopathy

BACKGROUND CONTEXT

Degenerative cervical myelopathy (DCM) is a progressive spinal condition that can lead to severe neurological dysfunction. Despite its degenerative pathophysiology, family history has shown to be a largely important factor in incidence and progression, suggesting that inherent genetic predisposition may play a role in pathophysiology.

PURPOSE

To determine the tissue-specific, functional genetic basis of hereditary predisposition to cervical myelopathy.

STUDY DESIGN

Retrospective case-control study using patient genetics and matched EHR from the Mount Sinai BioMe Biobank.

METHODS

In a large, diverse, urban biobank of 32,031 individuals, with 558 individuals with cervical myopathy, we applied transcriptomic imputation to identify genetically regulated gene expression signatures associated with DCM. We performed drug-repurposing analysis using the CMAP database to identify candidate therapeutic interventions to reverse the cervical myelopathy-associated gene signature.

RESULTS

We identified 16 genes significantly associated with DCM across 5 different tissues, suggesting tissue-specific manifestations of inherited genetic risk (upregulated: HES6, PI16, TMEM183A, BDH2, LINC00937, CLEC4D, USP43, SPATA1; downregulated: TTC12, CDK5, PAFAH1B2, RCSD1, KLHL29, PTPRG, RP11-620J15.3, C1RL). Drug repurposing identified 22 compounds with the potential to reverse the DCM-associated signature, suggesting points of therapeutic intervention.

CONCLUSIONS

The inherited genetic risk for cervical myelopathy is functionally associated with genes involved in tissue-specific nociceptive and proliferative processes. These signatures may be reversed by candidate therapeutics with nociceptive, calcium channel modulating, and antiproliferative effects.

CLINICAL SIGNIFICANCE

Understanding the genetic basis of DCM provides critical insights into the hereditary factors contributing to the disease, allowing for more personalized and targeted therapeutic approaches. The identification of candidate drugs through transcriptomic imputation and drug repurposing analysis offers potential new treatments that could significantly improve patient outcomes and quality of life by addressing the underlying genetic mechanisms of DCM.

Updates in current concepts in degenerative cervical myelopathy: a systematic review

Background

The incidence of degenerative cervical myelopathy (DCM) has increased over the years due to an increasing aging population, yet there is a dearth of recent comprehensive data evaluating the multiple facets of this degenerative condition. Recent publications have highlighted the biochemistry and biomechanics of DCM, which are paramount to understanding the degenerative nature of the condition and selecting the most optimal treatment options for improved patient outcomes. In addition, there have been recent studies establishing the superiority of surgical to non-surgical treatments for DCM, which until now was a poorly substantiated claim that has permeated the medical field for decades. The authors of this systematic review sought to collect and assess available high quality peer reviewed data to analyze the nature of DCM and gain a better understanding for its treatment choices.

Methods

PubMed and Cochrane Central Register of Controlled Trials were systematically searched on January 19, 2023 with date restrictions of 2015-2023 imposed. For initial data collection, five independent searches were completed using the following keywords: pathogenesis, pathophysiology, and epidemiology of DCM; cervical spondylotic myelopathy (CSM) and DCM recent developments; management and treatment for CSM and DCM; diagnosis and management of DCM; and pathophysiology of DCM. The results were screened for their application to DCM; any study that did not directly address DCM were identified and removed through abstract assessment, such studies included those pertaining to alternative fields including cardiology and psychiatry. Studies found relevant through full-text assessment and those published in English were included in this study and unpublished studies and studies found irrelevant based on titles and keywords were excluded from this study. The 115 articles that met criteria were critically appraised independently by the 2 reviewers and the principles of Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) were applied to assess the quality of evidence from each study.

Results

A total of 352 studies resulted from the original search. There were 71 duplicate articles that were removed and a total of 281 articles were screened. 166 articles were then removed based on the exclusion/inclusion criteria, title, and abstract. Of the 138 articles that remained, a final list of 115 articles was created based on the reporting measures.

Conclusions

DCM is a multifactorial disease that has the potential to impair neurological function and cause significant paralysis. Although the multiple facets of this disease have not been fully elucidated, there have been significant breakthroughs in understanding the mechanisms involved in this disease process. The use of complex imaging modalities, genetic sequencing, biomarkers, and pharmacological agents has provided insight into the factors involved in the progression of DCM, which has consequently cultivated more refined approaches for diagnosis and treatment of DCM.

We Choose to Call it 'Degenerative Cervical Myelopathy': Findings of AO Spine RECODE-DCM, an International and Multi-Stakeholder Partnership to Agree a Standard Unifying Term and Definition for a Disease

STUDY DESIGN

Modified DELPHI Consensus Process.

OBJECTIVE

To agree a single unifying term and definition. Globally, cervical myelopathy caused by degenerative changes to the spine is known by over 11 different names. This inconsistency contributes to many clinical and research challenges, including a lack of awareness.

METHOD

AO Spine RECODE-DCM (Research objectives and Common Data Elements Degenerative Cervical Myelopathy). To determine the index term, a longlist of candidate terms and their rationale, was created using a literature review and interviews. This was shared with the community, to select their preferred terms (248 members (58%) including 149 (60%) surgeons, 45 (18%) other healthcare professionals and 54 (22%) People with DCM or their supporters) and finalized using a consensus meeting. To determine a definition, a medical definition framework was created using inductive thematic analysis of selected International Classification of Disease definitions. Separately, stakeholders submitted their suggested definition which also underwent inductive thematic analysis (317 members (76%), 190 (59%) surgeons, 62 (20%) other healthcare professionals and 72 (23%) persons living with DCM or their supporters). Using this definition framework, a working definition was created based on submitted content, and finalized using consensus meetings.

RESULTS

Degenerative Cervical Myelopathy was selected as the unifying term, defined in short, as a progressive spinal cord injury caused by narrowing of the cervical spinal canal.

CONCLUSION

A consistent term and definition can support education and research initiatives. This was selected using a structured and iterative methodology, which may serve as an exemplar for others in the future.

The significance of metabolic disease in degenerative cervical myelopathy: a systematic review

Introduction

Degenerative cervical myelopathy (DCM) is a form of chronic spinal cord injury, with a natural history of potential for progression over time. Whilst driven by mechanical stress on the spinal cord from degenerative and congenital pathology, the neurological phenotype of DCM is likely to be modified by multiple systemic factors. The role of metabolic factors is therefore of interest, particularly given that ischaemia is considered a key pathological mechanism of spinal cord injury. The objective was therefore to synthesise current evidence on the effect of metabolism on DCM susceptibility, severity, and surgical outcomes.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English, with a focus on DCM and metabolism, including diabetes, cardiovascular disease, anaemia, and lipid profile, were eligible for inclusion. Risk of methodological bias was assessed using the Joanna Briggs Institute (JBI) critical assessment tools. Quality assessments were performed using the GRADE assessment tool. Patient demographics, metabolic factors and the relationships between metabolism and spinal cord disease, spinal column disease and post-operative outcomes were assessed.

Results

In total, 8,523 papers were identified, of which 57 met criteria for inclusion in the final analysis. A total of 91% (52/57) of included papers assessed the effects of diabetes in relation to DCM, of which 85% (44/52) reported an association with poor surgical outcomes; 42% of papers (24/57) discussed the association between cardiovascular health and DCM, of which 88% (21/24) reported a significant association. Overall, DCM patients with diabetes or cardiovascular disease experienced greater perioperative morbidity and poorer neurological recovery. They were also more likely to have comorbidities such as obesity and hyperlipidaemia.

Conclusion

Metabolic factors appear to be associated with surgical outcomes in DCM. However, evidence for a more specific role in DCM susceptibility and severity is uncertain. The pathophysiology and natural history of DCM are critical research priorities; the role of metabolism is therefore a key area for future research focus.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42021268814.

Machine Learning and Symptom Patterns in Degenerative Cervical Myelopathy: Web-Based Survey Study

BACKGROUND

Degenerative cervical myelopathy (DCM), a progressive spinal cord injury caused by spinal cord compression from degenerative pathology, often presents with neck pain, sensorimotor dysfunction in the upper or lower limbs, gait disturbance, and bladder or bowel dysfunction. Its symptomatology is very heterogeneous, making early detection as well as the measurement or understanding of the underlying factors and their consequences challenging. Increasingly, evidence suggests that DCM may consist of subgroups of the disease, which are yet to be defined.

OBJECTIVE

This study aimed to explore whether machine learning can identify clinically meaningful groups of patients based solely on clinical features.

METHODS

A survey was conducted wherein participants were asked to specify the clinical features they had experienced, their principal presenting complaint, and time to diagnosis as well as demographic information, including disease severity, age, and sex. K-means clustering was used to divide respondents into clusters according to their clinical features using the Euclidean distance measure and the Hartigan-Wong algorithm. The clinical significance of groups was subsequently explored by comparing their time to presentation, time with disease severity, and other demographics.

RESULTS

After a review of both ancillary and cluster data, it was determined by consensus that the optimal number of DCM response groups was 3. In Cluster 1, there were 40 respondents, and the ratio of male to female participants was 13:21. In Cluster 2, there were 92 respondents, with a male to female participant ratio of 27:65. Cluster 3 had 57 respondents, with a male to female participant ratio of 9:48. A total of 6 people did not report biological sex in Cluster 1. The mean age in this Cluster was 56.2 (SD 10.5) years; in Cluster 2, it was 54.7 (SD 9.63) years; and in Cluster 3, it was 51.8 (SD 8.4) years. Patients across clusters significantly differed in the total number of clinical features reported, with more clinical features in Cluster 3 and the least clinical features in Cluster 1 (Kruskal-Wallis rank sum test: χ22=159.46; P<.001). There was no relationship between the pattern of clinical features and severity. There were also no differences between clusters regarding time since diagnosis and time with DCM.

CONCLUSIONS

Using machine learning and patient-reported experience, 3 groups of patients with DCM were defined, which were different in the number of clinical features but not in the severity of DCM or time with DCM. Although a clearer biological basis for the clusters may have been missed, the findings are consistent with the emerging observation that DCM is a heterogeneous disease, difficult to diagnose or stratify. There is a place for machine learning methods to efficiently assist with pattern recognition. However, the challenge lies in creating quality data sets necessary to derive benefit from such approaches.

Natural history of degenerative cervical myelopathy: a meta-analysis and neurologic deterioration survival curve synthesis

BACKGROUND CONTEXT

Cervical spine surgery is rapidly increasing, and our knowledge of the natural history of degenerative cervical myelopathy (DCM) is limited.

PURPOSE

To synthesize accurate time-based estimates of meaningful neurologic decline in patients with DCM managed conservatively and to provide formulae to help communicate survivorship estimates to patients.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A systematic review and meta-analysis was conducted using Cochrane and PRISMA guidelines. A librarian-assisted search strategy using multiple databases with broad search terms and validated filter functions was used. All articles were reviewed in duplicate.

RESULTS

A total of 9570 studies were captured in the initial search, which after deletion of duplicates and manual review of abstracts and full texts revealed 6 studies for analyses. All studies were prospective cohorts or randomized controlled trials. The pooled survival estimates for neurologic stability (95% CrI) for mild DCM patients are: 91% (83%-97%) at one year; 85% (72%-94%) at 2 years; 84% (70%-94%) at 3 years; 75% (54%-90%) at 5 years; 66% (40%-86%) at 15 years; and 65% (39%-86%) at 20 years. The pooled survival estimates for neurologic stability (95% CrI) for moderate/severe DCM patients are: 83% (76%-89%) at 1 year; 72% (62%-81%) at 2 years; 71% (60%-80%) at 3 years; 55% (41%-68%) at 5 years; 44% (27%-59%) at 15 years; and 43% (25%-58%) at 20 years.

CONCLUSIONS

This is the first quantitative synthesis of the totality of published data on DCM natural history. Our review confirms a slow decline in neurologic function. We developed formulae which can be easily used by surgeons to communicate to patients their risk of neurologic deterioration. These formulae can be used to facilitate the shared decision-making process.

Is the type and/or co-existence of degenerative spinal pathology associated with the occurrence of degenerative cervical myelopathy? A single centre retrospective analysis of individuals with MRI defined cervical cord compression

BACKGROUND

Degenerative cervical myelopathy (DCM) arises from spinal degenerative changes injuring the cervical spinal cord. Most cord compression is incidental, referred to as asymptomatic spinal cord compression (ASCC). How and why ASCC differs from DCM is poorly understood. In this paper, we study a local cohort to identify specific types and groups of degenerative pathology more likely associated with DCM than ASCC.

METHODS

This study was a retrospective cohort analysis (IRB Approval ID: PRN10455). The frequency of degenerative findings between those with ASCC and DCM patients were compared using network analysis, hierarchical clustering, and comparison to existing literature to identify potential subgroups in a local cohort (N = 155) with MRI-defined cervical spinal cord compression. Quantitative measures of spinal cord compression (MSCC and MCC) were used to confirm their relevance.

RESULTS

ELF (8.7 %, 95 % CI 3.8-13.6 % vs 35.7 %, 95 % CI 27.4-44.0 %) Congenital Stenosis (3.9 %, 95 % CI 0.6-7.3 % vs 25.0 %, 95 % CI 17.5-32.5 %), and OPLL (0.0 %, 95 % CI 0.0-0.0 % vs 3.6 %, 95 % CI 0.3-6.8 %) were more likely in patients with DCM. Comparative network analysis indicated loss of lordosis was associated with ASCC, whilst ELF with DCM. Hierarchical Cluster Analysis indicated four sub-groups: multi-level disc disease with ELF, single-level disc disease without loss of lordosis and OPLL with DCM, and single-level disc disease with loss of lordosis with ASCC. Quantitative measures of cord compression were higher in groups associated with DCM, but similar in patients with single-level disc disease and loss of lordosis.

CONCLUSIONS

This study identified four subgroups based on degenerative pathology requiring further investigation.

Development of a validated search filter for Ovid Embase for degenerative cervical myelopathy

BACKGROUND

Degenerative cervical myelopathy (DCM) is a recently proposed umbrella term for symptomatic cervical spinal cord compression secondary to degeneration of the spine. Currently literature searching for DCM is challenged by the inconsistent uptake of the term 'DCM' with many overlapping keywords and numerous synonyms.

OBJECTIVES

Here, we adapt our previous Ovid medline search filter for the Ovid embase database, to support comprehensive literature searching. Both embase and medline are recommended as a minimum for systematic reviews.

METHODS

References contained within embase identified in our prior study formed a 'development gold standard' reference database (N = 220). The search filter was adapted for embase and checked against the reference database. The filter was then validated against the 'validation gold standard'.

RESULTS

A direct translation was not possible, as medline indexing for DCM and the keywords search field were not available in embase. We also used the 'focus' function to improve precision. The resulting search filter has 100% sensitivity in testing.

DISCUSSION AND CONCLUSION

We have developed a validated search filter capable of retrieving DCM references in embase with high sensitivity. In the absence of consistent terminology and indexing, this will support more efficient and robust evidence synthesis in the field.

Degenerative cervical myelopathy: Where have we been? Where are we now? Where are we going?

Degenerative cervical myelopathy (DCM), a recently coined term, encompasses a group of age-related and genetically associated pathologies that affect the cervical spine, including cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament (OPLL). Given the significant contribution of DCM to global disease and disability, there are worldwide efforts to promote research and innovation in this area. An AO Spine effort termed 'RECODE-DCM' was initiated to create an international multistakeholder consensus group, involving patients, caregivers, physicians and researchers, to focus on launching actionable discourse on DCM. In order to improve the management, treatment and results for DCM, the RECODE-DCM consensus group recently identified ten priority areas for translational research. The current article summarizes recent advancements in the field of DCM. We first discuss the comprehensive definition recently refined by the RECODE-DCM group, including steps taken to arrive at this definition and the supporting rationale. We then provide an overview of the recent advancements in our understanding of the pathophysiology of DCM and modalities to clinically assess and diagnose DCM. A focus will be set on advanced imaging techniques that may offer the opportunity to improve characterization and diagnosis of DCM. A summary of treatment modalities, including surgical and nonoperative options, is then provided along with future neuroprotective and neuroregenerative strategies. This review concludes with final remarks pertaining to the genetics involved in DCM and the opportunity to leverage this knowledge toward a personalized medicine approach.

Long-Term Survivorship of Cervical Spine Procedures; A Survivorship Meta-Analysis and Meta-Regression

STUDY DESIGN

Systematic Review.

OBJECTIVES

To conduct a meta-analysis on the survivorship of commonly performed cervical spine procedures to develop survival function curves for (i) second surgery at any cervical level, and (ii) adjacent level surgery.

METHODS

A systematic review of was conducted following PRISMA guidelines. Articles with cohorts of greater than 20 patients followed for a minimum of 36 months and with available survival data were included. Procedures included were anterior cervical discectomy and fusion (ACDF), cervical disc arthroplasty (ADR), laminoplasty (LAMP), and posterior laminectomy and fusion (PDIF). Reconstructed individual patient data were pooled across studies using parametric Bayesian survival meta-regression.

RESULTS

Of 1829 initial titles, 16 citations were included for analysis. 73 811 patients were included in the second surgery analysis and 2858 patients in the adjacent level surgery analysis. We fit a Log normal accelerated failure time model to the second surgery data and a Gompertz proportional hazards model to the adjacent level surgery data. Relative to ACDF, the risk of second surgery was higher with ADR and PDIF with acceleration factors 1.73 (95% CrI: 1.04, 2.80) and 1.35 (95% CrI: 1.25, 1.46) respectively. Relative to ACDF, the risk of second surgery was lower with LAMP with deceleration factor .06 (95% CrI: .05, .07). ADR decreased the risk of adjacent level surgery with hazard ratio .43 (95% CrI: .33, .55).

CONCLUSIONS

In cases of clinical equipoise between fusion procedures, our analysis suggests superior survivorship with anterior procedures. For all procedures, laminoplasty demonstrated superior survivorship.

Meeting the Shared Goals of a Student-Selected Component: Pilot Evaluation of a Collaborative Systematic Review

BACKGROUND

Research methodology is insufficiently featured in undergraduate medical curricula. Student-selected components are designed to offer some research opportunities but frequently fail to meet student or supervisor expectations, such as completion or publication. We hypothesized that a collaborative, educational approach to a systematic review (SR), whereby medical students worked together, may improve student experience and increase success.

OBJECTIVE

This study aimed to establish whether offering a small team of students the opportunity to take part in the screening phase of SRs led by an experienced postgraduate team could enhance the learning experience of students, overcome the barriers to successful research engagement, and deliver published output.

METHODS

Postgraduate researchers from the University of Cambridge led a team of 14 medical students to work on 2 neurosurgical SRs. One student was appointed as the lead for each SR. All students were provided with training on SR methodology and participated in title and abstract screening using Rayyan software. Students completed prepilot, midscreening, and postscreening questionnaires on their research background, perceptions, knowledge, confidence, and experience. Questions were scored on a Likert scale of 1 (strongly disagree) to 10 (strongly agree).

RESULTS

Of the 14 students involved, 29% (n=4) reported that they had received sufficient training in research methodology at medical school. Positive trends in student knowledge, confidence, and experience of SR methodology were noted across the 3 questionnaire time points. Mean responses to "I am satisfied with the level of guidance I am receiving," "I am enjoying being involved in the SR process," and "I could not gain this understanding of research from passive learning e.g., textbook or lecture" were greater than 8.0 at all time points. Students reported "being involved in this research has made me more likely to do research in the future" (mean 8.57, SD 1.50) and that "this collaborative SR improved my research experience" (mean 8.50, SD 1.56).

CONCLUSIONS

This collaborative approach appears to be a potentially useful method of providing students with research experience; however, it requires further evaluation.

Targeting patient recovery priorities in degenerative cervical myelopathy: design and rationale for the RECEDE-Myelopathy trial-study protocol

INTRODUCTION

Degenerative cervical myelopathy (DCM) is a common and disabling condition of symptomatic cervical spinal cord compression secondary to degenerative changes in spinal structures leading to a mechanical stress injury of the spinal cord. RECEDE-Myelopathy aims to test the disease-modulating activity of the phosphodiesterase 3/phosphodiesterase 4 inhibitor Ibudilast as an adjuvant to surgical decompression in DCM.

METHODS AND ANALYSIS

RECEDE-Myelopathy is a multicentre, double-blind, randomised, placebo-controlled trial. Participants will be randomised to receive either 60-100 mg Ibudilast or placebo starting within 10 weeks prior to surgery and continuing for 24 weeks after surgery for a maximum of 34 weeks. Adults with DCM, who have a modified Japanese Orthopaedic Association (mJOA) score 8-14 inclusive and are scheduled for their first decompressive surgery are eligible for inclusion. The coprimary endpoints are pain measured on a visual analogue scale and physical function measured by the mJOA score at 6 months after surgery. Clinical assessments will be undertaken preoperatively, postoperatively and 3, 6 and 12 months after surgery. We hypothesise that adjuvant therapy with Ibudilast leads to a meaningful and additional improvement in either pain or function, as compared with standard routine care.

STUDY DESIGN

Clinical trial protocol V.2.2 October 2020.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from HRA-Wales.The results will be presented at an international and national scientific conferences and in a peer-reviewed journals.

TRIAL REGISTRATION NUMBER

ISRCTN Number: ISRCTN16682024.

Dysregulation of metalloproteinases in spinal ligament degeneration

PURPOSE

Degenerative changes in the spinal ligaments, such as hypertrophy or ossification, are important pathophysiological mechanisms of secondary spinal stenosis and neurological compression. Extracellular matrix (ECM) remodeling is one of the major pathological changes in ligament degeneration, and in this remodeling, ECM proteinase-mediated degradation of elastin and collagen plays a vital role. Zinc-dependent endopeptidases, including matrix metalloproteinases (MMPs), a disintegrin and metalloproteinases (ADAMs), and ADAMs with thrombospondin-1 motifs (ADAMTSs) are key factors in ECM remodeling. This review aims to elucidate the underlying mechanisms of these metalloproteinases in the initiation and progression of spinal ligament degeneration.

METHODS

We clarify current literature on the dysregulation of MMPs/ADAMs/ADAMTS and their endogenous inhibitors in degenerative spinal ligament diseases. In addition, some instructive information was excavated from the raw data of the relevant high-throughput analysis.

RESULTS AND CONCLUSIONS

The dysregulation of metalloproteinases and their endogenous inhibitors may affect ligament degeneration by involving several interrelated processes, represented by ECM degradation, fibroblast proliferation, and osteogenic differentiation. Antagonists of the key targets of the processes may in turn ease ligament degeneration.

Evidence of impaired macroautophagy in human degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) is a common progressive disease of the spinal cord which can cause tetraplegia. Despite its prevalence, few studies have investigated the pathophysiology of DCM. Macroautophagy is a cellular process which degrades intracellular contents and its disruption is thought to contribute to many neurodegenerative diseases. The present study tests the hypothesis that macroautophagy is impaired in DCM. To address this, we utilised a collection of post-mortem cervical spinal cord samples and investigated seven DCM cases and five human controls. Immunohistochemical staining was used to visualise proteins involved in autophagy. This demonstrated significantly reduced numbers of LC3 puncta in cases versus controls (p = 0.0424). Consistent with reduced autophagy, we identified large aggregates of p62 in four of seven cases and no controls. Tau was increased in two of five cases compared to controls. BCL-2 was significantly increased in cases versus controls (p = 0.0133) and may explain this reduction in autophagy. Increased BCL-2 (p = 0.0369) and p62 bodies (p = 0.055) were seen in more severe cases of DCM. This is the first evidence that autophagy is impaired in DCM; the impairment appears greater in more severe cases. Further research is necessary to investigate whether macroautophagy has potential as a therapeutic target in DCM.

The Prevalence of Degenerative Cervical Myelopathy-Related Pathologies on Magnetic Resonance Imaging in Healthy/Asymptomatic Individuals: A Meta-Analysis of Published Studies and Comparison to a Symptomatic Cohort

Degenerative cervical myelopathy (DCM) is a progressive cervical spinal cord injury brought about by mechanical stress from degenerative changes in the cervical spine. It is typically diagnosed on clinical symptoms and examination findings together with MRI findings. In this study, we explore the significance of these degenerative pathology to onset of DCM by performing the first meta-analysis on the prevalence of degenerative features reported on MRI amongst healthy and asymptomatic populations and compare this to the prevalence of degenerative features reported on MRI amongst a symptomatic population calculated in a previous review. We conducted a systematic review and meta-analysis in accordance with PRISMA guidelines, cognizant of their adaptation for epidemiological studies. A search strategy was used to identify original research carrying out MRI screening of cervical spines of asymptomatic patients in MEDLINE and Embase from 1985 to present day. The search yielded a total of 1098 studies of which 17 were included in this meta-analysis covering a total of 5059 patients. Ossification of posterior longitudinal ligament (pooled asymptomatic prevalence of 0.4%, 95% Confidence Interval [0.1%, 0.8%]), enlargement of ligamentum flavum (pooled asymptomatic prevalence of 11.8%, 95% Confidence Interval [5.3%, 18.4%]) and degenerative multilevel disc pathology (pooled asymptomatic prevalence of 64.5%, 95% Confidence Interval [48.3%, 80.8%], I² 100%) were found to be significantly lower in asymptomatic populations. Symptomatic populations have a prevalence of 10.5% (95% Confidence Interval [7.7%, 13.3%]) for ossification of posterior longitudinal ligament, 56.8% (95% Confidence Interval [52.3%, 61.3%]) for enlargement of ligamentum flavum and 89.7% (95% Confidence Interval [86.9%, 92.5%]) for degenerative multilevel disc pathology [18]. Understanding the natural history of DCM is a recognised research priority, and whilst these perspectives require further evaluation, they may be of significant relevance to the evolving biomechanical understanding of the disease.

Degenerative Cervical Myelopathy: Development and Natural History [AO Spine RECODE-DCM Research Priority Number 2]

STUDY DESIGN

Narrative review.

OBJECTIVES

To discuss the current understanding of the natural history of degenerative cervical myelopathy (DCM).

METHODS

Literature review summarizing current evidence pertaining to the natural history and risk factors of DCM.

RESULTS

DCM is a common condition in which progressive arthritic disease of the cervical spine leads to spinal cord compression resulting in a constellation of neurological symptoms, in particular upper extremity dysfunction and gait impairment. Anatomical factors including cord-canal mismatch, congenitally fused vertebrae and genetic factors may increase individuals' risk for DCM development. Non-myelopathic spinal cord compression (NMSCC) is a common phenomenon with a prevalence of 24.2% in the healthy population, and 35.3% among individuals >60 years of age. Clinical radiculopathy and/or electrophysiological signs of cervical cord dysfunction appear to be risk factors for myelopathy development. Radiological progression of incidental Ossification of the Posterior Longitudinal Ligament (OPLL) is estimated at 18.3% over 81-months and development of myelopathy ranges between 0-61.5% (follow-up ranging from 40 to 124 months between studies) among studies. In patients with symptomatic DCM undergoing non-operative treatment, 20-62% will experience neurological deterioration within 3-6 years.

CONCLUSION

Current estimates surrounding the natural history of DCM, particularly those individuals with mild or minimal impairment, lack precision. Clear predictors of clinical deterioration for those treated with non-operative care are yet to be identified. Future studies are needed on this topic to help improve treatment counseling and clinical prognostication.

A New Framework for Investigating the Biological Basis of Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 5]: Mechanical Stress, Vulnerability and Time

STUDY DESIGN

Literature Review (Narrative).

OBJECTIVE

To propose a new framework, to support the investigation and understanding of the pathobiology of DCM, AO Spine RECODE-DCM research priority number 5.

METHODS

Degenerative cervical myelopathy is a common and disabling spinal cord disorder. In this perspective, we review key knowledge gaps between the clinical phenotype and our biological models. We then propose a reappraisal of the key driving forces behind DCM and an individual's susceptibility, including the proposal of a new framework.

RESULTS

Present pathobiological and mechanistic knowledge does not adequately explain the disease phenotype; why only a subset of patients with visualized cord compression show clinical myelopathy, and the amount of cord compression only weakly correlates with disability. We propose that DCM is better represented as a function of several interacting mechanical forces, such as shear, tension and compression, alongside an individual's vulnerability to spinal cord injury, influenced by factors such as age, genetics, their cardiovascular, gastrointestinal and nervous system status, and time.

CONCLUSION

Understanding the disease pathobiology is a fundamental research priority. We believe a framework of mechanical stress, vulnerability, and time may better represent the disease as a whole. Whilst this remains theoretical, we hope that at the very least it will inspire new avenues of research that better encapsulate the full spectrum of disease.

Establishing Diagnostic Criteria for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 3]

STUDY DESIGN

Narrative review.

OBJECTIVES

To discuss the importance of establishing diagnostic criteria in Degenerative Cervical Myelopathy (DCM), including factors that must be taken into account and challenges that must be overcome in this process.

METHODS

Literature review summarising current evidence of establishing diagnostic criteria for DCM.

RESULTS

Degenerative Cervical Myelopathy (DCM) is characterised by a degenerative process of the cervical spine resulting in chronic spinal cord dysfunction and subsequent neurological disability. Diagnostic delays lead to progressive neurological decline with associated reduction in quality of life for patients. Surgical decompression may halt neurologic worsening and, in many cases, improves function. Therefore, making a prompt diagnosis of DCM in order to facilitate early surgical intervention is a clinical priority in DCM.

CONCLUSION

There are often extensive delays in the diagnosis of DCM. Presently, no single set of diagnostic criteria exists for DCM, making it challenging for clinicians to make the diagnosis. Earlier diagnosis and subsequent specialist referral could lead to improved patient outcomes using existing treatment modalities.

The Role of Nutrition in Degenerative Cervical Myelopathy: A Systematic Review

Introduction

Degenerative cervical myelopathy (DCM) is the commonest cause of adult spinal cord impairment worldwide, encompassing chronic compression of the spinal cord, neurological disability and diminished quality of life. Evidence on the contribution of environmental factors is sparse; in particular, the role of nutrition in DCM is unknown. The objective of this review was to assess the effect of nutrition on DCM susceptibility, severity and surgical outcome.

Methods

A systematic review in MEDLINE and Embase was conducted following PRISMA guidelines. Full-text papers in English papers, focussing on cervical myelopathy and nutrition, published before January 2020 were considered eligible. Quality assessments were performed using the GRADE assessment tool. Patient demographics, nutritional factor and DCM outcomes measures were recorded. Relationships between nutritional factors, interventions and disease prognosis were assessed.

Results

In total, 5835 papers were identified of which 44 were included in the final analysis. DCM patients with pathological weight pre-operatively were more likely to see poorer improvements post-surgically. These patients experienced poorer physical and mental health improvements from surgery compared to normal weight patients and were more likely to suffer from post-operative complications such as infection, DVT, PE and hospital readmissions. Two trials reporting benefits of nutritional supplements were identified, with 1 suggesting Cerebrolysin to be significant in functional improvement. An unbalanced diet, history of alcohol abuse and malnourishment were associated with poorer post-operative outcome.

Conclusion

Although the overall strength of recommendation is low, current evidence suggests nutrition may have a significant role in optimising surgical outcome in DCM patients. Although it may have a role in onset and severity of DCM, this is a preliminary suggestion. Further work needs to be done on how nutrition is defined and measured, however, the beneficial results from studies with nutritional interventions suggest nutrition could be a treatment target in DCM.

Degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) frequently leads to severe neurologic disability but is still frequently underdiagnosed. One explanation may be the variability of the symptoms presented by the patients, from paresthesia to quadriplegia, making it another great masquerader. What do we know? How can we manage better these patients? We will review the keys points concerning its challenging diagnosis (clinical and radiologic), some of the recent discoveries about DCM, notably the underlying genetic mutations identified, linked to its pathophysiology, before addressing the consensual points concerning its management and the major evolutive risk: acute decompensation.

Degenerative Cervical Myelopathy and the Aging Spine: Introduction to the Special Issue

Degenerative Cervical Myelopathy (DCM) is the most common cause of spinal cord injury in the world, but despite this, there remains many areas of uncertainty regarding the management of the condition. This special issue was dedicated to presenting current research topics in DCM. Within this issue, 12 publications are presented, including an introductory narrative overview of DCM and 11 articles comprising 9 research papers and 2 systematic reviews focusing on different aspects, ranging from genetic factors to clinical assessments, imaging, sagittal balance, surgical treatment, and outcome prediction. These articles represented contributions from a diverse group of researchers coming from multiple countries, including Switzerland, Germany, Italy, United Kingdom, United States, South Korea, and Canada.