Evidence of an inherited predisposition for cervical spondylotic myelopathy

Evaluation of Genetic and Nongenetic Risk Factors for Degenerative Cervical Myelopathy

STUDY DESIGN

Cohort study.

OBJECTIVE

We aimed to evaluate the associations of genetic and nongenetic factors with degenerative cervical myelopathy (DCM).

SUMMARY OF BACKGROUND DATA

There is mounting evidence for an inherited predisposition for DCM, but uncertainty remains regarding specific genetic markers involved. Similarly, nongenetic factors are thought to play a role.

MATERIALS AND METHODS

Using diagnosis codes from hospital records linked to the UK Biobank cohort, patients with cervical spondylosis were identified followed by the identification of a subset with DCM. Nongenetic variables evaluated included age, sex, race, Townsend deprivation index, body mass index, occupational demands, osteoporosis, and smoking. Genome-wide association analyses were conducted using logistic regression adjusted for age, sex, population principal components, and follow-up.

RESULTS

A total of 851 DCM cases out of 2787 cervical spondylosis patients were identified. Several nongenetic factors were independently associated with DCM including age [odds ratio (OR)=1.11, 95% CI=1.01-1.21, P =0.024], male sex (OR=1.63, 95% CI=1.37-1.93, P <0.001), and relative socioeconomic deprivation (OR=1.03, 95% CI=1.00-1.06, P =0.030). Asian race was associated with lower DCM risk (OR=0.44, 95% CI=0.22-0.85, P =0.014). We did not identify genome-wide significant (≤5×10 -8 ) single-nucleotide polymorphisms (SNPs) associated with DCM. The strongest genome-wide signals were at SNP rs67256809 in the intergenic region of the genes LINC02582 and FBXO15 on chromosome 18 ( P =1.12×10 -7 ) and rs577081672 in the GTPBP1 gene on chromosome 22 ( P =2.9×10 -7 ). No SNPs reported in prior DCM studies were significant after adjusting for replication attempts.

CONCLUSIONS

Increasing age, male sex, and relative socioeconomic deprivation were identified as independent risk factors for DCM, whereas Asian race was inversely associated. SNPs of potential interest were identified in GTPBP1 and an intergenic region on chromosome 18, but these associations did not reach genome-wide significance. Identification of genetic and nongenetic DCM susceptibility markers may guide understanding of DCM disease processes, inform risk, guide prevention and potentially inform surgical outcomes.

LEVEL OF EVIDENCE

Prognostic level III.

Genetic Variations in IL-1β, TNF-α, and TGF-β Associated with the Severity of Chronic Cervical Spondylitis in Patients

Chronic cervical spondylitis (CCS), a degenerative disorder of the spine, is known for causing disability among old and young people. Single-nucleotide polymorphisms (SNPs) in various cytokine genes have demonstrated an impactful association with several inflammatory disorders. In the present study, we have investigated the SNPs and allelic distribution of the three most prevalent cytokines genes, IL-1β (-511C/T), TNF-α (-308G/A), and TGF-β (-509C/T), along with serum levels of these cytokines in 252 subjects. SNPs were analyzed using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), and digested fragments were separated and visualized using agarose gel electrophoresis and Native Polyacrylamide gel electrophoresis (PAGE). The serum cytokine levels were analyzed with a flow cytometer using a customized multiplex bead-based assay. It was observed that these SNPs did not reflect the susceptibility to CCS but were associated with susceptibility to CCS. We found a significant association between the C/C and G/G genotypes and the C and G alleles of IL-1β and TNF-α, respectively, suggesting a lower risk of CCS. The frequency distribution of risk alleles (-511T) and (-308A) were simultaneously higher in CCS compared to the control, reflecting the susceptibility to CCS. TGF-β showed a significant association with disease susceptibility, along with a significant correlation between age and the chronicity of CCS. The serum cytokine levels were significantly different in CCS and controls.

The efficacy and safety of dry cupping in cervical spondylosis with optimization of cup application time - a randomized clinical trial

OBJECTIVES

Dry cupping therapy (DCT) is considered beneficial in the amelioration of cervical spondylosis (CS) symptoms in Unani medicine. Therefore, the focus of this study was to ascertain the efficacy of DCT and optimal cup application time duration for CS.

METHODS

It was a randomized clinical trial involving 45 participants with clinically diagnosed CS. The eligible subjects were randomly categorized into three groups, each having 15 participants. Each of the three groups, i.e., A, B, and C, received DCT daily for 15 days for 8 min, 10 min, and 12 min, respectively. All the participants were evaluated at the baseline, 7th, and 15th days of the trial using the neck disability index (NDI) as well as the visual analogue scale (VAS).

RESULTS

The baseline mean ± SD of NDI and VAS scores were significantly reduced in all the three groups at the end of the trial. Although all three groups were statistically equal in terms of NDI, group-C demonstrated greater efficacy in terms of VAS.

CONCLUSIONS

The per-protocol analysis showed that dry cupping effectively alleviated neck pain across all treatment groups. Although, this effect on neck disability index was statistically equal in all three groups, the 12-min protocol was more successful in reducing pain.

Evidence for excess familial clustering of Post Traumatic Stress Disorder in the US Veterans Genealogy resource

A genealogy of the United States has been record-linked to National Veteran's Health Administration (VHA) patient data to allow non-identifiable analysis of familial clustering. This genealogy, including over 70 million individuals linked to over 1 million VHA patients, is the largest such combined resource reported. Analysis of familial clustering among VHA patients diagnosed with Post Traumatic Stress Disorder (PTSD) allowed a test of the hypothesis of an inherited contribution to PTSD. PTSD is associated strongly with military service and extended familial clustering data have not previously been presented. PTSD-affected VHA patients with genealogy data were identified by presence of an ICD diagnosis code in the VHA medical record in at least 2 different years. The Genealogical Index of Familiality (GIF) method was used to compare the average relatedness of VHA patients diagnosed with PTSD with their expected average relatedness, estimated from randomly selected sets of matched linked VHA patient controls. Relative risks for PTSD were estimated in first-, second-, and third-degree relatives of PTSD patients who were also VHA patients, using sex and age-matched rates for PTSD estimated from all linked VHA patients. Significant excess pairwise relatedness, and significantly elevated risk for PTSD in first-, second-, and third-degree relatives was observed; multiple high-risk extended PTSD pedigrees were identified. The analysis provides evidence for excess familial clustering of PTSD and identified high-risk PTSD pedigrees. These results support an inherited contribution to PTSD predisposition and identify a powerful resource of high-risk PTSD pedigrees for predisposition gene identification.

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.

Degenerative Cervical Myelopathy: Insights into Its Pathobiology and Molecular Mechanisms

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

Prospects of cell replacement therapy for the treatment of degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) presents insidiously during middle-age with deterioration in neurological function. It accounts for the most common cause of non-traumatic spinal cord injury in developed countries and disease prevalence is expected to rise with the aging population. Whilst surgery can prevent further deterioration, biological therapies may be required to restore neurological function in advanced disease. Cell replacement therapy has been inordinately focused on treatment of traumatic spinal cord injury yet holds immense promise in DCM. We build upon this thesis by reviewing the pathophysiology of DCM as revealed by cadaveric and molecular studies. Loss of oligodendrocytes and neurons occurs via apoptosis. The tissue microenvironment in DCM prior to end-stage disease is distinct from that following acute trauma, and in many ways more favourable to receiving exogenous cells. We highlight clinical considerations for cell replacement in DCM such as selection of cell type, timing and method of delivery, as well as biological treatment adjuncts. Critically, disease models often fail to mimic features of human pathology. We discuss directions for translational research towards clinical application.

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.

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

Degenerative cervical myelopathy (DCM) is estimated to be the most common cause of adult spinal cord impairment. Evidence that is suggestive of a genetic basis to DCM has been increasing over the last decade. A systematic search was conducted in MEDLINE, EMBASE, Cochrane, and HuGENet databases from their origin up to 14th December 2019 to evaluate the role of single genes in DCM in its onset, clinical phenotype, and response to surgical intervention. The initial search yielded 914 articles, with 39 articles being identified as eligible after screening. We distinguish between those contributing to spinal column deterioration and those contributing to spinal cord deterioration in assessing the evidence of genetic contributions to DCM. Evidence regarding a total of 28 candidate genes was identified. Of these, 22 were found to have an effect on the radiological onset of spinal column disease, while 12 genes had an effect on clinical onset of spinal cord disease. Polymorphisms of eight genes were found to have an effect on the radiological severity of DCM, while three genes had an effect on clinical severity. Polymorphisms of six genes were found to have an effect on clinical response to surgery in spinal cord disease. There are clear genetic effects on the development of spinal pathology, the central nervous system (CNS) response to bony pathology, the severity of both bony and cord pathology, and the subsequent response to surgical intervention. Work to disentangle the mechanisms by which the genes that are reviewed here exert their effects, as well as improved quality of evidence across diverse populations is required for further investigating the genetic contribution to DCM.

Thunder-Fire Moxibustion for Cervical Spondylosis: A Systematic Review and Meta-Analysis

BACKGROUND

Cervical spondylosis (CS) refers to the degenerative changes in the cervical spinal column, which affect the majority of middle-aged and elderly people. Thunder-fire moxibustion originated from thunder-fire miraculous needle, which has been applied widely for treating pain syndromes for thousands of years. The aim of our research is to provide evidence to assess the efficacy and safety of thunder-fire moxibustion in treating CS. Methods and analysis. Retrieved literature databases included Cochrane Library, MEDLINE, Web of Science, EBSCO, EBASE, Springer, PubMed, WFDP, CNKI, VIP, and CBM. The period of retrieval was from the establishment of the database to December 2018. Randomized controlled trials which compared thunder-fire moxibustion and other therapies in CS were included. The quality of inclusive trials was accessed though a Cochrane risk of bias tool. According to the test results of heterogeneity, a random effect model or fixed effect model was used to analyze the data.

RESULTS

Meta-analysis was conducted for the total effective rate of thunder-fire moxibustion, traditional Chinese medicine syndrome score, pain score, satisfaction score, and score of the symptoms and functional rehabilitation of cervical vertigo. The analysis results were as follows: compared with other therapies, the efficacy of thunder-fire moxibustion was statistically significant, total effective rate increased (OR = 2.48; 95% CI [1.80, 3.41]; P < 0.00001), traditional Chinese medicine syndrome score decreased (SMD = -3.05; 95% CI[-4.18, -1.93]; P < 0.00001), traditional Chinese medicine syndrome score decreased (SMD = -3.05; 95% CI[-4.18, -1.93]; P < 0.00001), traditional Chinese medicine syndrome score decreased (SMD = -3.05; 95% CI[-4.18, -1.93]; P < 0.00001), traditional Chinese medicine syndrome score decreased (SMD = -3.05; 95% CI[-4.18, -1.93]; P < 0.00001), traditional Chinese medicine syndrome score decreased (SMD = -3.05; 95% CI[-4.18, -1.93].

CONCLUSION

Based on the existing evidence, the curative effect and safety of thunder-fire moxibustion on CS were statistically significant. We should interpret the results scrupulously because of the low evidence level. Large-scale, high-quality, rigorous RCTs with long-term follow-up should be performed in the future.

Role of MRI in Cervical Spondylotic Myelopathy with Other Pathological Findings: Case Report and Literature Review

Introduction

Cervical spondylotic myelopathy (CSM) is a neck condition that arises when the spinal cord becomes compressed due to the wear-and-tear changes that occur in the spine as we age.

Case report

The patient was a 52-year-old male, who complains of neck pain, paranesthesia in upper extremities, lower back pain and bilateral calf pain, muscle weakness in the lower and upper extremities, fatigue and general body pain that started four weeks ago associated with other clinical manifestation. Magnetic Resonance Imaging (MRI) of the cervical spine revealed canal stenosis and increased T2 signal within the spinal cord. CSM is a rare condition there are very few or no cases described in literature when CSM in C3/C4 is associated with a lack of B12 and other pathologies such as and hypoplasia of the mastoid air-cell with system maxillary sinus aplasia.

Conclusion

The case described in the present study suggested that the incidence of CSM may be correlated with VB12 deficiency, particularly for cases in which the clinical manifestations and the imaging do not fully match.

Modified expansive laminoplasty and fusion compared with anterior cervical surgeries in treating four-level cervical spondylotic myelopathy

Objective

To compare modified expansive laminoplasty and fusion (MELF) with anterior cervical corpectomy and fusion (ACCF), and anterior cervical discectomy and fusion (ACDF), in treating four-level cervical spondylotic myelopathy (CSM).

Methods

This retrospective study included patients with four-level CSM who had undergone surgery at the Affiliated Hospital of Qingdao University between January 2013 and May 2015. D-values, Cobb’s angle, Japanese Orthopaedic Association (JOA) score and quality of life (SF-36 scores) were compared between patients treated with ACCF/ACDF versus MELF.

Results

Twenty-six patients who underwent ACCF/ACDF and 26 who underwent MELF were included, and all showed bone fusion following treatment. The most common complications were dysphasia (12/26) in the ACCF/ACDF group and axial neck pain (7/26) in the MELF group. C5 nerve root palsy was not observed in either group. D value and Cobb’s angle changes showed that ACDF/ACCF was more effective in curve correction than MELF. Postoperative improvements in JOA and SF-36 scores were noted in both groups, with no statistically significant between-group differences.

Conclusion

Anterior and posterior approaches may produce similar clinical outcomes in the surgical management of four-level CSM. MELF may avoid known complications of the posterior approach.

Inciting Events Associated With Cervical Radiculopathy

BACKGROUND

Cervical radiculopathy (CR) is a clinical diagnosis defined as a combination of neck, shoulder, and arm pain, often accompanied by sensory and motor symptoms. CR is often caused by degenerative spine pathology associated with impingement of a cervical nerve root, and this pathology can be visualized using magnetic resonance imaging (MRI) or computed tomography (CT). [Correction added September 4, 2019, after online publication: 'computer tomography' corrected to 'computed tomography'] Factors that are associated with the onset of CR have not been explored.

OBJECTIVE

To investigate the types and frequencies of patient-reported inciting events associated with CR in patients with imaged-confirmed pathologies that correlate with symptoms.

DESIGN

Prospective observational case series.

SETTING

Two spine physiatry and three orthopedic spine surgery practices.

PATIENTS

One hundred twenty-two patients with symptoms suggestive of CR were recruited. Of these, 107 patients had MRI or CT evidence of cervical disk herniation or foraminal stenosis that correlated with symptoms and matched our inclusion criteria.

METHODS

We categorized patient-reported inciting events associated with onset of CR into six categories reflecting increasing severity of inciting event, and recorded the clinical characteristics, physical examination findings, pain intensity, and disability. We analyzed the characteristics of patients based on subgroups of inciting events.

RESULTS

Two-thirds of patients reported that they either awoke with symptoms or symptoms began without a memorable event, and one-third of patients reported inciting physical activity or trauma associated with the onset of CR. Clinical characteristics of CR were not influenced by categories of inciting events.

CONCLUSION

Most CR with correlating spine pathology was found to have onset without a specific inciting events. Furthermore, physical inciting events did not influence the severity of clinical manifestation of CR.

LEVEL OF EVIDENCE

IV.

Genetics Underlying an Individualized Approach to Adult Spinal Disorders

Adult spinal disorders are a significant cause of morbidity across the world and carry significant health and economic burdens. Genetic predispositions are increasingly considered for these conditions and are becoming understood. Advances in molecular technologies since the mid-1990s have made possible genetic characterizations of these diseases in many populations, and recent findings have provided insight into the underlying pathophysiologic mechanisms. These studies have made clear the genetic heterogeneity producing clinical phenotypes and suggest that individualized treatments are possible in the future. We review the genetics and heritability of cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament and perform a systematic review of the genetics of adult lumbar degenerative scoliotic deformity, highlighting recent discoveries and the potential for personalized future therapeutics for these patients.

Effects of brain derived neurotrophic factor Val66Met polymorphism in patients with cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is the leading cause of spinal cord related disability in the elderly. It results from degenerative narrowing of the spinal canal, which causes spinal cord compression. This leads to gait instability, loss of dexterity, weakness, numbness and urinary dysfunction. There has been indirect data that implicates a genetic component to CSM. Such a finding may contribute to the variety in presentation and outcome in this patient population. The Val66Met polymorphism, a mutation in the brain derived neurotrophic factor (BDNF) gene, has been implicated in a number of brain and psychological conditions, and here we investigate its role in CSM. Ten subjects diagnosed with CSM were enrolled in this prospective study. Baseline clinical evaluation using the modified Japanese Orthopaedic Association (mJOA) scale, Nurick and 36-Item Short Form Health Survey (SF-36) were collected. Each subject underwent objective testing with gait kinematics, as well as hand functioning using the Purdue Peg Board. Blood samples were analyzed for the BDNF Val66Met mutation. The prevalence of the Val66Met mutation in this study was 60% amongst CSM patients compared to 32% in the general population. Individuals with abnormal Met allele had worse baseline mJOA and Nurick scores. Moreover, baseline gait kinematics and hand functioning testing were worse compared to their wild type counterpart. BDNF Val66Met mutation has a higher prevalence in CSM compared to the general population. Those with BDNF mutation have a worse clinical presentation compared to the wild type counterpart. These findings suggest implication of the BDNF mutation in the development and severity of CSM.

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.

Genetics and heritability of cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament: results of a systematic review

STUDY DESIGN

Systematic review.

OBJECTIVE

To answer the following 3 clinical questions: (1) What is the evidence supporting a heritable predisposition for cervical spondylotic myelopathy (CSM) and ossification of the posterior longitudinal ligament (OPLL)? (2) What specific genetic polymorphisms have been associated with CSM and OPLL? (3) What is the evidence supporting a genetic basis for predicting postoperative outcomes for patients with CSM and OPLL?

SUMMARY OF BACKGROUND DATA

OPLL and CSM are thought to be multifactorial conditions resulting from a combination of environmental and genetic factors.

METHODS

A systematic review of the English language literature was undertaken for articles published between 1980 and November 7, 2012. The strength of evidence was determined by 2 independent reviewers using the Grading of Recommendation Assessment, Development and Evaluation (GRADE) criteria for studies addressing the first question of heritability and using the criteria set forth by the HuGENet Working Group in the Venice Interim Guidelines to address the last 2 questions of genetic association.

RESULTS

Of the 118 citations identified through the initial literature search, a total of 23 articles remained after application of inclusion/exclusion criteria. The 3 family association studies related to question 1 supported the principle of an inherited predisposition to CSM and OPLL; however, the strength of evidence supporting these findings was low. Within the 19 case-control studies related to question 2, 2 single nucleotide polymorphisms (COL6A1/Intron 32(-29) and COL11A2/Intron 6(-4)) were observed at higher frequencies in OPLL cases than in controls in more than 1 study and may be associated with its development. There was insufficient evidence to support an association between CSM and any specific single nucleotide polymorphism or haplotype or to support the association of specific gene alleles with postoperative CSM outcomes.

CONCLUSION

Existing family studies provide support for the principle of an inherited predisposition to CSM and OPLL. Multiple studies support the association of 2 collagen gene related single nucleotide polymorphisms with OPLL; however, there is insufficient evidence to support the association between CSM and any genetic polymorphism or to support a genetic predictor of surgical outcome. SUMMARY STATEMENTS: STATEMENT 1: Existing family studies provide support for the principle of an inherited predisposition to CSM and OPLL. STATEMENT 2: Two SNPs related to the collagen 6A1 gene (COL6A1/Intron 32(-29)) and the collagen 11A2 gene (COL11A2/Intron 6(-4)) have been associated with OPLL in multiple studies and may be associated with its development. STATEMENT 3: No statement can be made from the literature regarding the association of specific SNPs or haplotypes with CSM. STATEMENT 4: No statement can be made from the literature regarding genetic predictors of surgical outcome in the context of OPLL or CSM.

Risk factors for development of myelopathy in patients with cervical spondylotic cord compression

PURPOSE

To clarify risk factors for the development of myelopathy in patients with cervical spondylotic cord compression.

METHOD

The authors reviewed articles in which risk factors for the development of myelopathy in patients with cervical spondylotic cord compression were discussed. Ossification of the posterior longitudinal ligament (OPLL) was also reviewed as a disease which causes cervical cord compression to clarify pathomechanism of the development of myelopathy.

RESULTS

Cervical motion segment disorders are considered to be multifactorial, and developmental size of the canal and foramina, pathological encroachment, biomechanical effects, and circulatory deficiencies are always present to some degree. Static and dynamic factors should be considered for the development of myelopathy. To clarify the pathomechanism of the development of myelopathy in patients with cervical spondylotic spinal cord compression, the exact natural history of CSM should be understood.

CONCLUSION

Several predictable risk factors for the development of myelopathy have been proposed in CSM or OPLL studies, but they were not definitive. Further prospective population-based study is needed to clarify the mechanism.

Risk factors for development of cervical spondylotic myelopathy: results of a systematic review

Study design: Systematic review.

Study rationale: Cervical spondylotic myelopathy (CSM) is a common cause of spinal cord dysfunction that may be asymptomatic or may present with severe symptoms. Since CSM has an insidious manifestation, identification of risk factors associated with this condition may aid clinicians in monitoring high-risk patients and implementing appropriate management strategies.

Objective: To assess sociodemographic, clinical, radiographic, and genetic risk factors associated with presence of CSM in patients 18 years or older.

Methods: A systematic review of the literature was performed using PubMed, the National Guideline Clearinghouse Databases, and bibliographies of key articles to assess risk factors associated with CSM. Articles were reviewed by two independent reviewers based on predetermined inclusion and exclusion criteria. Each article was evaluated using a predefined quality-rating scheme.

Results: From 486 citations, eight articles met all inclusion and exclusion criteria. Larger vertebral body and smaller spinal canal and Torg/Pavlov ratio were associated with CSM diagnosis, while gender was not associated with a CSM diagnosis across multiple studies. There were inconsistent reports with respect to increased age as a risk factor for CSM diagnosis.

Conclusion: The limited data available suggests that inherent anatomical features that may contribute to congenital cervical stenosis may be associated with CSM. This systematic review is limited by the small number of high-quality studies evaluating prognostic factors for CSM. The overall strength of evidence for all risk factors evaluated is low.

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.