Mechanical and cellular processes driving cervical myelopathy

Subclinical respiratory dysfunction and impaired ventilatory adaptation in degenerative cervical myelopathy

Degenerative cervical myelopathy (DCM) is a debilitating neurological condition characterized by chronic compression of the cervical spinal cord leading to impaired upper and lower limb function. Despite damage to areas of the cervical spinal cord that house the respiratory network, respiratory dysfunction is not a common symptom of DCM. However, DCM may be associated with respiratory dysfunction, and this can affect the ventilatory response to respiratory challenges during emergence from anesthesia, exercise, or pulmonary disease. Surgical spinal cord decompression, which is the primary treatment for DCM, leads to improved sensorimotor function in DCM; yet its impact on respiratory function is unknown. Here, using a clinically relevant model of DCM, we evaluate respiratory function during disease progression and assess adaptive ventilation to hypercapnic challenge before and after surgical intervention. We show that despite significant and progressive forelimb and locomotor deficits, there was no significant decline in eupneic ventilation from the early to late phases of spinal cord compression. Additionally, for the first time, we demonstrate that despite normal ventilation under resting conditions, DCM impairs acute adaptive ventilatory ability in response to hypercapnia. Remarkably, akin to DCM patients, surgical decompression treatment improved sensorimotor function in a subset of mice. In contrast, none of the mice that underwent surgical decompression recovered their ability to respond to hypercapnic ventilatory challenge. These findings underscore the impact of chronic spinal cord compression on respiratory function, highlighting the challenges associated with ventilatory response to respiratory challenges in individuals with DCM. This research highlights the impact of cervical spinal cord compression on respiratory dysfunction in DCM, as well as the persistence of adaptive ventilatory dysfunction after surgical spinal cord decompression. These results indicate the need for additional interventions to enhance recovery of respiratory function after surgery for DCM.

Moving Beyond the Neck and Arm: The Pain Experience of People With Degenerative Cervical Myelopathy Who Have Pain

STUDY DESIGN

Cross-sectional internet survey of people living with degenerative cervical myelopathy.

OBJECTIVE

The purpose of this study was to quantify pain distribution, severity, and interference in persons with degenerative cervical myelopathy.

METHODS

Eighty-two participants with degenerative cervical myelopathy were recruited for this internet survey. This survey utilized the Michigan Body Map and brief pain inventory (BPI) to assess anatomical distribution and severity of pain as well as the patient derived modified Japanese Orthopedic Association scale (p-mJOA) for myelopathic severity and SF-36 for measures of health-related quality of life. Internal consistency was evaluated with Cronbach's alpha. Pearson's correlations were assessed with p-mJOA and SF-36. Multivariate analysis of variance was used to determine if history of prior surgery or concomitant pain diagnosis impacted experience of pain.

RESULTS

Michigan body map distribution and brief pain inventory severity and interference were correlated with p-mJOA and SF-36 scores (p < 0.05). Pain was moderate to severe in 78% of participants. Pain was commonly widespread. Pain scales were sufficiently internally consistent (α > 0.9). History of surgery or other pain diagnosis did not impact experience of pain in myelopathy.

CONCLUSIONS

Pain is commonly identifiable in large areas of the body, is frequently moderate to severe in intensity and impacts quality of life and severity of myelopathy in a cohort of individuals with myelopathy who have pain.

Current Management of Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy (CSM) develops insidiously as degenerative changes of the cervical spine impact the spinal cord. Unfortunately, CSM is a form of spinal cord injury in older patients that often experiences delayed treatment. This summary evaluates the pathophysiology, natural history, diagnosis, and current management of CSM. Frequently, patients do not appreciate or correlate their symptomatology with cervical spine disease, and those with radiographic findings may be clinically asymptomatic. Providers should remember the classic symptoms of CSM-poor hand dexterity, new unsteady gait patterns, new onset and progressive difficulty with motor skills. An magnetic resonance imaging is required in patients with suspected CSM, but computerized tomography myelography is an alternative in patients with implants as contraindications to magnetic resonance imaging. The management of those with CSM has continued to be a controversial topic. In general, patients with incidental findings of cervical cord compression that are asymptomatic can be managed conservatively. Those with daily moderate-severe disease that significantly affects activities of daily living should be treated operatively.

Potential benefit of olive leaf extract in cervical spondylotic myelopathy model

Introduction

Cervical spondylosis is the most common cause of myelopathy in the cervical due to chronic compression of the spinal cord in patients aged 55 years or older. Recent studies suggest that olive extracts suppress inflammation and reduce stress oxidative injury. The purpose of this study was to determine the potential neuroprotective effects of olive leaf extract (OLE) in an experimental cervical spondylotic myelopathy model.

Methods

This study was divided into 6 groups; Control Negative (Sham-Operated) Group, Control Positive 1 & 2 (early chronic and chronic), Treatment Groups 1, 2 & 3 (prophylactic, concomitant & late). Olive leaf extract (OLE) give 350 mg/kg BW and spinal cord sample was taken at the compression level C5. Histopathological assessment and immunohistochemistry of Amyloid-β, p-Tau, TDP-43 dan CD-68 dan evaluation of functional motoric outcome was done before animals were terminated.

Results

Chronic spinal cord compression increased the expression of Amyloid-β, p-Tau, TDP-43 dan CD-68. OLE 350 mg/kg BW decreased the expression of these biomarkers and increased functional motoric outcome, especially as prophylactic dan concomitant treatment.

Discussion

These findings indicate that OLE may be effective in protecting cervical spondylotic myelopathy.

•

Cervical Spondylotic Myelopathy.

•

Spine.

•

Amyloid-β.

•

p-Tau.

•

TDP-43.

•

CD-68.

Progressive spinal cord compression technique in experimental rabbit animal model for cervical spondylotic myelopathy

INTRODUCTION

Cervical spondylotic myelopathy (CSM) presently estimated at 54% population, commonly cause of myelopathy due to chronic compression of the spinal cord in older people. Physiological injuries caused by static and dynamic forces including compressed, pinched, and pulled out inducing secondary injuries at the molecular level.

METHODS

We examined the rabbit model approach with the clinical case of spondylotic myelopathy, in which the disk and facet maintained the cervical spine mobility, and compression was given 0.5 mm per week three times in this model. In this study, a group of 14 days was made (early into the chronic phase) and the 21 day group had a chronic process for 1 week, that period can be categorized as a chronic process and CSM is a chronic process. By examining motor scores, histological examination and immunohistochemistry of the spinal cord, this model efficiently produces myelopathy. The distribution of microglia expressing GFAP, S100-β, and Neurofilaments were observed by immunohistochemical techniques.

RESULTS

There was a significant difference in the number of cells expressing GFAP between the control group and the 21-day compression group (p = 0.001). There is a decrease in S100-β expression of spinal cord tissue after receiving compression exposure. There was a significant difference in the number of cells expressing NF between the control group, the 14-day compression group (p = 0.04) and 21-day compression group (p = 0.04).

DISCUSSION

Neurons have the intrinsic ability to regenerate after injury, although not spontaneously. Cervical spondylotic myelopathy causes permanent neurological disorders, partly due to glial scar formation consisting of astrocytes and microglia. The difference between our study and previous research methods is that we perform compression of the spinal cord in stages (0.5 mm, 1.0 mm & 1.5 mm) so that it is more like the natural occurrence of chronic spinal cord compression.

CONCLUSION

An increasing of GFAP value in this study indicates the presence of astrocyte activity which can be associated with chronic spinal cord injury. There is a decrease in S100-β expression of spinal cord tissue neuron cells after receiving compression exposure. The expression of NF decreased indicating degenerative axons.

Expression of AIF and Caspase-3 in New Zealand rabbit with Cervical Spondylosis Myelopathy model

Introduction

Cervical spondylosis myelopathy (CSM) is a clinical syndrome of motoric or sensoric, caused by degenerative process chronically causing narrowing of cervical canal and compressing the spinal cord. The narrowing of canalis spinalis causing chronic compression and disrupting vascular patency in spinal cord. This is worsened on repetitive trauma on flexion, extension and rotation. CSM has an incidence of 4.04 in 100.000 cases per year and the total patients undergoing treatment operative or nonoperatively in year increasing for 7 times. Apoptosis plays a critical role in important biological processes such as morphogenesis, tissue homeostasis, and immunity; furthermore, its aberrant activation or impairment may contribute to a number of diseases. The understanding of CSM pathophysiology from apoptotic pathway is an essential topic to discussed and the treatment of this case in future.

Method

This study uses experimental study with Post test Only Control Group, using New Zealand rabbits. The rabbits given the compression on cervical as high as C5 to induce CSM. The tissue was taken from spinal cord on compression area and histopathology examination was done to calculate apoptotic factor expression such as AIF and caspase-3.

Result

Chronic compression on spinal cord causing myelopathy clinically on animal study, resulted in weakness of all extremities. Based on this study, the expression of AIF and caspase-3 is increasing in compression group in day 14 to day 21.

Conclusion

Chronic compression in spinal cord causing increase in AIF and caspase-3 in day 14 and day 21, and this may be caused by increasing of apoptotic expression on animal study.

Utility of Advanced DWI in the Detection of Spinal Cord Microstructural Alterations and Assessment of Neurologic Function in Cervical Spondylotic Myelopathy Patients

BACKGROUND

Diffusion-weighted imaging (DWI) can quantify the microstructural changes in the spinal cord. It might be a substitute for T2 increased signal intensity (ISI) for cervical spondylotic myelopathy (CSM) evaluation and prognosis.

PURPOSE

The purpose of the study is to investigate the relationship between DWI metrics and neurologic function of patients with CSM.

STUDY TYPE

Retrospective.

POPULATION

Forty-eight patients with CSM (18.8% females) and 36 healthy controls (HCs, 25.0% females).

FIELD STRENGTH/SEQUENCE

3 T; spin-echo echo-planar imaging-DWI; turbo spin-echo T1/T2; multi-echo gradient echo T2*.

ASSESSMENT

For patients, conventional MRI indicators (presence and grades of T2 ISI), DWI indicators (neurite orientation dispersion and density imaging [NODDI]-derived isotropic volume fraction [ISOVF], intracellular volume fraction, and orientation dispersion index [ODI], diffusion tensor imaging [DTI]-derived fractional anisotropy [FA] and mean diffusivity [MD], and diffusion kurtosis imaging [DKI]-derived FA, MD, and mean kurtosis), clinical conditions, and modified Japanese Orthopaedic Association (mJOA) were recorded before the surgery. Neurologic function improvement was measured by the 3-month follow-up recovery rate (RR). For HCs, DWI, and mJOA were measured as baseline comparison.

STATISTICAL TESTS

Continuous (categorical) variables were compared between patients and HCs using Student's t-tests or Mann-Whitney U tests (chi-square or Fisher exact tests). The relationships between DWI metrics/conventional MRI findings, and the pre-operative mJOA/RR were assessed using correlation and multivariate analysis. P < 0.05 was considered statistically significant.

RESULTS

Among patients, grades of T2 ISI were not correlated with pre-surgical mJOA/RR (P = 0.717  and 0.175, respectively). NODDI ODI correlated with pre-operative mJOA (r = -0.31). DTI FA, DKI FA, and NODDI ISOVF were correlated with the recovery rate (r = 0.31, 0.41, and -0.34, respectively). In multivariate analysis, NODDI ODI (DTI FA, DKI FA, NODDI ISOVF) significantly contributed to the pre-operative mJOA (RR) after adjusting for age.

DATA CONCLUSION

DTI FA, DKI FA, and NODDI ISOVF are predictors for prognosis in patients with CSM. NODDI ODI can be used to evaluate CSM severity.

LEVEL OF EVIDENCE

3 TECHNICAL EFFICACY STAGE: 5.

T1 Mapping for Microstructural Assessment of the Cervical Spinal Cord in the Evaluation of Patients with Degenerative Cervical Myelopathy

BACKGROUND AND PURPOSE

Although current radiologic evaluation of degenerative cervical myelopathy by conventional MR imaging accurately demonstrates spondylosis or degenerative disc disease causing spinal cord dysfunction, conventional MR imaging still fails to provide satisfactory anatomic and clinical correlations. In this context, we assessed the potential value of quantitative cervical spinal cord T1 mapping regarding the evaluation of patients with degenerative cervical myelopathy.

MATERIALS AND METHODS

Twenty patients diagnosed with mild and moderate-to-severe degenerative cervical myelopathy and 10 healthy subjects were enrolled in a multiparametric MR imaging protocol. Cervical spinal cord T1 mapping was performed with the MP2RAGE sequence procedure. Retrieved data were processed and analyzed regarding the global spinal cord and white and anterior gray matter on the basis of the clinical severity and the spinal canal stenosis grading.

RESULTS

Noncompressed levels in healthy controls demonstrated significantly lower T1 values than noncompressed, mild, moderate, and severe stenotic levels in patients. Concerning the entire spinal cord T1 mapping, patients with moderate-to-severe degenerative cervical myelopathy had higher T1 values compared with healthy controls. Regarding the specific levels, patients with moderate-to-severe degenerative cervical myelopathy demonstrated a T1 value increase at C1, C7, and the level of maximal compression compared with healthy controls. Patients with mild degenerative cervical myelopathy had lower T1 values than those with moderate-to-severe degenerative cervical myelopathy at the level of maximal compression. Analyses of white and anterior gray matter confirmed similar results. Strong negative correlations between individual modified Japanese Orthopaedic Association scores and T1 values were also observed.

CONCLUSIONS

In this preliminary study, 3D-MP2RAGE T1 mapping demonstrated increased T1 values in the pathology tissue samples, with diffuse medullary alterations in all patients with degenerative cervical myelopathy, especially relevant at C1 (nonstenotic level) and at the maximal compression level. Encouraging correlations observed with the modified Japanese Orthopaedic Association score make this novel approach a potential quantitative biomarker related to clinical severity in degenerative cervical myelopathy. Nevertheless, patients with mild degenerative cervical myelopathy demonstrated nonsignificant results compared with healthy controls and should now be studied in multicenter studies with larger patient populations.

Handgrip Strength Correlated with Falling Risk in Patients with Degenerative Cervical Myelopathy

Background: Few studies have investigated associations between hand grip strength (HGS) and the surgical outcomes of degenerative cervical myelopathy (DCM). Methods: This study was designed as a prospective observational study of 203 patients who had undergone fusion surgery for DCM. We divided the patients according to sex and HGS differences. Clinical outcome parameters, including HGS, a fall diary and four functional mobility tests (alternative step test, six-meter walk test, timed up and go test, and sit-to-stand test) were measured preoperatively, at 3 months and 1 year after surgery. Results: Mean patient ages were 59.93 years in the male group and 67.33 years in the female group (p = 0.000; independent t-test). The mean HGS of both hands improved significantly at postoperative 3 months and 1 year in all patients (p = 0.000 for both; ANOVA). In male patients, preoperative risk of falls was negatively correlated with HGS (p = 0.000). In female patients, pre- and postoperative risk of falls were correlated negatively with HGS (p = 0.000). The postoperative incidence of falls decreased in both groups (p = 0.000) Conclusions: Postoperative HGS in patients with DCM is correlated with postoperative falls and functional outcome differently, when comparing male and female patients, for predicting favorable outcomes and neurologic deficit recovery after surgery in DCM patients.

No Difference in Functional Outcome but Higher Revision Rate Among Smokers Undergoing Cervical Artificial Disc Replacement: Analysis of a Spine Registry

BACKGROUND

Smoking is a known predictor of negative outcomes in spinal surgery. However, its effect on the functional outcomes and revision rates after ADR is not well-documented. This study is a retrospective analysis of prospectively collected data at a major tertiary center. The objective was to elucidate the impact of smoking on functional outcomes in cervical artificial disc replacement (ADR).

METHODS

Patients who underwent cervical ADR for myelopathy or radiculopathy from 2004 to 2015 with a minimum of 2 years of follow-up were included in the study. Patient function was assessed using Short Form-36 (SF-36), American Association of Orthopaedic Surgery (AAOS) cervical spine, and Japanese Orthopaedic Association (JOA) scoring systems preoperatively and at 2 years postoperatively. Incidence of further surgery on affected and adjacent segments was analyzed as well.

RESULTS

A total of 137 patients were included in the study, consisting of 117 nonsmokers and 20 smokers. There were 60 patients who presented with myelopathy and 77 with radiculopathy. The mean age of smokers was 42.6 years, compared with 46.4 years in the nonsmoker group (P < .01). Statistical improvement was noted in postoperative range of motion, as well as AAOS, SF-36, and JOA scores in both groups, with no difference between groups at 2 years of follow-up. A total of 84.2% of nonsmokers and 87.5% of smokers reported as surgery having met their expectations. A total of 5 of 117 nonsmokers (5.1%) and 4 of 20 smokers (20%) needed revision surgery (P = .018). Three of the 4 smokers who required surgery for adjacent or multisegment disease, whereas only 2 of the nonsmokers needed an operation for adjacent segment disease.

CONCLUSIONS

Our analysis indicates that there is no difference in functional outcome or patient satisfaction between smokers and nonsmokers. Smokers have a higher chance of revision surgery after an artificial disc replacement compared with nonsmokers at 2 years.

LEVEL OF EVIDENCE

3.

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.

High field structural MRI in the management of degenerative cervical myelopathy

Introduction: This is a narrative overview of the pathophysiology, investigation and management of Degenerative Cervical Myelopathy (DCM). This review article also takes a look ahead to the impact high resolution MRI may have on treatment.Background: DCM is the most common cause of spinal dysfunction and yet it remains poorly understood. It is becoming increasingly common in our ageing population. Disc and facet joint abnormalities, osteophytes, spondylothisthesis and ligamentous hypertrophy all act together to produce spinal canal and neuronal foramina stenosis which in turn causes neural compromise. Its impact on the quality of life of this patient group and the wider economy is vast. Some patients with overt cord compression and MRI signal change in their cervical cord may only have subtle clinical signs whilst others with less striking imaging may be profoundly myelopathic. Who to operate on and when remains a neurosurgical dilemma in this group of patients.Methods: A number of articles with a broad variation in methodology were reviewed and referenced during the production of this paper.Results: This paper is a narrative review. The results presented in all the referenced articles were considered.Conclusion: The process of developing new imaging techniques will give a greater understanding of the causes of the symptoms of DCM and in a wider context facilitate further surgical and medical strategies that are more cost effective and beneficial to patients. The advent of 7T MRI or further optimisation of safer 3T MRI sequences may soon provide this opportunity and the diagnostic gap in spinal cord imaging can begin to close.

Cervical myelopathy causing numbness and paresthesias in lower extremities: A case report identifying the cause of a false positive Sharp-Purser test

INTRODUCTION

The patient was referred to an outpatient physical therapy clinic for lumbar radiculopathy by a primary care physician and subsequently referred for imaging due to suspicion of cervical myelopathy. The case highlights the clinical reasoning of the physical therapist differentiating between lumbar stenosis, cervical myelopathy, and upper cervical instability. To the author's knowledge, this is the only case report in the literature to describe the mechanism that could underpin a false positive Sharp-Purser test (SPT). The case also highlights the importance of interpreting the outcomes of special tests cautiously.

CASE DESCRIPTION

A 55-year-old female was referred to outpatient physical therapy for lumbar radiculopathy. The patient's complaint was a one-year history of intermittent bilateral lower buttock paresthesias radiating to the bilateral posterior thighs. She reported a three-month history of bilateral anterior thigh numbness that would present after sitting for 30 minutes. Lumbar stenosis was initially suspected, however the patient's failure to improve but rather worsen with flexed postures suggested this diagnosis was improbable. The patient experienced bilateral anterior thigh numbness with active cervical flexion, and had a reduction in symptoms with the SPT.

OUTCOMES

Magnetic resonance imaging revealed multi-focal disc-osteophyte complexes with central canal stenosis from C4-7. The patient underwent an anterior cervical discectomy and fusion with a good outcome.

DISCUSSION

A large disc herniation causing central canal stenosis could underpin a false positive SPT. Special tests should always be used with caution, as they can lead to inaccurate diagnoses if there is a false positive.

Kinematic analysis of cervical spine canal diameter and its association with grade of degeneration

OBJECTIVES

To investigate the cervical spinal canal diameters variance under positional MRI, and also the relationship between cervical canal diameter variance rate and grade of degeneration.

METHODS

From January 2013 to January 2015, a consecutive of 273 symptomatic patients (166 males and 207 females) with an average age of 44.6 years (range 21-89 years) underwent positional cervical MRI. T2-weighted sagittal images of 1638 cervical intervertebral discs from 273 subjects were classified into five grades. The canal diameter and canal diameter variance rate at three positions and their comparison among five grade of degeneration were evaluated. The measurements were tabulated and analyzed using SPSS. 13.0. p values less than 0.05 were considered to indicate a statistically significant difference.

RESULTS

The sagittal cervical canal diameter at the C5/6 level were the smallest compared with the other levels regardless of neutral, flexion or extension positions, C5/6 level had the largest canal diameter variance rate in both flexion and extension (8.14 ∓ 0.38 and 7.81 ∓ 0.31 %, respectively), second was C4/5 level (7.65 ∓ 0.39 and 7.67 ∓ 0.32 %, respectively). A total of 1638 discs were classified into 5 groups, each level showed the similar tendency that no matter what position, with the increasing grade of degenerative disc degree, spine canal diameter decreased gradually. For C5/6 under extension and flexion position, significant difference was also noted between grade 2 and 3; For C4/5 under extension position, significant difference existed between grade 1 and 2, grade 1 and 3, while under flexion position, significant difference existed between grade 2 and 4, and the results also showed no significant difference at the same degree of degeneration on both levels between extension and flexion position.

CONCLUSIONS

C5/6 and C4/5 is of higher risk of suffering SCI than other levels, C4/5 level predispose SCI at earlier stage than C5/6, patients presenting with intermediate signal and slight decreased disc height on T2 weighted MRI at C4/5 level should be paid attention.