Degenerative Cervical Myelopathy Research Articles

Early surgery compared to nonoperative management for mild degenerative cervical myelopathy: a cost-utility analysis

Early surgery compared to nonoperative management for mild degenerative cervical myelopathy: a cost-utility analysis

55. Surgical approach is associated with postoperative C5 palsy after decompression for degenerative cervical myelopathy: an analysis of the multicenter, prospective, randomized CSM-Protect clinical trial

55. Surgical approach is associated with postoperative C5 palsy after decompression for degenerative cervical myelopathy: an analysis of the multicenter, prospective, randomized CSM-Protect clinical trial

36. Deterioration after surgery for degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research Network

36. Deterioration after surgery for degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research Network

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

BackgroundIn recent years, structural and functional reorganization of the brain and changes in brainstem structural connectivity have been shown in patients with degenerative cervical myelopathy (DCM). We hypothesized that volume loss in the basal ganglia, thalami, and brainstem structures exists and is associated with spinal cord compression severity in patients with DCM. MethodsForty-seven patients with DCM and 25 patients with cervical radiculopathy were evaluated using cervical spinal cord and brain magnetic resonance imaging (MRI). Brainstem structures, basal ganglia, and thalami volumes were evaluated with FreeSurfer and compared between groups with correction for individual intracranial volume, as well as patient age and sex. Additionally, spinal cord MRI data were analysed with the Spinal Cord Toolbox, and cross-sectional area (CSA) and fractional anisotropy (FA) values were calculated. Correlations between MR-morphometry data and spinal cord structural changes, as well as disease duration, were also evaluated in patients with DCM. ResultsA statistically significant reduction in the volume of the whole brainstem was revealed in the DCM group compared to the radiculopathy group (p < 0.01, FDR-corrected). Additionally, reductions in medulla oblongata, pons and midbrain volumes were found in patients with DCM (p < 0.01, p < 0.01 and p < 0.05, respectively, FDR-corrected). Additionally, a trend in the loss of volume of the left putamen was found (p = 0.087, FDR-corrected). Furthermore, medulla oblongata volume was correlated with spinal cord compression severity (R = 0.54, adjusted p < 0.001) and white matter damage (R = 0.46, adjusted p < 0.05) in patients with DCM. Negative correlations between the duration of the disease and the severity of spinal cord compression (R = −0.42, adjusted p < 0.05) and white matter damage (R = −0.49, adjusted p < 0.05) were also revealed, as well as a trend toward a negative association between the duration of the disease and the volume of the medulla oblongata (R = −0.35; adjusted p < 0.1). ConclusionsWe revealed a reduction in the volume of brainstem structures in patients with DCM compared to patients with radiculopathy. Moreover, we found that these changes are associated with cord compression severity.

An innovative approach to assess spinal canal expansion following French-door cervical laminoplasty by intraoperative ultrasonography.

To investigate the feasibility and effectiveness of applying intraoperative ultrasound (IOUS) to evaluate spinal canal expansion in patients undergoing French-door cervical laminoplasty (FDCL). Twenty-five patients who underwent FDCL for multilevel degenerative cervical myelopathy were prospectively recruited. Formulae describing the relationship between laminoplasty opening angle (LOA) and laminoplasty opening size, the increase in sagittal canal diameter and the spinal canal area were deduced with trigonometric functions. The LOA was measured with IOUS imaging during surgery, and other spinal canal parameters were assessed. Actual spinal canal enlargement was verified on postoperative CT images. Linear correlation analysis and Bland‒Altman analysis were used to evaluate correlation and agreement between the intraoperative and postoperative measurements. The LOA at C5 measured with IOUS was 27.54 ± 3.12°, and it was 27.23 ± 3.02° on postoperative CT imaging. Linear correlation analysis revealed a significant correlation between IOUS and postoperative CT measurements (r = 0.88; p < 0.01). Bland-Altman plots showed good agreement between these two methods, with a mean difference of 0.30°. For other spinal canal expansion parameter measurements, correlation analysis showed a moderate to a high degree of correlation (p < 0.01), and Bland-Altman analysis indicated good agreement. In conclusion, during the French-door cervical laminoplasty procedure, application of IOUS can accurately evaluate spinal canal expansion. This innovative method may be helpful in improving surgical accuracy by enabling the operator to measure and determine canal enlargement during surgery, leading to ideal clinical outcomes and fewer postoperative complications. The use of intraoperative ultrasonography to assess spinal canal expansion following French-door cervical laminoplasty may improve outcomes for patients undergoing this procedure by providing more accurate measurements of spinal canal expansion. • Spinal canal expansion after French-door cervical laminoplasty substantially influences operative prognosis; insufficient or excessive lamina opening may result in unexpected outcomes. • Prediction of spinal canal expansion during surgery was previously impracticable, but based on this study, intraoperative ultrasonography offers an innovative approach and strongly agrees with postoperative CT measurement. • Since this is the first research to offer real-time canal expansion guidance for cervical laminoplasty, it may improve the accuracy of the operation and produce ideal clinical outcomes with fewer postoperative complications.

Adverse effects of frailty on the outcomes of surgery for degenerative cervical myelopathy: results from a prospective multicenter international data set of 757 patients.

The goal of this study was to determine the effect of the degree of frailty on long-term neurological and functional outcomes after surgery for degenerative cervical myelopathy (DCM). A combined database of patients enrolled in the Cervical Spondylotic Myelopathy-North America and Cervical Spondylotic Myelopathy-International prospective international multicenter observational studies who underwent surgery for DCM was used as the source data. All patients underwent baseline and follow-up assessment at 2 years after surgery for functional, disability, and quality of life measurements (modified Japanese Orthopaedic Association [mJOA] scale, Neck Disability Index, SF-36 physical and mental component summary scores). Patients were separated into 4 groups according to their baseline modified frailty index 5-point scale score: not frail, pre-frail, frail, and severely frail. Differences among groups were analyzed at baseline and at 2 years after surgery, including change in scores (delta values) and the odds ratio of achieving the minimum clinically important difference (MCID) through univariate and multivariable logistic regression adjusting for age, approach, number of levels treated, and sex. A total of 757 patients (63% male) with a mean age of 56 (95% CI 55.5-57.2) years were included: 470 patients underwent an anterior approach, 310 had a posterior approach, and 23 had a combined anterior/posterior approach. A total of 50% (n = 378) of patients were classified as not frail, with 33% (n = 250) pre-frail, 13% (n = 101) frail, and 4% (n = 28) severely frail. The baseline mJOA score was significantly lower with increasing frailty (14.00 [95% CI 13.75-14.19] for not frail vs 9.71 [95% CI 9.01-10.42] for severely frail patients; p < 0.05), but the change at 2 years was not significantly different among all groups (2.43 [95% CI 2.16-2.71] for not frail vs 2.56 [95% CI 1.10-4.02] for severely frail). The SF-36 delta values were also not different among groups, but significantly worse at baseline with increasing frailty. The odds ratio of achieving MCID for mJOA was significantly higher in the not frail group (1.89 [95% CI 1.36-2.61]; p < 0.05) compared to the other frailty cohorts, which remained after adjusting for age, approach, levels treated, and sex. The odds ratio of achieving MCID for the SF-36 domains was similar among all frailty groups. Increasing frailty is associated with worse baseline functional and quality of life measures in patients undergoing surgery for DCM. Frailty does not affect the magnitude of improvement in outcome measures after surgery, but reduces the chance of achieving the MCID for functional impairment significantly. Preoperative frailty assessment can therefore help guide clinicians in managing expectations after surgery for DCM. Potentially modifiable factors should be optimized in frail patients preoperatively to enhance functional outcomes.

Spine

The August 2023 Spine Roundup360 looks at: Changes in paraspinal muscles correspond to the severity of degeneration in patients with lumbar stenosis; Steroid injections are not effective in the prevention of surgery for degenerative cervical myelopathy; A higher screw density is associated with fewer mechanical complications after surgery for adult spinal deformity; Methylprednisolone following minimally invasive lumbar decompression: a large prospective single-institution study; Occupancy rate of pedicle screw below 80% is a risk factor for upper instrumented vertebral fracture following adult spinal deformity surgery; Deterioration after surgery for degenerative cervical myelopathy: an observational study from the Canadian Spine Outcomes and Research Network.

Developing predictive models for surgical outcomes in patients with degenerative cervical myelopathy: a comparison of statistical and machine learning approaches

BACKGROUND CONTEXTMachine learning (ML) is widely used to predict the prognosis of numerous diseases. PURPOSEThis retrospective analysis aimed to develop a prognostic prediction model using ML algorithms and identify predictors associated with poor surgical outcomes in patients with degenerative cervical myelopathy (DCM). STUDY DESIGNA retrospective study. PATIENT SAMPLEA total of 406 symptomatic DCM patients who underwent surgical decompression were enrolled and analyzed from three independent medical centers. OUTCOME MEASURESWe calculated the area under the curve (AUC), classification accuracy, sensitivity, and specificity of each model. METHODSThe Japanese Orthopedic Association (JOA) score was obtained before and 1 year following decompression surgery, and patients were grouped into good and poor outcome groups based on a cut-off value of 60% based on a previous study. Two datasets were fused for training, 1 dataset was held out as an external validation set. Optimal feature-subset and hyperparameters for each model were adjusted based on a 2,000-resample bootstrap-based internal validation via exhaustive search and grid search. The performance of each model was then tested on the external validation set. RESULTSThe Support Vector Machine (SVM) model showed the highest predictive accuracy compared to other methods, with an AUC of 0.82 and an accuracy of 75.7%. Age, sex, disease duration, and preoperative JOA score were identified as the most commonly selected features by both the ML and statistical models. Grid search optimization for hyperparameters successfully enhanced the predictive performance of each ML model, and the SVM model still had the best performance with an AUC of 0.93 and an accuracy of 86.4%. CONCLUSIONSOverall, the study demonstrated that ML classifiers such as SVM can effectively predict surgical outcomes for patients with DCM while identifying associated predictors in a multivariate manner.

Demographic and Clinical Characteristics of Patients With Cervical Spine Degeneration Reveal Frequent Cervicolumbar Tandem Spinal Stenosis in Mexico.

Limited literature exists regarding the differences in demographics, causes, comorbidities, presentation, and structural changes associated with cervical spine degeneration in patients from distinct geographic regions. The authors aimed to evaluate the demographic and clinical characteristics of patients with cervical spine degeneration admitted to a single center in Mexico. This study enrolled patients with degenerative disease of the cervical spine. Clinical data were retrieved from medical records and retrospectively characterized. A total of 50 patients with cervical spine degeneration were included in the analysis. Of these, 26% were men with a median age of 54 years. Hypertension, depression, anxiety, obesity, and alcohol consumption were presented in about a quarter of the participants. In addition, we observed hypertriglyceridemia and hypercholesterolemia in 72% and 46% of participants, respectively. The median duration of symptoms was 11 months, including radicular arm/neck pain (80%), tingling (80%), reduced muscle strength (48%), and gait disturbances (48%). Forty percent of patients had 2 cervical segments radiologically involved, mainly at C5-C6, with changes such as disc herniation (88%), foraminal stenosis with nerve root compression (67%), reduced spinal canal-to-vertebral body ratio (38%), and ligamentum flavum hypertrophy (24%). Also, 22% of patients showed degenerative cervical myelopathy. Strikingly, 48% of enrolled individuals showed cervicolumbar tandem spinal stenosis, mainly in L4-L5 and L5-S1, who were generally older, had a longer duration of symptoms, and had a higher comorbidity burden, including hyperglycemia, hypertension, and depression. The demographic and clinical characteristics of degenerative cervical spine disease in Mexico differ with respect to other geographical regions by a younger age of diagnosis, a high frequency of cardiovascular, metabolic, and mental health comorbidities, and an increased prevalence of concomitant lumbar spinal stenosis. Our findings reveal a considerably high burden of cervicolumbar tandem spinal stenosis as a distinctive feature of Mexican patients with cervical spine degeneration.

Probabilistic graphical modelling using Bayesian networks for predicting clinical outcome after posterior decompression in patients with degenerative cervical myelopathy

Background Probabilistic graphical modelling (PGM) can be used to predict risk at the individual patient level and show multiple outcomes and exposures in a single model. Objective To develop PGM for the prediction of clinical outcome in patients with degenerative cervical myelopathy (DCM) after posterior decompression and to use PGM to identify causal predictors of the outcome. Methods We included data from 59 patients who had undergone cervical posterior decompression for DCM. The candidate predictive parameters were age, sex, body mass index, trauma history, symptom duration, preoperative and last Japanese Orthopaedic Association (JOA) scores, gait impairment, claudication, bladder dysfunction, Nurick grade, American Spinal Injury Association (ASIA) grade, smoking, diabetes mellitus, cardiopulmonary disorders, hypertension, stroke, Parkinson’s disease, dementia, psychiatric disorders, arthritis, ossification of the posterior longitudinal ligament, cord signal change, postoperative kyphosis and the cord compression ratio. Results In regression analyses, preoperative JOA (PreJOA) score, presence of a psychiatric disorder, and ASIA grade were identified as significant factors associated with the last JOS score. Dementia, sex, PreJOA score and gait impairment were causal factors in the PGM. Sex, dementia and PreJOA score were direct causal factors related to the last follow-up JOA (LastJOA) score. Being female, having dementia, and having a low PreJOA score were significantly related to having a low LastJOA score. Conclusions The causal predictors of surgical outcome for DCM were sex, dementia and PreJOA score. Therefore, PGM may be a useful personalized medicine tool for predicting the outcome of patients with DCM.

Differences of spinal cord gadolinium enhancement features of neuromyelitis optica spectrum disorder and long-segment degenerative cervical myelopathy.

Neuromyelitis optica spectrum disorder (NMOSD) and long-segment degenerative cervical myelopathy (DCM) may have a similar appearance on MRI. This study aimed to identify the differences in spinal cord gadolinium enhancement features between NMOSD and long-segment DCM. Spinal cord gadolinium enhancement of 27 NMOSD patients and 30 long-segment DCM patients were retrospectively analyzed. Enhancements were evaluated for their number, length, location on the sagittal images, distribution on the axial images, and form on the sagittal images. The Wilcoxon rank sum test was performed to compare numerical variables. The Pearson chi-squared test was performed to compare categorical variables. The median number of enhanced lesions (p < 0.05), the median length of the enhancements (p < 0.05), and the location of enhancement on sagittal images (p < 0.05) of NMOSD patients and long-segment DCM patients showed significant differences. The axial distribution of enhancements did not show a significant difference between NMOSD and long-segment DCM patients (p = 0.115). On the sagittal images, linear and ring-formed enhancements were observed in 10 (27.0%) and 17 (63.0%) NMOSD patients, respectively. The enhancements in long-segment DCM patients had a transverse band or pancake-like appearance in 15 (50%) patients and an irregular flake-like appearance with a longitudinally oriented long axis in 15 patients (50%). By analyzing the number, length, location, and form of the gadolinium enhancements, NMOSD and long-segment DCM could be well-differentiated.

Secondary analysis of a James Lind Alliance priority setting partnership to facilitate knowledge translation in degenerative cervical myelopathy (DCM): insights from AO Spine RECODE-DCM

ObjectivesTo explore whether a James Lind Alliance Priority Setting Partnership could provide insights on knowledge translation within the field of degenerative cervical myelopathy (DCM).DesignSecondary analysis of a James Lind Alliance...

The Hoffmann parallax: a prospective study to determine the benefit of Hoffmann's sign.

Degenerative cervical myelopathy (DCM) is the most common cause of age-related spinal cord dysfunction worldwide. Despite the widespread use of provocative physical exam maneuvers in the workup of DCM, the clinical significance of Hoffmann's sign is controversial. The purpose of this study was to prospectively assess the diagnostic performance of Hoffmann's sign for DCM in a cohort of patients treated by a single spine surgeon. Patients were divided into two groups based on the presence of a Hoffmann sign on physical examination. Advanced imaging studies were independently reviewed by four raters for confirmation of a diagnosis of cervical cord compression. Prevalence, sensitivity, specificity, likelihood, and relative risk ratios for the Hoffmann sign were calculated, with subsequent Chi-square and receiver operator characteristic (ROC) analysis to further characterize correlative findings. Fifty-two patients were included - of whom, thirty-four (58.6%) patients presented with a Hoffmann sign, and eleven (21.1%) patients demonstrated cord compression on imaging. The Hoffmann sign demonstrated a sensitivity of 20% and a specificity of 35.7% (LR = 0.32; 0.16-1.16). Chi-square analysis revealed that imaging findings positive for cord compression were proportionally greater for patients lacking a Hoffmann sign than those with a confirmed Hoffmann sign (p =0.032) ROC analysis demonstrated that a negative Hoffmann sign performed moderately well in predicting cord compression (AUC.721; p =0.031). The Hoffmann sign is an unreliable marker for cervical cord compression, and the lack of a Hoffmann sign may be more predictive of cervical cord compression.

Automated signal intensity analysis of the spinal cord for detection of degenerative cervical myelopathy — a matched-pair MRI study

PurposeDetection of T2 hyperintensities in suspected degenerative cervical myelopathy (DCM) is done subjectively in clinical practice. To gain objective quantification for dedicated treatment, signal intensity analysis of the spinal cord is purposeful. We investigated fully automated quantification of the T2 signal intensity (T2-SI) of the spinal cord using a high-resolution MRI segmentation.MethodsMatched-pair analysis of prospective acquired cervical 3D T2-weighted sequences of 114 symptomatic patients and 88 healthy volunteers. Cervical spinal cord was segmented automatically through a trained convolutional neuronal network with subsequent T2-SI registration slice-by-slice. Received T2-SI curves were subdivided for each cervical level from C2 to C7. Additionally, all levels were subjectively classified concerning a present T2 hyperintensity. For T2-positive levels, corresponding T2-SI curves were compared to curves of age-matched volunteers at the identical level.ResultsForty-nine patients showed subjective T2 hyperintensities at any level. The corresponding T2-SI curves showed higher signal variabilities reflected by standard deviation (18.51 vs. 7.47 a.u.; p < 0.001) and range (56.09 vs. 24.34 a.u.; p < 0.001) compared to matched controls. Percentage of the range from the mean absolute T2-SI per cervical level, introduced as “T2 myelopathy index” (T2-MI), was correspondingly significantly higher in T2-positive segments (23.99% vs. 10.85%; p < 0.001). ROC analysis indicated excellent differentiation for all three parameters (AUC 0.865–0.920).ConclusionThis fully automated T2-SI quantification of the spinal cord revealed significantly increased signal variability for DCM patients compared to healthy volunteers. This innovative procedure and the applied parameters showed sufficient diagnostic accuracy, potentially diagnosing radiological DCM more objective to optimize treatment recommendation.Trial registrationDRKS00012962 (17.01.2018) and DRKS00017351 (28.05.2019)

Effect of vitamin D deficiency on surgical outcomes of degenerative cervical myelopathy

Due to its association with bone metabolic status and muscle strength/mass, vitamin D deficiency has the potential to affect neurological symptom recovery after surgery for degenerative cervical myelopathy (DCM). However, few studies have investigated the effects of vitamin D deficiency (serum 25(OH)D <20 ng/mL) on surgical outcomes in DCM patients. Herein, we investigated the prevalence of vitamin D deficiency in patients with DCM, and determined whether vitamin D deficiency affects surgical outcomes for DCM. In this retrospective observational study we assessed the recovery rate 1 year after surgery in 91 patients diagnosed with DCM who underwent surgery. First, we analyzed the correlation between vitamin D levels and various background factors. Then, patients were divided into 2 groups according to vitamin D sufficiency, and univariate analysis was performed on vitamin D and surgical outcomes. Finally, Spearman correlation analyses were performed to identify factors correlated with recovery rate after surgery for DCM. The average Japanese Orthopedic Association score for the assessment of cervical myelopathy (C-JOA score) improved postoperatively. Age was positively correlated with vitamin D levels, and parathyroid hormone levels were negatively correlated with vitamin D levels. Among the 91 patients, 79.1% of patients were diagnosed with vitamin D deficiency. No significant differences in recovery rate were found between the vitamin D-deficient and vitamin D-sufficient groups. Finally, the Spearman correlation analysis showed a positive correlation between the preoperative C-JOA motor dysfunction score in the lower extremities and the recovery rate, while age demonstrated a negative correlation with recovery rate. No association was found between vitamin D deficiency and clinical outcomes after surgery for DCM. The results of this study do not support the need to normalize vitamin D levels for achieving neurological improvements in patients with DCM.

Comparing the Effectiveness and Safety of Anterior Cervical Discectomy and Fusion with Four Different Fixation Systems: A Systematic Review and Network Meta-analysis

Background: Anterior cervical discectomy and fusion (ACDF) is the classic procedure for the treatment of degenerative cervical myelopathy (DCM). Cage with plate (CP), polyetheretherketone cage alone (PCA), ROI-C and Zero-P are the most widely used fixation systems in ACDF. However, there is insufficient evidence to determine the optimal system for ACDF. Purpose: A comprehensive analysis to show which of the CP, PCA, ROI-C and Zero-P after ACDF has the best clinical efficacy and the most reliable safety. Methods: We searched the Embase, Pubmed, and Cochrane library up to the date of February 13th, 2021. Studies included relevant randomized controlled trials (RCTs) and cohort studies with a comparison of different fixation systems among CP, PCA, ROI-C and Zero-P were identified. Results: We screened 43 trials eligible, including 3045 patients. No significant differences were found in the NDI score. PCA has shown a significantly less recovery of cervical lordosis than CP and Zero-P. For the non-fusion rate, PCA was significantly higher than CP. PCA had a significantly higher subsidence rate than CP and Zero-P, and ROI-C was also significantly higher than CP. For the incidence of complications, CP was significantly higher than the others. The surface under the cumulative ranking curves (SUCRA) for NDI score improvement was: SSC, PCA, and CP. ROI-C, Zero-P, PCA, and CP; for cervical lordosis recovery: CP, Zero-P, ROI-C, and PCA; for non-fusion rate: PCA, Zero-P, ROI-C, and CP; for subsidence rate: PCA, ROI-C, Zero-P, and CP; for complications: CP, PCA, ROI-C, and Zero-P. Conclusion: Despite the third-ranking spectrums of fusion rate, Zero-P still could be recommended for its second-ranking spectrums of the NDI score improvement efficacy, cervical lordosis recovery, and reduction of subsidence rate, with the least ranking of complications. Registration: The number of PROSPERO is CRD42021230735 (www.crd.york.ac.uk/PROSPERO).

Spinal Cord Signal Intensity Predicts Functional Outcomes in the Operative Management of Degenerative Cervical Myelopathy.

Prospective single institutional cohort study on degenerative cervical myelopathy (DCM) from 2009 to 2022. This study aims to assess the relationship among preoperative spinal cord signal change, postoperative signal change evolution, and functional outcome in patients undergoing surgery for DCM. There is conflicting evidence on whether spinal cord signal intensity influences functional outcomes in patients with DCM. This prospective study investigated 104 patients with DCM that underwent both preoperative and routine postoperative cervical spine magnetic resonance imaging (MRI) as part of a research protocol. Signal intensity/grade, modified Japanese Orthopedic Association (mJOA) scores, signal resolution, and patient demographics were assessed. Sixty-eight of the subjects were found to have abnormal T2 spinal cord signal intensity changes on their preoperative MRI. The total mean preoperative mJOA score was 13.6, increasing postoperatively to 16 (P < 0.001). The presence or absence of preoperative spinal cord signal change was not associated with the change in mJOA score or neurological recovery rate after surgery. Of the 68 patients with preoperative T2 signal change, 36 were found to have an improvement in the T2-weighted signal grade after surgery and 32 had no change in postoperative signal grade. The mean improvement in mJOA score (3.7) and neurological recovery rate (70.3%) was significantly higher in the patients with preoperative signal change whose postoperative MRI signal change grade improved by at least one point compared with those that did not (2.0, 50.5%), (P < 0.001, P < 0.003). The presence of preoperative T2-weighted signal change was associated with lower preoperative mJOA scores, but no change in mJOA after surgery or postoperative neurological recovery rate. However, improvement in T2-weighted spinal cord signal grade on postoperative MRI was significantly associated with a degree of neurological improvement after surgery.

Difference between Anterior and Posterior Cord Compression and Its Clinical Implication in Patients with Degenerative Cervical Myelopathy.

In degenerative cervical myelopathy (DCM), the low anteroposterior compression ratio of the spinal cord is known to be associated with a neurologic deficit. However, there is little detailed analysis of spinal cord compression. Axial magnetic resonance images of 183 DCM patients at normal C2-C3 and maximal cord compression segments were analyzed. The anterior (A), posterior (P), and anteroposterior length and width (W) of the spinal cord were measured. Correlation analyses between radiographic parameters and each section of Japanese Orthopedic Association (JOA) scores and comparisons of the patients divided by A (below or above 0, 1, or 2 mm) were performed. Between C2-C3 and maximal compression segments, the mean differences of A and P were 2.0 (1.2) and 0.2 (0.8) mm. The mean anteroposterior compression ratios were 0.58 (0.13) at C2-C3 and 0.32 (0.17) at maximal compression. The A and A/W ratio were significantly correlated with four sections and the total JOA scores (p < 0.05), but the P and P/W ratio did not demonstrate any correlations. Patients with A < 1 mm had significantly lower JOA scores than those with A ≥ 1 mm. In patients with DCM, spinal cord compression occurs mainly in the anterior part and the anterior cord length of <1 mm is particularly associated with neurologic deficits.

Determinants of spinal cord stress and strain in degenerative cervical myelopathy: a patient-specific finite element study.

Degenerative cervical myelopathy (DCM) is the commonest cause of spinal cord dysfunction in older adults and is characterized by chronic cervical spinal cord compression. Spinal cord stress and strain during neck motion are also known contributors to the pathophysiology of DCM, yet these factors are not routinely assessed for surgical planning. The aim of this study was to measure spinal cord stress/strain in DCM using patient-specific 3D finite element models (FEMs) and determine whether spinal cord compression is the primary determinant of spinal cord stress/strain. Three-dimensional patient-specific FEMs were created for six DCM patients (mild [n = 2], moderate [n = 2] and severe [n = 2]). Flexion and extension of the cervical spine were simulated with a pure moment load of 2 Nm. Segmental spinal cord von Mises stress and maximum principal strain were measured. Measures of spinal cord compression and segmental range of motion (ROM) were included in a regression analysis to determine associations with spinal cord stress and strain. Segmental ROM in flexion-extension and axial rotation was independently associated with spinal cord stress (p < 0.001) and strain (p < 0.001), respectively. This relationship was not seen for lateral bending. Segmental ROM had a stronger association with spinal stress and strain as compared to spinal cord compression. Compared to the severity of spinal cord compression, segmental ROM is a stronger determinant spinal cord stress and strain. Surgical procedures that address segmental ROM in addition to cord compression may best optimize spinal cord biomechanics in DCM.

Early surgery compared to nonoperative management for mild degenerative cervical myelopathy: a cost-utility analysis

BACKGROUND CONTEXTDegenerative cervical myelopathy (DCM) is a form of acquired spinal cord compression and contributes to reduced quality of life secondary to neurological dysfunction and pain. There remains uncertainty regarding optimal management for individuals with mild myelopathy. Specifically, owing to lacking long-term natural history studies in this population, we do not know whether these individuals should be treated with initial surgery or observation. PURPOSEWe sought to perform a cost-utility analysis to examine early surgery for mild degenerative cervical myelopathy from the healthcare payer perspective. STUDY DESIGN/SETTINGWe utilized data from the prospective observational cohorts included in the Cervical Spondylotic Myelopathy AO Spine International and North America studies to determine health related quality of life estimates and clinical myelopathy outcomes. PATIENT SAMPLEWe recruited all patients that underwent surgery for DCM enrolled in the Cervical Spondylotic Myelopathy AO Spine International and North America studies between December 2005 and January 2011. OUTCOME MEASURESClinical assessment measures were obtained using the Modified Japanese Orthopedic Association scale and health-related quality of life measures were obtained using the Short Form-6D utility score at baseline (preoperative), 6 months, 12 months and 24 months postsurgery. Cost measures inflated to January 2015 values were obtained using pooled estimates from the hospital payer perspective for surgical patients. METHODSWe employed a Markov state transition model with Monte Carlo microsimulation using a lifetime horizon to obtain an incremental cost utility ratio associated with early surgery for mild myelopathy. Parameter uncertainty was assessed through deterministic means using one-way and two-way sensitivity analyses and probabilistically using parameter estimate distributions with microsimulation (10,000 trials). Costs and utilities were discounted at 3% per annum. RESULTSInitial surgery for mild degenerative cervical myelopathy was associated with an incremental lifetime increase of 1.26 quality-adjusted life years (QALY) compared to observation. The associated cost incurred to the healthcare payer over a lifetime horizon was $12,894.56, resulting in a lifetime incremental cost-utility ratio of $10,250.71/QALY. Utilizing a willingness to pay threshold in keeping with the World Health Organization definition of "very cost-effective" ($54,000 CDN), the probabilistic sensitivity analysis demonstrated that 100% of cases were cost-effective. CONCLUSIONSSurgery compared to initial observation for mild degenerative cervical myelopathy was cost-effective from the Canadian healthcare payer perspective and was associated with lifetime gains in health-related quality of life.