Diffusion tensor imaging predicts functional impairment in mild-to-moderate cervical spondylotic myelopathy

Current Status and Trends of Research on Cervical Spondylotic Myelopathy from the Perspective of Bibliometrics

This review was performed to analyze the research on cervical spondylotic myelopathy published during the past 25 years, summarize the developments in existing research, and predict future hotspots in the field. The goal is to provide a comprehensive overview and exploration of developments in this research area. A bibliometric analysis was performed using CiteSpace and VOSviewer to quantitatively and visually analyze relevant literature from Web of Science between 1998 and 2023. Co-occurrence analysis and co-citation analysis were conducted to evaluate papers, authors, journals, countries, and keywords. In total, 1886 papers were included. The overall publication output in this field increased throughout the review period. Stable author collaboration groups were formed, with the most influential author being Fehlings M.G. Japan and the United States contributed the highest number of publications. The predicted future research hotspots include risk factor analysis, outcome prediction, and machine learning. This study provides both an overview of the research trajectory in the field of cervical spondylotic myelopathy for scholars interested in this area, as well as offering insights and references for future research directions in the field.

The use of diffusion tensor imaging in spinal pathology: a comprehensive literature review

STUDY DESIGN

We reviewed the available literature systematically without meta-analysis following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines.

OBJECTIVE

To evaluate contemporary literature on use of spinal diffusion tensor imaging(sDTI) in spinal pathology.

BACKGROUND

sDTI reveals the location and functional state of critical long tracts and is a potentially useful adjunct in disease management.

METHODS

Studies were included if they presented or discussed data from investigative or therapeutic procedures involving sDTI on human subjects in the setting of surgically amenable spinal pathology. Studies were excluded if they were (1) restricted to computational models investigating parameters using data not obtained clinically, (2) about cranial DTI methods, (3) about spinal pathology data not related to surgical management, (4) discussions or overviews of methods/techniques with minimal inclusion of objective experimental or clinical data.

RESULTS

Degenerative pathologies of interest were restricted to either cervical myelopathy (22/29,75.9%) or lumbar spondylosis 7/29,24.1%). Mass-occupying lesions included intradural pathology and discussed preoperative (7/9,77.8%) and intraoperative imaging(2/9,22.2%) as an adjunct to surgery 22.2%. Traumatic pathology focused on spinal cord injury prognosis and severity grading.

CONCLUSIONS

sDTI seems useful in surgical decision making and outcome measurements and in establishing clinical prognoses over a wide range of surgical pathologies. Further research is warranted with longer follow-up and larger population sizes in a prospective and controlled protocol.

Imaging protocols for non-traumatic spinal cord injury: current state of the art and future directions

INTRODUCTION

Non-traumatic spinal cord injury (NTSCI) is a term used to describe damage to the spinal cord from sources other than trauma. Neuroimaging techniques such as computerized tomography (CT) and magnetic resonance imaging (MRI) have improved our ability to diagnose and manage NTSCIs. Several practice guidelines utilize MRI in the diagnostic evaluation of traumatic and non-traumatic SCI to direct surgical intervention.

AREAS COVERED

The authors review practices surrounding the imaging of various causes of NTSCI as well as recent advances and future directions for the use of novel imaging modalities in this realm. The authors also present discussions around the use of simple radiographs and advanced MRI modalities in clinical settings, and briefly highlight areas of active research that seek to advance our understanding and improve patient care.

EXPERT OPINION

Although several obstacles must be overcome, it appears highly likely that novel quantitative imaging features and advancements in artificial intelligence (AI) as well as machine learning (ML) will revolutionize degenerative cervical myelopathy (DCM) care by providing earlier diagnosis, accurate localization, monitoring for deterioration and neurological recovery, outcome prediction, and standardized practice. Some intriguing findings in these areas have been published, including the identification of possible serum and cerebrospinal fluid biomarkers, which are currently in the early phases of translation.

Diffusion Tensor Imaging in Diagnosing and Evaluating Degenerative Cervical Myelopathy: A Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic review.

OBJECTIVE

Degenerative cervical myelopathy (DCM) is a common spinal cord disorder necessitating surgery. We aim to explore how effectively diffusion tensor imaging (DTI) can distinguish DCM from healthy individuals and assess the relationship between DTI metrics and symptom severity.

METHODS

We included studies with adult DCM patients who had not undergone decompressive surgery and implemented correlation analyses between DTI parameters and severity, or compared healthy controls and DCM patients.

RESULTS

57 studies were included in our meta-analysis. At the maximal compression (MC) level, fractional anisotropy (FA) exhibited lower values in DCM patients, while apparent diffusion coefficient (ADC), mean diffusivity (MD), and radial diffusivity (RD) were notably higher in the DCM group. Moreover, our investigation into the diagnostic utility of DTI parameters disclosed high sensitivity, specificity, and area under the curve values for FA (.84, .80, .83 respectively) and ADC (.74, .84, .88 respectively). Additionally, we explored the correlation between DTI parameters and myelopathy severity, revealing a significant correlation of FA (.53, 95% CI:0.40 to .65) at MC level with JOA/mJOA scores.

CONCLUSION

Current guidelines for DCM suggest decompressive surgery for both mild and severe cases. However, they lack clear recommendations on which mild DCM patients might benefit from conservative treatment vs immediate surgery. ADC's role here could be pivotal, potentially differentiating between healthy individuals and DCM. While it may not correlate with symptom severity, it might predict surgical outcomes, making it a valuable imaging biomarker for clearer management decisions in mild DCM.

Diagnostic efficacy of tract-specific diffusion tensor imaging in cervical spondylotic myelopathy with electrophysiological examination validation

PURPOSE

This study aimed to investigate the effectiveness of tract-specific diffusion tensor imaging (DTI) metrics in identifying the responsible segments for neurological dysfunction in cervical spondylotic myelopathy (CSM).

METHODS

The study encompassed nineteen participants diagnosed with CSM, including 10 males and 9 females. Additionally, a control group consisting of ten healthy caregivers (5 males and 5 females) were recruited with no symptoms and no compressions on magnetic resonance imaging (MRI). All participants underwent a comprehensive physical examination, MRI assessment, and DTI examination conducted by a senior chief physician. Several parameters were collected from the MR images, including the aspect ratio (defined as the anteroposterior diameter / the transverse diameter of the corresponding segment's spinal cord), transverse ratio (defined as the transverse diameter of the corresponding segment's spinal cord / the transverse diameter of the spinal cord at C2/3), and T2 high signal of the spinal cord. Furthermore, quantitative DTI metrics, such as axial diffusivity (AD), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA), were calculated using automatic region-of-interest (ROI) analysis for both whole spinal cord column and dorsal column. Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic efficacy of the aspect ratio, transverse ratio, and DTI parameters. The area under the curve (AUC), sensitivity, and specificity were calculated. Intraoperative spinal cord electrophysiological examination was performed as the objective measure of spinal cord function during surgery.

RESULTS

As determined by electrophysiological examination, neurological dysfunction was found in 2 patients due to C3/4 compression, in 10 patients due to C4/5 compression, in 6 patients due to C5/6 compression, and in 1 patient due to C6/7 compression. The modified Japanese Orthopedic Association scale (mJOA) was 12.71 ± 1.55 in the CSM group, with 4.87 ± 0.72 for sensory nerve function and 5.05 ± 1.35 for motor nerve function. For the control group, none of the volunteers had neurological dysfunction. T2 high signal was found at the most stenotic segment in 13 patients of the CSM group. Considering all the cervical segments, the aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) was more capable of determining the responsible segment than transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). AD, MD, and RD were significantly higher while FA was significantly lower in the responsible segment than in the irresponsible segment (P < 0.05). The AUC of DTI-Dorsal column parameters (AD, MD, RD, FA) was larger than the corresponding parameters of the DTI (Whole spinal cord). AD of DTI-Dorsal Column possessed the greatest efficacy (AUC = 0.823, sensitivity = 84.21%, specificity = 77.32%) to determine the responsible segment, larger than AD of DTI-Whole spinal cord (AUC = 0.822, P = 0.001, Sensitivity = 89.47%, Specificity = 77.32%), aspect ratio (AUC = 0.823, P = 0.001, Sensitivity = 68.42%, Specificity = 82.47%) and transverse ratio (AUC = 0.661, P = 0.027, Sensitivity = 68.42%, Specificity = 67.01%). Subgroup analysis revealed that the diagnostic efficacy of DTI and MRI parameters was influenced by cervical spine segment.

CONCLUSIONS

When considering all cervical segments, AD from the DTI-Dorsal Column exhibited the most significant potential in identifying responsible segments. This potential was found to be superior to that of DTI-Whole spinal cord, aspect ratio, the most stenotic segment, T2 high signals, transverse ratio, motor nerve dysfunction, and sensory nerve dysfunction. The diagnostic effectiveness of both DTI and MRI parameters was notably influenced by the specific cervical spine segment.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE STATEMENT

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

KEY POINTS

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

Evaluating tissue injury in cervical spondylotic myelopathy with spinal cord MRI: a systematic review

PURPOSE

Cervical Spondylotic Myelopathy (CSM) is a degenerative condition that leads to loss of cervical spinal cord (CSC) integrity. Various spinal cord Magnetic Resonance Imaging (MRI) methods can identify and characterize the extent of this damage. This systematic review aimed to evaluate the diagnostic, biomarker, and predictive utilities of different spinal cord MRI methods in clinical research studies of CSM. The aim was to provide a comprehensive understanding of the progress in this direction for future studies and effective diagnosis and management of CSM.

METHODS

A comprehensive literature search was conducted on PubMed and EMBASE from 2010 to 2022 according to PRISMA guidelines. Studies with non-human subjects, less than 3T magnetic field strength, non-clinical design, or not quantitatively focusing on the structural integrity of CSC were excluded. The extracted data from each study included demographics, disease severity, MRI machine characteristics, quantitative metrics, and key findings in terms of diagnostic, biomarker, and predictive utilities of each MRI method. The risk of bias was performed using the guide from AHRQ. The quality of evidence was assessed separately for each type of utility for different MRI methods using GRADE.

RESULTS

Forty-seven studies met the inclusion criteria, utilizing diffusion-weighted imaging (DTI) (n = 39), magnetization transfer (MT) (n = 6), MR spectroscopy (n = 3), and myelin water imaging (n = 1), as well as a combination of MRI methods (n = 12). The metric fractional anisotropy (FA) showed the highest potential in all facets of utilities, followed by mean diffusivity. Other promising metrics included MT ratio and intracellular volume fraction, especially in multimodal studies. However, the level of evidence for these promising metrics was low due to a small number of studies. Some studies, mainly DTI, also reported the usefulness of spinal cord MRI in mild CSM.

CONCLUSIONS

Spinal cord MRI methods can potentially facilitate the diagnosis and management of CSM by quantitatively interrogating the structural integrity of CSC. DTI is the most promising MRI method, and other techniques have also shown promise, especially in multimodal configurations. However, this field is in its early stages, and more studies are needed to establish the usefulness of spinal cord MRI in CSM.

Utility of MRI in Quantifying Tissue Injury in Cervical Spondylotic Myelopathy

Cervical spondylotic myelopathy (CSM) is a progressive disease that worsens over time if untreated. However, the rate of progression can vary among individuals and may be influenced by various factors, such as the age of the patients, underlying conditions, and the severity and location of the spinal cord compression. Early diagnosis and prompt treatment can help slow the progression of CSM and improve symptoms. There has been an increased use of magnetic resonance imaging (MRI) methods in diagnosing and managing CSM. MRI methods provide detailed images and quantitative structural and functional data of the cervical spinal cord and brain, allowing for an accurate evaluation of the extent and location of tissue injury. This review aims to provide an understanding of the use of MRI methods in interrogating functional and structural changes in the central nervous system in CSM. Further, we identified several challenges hindering the clinical utility of these neuroimaging methods.

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

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

A meta-analysis of the role of diffusion tensor imaging in cervical spinal cord compression

BACKGROUND AND PURPOSE

At present, the role of diffusion tensor imaging (DTI) remains controversial. This study aimed to confirm the role of DTI by comparing the differences in fractional anisotropy (FA) values between patients with cervical spinal cord compression (CSCC) and healthy individuals.

METHODS

A systematic and comprehensive literature search was conducted using the Web of Science, Embase, PubMed, and Cochrane Library databases to compare the mean FA values of patients with CSCC and healthy controls across all compression levels in the cervical spinal cord. Essential data from the literature, such as demographic information, imaging parameters, and DTI analysis method, were extracted. Fixed- or random-effect models based on I² heterogeneity were applied to the pooled and subgroup analyses.

RESULTS

Ten studies containing 445 patients and 197 healthy volunteers were eligible. The pooled results demonstrated a decrease in mean FA values across all compression levels in the experiment group compared to those in healthy controls (standardized mean difference = -1.54; 95% confidence interval = [-1.95, -1.14]; p < .001). Meta-regression revealed that the scanner field strength and DTI analysis method had a significant effect on heterogeneity.

CONCLUSIONS

Our results show that FA values in the spinal cord decline in patients with CSCC, thus confirming the crucial role of DTI in CSCC.

Prognostic effect of increased postoperative MRI T2WI high signal intensity in degenerative cervical myelopathy

BACKGROUND CONTEXT

High cord signals (HCS) are common in patients undergoing surgery for degenerative cervical myelopathy (DCM). Few studies have investigated the prognostic effects of postoperative HCS changes.

PURPOSE

To investigate whether different changes in the postoperative magnetic resonance imaging (MRI) T2-weighted images (T2WIs) signal intensity ratio (SIR) is related to patient outcomes, predictors of unsatisfactory recovery, and the factors associated with changes in postoperative SIR.

STUDY DESIGN

A retrospective chart review at a single institution.

PATIENT SAMPLE

The study population included all consecutive patients who showed HCS in preoperative MRI T2WIs and underwent double-door laminoplasty for DCM from December 2017 to December 2020.

OUTCOME MEASURES

Patient self-reported measures included the Japanese Orthopedic Association (JOA) score, 36-Item Short Form Survey (SF-36) physical component score, and SF-36 mental component score. Imaging measures included SIR, length of HCS, and canal narrowing ratio (CNR).

METHODS

We reviewed patient records and analyzed the statistical associations of MRI T2WI measures with the JOA score, SF-36 physical, and mental component scores.

RESULTS

Fifty-three patients were categorized into three groups based on the postoperative HCS changes, identified from MRI T2WI before and after surgery: reduced (Group A, N=26); unchanged (Group B, N=12); and increased (Group C, N=15). The neurological recovery rates 12 months after surgery were 67.72%±17.45% in Group A, 51.53%±16.00% in Group B, and 13.35%±21.35% in Group C (p<.001). Significant differences across the three groups were found in symptom duration, postoperative SIR and length of HCS, pre- and postoperative CNR, recovery rate, JOA, SF-36 scores, with patients in Group C having the worst outcomes. Longer DCM symptom duration, greater preoperative CNR, and increased postoperative HCS were prognostic factors for a recovery rate<50%. Preoperative CNR, with an optimal threshold of 57.303%, was an independent risk factor for increased postoperative HCS.

CONCLUSIONS

Less than one-third of DCM patients with preoperative HCS exhibited an increase in HCS after double-door laminoplasty and reported worse outcomes at the 12-month follow-up when compared to patients with decreased or unchanged postoperative HCS.

Application of Neurite Orientation Dispersion and Density Imaging to Evaluate and Predict the Surgical Outcome for Degenerative Cervical Myelopathy

Objectives

Although the neurite orientation dispersion and density imaging (NODDI) has been shown useful to evaluate the spinal cord dysfunction, there are few prospective studies on analyzing the operation recovery of degenerative cervical myelopathy (DCM) disease using NODDI. This study aims to investigate the preoperative evaluation and predictive ability of NODDI in DCM patients who received posterior cervical laminoplasty.

Methods

This prospective study included 55 patients with DCM from January to December 2017. NODDI metrics, including intracellular volume fraction (Vic), isotropic volume fraction (Viso), and orientation dispersion index (ODI) were measured at the maximally compressed (MC) level and the non‐compressed C2 level in each patient at the preoperative and the 3‐ and 6‐month postoperative follow‐up stages. Neurological function was assessed using the modified Japanese Orthopaedic Association (mJOA) scoring system at each stage. Spearman's correlation and Kendall's tau‐b correlation were used to analyze the relationship between NODDI metrics and mJOA scores. Wilcoxon signed rank test was used to examine the changes in the NODDI and mJOA scores between the preoperative and 6‐month follow‐up stages. ROC analysis was used to further evaluate the predictive capability.

Results

Preoperative Vic at the level of C2 has a significant correlation with the preoperative mJOA score (r = 0.278, p = 0.048). Vic and Viso at the MC level were significantly different between the preoperative period and 6‐month follow‐up. Viso at the MC level was correlated with the mJOA score at 6‐month follow‐up (r = −0.302, p = 0.044). Vic and ODI at the C2 level predicted the surgical prognosis, with areas under the receiver‐operating characteristic curve of 0.663 (p = 0.042) and 0.716 (p = 0.014).

Conclusions

The preoperative NODDI metrics at the C2 level are capable of evaluating the severity of spinal cord dysfunction and predict the surgical outcome.

Changes and clinical correlation of diffusion tensor imaging parameters of compressed spinal cord and nerve root in patients with cervical spondylosis

BACKGROUND

Diffusion tensor imaging (DTI) was used to quantitatively study the characteristics of the related spinal cord and nerve root compression parameters in patients with cervical spondylosis (CS), and diffusion tensor tractography (DTT) was used to visualize the spinal cord and nerve root and analyze their relevance to clinical evaluation.

METHODS

A total of 67 patients with CS and 30 healthy volunteers received 3.0 T magnetic resonance imaging. Cervical DTI and DTT were performed in all the participants, where the b value of DTI was set at 800 s/mm2. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the spinal cord and cervical nerve roots were measured by using DTI. Patients with CS were scored according to the modified Japanese Orthopedic Association (mJOA) score.

RESULTS

In all the participants, the spinal cord and cervical nerve roots were clearly visible by DTT. Compared to the healthy volunteers, the FA values were significantly decreased and ADC values were significantly increased in patients with CS. mJOA score was significantly correlated with the DTI index (ADC and FA) values. Receiver operator characteristic curve analysis revealed that FA and ADC could identify mild, moderate, and severe CS.

CONCLUSIONS

DTI parameters of cervical spinal cord and nerve root compression are associated with the clinical evaluation of patients with CS and may be helpful in assessing the severity of CS.

Quantitative MR Markers in Non-Myelopathic Spinal Cord Compression: A Narrative Review

Degenerative spinal cord compression is a frequent pathological condition with increasing prevalence throughout aging. Initial non-myelopathic cervical spinal cord compression (NMDC) might progress over time into potentially irreversible degenerative cervical myelopathy (DCM). While quantitative MRI (qMRI) techniques demonstrated the ability to depict intrinsic tissue properties, longitudinal in-vivo biomarkers to identify NMDC patients who will eventually develop DCM are still missing. Thus, we aim to review the ability of qMRI techniques (such as diffusion MRI, diffusion tensor imaging (DTI), magnetization transfer (MT) imaging, and magnetic resonance spectroscopy (1H-MRS)) to serve as prognostic markers in NMDC. While DTI in NMDC patients consistently detected lower fractional anisotropy and higher mean diffusivity at compressed levels, caused by demyelination and axonal injury, MT and 1H-MRS, along with advanced and tract-specific diffusion MRI, recently revealed microstructural alterations, also rostrally pointing to Wallerian degeneration. Recent studies also disclosed a significant relationship between microstructural damage and functional deficits, as assessed by qMRI and electrophysiology, respectively. Thus, tract-specific qMRI, in combination with electrophysiology, critically extends our understanding of the underlying pathophysiology of degenerative spinal cord compression and may provide predictive markers of DCM development for accurate patient management. However, the prognostic value must be validated in longitudinal studies.

Degenerative cervical myelopathy delays responses to lateral balance perturbations regardless of predictability

The aim of this study was to quantify balance impairments in standing in people with degenerative cervical myelopathy (PwDCM) in response to external perturbations. PwDCM have damage to their spinal cord due to degeneration of the cervical vertebral column, but little is known about balance. Balance was quantified by capturing kinetics, kinematic, and electromyographic data during standing in response to lateral waist pulls. Participants received pulls during predictable and unpredictable contexts in three stance widths at two magnitudes. In response to lateral waist pulls, PwDCM had larger center of mass excursion (P < 0.001) and delayed gluteus medius electromyography onset (P < 0.001) and peak (P < 0.001) timing. These main effects of history of myelopathy were consistent across predictability, stance width, and magnitude. A multilinear regression determined that gluteus medius peak timing + tibialis anterior peak timing most strongly predicted center of mass excursion (R² = 0.50, P < 0.001). These data suggest that PwDCM have delays in generating voluntary and reactive motor commands, contributing to balance impairments. Future rehabilitation strategies should focus on generating rapid muscular contractions. Additionally, frontal plane postural control is regulated by the gluteus medius and the tibialis anterior, whereas other muscles (e.g. gluteus minimus, ankle invertors/evertors) not studied here may also contribute.NEW & NOTEWORTHY Frontal plane reactive postural control is impaired in persons with degenerative cervical myelopathy because of delayed muscle responses. Additionally, postural control varies across stance width, predictability, and perturbation magnitude.

Imaging and Electrophysiology for Degenerative Cervical Myelopathy [AO Spine RECODE-DCM Research Priority Number 9]

STUDY DESIGN

Narrative review.

OBJECTIVE

The current review aimed to describe the role of existing techniques and emerging methods of imaging and electrophysiology for the management of degenerative cervical myelopathy (DCM), a common and often progressive condition that causes spinal cord dysfunction and significant morbidity globally.

METHODS

A narrative review was conducted to summarize the existing literature and highlight future directions.

RESULTS

Anatomical magnetic resonance imaging (MRI) is well established in the literature as the key imaging tool to identify spinal cord compression, disc herniation/bulging, and inbuckling of the ligamentum flavum, thus facilitating surgical planning, while radiographs and computed tomography (CT) provide complimentary information. Electrophysiology techniques are primarily used to rule out competing diagnoses. However, signal change and measures of cord compression on conventional MRI have limited utility to characterize the degree of tissue injury, which may be helpful for diagnosis, prognostication, and repeated assessments to identify deterioration. Early translational studies of quantitative imaging and electrophysiology techniques show potential of these methods to more accurately reflect changes in spinal cord microstructure and function.

CONCLUSION

Currently, clinical management of DCM relies heavily on anatomical MRI, with additional contributions from radiographs, CT, and electrophysiology. Novel quantitative assessments of microstructure, perfusion, and function have the potential to transform clinical practice, but require robust validation, automation, and standardization prior to uptake.

Predicting postoperative recovery in cervical spondylotic myelopathy: construction and interpretation of T2*-weighted radiomic-based extra trees models

OBJECTIVES

Conventional MRI may not be ideal for predicting cervical spondylotic myelopathy (CSM) prognosis. In this study, we used radiomics in predicting postoperative recovery in CSM. We aimed to develop and validate radiomic feature-based extra trees models.

METHODS

There were 151 patients with CSM who underwent preoperative T₂-/ T₂^*-weighted imaging (WI) and surgery. They were divided into good/poor outcome groups based on the recovery rate. Datasets from multiple scanners were randomised into training and internal validation sets, while the dataset from an independent scanner was used for external validation. Radiomic features were extracted from the transverse spinal cord at the maximum compressed level. Threshold selection algorithm, collinearity removal, and tree-based feature selection were applied sequentially in the training set to obtain the optimal radiomic features. The classification of intramedullary increased signal on T₂/T₂^*WI and compression ratio of the spinal cord on T₂^*WI were selected as the conventional MRI features. Clinical features were age, preoperative mJOA, and symptom duration. Four models were constructed: radiological, radiomic, clinical-radiological, and clinical-radiomic. An AUC significantly > 0.5 was considered meaningful predictive performance based on the DeLong test. The mean decrease in impurity was used to measure feature importance. p < 0.05 was considered statistically significant.

RESULTS

On internal and external validations, AUCs of the radiomic and clinical-radiomic models, and radiological and clinical-radiological models ranged from 0.71 to 0.81 (significantly > 0.5) and 0.40 to 0.55, respectively. Wavelet-LL first-order variance was the most important feature in the radiomic model.

CONCLUSION

Radiomic features, especially wavelet-LL first-order variance, contribute to meaningful predictive models for CSM prognosis.

KEY POINTS

• Conventional MRI features may not be ideal in predicting prognosis. • Radiomics provides greater predictive efficiency in the recovery from cervical spondylotic myelopathy.

Diffusion tensor imaging-based quantitative analysis of the spinal cord in Pembroke Welsh Corgis with degenerative myelopathy

Canine degenerative myelopathy (DM) is a progressive neurodegenerative disease of the spinal cord. The diagnosis is based on the observation of clinical signs, genetic testing, and exclusion of other spinal cord diseases, and a definitive diagnosis of DM can only be confirmed by postmortem histopathological findings. The aim of this study was to investigate the diagnostic ability of diffusion tensor imaging (DTI) for DM. Eight DM-affected Pembroke Welsh Corgis, thirteen dogs with thoracolumbar intervertebral disk herniation (IVDH), and six healthy control dogs were included. All dogs were scanned using a 3.0-T MRI system. Apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were calculated for each intervertebral disk level slice between T8–T9 and L2–L3 intervertebral disk levels, and the entire area of the thoracolumbar spinal cord between T8–T9 and L2–L3 intervertebral disk levels (T8–L3 region). The ADC and FA values of the T8–L3 region were significantly lower in the DM group than in the IVDH group. The ADC values for the T8–L3 region had a moderate negative correlation with clinical duration (r_s= −0.723, P=0.043); however, the FA values of other intervertebral disk levels and T8–L3 region had no correlation with clinical durations. The measurement of DTI indices can be used to quantitatively assess neurodegeneration and may have diagnostic value for DM. In particular, the ADC value of the T8–L3 region may aid in making a non-invasive premortem diagnosis of DM.

Optimal machine learning methods for radiomic prediction models: Clinical application for preoperative T2*-weighted images of cervical spondylotic myelopathy

INTRODUCTION

Predicting the postoperative neurological function of cervical spondylotic myelopathy (CSM) patients is generally based on conventional magnetic resonance imaging (MRI) patterns, but this approach is not completely satisfactory. This study utilized radiomics, which produced advanced objective and quantitative indicators, and machine learning to develop, validate, test, and compare models for predicting the postoperative prognosis of CSM.

MATERIALS AND METHODS

In total, 151 CSM patients undergoing surgical treatment and preoperative MRI was retrospectively collected and divided into good/poor outcome groups based on postoperative modified Japanese Orthopedic Association (mJOA) scores. The datasets obtained from several scanners (an independent  scanner) for the training (testing) cohort were used for cross-validation (CV). Radiological models based on the intramedullary hyperintensity and compression ratio were constructed with 14 binary classifiers. Radiomic models based on 237 robust radiomic features were constructed with the same 14 binary classifiers in combination with 7 feature reduction methods, resulting in 98 models. The main outcome measures were the area under the receiver operating characteristic curve (AUROC) and accuracy.

RESULTS

Forty-one (11) radiomic models were superior to random guessing during CV (testing), with significant increased AUROC and/or accuracy (P AUROC < .05 and/or P accuracy < .05). One radiological model performed better than random guessing during CV (P accuracy < .05). In the testing cohort, the linear SVM preprocessor + SVM, the best radiomic model (AUROC: 0.74 ± 0.08, accuracy: 0.73 ± 0.07), overperformed the best radiological model (P AUROC = .048).

CONCLUSION

Radiomic features can predict postoperative spinal cord function in CSM patients. The linear SVM preprocessor + SVM has great application potential in building radiomic models.

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.

Detection of cerebral reorganization associated with degenerative cervical myelopathy using diffusion spectral imaging (DSI)

Degenerative Cervical Myelopathy (DCM) is a spinal cord disorder that causes significant physical disabilities in older patients. While most DCM research focuses on the spinal cord, widespread reorganization of the brain may occur to compensate for functional impairment. This observational study used diffusion spectrum imaging (DSI) to examine reorganization of cerebral white matter associated with neurological impairment as measured by the modified Japanese Orthopedic Association (mJOA), and severity of neck disability as measured by the Neck Disability Index (NDI) score. A total of 47 patients were included in the cervical spondylosis (CS) cohort: 38 patients with DCM (mean mJOA = 14.6, and mean NDI = 12.0), and 9 neurologically asymptomatic patients with spinal cord compression (mJOA = 18, and mean NDI = 7.0). 28 healthy volunteers (HCs) served as the control group. Lower generalized fractional anisotropy (GFA) was observed throughout much of the brain in patients compared to HCs (p < 0.05). Fiber pathways associated with somatosensory functions, such as the corpus callosum and corona radiata, showed increased quantitative anisotropy (QA) in patients compared to HCs. Correlation analyses further suggested that structural connectivity was enhanced to compensate for neurological dysfunction within sensorimotor regions, where fibers such as the posterior corona radiata had NQA values that were negatively associated with mJOA (p = 0.0020, R² = 0.2935) and positively associated with NDI score (p = 0.0164, R² = 0.1889). Altogether, these results suggest that DCM and neurologically asymptomatic spinal cord compression patients tend to have long-term reorganization within the brain, particularly in those regions responsible for the perception and integration of sensory information, motor regulation, and pain modulation.

Compensatory brainstem functional and structural connectivity in patients with degenerative cervical myelopathy by probabilistic tractography and functional MRI

Degenerative cervical myelopathy (DCM) is the most common cause of spinal cord impairment in adults. Previous supraspinal investigations have primarily focused on cortical changes in this patient population. As the nexus between the brain and the spinal cord, the brainstem has been understudied in patients with DCM. The current study examined the structural and functional connectivity between the brainstem and cortex in DCM patients using probabilistic tractography and resting-state functional MRI. A total of 26 study patients and 32 neurologically intact, healthy volunteers (HCs) participated in this prospective analysis. The study cohort included DCM patients (n = 18), as well as neurologically asymptomatic patients with evidence of cervical spine degenerative changes and spinal cord compression (n = 8). Results of the study demonstrated significant differences in fiber density (FD), fiber cross-section (FDC), and the functional connectivity (FC) between the study cohort and HCs. Through seeding the brainstem, the study cohort showed reductions in FD and FDC along the corticospinal tract, including regions extending through the corona radiata and internal capsule. By correlating FD and FDC with the Neck Disability Index (NDI), and the modified Japanese Orthopaedic Association (mJOA), we identified increasing total volume of projections to the thalamus, basal ganglia, and internal capsule, and increased functional connectivity to visual network and the posterior parietal cortices. These results support our hypothesis that DCM patients tend to have long-term FC reorganization not only localized to sensorimotor regions, but also to regulatory and visual processing regions, designed to ultimately preserve neurological function.

The Evaluation and Prediction of Laminoplasty Surgery Outcome in Patients with Degenerative Cervical Myelopathy Using Diffusion Tensor MRI

BACKGROUND AND PURPOSE

DTI has been proved valuable for the diagnosis of degenerative cervical myelopathy, whereas its capacity for predicting the outcome of surgery is still under debate. Here we conduct a prospective cohort study to analyze the capacity of DTI for evaluating and predicting laminoplasty surgery outcome for degenerative cervical myelopathy.

MATERIALS AND METHODS

We recruited 55 patients with degenerative cervical myelopathy who underwent DTI before surgery and at 3- and 6-month follow-up stages, and 20 healthy subjects. For clinical assessment, the modified Japanese Orthopedic Association scale was recorded for each patient at different stages. DTI metrics were compared between patients before surgery and healthy subjects. Spearman correlation and receiver operating characteristic were used to analyze the evaluation and prediction capacity of DTI for the modified Japanese Orthopedic Association scale, respectively. We analyzed different vertebral levels: maximal compression level, average of all compression levels, and C2 level.

RESULTS

DTI metrics were significantly different between patients before surgery and healthy subjects. Before surgery, DTI for the maximal compression level or DTI for the average of all compression levels had no significant correlation with the modified Japanese Orthopedic Association scale. For all stages, DTI at the C2 level was correlated with the modified Japanese Orthopedic Association scale. DTI metrics at the C2 level before surgery were significantly correlated with the postoperative modified Japanese Orthopedic Association scale recovery rate. Receiver operating characteristic analysis demonstrated that fractional anisotropy at C2 was capable of predicting the postoperative modified Japanese Orthopedic Association scale recovery rate (P = .04).

CONCLUSIONS

The DTI metrics before laminoplasty surgery, especially fractional anisotropy at the C2 level, have the potential for evaluating and predicting the degenerative cervical myelopathy surgery outcome.

Progression Prediction of Mild Cervical Spondylotic Myelopathy by Somatosensory-evoked Potentials

STUDY DESIGN

Retrospective study to correlate classification of somatosensory-evoked potentials (SEPs) with symptomatic progress of patients with mild cervical spondylotic myelopathy (CSM).

OBJECTIVE

The aim of this study was to evaluate the usefulness of SEPs for predicting symptomatic progress of mild CSM.

SUMMARY OF BACKGROUND DATA

SEPs have been used for clinical diagnosis and intraoperative neuromonitoring in patients with CSM. However, the prognostic value of SEPs in predicting the progression of CSM remains unclear.

METHODS

A total of 200 patients with a clinical diagnosis of mild CSM were enrolled between September 2014 and February 2018. All patients received clinical assessment with the modified Japanese Orthopedic Association scale (mJOA), magnetic resonance imaging, and SEP tests in the first clinical visit and at 1-year follow-up. A classification of upper and lower limbs SEP was developed. At 1-year follow-up, patients with symptom decline >2 points in mJOA were considered progressive myelopathy cases. The relationship of progressive myelopathy and classifications of SEP was investigated.

RESULTS

Fifty-four of 200 cases presented with progressive myelopathy. The incidence of progressive myelopathy was 2.6%, 27.7%, 23.8%, 86.7%, and 100% in Class I, II, III, IV, and V of upper SEPs, respectively, and 18.8%, 39.4%, 42.3%, and 62.5% in Class I, II, III, and IV of lower SEPs, respectively. For the combination classification of upper and lower SEPs, the incidence of progressive myelopathy was 0%, 13.7%, 24.3%, 91.1%, and 100% in Class I, II, III, IV, and V, respectively. There was a significant correlation of the incidence of progressive myelopathy with SEP classification for the upper SEPs (r = 0.94, P < 0.01) and the combination SEPs (r = 0.95, P < 0.01).

CONCLUSION

The incidence of progressive degenerative myelopathy increased with the upper and combination SEP classifications. Thus, classification of SEPs could predict the clinical decline in mJOA in CSM, reflecting the probability of worsening of myelopathy.

LEVEL OF EVIDENCE

4.

Utility and validity of neurite orientation dispersion and density imaging with diffusion tensor imaging to quantify the severity of cervical spondylotic myelopathy and assess postoperative neurological recovery

BACKGROUND CONTEXT

Predicting postoperative prognosis with preoperative diagnostic imaging has clinical importance. Recent studies have indicated the utility of diffusion tensor imaging (DTI) to quantify the severity of cervical spondylotic myelopathy (CSM) and assess the prognosis of surgical outcomes. However, how to apply DTI to evaluate CSM in a clinical setting is not fully elucidated. Neurite orientation dispersion and density imaging (NODDI) is a model-based practical diffusion-weighted magnetic resonance imaging analysis for estimating specific microstructural features related directly to neuronal morphology. In a prior study, we indicated preoperative NODDI parameters are a promising tool with which to predict neuronal recovery after decompression surgery in patients with CSM with 2 years follow-up. However, the correlation between NODDI parameters and postoperative long-term outcomes and change of parameters over time postoperatively has remained largely unknown.

STUDY DESIGN

Retrospective cohort study.

PURPOSE

To determine the change of parameters of NODDI and conventional DTI over time, and the relationship between parameters and neurological recovery 2 years after surgery.

PATIENT SAMPLE

We included 28 consecutive patients with nontraumatic cervical lesions from CSM who underwent laminoplasty and were followed up for >2 years. Patients underwent magnetic resonance imaging before and approximately 2 weeks, 6 months, and 1 year after surgery.

OUTCOME MEASURES

In addition to conventional DTI metrics, we evaluated intracellular volume fraction (ICVF) and orientation dispersion index, which are metrics derived from NODDI. The Japanese Orthopedic Association (JOA) scoring system was used before and 2 years after surgery to assess neurological outcome (JOA recovery rate).

METHODS

NODDI and conventional DTI values were measured at the C2-C3 intervertebral level (control value) and the most compressed levels (C3-C7 intervertebral levels) were measured by 3 observers. The changes of these values from preoperatively, 2 weeks after surgery, 6 months after surgery, and 1 year after surgery, were determined. The correlations between preoperative neurological severity, postoperative neuronal recovery, and preoperative DTI or NODDI metrics were determined. No financial or material support was obtained for this study. There is no conflict of interest.

RESULTS

The preoperative ICVF and fractional anisotropy at the most compressed level were significantly less than the preoperative values at the control C2-C3 intervertebral level and fractional anisotropy at the most compressed level was increased in the immediate postoperative period. By contrast, ICVF at the most compressed level was not increased in the immediate postoperative period and a significant increase was observed at 6 months after surgery. Preoperative ICVF was significantly correlated with JOA recovery rate at 2 years after surgery.

CONCLUSIONS

NODDI is a reproducible and reliable method for evaluation of CSM. ICVF improved after surgery and recovery of physical findings accompanied this change. ICVF may be applied clinically to predict postoperative recovery.

MR diffusion tensor imaging of the spinal cord: can it help in early detection of cervical spondylotic myelopathy and assessment of its severity?

Background

The aim of this study is to evaluate the potential application of MR diffusion tensor imaging (with calculation of fractional anisotropy (FA) values) in assessment of the spondylotic cervical spinal canal compromise and comparison with the information issued from conventional MR sequences for early detection of cervical spondylotic myelopathy (CSM). Thirty patients (11 males and 19 females) were included in this study; age ranged from 22 to 70 years (mean age = 44). All patients had conventional and diffusion tensor imaging (DTI) examinations of the cervical spine for detection and assessment of degree of cervical cord myelopathy. FA values of the whole cord circumference and at 3, 6, 9, 12 o’clock positions of the normal cord (opposite to C2), opposite to the most affected disc, and below the level of the most affected disc were measured.

Results

High statistically significant P values were obtained when comparing the FA values of the normal cord with the cord opposite to the most affected disc, the normal cord with the cord below the affected disc and the cord at the level of the most affected disc with the cord below the level of the most affected disc.

Conclusions

DTI of the cervical spinal cord with FA measurement in patients with cervical spondylosis helps in early detection of cervical cord compressive myelopathy prior to appearance of changes in conventional MRI, which can improve the clinical outcome and help in treatment plans.

Comparison between quantitative measurements of diffusion tensor imaging and T2 signal intensity in a large series of cervical spondylotic myelopathy patients for assessment of disease severity and prognostication of recovery

OBJECTIVE

Cervical spondylotic myelopathy (CSM) is a common cause of spinal cord dysfunction. Recently, it has been shown that diffusion tensor imaging (DTI) may be a better biomarker than T2-weighted signal intensity (T2SI) on MRI for CSM. However, there is very little literature on a comparison between the quantitative measurements of DTI and T2SI in the CSM patient population to determine disease severity and recovery.

METHODS

A prospective analysis of 46 patients with both preoperative DTI and T2-weighted MRI was undertaken. Normalized T2SI (NT2SI), regardless of the presence or absence of T2SI at the level of maximum compression (LMC), was determined by calculating the T2SI at the LMC/T2SI at the level of the foramen magnum. Regression analysis was performed to determine the relationship of fractional anisotropy (FA), a quantitative measure derived from DTI, and NT2SI individually as well their combination with baseline preoperative modified Japanese Orthopaedic Association (mJOA) score and ∆mJOA score at the 3-, 6-, 12-, and 24-month follow-ups. Goodness-of-fit analysis was done using residual diagnostics. In addition, mixed-effects regression analysis was used to evaluate the impact of FA and NT2SI individually. A p value < 0.05 was selected to indicate statistical significance.

RESULTS

Regression analysis showed a significant positive correlation between FA at the LMC and preoperative mJOA score (p = 0.041) but a significant negative correlation between FA at the LMC and the ΔmJOA score at the 12-month follow-up (p = 0.010). All other relationships between FA at the LMC and the baseline preoperative mJOA score or ∆mJOA score at the 3-, 6-, and 24-month follow-ups were not statistically significant. For NT2SI and the combination of FA and NT2SI, no significant relationships with preoperative mJOA score or ∆mJOA at 3, 6, and 24 months were seen on regression analysis. However, there was a significant correlation of combined FA and NT2SI with ∆mJOA score at the 12-month follow-up. Mixed-effects regression revealed that FA measured at the LMC was the only significant predictor of ΔmJOA score (p = 0.03), whereas NT2SI and time were not. Goodness-of-fit analysis did not show any evidence of lack of fit.

CONCLUSIONS

In this large prospective study of CSM patients, FA at LMC appears to be a better biomarker for determining long-term outcomes following surgery in CSM patients than NT2SI or the combination values at LMC.

Outcome Measures and Variables Affecting Prognosis of Cervical Spondylotic Myelopathy: WFNS Spine Committee Recommendations

This study is conducted to review the literature systematically to determine most reliable outcome measures, important clinical and radiological variables affecting the prognosis in cervical spondylotic myelopathy patients. A literature search was performed for articles published during the last 10 years. As functional outcome measures we recommend to use modified Japanese Orthopaedic Association scale, Nurick’s grade, and Myelopathy Disability Index. Three clinical variables that affect the outcomes are age, duration of symptoms, and severity of the myelopathy. Examination findings require more detailed study to validate their effect on the outcomes. The predictive variables affecting the outcomes are hand atrophy, leg spasticity, clonus, and Babinski’s sign. Among the radiological variables, the curvature of the cervical spine is the most important predictor of prognosis. Patients with instability are expected to have a poor surgical outcome. Spinal cord compression ratio is a critical factor for prognosis. High signal intensity on T2-weighted magnetic resonance images is a negative predictor for prognosis. The most important predictors of outcome are preoperative severity and duration of symptoms. T2 hyperintensity and cord compression ratio can also predict outcomes. New radiological tests may give promising results in the future.

Recent advances in the management of cervical spondylotic myelopathy: bibliometric analysis and surgical perspectives

OBJECTIVE

Cervical spondylotic myelopathy (CSM) has become a prevalent cause of spinal cord dysfunction among the aging population worldwide. Although great strides have been made in spine surgery in past decades, the optimal timing and surgical strategy to treat CSM have remained controversial. In this article the authors aimed to analyze the current trends in studies of CSM and to summarize the recent advances of surgical techniques in its treatment.

METHODS

The PubMed database was searched using the keywords pertaining to CSM in human studies that were published between 1975 and 2018. Analyses of both the bibliometrics and contents, including the types of papers, authors, affiliations and countries, number of patients, and the surgical approaches were conducted. A systematic review of the literature was also performed with emphasis on the diagnosis and treatment of mild CSM.

RESULTS

A total of 1008 papers published during the span of 44 years were analyzed. These CSM studies mainly focused on the natural history, diagnosis, and treatment, and only a few prospective randomized trials were reported. For the authors and affiliations, there was a shift of clustering of papers toward Asian countries in the past decades. Regarding the treatment for CSM, there was an exponential growth of surgical series published, and there was a trend toward slightly more anterior than posterior approaches through the past decade. Patients with CSM had increased risks of neurological deterioration or spinal cord injury with nonoperative management. Because surgery might reduce the risks, and early surgery was likely to be correlated with better outcomes, there was a trend toward attention to mildly symptomatic CSM.

CONCLUSIONS

There is emerging enthusiasm for research on CSM worldwide, with more publications originating in Asian countries over the past few decades. The surgical management of CSM is evolving continuously toward early and anterior approaches. More prospective investigations on the optimal timing and choices of surgery are therefore needed.

Neck disability in patients with cervical spondylosis is associated with altered brain functional connectivity

Cervical degenerative disease is a major cause of neck disability, but it has been understudied in patients with cervical spondylotic (CS), largely due to the fact that the neurological impairment associated with this condition tends to be the primary treatment focus. This observational study examined the cerebral functional alterations occurring in advanced cervical spondylosis and myelopathy using resting state functional MRI. Associations between functional connectivity (FC) and neck disability using the Neck Disability Index (NDI) were assessed. Results of the study demonstrated an increase in FC with increasing in neck disability in regions associated with sensorimotor system (both postcentral gyri and precentral gyri, bilaterally, with the SMA; bilateral precentral gyri and the left postcentral gyrus, with the left superior frontal gyrus; bilateral SMA and the left putamen, with the superior frontal gyri). Accounting for the difference in neurological function (mJOA score), strong connectivity between the precentral gyri and the SMA associated with the neck disability. Consistent with studies in chronic pain conditions, these findings suggest neck disability is associated with altered cerebral FC in cervical spondylosis patients.

Compressive Pressure Versus Time in Cauda Equina Syndrome: A Systematic Review and Meta-Analysis of Experimental Studies

STUDY DESIGN

Systematic review and meta-analysis.

OBJECTIVE

To examine the relationship between compressive pressure and its duration in cauda equina compression, and the effects of subsequent decompression, on neurophysiological function, and pathophysiology in animal studies. We further aim to investigate these relationships with systemic blood pressure to assess whether a vascular component in the underlying mechanism may contribute to the clinical heterogeneity of this disease.

SUMMARY OF BACKGROUND DATA

The complex relationship between preoperative factors and outcomes in cauda equina syndrome (CES) suggests heterogeneity within CES which may inform better understanding of pathophysiological process, their effect on neurological function, and prognosis.

METHODS

Systematic review identified 17 relevant studies including 422 animals and reporting electrophysiological measures (EP), histopathology, and blood flow. Modeling using meta-regression analyzed the relationship between compressive pressure, duration of compression, and electrophysiological function in both compression and decompression studies.

RESULTS

Modeling suggested that electrophysiological dysfunction in acute cauda equina compression has a sigmoidal response, with particularly deterioration when mean arterial blood pressure is exceeded and, additionally, sustained for approximately 1 hour. Accounting for pressure and duration may help risk-stratify patients pre-decompression. Outcomes after decompression appeared to be related more to the degree of compression, where exceeding systolic blood pressure tended to result in an irreversible lesion, rather than duration of compression. Prognosis was most strongly associated with residual pre-decompression function.

CONCLUSION

Compressive pressure influences effects and outcomes of cauda equina compression. We suggest the presence of two broad phenotypic groups within CES defined by the degree of ischaemia as a potential explanatory pathophysiological mechanism.

LEVEL OF EVIDENCE

1.

Changes in diffusion tensor imaging indices of the lumbosacral enlargement correlate with cervical spinal cord changes and clinical assessment in patients with cervical spondylotic myelopathy

OBJECTIVES

We examined whether changes in diffusion tensor imaging (DTI) indices of the lumbosacral enlargement are similar to those at the cervical level, and correlate with clinical assessments in patients with cervical spondylotic myelopathy (CSM).

PATIENTS AND METHODS

Patients with CSM and healthy volunteers (40-42/group) received DTI scans at both lumbosacral enlargement and cervical spinal cord. Modified Japanese Orthopedic Association (mJOA) score was also recorded for those with CSM. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values of DTI in the two groups were compared. We also examined the correlation between DTI indices (ADC and FA) of the lumbosacral enlargement and those of the cervical spinal cord, and between DTI indices and mJOA in the CSM group.

RESULTS

Compared with the values of healthy subjects, the ADC values of patients with CSM were significantly increased, and FA values were significantly decreased at both cervical spinal cord and lumbosacral enlargement. Changes in FA value of the cervical cord showed a positive correlation to those of the lumbosacral enlargement in the CSM group. Importantly, a linear correlation was detected between mJOA score and DTI indices (ADC and FA) of the cervical cord, as well as FA value of the lumbosacral enlargement in the CSM group.

CONCLUSION

DTI indices, especially FA, of the lumbosacral enlargement correlate with clinical assessments of patients with CSM, and hence may be useful for evaluating the severity of cervical cord injury.

Value of conventional MRI and diffusion tensor imaging parameters in predicting surgical outcome in patients with degenerative cervical myelopathy

BACKGROUND

In addition to conventional magnetic resonance imaging (cMRI), diffusion tensor imaging (DTI) has been investigated as a potential diagnostic and prognostic tool for patients with degenerative cervical myelopathy (DCM).

OBJECTIVE

To assess the efficacy of cMRI and DTI parameters in prediction of surgical outcome in DCM patients.

METHODS

One hundred and forty-two patients with DCM who underwent presurgical cMRI and DTI of the cervical spine were included. Quantitative parameters obtained by cMRI included compression ratio (CR), transverse area (TA), and signal intensity ratio (SIR). DTI was evaluated for apparent diffusion coefficient (ADC) and fractional anisotropy (FA). The Japanese Orthopaedic Association (JOA) score and recovery rate were used to evaluate clinical outcomes. A JOA recovery rate < 50% was defined as a poor surgical outcome. The relationship of surgical outcome with various imaging parameters was examined. Receiver operating characteristic (ROC) curves were used to measure the predictive ability and determine the best cut-off values of the quantitative parameters.

RESULTS

By ROC curve analyses of imaging parameters, the largest area under the ROC curve (AUC) was for FA (0.750), followed by ADC (0.719), TA (0.716), SIR (0.673), and CR (0.591). The cut-off values with the best compromise between sensitivity and specificity were set at 0.390 for FA, 1.344 × 10-3 mm2/s for ADC, 46.02 mm2 for TA, 1.556 for SIR, and 26.56% for CR. Multivariate logistic regression model revealed that JOA score ⩽ 8 points, TA ⩽ 46.02 mm2, and FA ⩽ 0.390 were independently associated with poor surgical outcome. The AUC value for the three-predictor model was 0.871, indicating strong predictive discrimination, and was significantly higher than the AUC value for the model containing only the JOA score (0.763; P= 0.003).

CONCLUSIONS

JOA score is a reasonable predictor of surgical outcome in DCM. However, a model inclusive of TA and FA provides superior predictive ability. Thus, quantitative analysis of cMRI and DTI is useful for predicting surgical outcome in DCM.

Usefulness of conventional magnetic resonance imaging, diffusion tensor imaging and neurite orientation dispersion and density imaging in evaluating postoperative function in patients with cervical spondylotic myelopathy

Objective

The objective of this study was to evaluate the usefulness of T2 high signal intensity (T2-HSI) and decreased anteroposterior diameter (APD), diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI) in evaluating postoperative cervical cord function.

Methods

The study included 57 postoperative cervical spondylotic myelopathy patients. Clinical evaluation and functional recovery assessments were performed using the modified Japanese Orthopaedic Association (mJOA) score and recovery rate. The presence of T2-HSI and decreased APD was recorded for exploring the relevance. Spearman correlation was applied to investigate the relationships between DTI and NODDI metrics and mJOA score. Multiple comparisons of T2 signal intensity, APD and diffusion metrics were evaluated by using multiple linear regression.

Results

Only the recovery rate was significantly different between T2-HSI and non-T2-HSI (nT2-HSI) patients (χ² = 4.466, p = 0.045). Significant differences were not observed between cervical cords with and without decreased APD. Diffusion metrics, including fractional anisotropy (p = 0.0005), mean diffusivity (p = 0.0008), radial diffusivity (p = 0.0003) and intracellular volume fraction (p = 0.001), were significantly correlated with mJOA score. The ability of T2 signal intensity (p = 0.421) and APD (p = 0.420) to evaluate the postoperative function was inferior to that of fractional anisotropy (p = 0.002), mean diffusivity (p = 0.001), radial diffusivity (p = 0.001) and intracellular volume fraction (p = 0.004).

Conclusion

Conventional magnetic resonance imaging signs could be considered as a reference to make an approximate assessment, whereas DTI and NODDI could be better quantitative tools for evaluating the postoperative function and may help in interpreting residual symptoms.

The translational potential of this article

DTI and NODDI could provide reliable postoperative evaluation and analysis for cervical spondylotic myelopathy patients.

A Follow-up Study of Postoperative DCM Patients Using Diffusion MRI with DTI and NODDI

STUDY DESIGN

A retrospective cohort study.

OBJECTIVE

The aim of this study was to investigate the relationship between spinal cord microstructures and spinal cord dysfunction in degenerative cervical myelopathy (DCM) patients; a follow-up study was carried out using diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI), an advanced diffusion model.

SUMMARY OF BACKGROUND DATA

DTI has been used for diagnosis of DCM. Although DTI has advantages of high sensitivity and quantitative features, it is limited by its low specificity for measuring microstructures.

METHODS

Fifty-eight postoperative DCM patients with 12 to 14 months of surgical recovery were recruited, as well as 14 healthy volunteers for control group. All DTI and NODDI metrics were measured at the most stenotic levels of patients and at all levels of control group. A t test was used to compare the metrics between patient and control groups, and Spearman correlation was used to test the relationship between the metrics and clinical assessment, modified Japanese Orthopedic Association (mJOA) scores.

RESULTS

t test showed that DTI metrics, neurite density Vic, and free water fraction Viso had significant differences between control group and the most stenotic levels in patients. For DTI metrics, fractional anisotropy (FA), radial diffusivity (RD), and mean diffusivity (MD) in patients were significantly correlated with mJOA. For NODDI metrics, only Vic is positively correlated with mJOA.

CONCLUSION

The results of t test and correlation with mJOA suggest that DTI and NODDI are valuable for evaluating spinal cord function. Results of NODDI indicate that the reason for FA reduction in DCM may be decreased neurite density, not increased orientation dispersion.

LEVEL OF EVIDENCE

3.

Highly Accurate Analysis of the Cervical Neural Tract of the Elderly Using ZOOM DTI

Background/Aims

To investigate the fractional anisotropy (FA) values of the cervical spinal cord in elderly individuals using zonally magnified oblique multislice (ZOOM) diffusion tensor imaging (DTI).

Methods

Fourteen healthy elderly volunteers (group E) and 10 young volunteers (group Y) were enrolled. We assessed the FA, apparent diffusion coefficient (ADC), and λ₁–λ₃ values using 3-T magnetic resonance imaging. The region of interest was contoured entirely inside the spinal cord, with no gray/white matter distinction, in order to avoid including the cerebrospinal fluid.

Results

As lower cervical levels were approached, the FA values gradually decreased, while the ADC values increased. The mean FA values at each cervical level were as follows in groups E and Y: 0.71 and 0.70 at the C2/3 level, 0.66 and 0.66 at the C3/4 level, 0.63 and 0.62 at the C4/5 level, 0.57 and 0.57 at the C5/6 level, and 0.58 and 0.57 at the C6/7 level, respectively. The mean ADC values in groups E and Y were 1.06 and 0.99 at the C2/3 level, 1.05 and 1.06 at the C3/4 level, 1.14 and 1.06 at the C4/5 level, 1.18 and 1.21 at the C5/6 level, and 1.39 and 1.46 at the C6/7 level, respectively. There were no significant differences between the elderly and young participants.

Conclusion

In both asymptomatic elderly and young individuals, the FA values gradually decreased and the ADC values increased moving towards lower cervical levels. Age did not affect the FA values, even though mild cord compression was evident due to spondylotic changes. ZOOM DTI has the potential to provide more information than conventional DTI.

Reproducibility, temporal stability, and functional correlation of diffusion MR measurements within the spinal cord in patients with asymptomatic cervical stenosis or cervical myelopathy

OBJECTIVE The purpose of this study was to quantify the reproducibility, temporal stability, and functional correlation of diffusion MR characteristics in the spinal cord in patients with cervical stenosis with or without myelopathy. The association between longitudinal diffusion tensor imaging (DTI) measurements and serial neurological function assessment was explored at both the group and individual level. METHODS Sixty-six nonoperatively treated patients with cervical stenosis were prospectively followed (3 months to > 5 years) using synchronous serial MRI and functional outcome assessment. A total of 183 separate MRI examinations were performed, separated by at least 3 months, and each patient had a minimum of 2 MRI scans (range 2-5 scans). Anatomical and DTI measurements were performed within the spinal cord at the C1-2 region as well as at the area of highest compression. Coefficients of variance (COVs) were compared across measurements in both reference tissue and areas of compression for anatomical measurements, fractional anisotropy (FA), and mean diffusivity (MD). The correlation between diffusion MR measures at the site of compression and evaluations of neurological function assessed using the modified Japanese Orthopaedic Association (mJOA) scale at multiple time points was evaluated. RESULTS The COVs for anatomical measurements (Torg ratio and canal diameter) were between 7% and 10%. The median COV for FA measurements at the site of compression was 9%, and for reference tissue at C1-2 it was 6%. The median COV for MD at the site of compression was approximately 12%, and for reference tissue at C1-2 it was 10%. The FA and MD measurements of C1-2 averaged 0.61 and 0.91 μm²/msec, respectively, whereas the FA and MD measurements at the site of compression averaged 0.51 and 1.26 μm²/msec, respectively. Both FA (slope = 0.037; R² = 0.3281, p < 0.0001) and MD (slope = -0.074; R² = 0.1101, p = 0.0084) were significantly correlated with the mJOA score. The FA decreased by approximately 0.032 units per mJOA unit decrease (R² = 0.2037, p < 0.0001), whereas the MD was increased by approximately 0.084 μm²/msec for every mJOA unit decrease (R² = 0.1016, p < 0.0001). CONCLUSIONS Quantitative DTI measurements of the spinal cord in patients with cervical stenosis with or without myelopathy have a median COV of 5%-10%, similar to anatomical measurements. The reproducibility of these measurements and significant correlation with functional outcome status suggest a potential role in the evaluation and longitudinal surveillance of nonoperatively treated patients. With respect to the specific DTI measurements, FA within the spinal cord appears slightly more sensitive to neurological function and more stable than measures of MD. Therefore, DTI of the spinal cord may be a clinically feasible imaging technique for longitudinally monitoring patients with cervical spondylotic myelopathy.

Reduced Field-of-View Diffusion Tensor Imaging of the Spinal Cord Shows Motor Dysfunction of the Lower Extremities in Patients With Cervical Compression Myelopathy

STUDY DESIGN

A cross-sectional study.

OBJECTIVE

The aim of this study was to quantify spinal cord dysfunction at the tract level in patients with cervical compressive myelopathy (CCM) using reduced field-of-view (rFOV) diffusion tensor imaging (DTI).

SUMMARY OF BACKGROUND DATA

Although magnetic resonance imaging (MRI) is the standard used for radiological evaluation of CCM, information acquired by MRI does not necessarily reflect the severity of spinal cord disorder. There is a growing interest in developing imaging methods to quantify spinal cord dysfunction. To acquire high-resolution DTI, a new scheme using rFOV has been proposed.

METHODS

We enrolled 10 healthy volunteers and 20 patients with CCM in this study. The participants were studied using a 3.0-T MRI system. For DTI acquisitions, diffusion-weighted spin-echo rFOV single-shot echo-planar imaging was used. Regions-of-interest (ROI) for the lateral column (LC) and posterior column (PC) tracts were determined on the basis of a map of fractional anisotropy (FA) of the spinal cord and FA values were measured. The FA of patients with CCM was compared with that of healthy controls and correlated with Japanese Orthopaedic Association (JOA) score.

RESULTS

In LC and PC tracts, FA values in patients with CCM were significantly lower than in healthy volunteers. Total JOA scores correlated moderately with FA in LC and PC tracts. JOA subscores for motor dysfunction of the lower extremities correlated strongly with FA in LC and PC tracts.

CONCLUSION

It is feasible to evaluate the cervical spinal cord at the tract level using rFOV DTI. Although FA values at the maximum compression level were not well correlated with total JOA scores, they were strongly correlated with JOA subscores for motor dysfunction of the lower extremities. Our findings suggest that FA reflects white matter dysfunction below the maximum compression level and FA can be used as an imaging biomarker of spinal cord dysfunction.

LEVEL OF EVIDENCE

4.

The functional relevance of diffusion tensor imaging in comparison to conventional MRI in patients with cervical compressive myelopathy

OBJECTIVE

To determine the functional relevance of diffusion tensor imaging (DTI) metrics and conventional MRI (signal intensity change in T2, compression ratio) by measuring the correlation of these parameters with clinical outcome measured by the modified Japanese Orthopedic Association (mJOA) score.

MATERIALS AND METHODS

A total of 20 cervical myelopathy (CM) patients participated in this prospective cohort study. The severities of CM were assessed using the mJOA score. Conventional MRIs (T2-weighted images) measuring the signal changes of spinal cords and the degree of compression at the lesion level and DTI metrics [fractional anisotropy (FA), apparent diffusion coefficient (ADC)] at each lesion and below each lesion (C7/T1) level were acquired using a 3-T Achieva MRI. These parameters were correlated with the mJOA scores to determine the functional relevance.

RESULTS

Ninety percent of CM patients showed signal changes and 30 % of patients noted a more than 40% canal compression ratio in conventional MRIs at the lesion level; however, these findings were not correlated with the mJOA score (p < 0.05). In contrast, FA values on DTI showed high sensitivity to CM (100%), which was well correlated with the mJOA score (p = 0.034, r = 0.475) below the lesion level (C7/T1).

CONCLUSIONS

This study showed a meaningful symptomatic correlation between mJOA scores and FA values below the lesion levels in CM patients. It could give us more understanding of the pathological changes in spinal cords matched with various clinical findings in CM patients than the results from conventional MRI.

Diffusion tensor imaging profiles reveal specific neural tract distortion in normal pressure hydrocephalus

Background

The pathogenesis of normal pressure hydrocephalus (NPH) remains unclear which limits both early diagnosis and prognostication. The responsiveness to intervention of differing, complex and concurrent injury patterns on imaging have not been well-characterized. We used diffusion tensor imaging (DTI) to explore the topography and reversibility of white matter injury in NPH pre- and early after shunting.

Methods

Twenty-five participants (sixteen NPH patients and nine healthy controls) underwent DTI, pre-operatively and at two weeks post-intervention in patients. We interrogated 40 datasets to generate a full panel of DTI measures and corroborated findings with plots of isotropy (p) vs. anisotropy (q).

Results

Concurrent examination of DTI measures revealed distinct profiles for NPH patients vs. controls. PQ plots demonstrated that patterns of injury occupied discrete white matter districts. DTI profiles for different white matter tracts showed changes consistent with i) predominant transependymal diffusion with stretch/ compression, ii) oedema with or without stretch/ compression and iii) predominant stretch/ compression. Findings were specific to individual tracts and dependent upon their proximity to the ventricles. At two weeks post-intervention, there was a 6·7% drop in axial diffusivity (p = 0·022) in the posterior limb of the internal capsule, compatible with improvement in stretch/ compression, that preceded any discernible changes in clinical outcome. On PQ plots, the trajectories of the posterior limb of the internal capsule and inferior longitudinal fasciculus suggested attempted ‘round trips’. i.e. return to normality.

Conclusion

DTI profiling with p:q correlation may offer a non-invasive biomarker of the characteristics of potentially reversible white matter injury.

Clinically Feasible Microstructural MRI to Quantify Cervical Spinal Cord Tissue Injury Using DTI, MT, and T2*-Weighted Imaging: Assessment of Normative Data and Reliability

BACKGROUND AND PURPOSE

DTI, magnetization transfer, T2*-weighted imaging, and cross-sectional area can quantify aspects of spinal cord microstructure. However, clinical adoption remains elusive due to complex acquisitions, cumbersome analysis, limited reliability, and wide ranges of normal values. We propose a simple multiparametric protocol with automated analysis and report normative data, analysis of confounding variables, and reliability.

MATERIALS AND METHODS

Forty healthy subjects underwent T2WI, DTI, magnetization transfer, and T2*WI at 3T in <35 minutes using standard hardware and pulse sequences. Cross-sectional area, fractional anisotropy, magnetization transfer ratio, and T2*WI WM/GM signal intensity ratio were calculated. Relationships between MR imaging metrics and age, sex, height, weight, cervical cord length, and rostrocaudal level were analyzed. Test-retest coefficient of variation measured reliability in 24 DTI, 17 magnetization transfer, and 16 T2*WI datasets. DTI with and without cardiac triggering was compared in 10 subjects.

RESULTS

T2*WI WM/GM showed lower intersubject coefficient of variation (3.5%) compared with magnetization transfer ratio (5.8%), fractional anisotropy (6.0%), and cross-sectional area (12.2%). Linear correction of cross-sectional area with cervical cord length, fractional anisotropy with age, and magnetization transfer ratio with age and height led to decreased coefficients of variation (4.8%, 5.4%, and 10.2%, respectively). Acceptable reliability was achieved for all metrics/levels (test-retest coefficient of variation < 5%), with T2*WI WM/GM comparing favorably with fractional anisotropy and magnetization transfer ratio. DTI with and without cardiac triggering showed no significant differences for fractional anisotropy and test-retest coefficient of variation.

CONCLUSIONS

Reliable multiparametric assessment of spinal cord microstructure is possible by using clinically suitable methods. These results establish normalization procedures and pave the way for clinical studies, with the potential for improving diagnostics, objectively monitoring disease progression, and predicting outcomes in spinal pathologies.

Ex vivo 1H MR spectroscopy and histology after experimental chronic spinal cord compression

BACKGROUND

Proton magnetic resonance imaging (MRS) is used increasingly to image the spinal cord in compressive cervical myelopathy (CSM). However, detailed analyses of the underlying histomorphological changes leading to MRS alterations are still lacking. The aim of our study was to correlate neuroimaging and neuropathologic alterations in a rabbit myelopathy model.

METHODS

Chronic spinal cord compression was induced in a rabbit model (n=16) allowing for a gradual 270° compression of the spinal cord. Spinal cord compression core areas were divided into two samples for (A) 1H MRS and (B) histopathological analyses. Postoperatively the animals underwent a neurological examination twice a day and outcome was categorized in pattern of injury and amount of recovery.

RESULTS

Three groups were observed and categorized: (I) animals with severe deficits and no or minimal recovery; (II) animals with severe deficits and complete or almost complete recovery; (III) animals with mild to moderate deficits and a complete recovery. Significant differences in the lesioned spinal cords between the different recovery groups were found for N-acetyl-aspartate and choline. NAA/Cr was detected significantly (P<0.001, ANOVA) less in the group that did show permanent neurological deficits. To the contrary, choline was detected significantly (P<0.001, ANOVA) more in the group that did show permanent neurological deficits. Histologically the first group showed more apoptosis and necrosis than the second and third group.

CONCLUSIONS

MR spectroscopy (MRS) may be helpful for clinicians in improving the prognostic accuracy in cervical myelopathies since this method nicely reflects the extent and severity of spinal cord damage.

A Novel MRI Biomarker of Spinal Cord White Matter Injury: T2*-Weighted White Matter to Gray Matter Signal Intensity Ratio

BACKGROUND AND PURPOSE

T2*-weighted imaging provides sharp contrast between spinal cord GM and WM, allowing their segmentation and cross-sectional area measurement. Injured WM demonstrates T2*WI hyperintensity but requires normalization for quantitative use. We introduce T2*WI WM/GM signal-intensity ratio and compare it against cross-sectional area, the DTI metric fractional anisotropy, and magnetization transfer ratio in degenerative cervical myelopathy.

MATERIALS AND METHODS

Fifty-eight patients with degenerative cervical myelopathy and 40 healthy subjects underwent 3T MR imaging, covering C1-C7. Metrics were automatically extracted at maximally compressed and uncompressed rostral/caudal levels. Normalized metrics were compared with t tests, area under the curve, and logistic regression. Relationships with clinical measures were analyzed by using Pearson correlation and multiple linear regression.

RESULTS

The maximally compressed level cross-sectional area demonstrated superior differences (P = 1 × 10^-13), diagnostic accuracy (area under the curve = 0.890), and univariate correlation with the modified Japanese Orthopedic Association score (0.66). T2*WI WM/GM showed strong differences (rostral: P = 8 × 10^-7; maximally compressed level: P = 1 × 10^-11; caudal: P = 1 × 10^-4), correlations (modified Japanese Orthopedic Association score; rostral: -0.52; maximally compressed level: -0.59; caudal: -0.36), and diagnostic accuracy (rostral: 0.775; maximally compressed level: 0.860; caudal: 0.721), outperforming fractional anisotropy and magnetization transfer ratio in most comparisons and cross-sectional area at rostral/caudal levels. Rostral T2*WI WM/GM showed the strongest correlations with focal motor (-0.45) and sensory (-0.49) deficits and was the strongest independent predictor of the modified Japanese Orthopedic Association score (P = .01) and diagnosis (P = .02) in multivariate models (R² = 0.59, P = 8 × 10^-13; area under the curve = 0.954, respectively).

CONCLUSIONS

T2*WI WM/GM shows promise as a novel biomarker of WM injury. It detects damage in compressed and uncompressed regions and contributes substantially to multivariate models for diagnosis and correlation with impairment. Our multiparametric approach overcomes limitations of individual measures, having the potential to improve diagnostics, monitor progression, and predict outcomes.

Psychometric analysis and critical appraisal of the original, revised, and modified versions of the Japanese Orthopaedic Association score in the assessment of patients with cervical spondylotic myelopathy

OBJECTIVE Cervical spondylotic myelopathy (CSM) is the most common cause of nontraumatic spinal cord impairment and disability in the world. Given that the Japanese Orthopaedic Association (JOA) score is the most frequently used outcome measure in clinical research and practice for treating patients with CSM, this review was undertaken to comprehensively and critically evaluate the psychometric properties of the JOA score. METHODS The authors identified studies (published in the period of January 1975 to November 2015) on the psychometric properties of the original, revised, and modified versions of the JOA score in Medline, PsycINFO, Excerpta Medica dataBASE (EMBASE), American College of Physicians Journal Club, and Cochrane Database of Systematic Reviews. Additional publications were captured in a secondary search of the bibliographies in both original research articles and literature reviews identified in the original search. The JOA scores were evaluated for item generation and reduction, internal consistency, reliability, validity, and responsiveness. This review included all those versions of the JOA score whose psychometric properties had been reported in at least 2 published studies. RESULTS The primary search strategy identified 59 studies, of which 9 fulfilled the inclusion and exclusion criteria. An additional 18 publications were captured in the secondary search and included in the analysis. The key findings from the 27 studies analyzed indicated the following: 1) the original JOA score (1975) was the source for the revised JOA score (1994) and 3 modified versions (1991, 1993, and 1999 JOA scores) reported or used in at least 2 published studies; 2) the revised and modified versions of the JOA score are markedly different from each other; 3) only the revised JOA score (1994) was validated with the original JOA score; and 4) the 1975 JOA score is the most appropriate instrument for assessing patients in Asian populations (especially from Japan) because of its psychometric attributes, and the 1991 JOA score is the most appropriate version for use in Western populations. CONCLUSIONS The authors' results indicate that the original (1975), revised (1994), and modified (1991, 1993, and 1999) versions of the JOA score are substantially different from each other in terms of their content and have been incompletely examined for their psychometric properties and cultural sensitivity. Whereas the 1975 JOA score is the most appropriate version for assessing individuals from Asian populations (particularly those eating with chopsticks), the 1991 JOA score is most suitable for evaluating patients in Western populations. Nonetheless, further investigation of the psychometric properties of the 1975 and 1991 JOA scores is recommended because of a paucity of studies reporting on the responsiveness of these 2 scoring instruments.

Magnetic resonance imaging assessment of degenerative cervical myelopathy: a review of structural changes and measurement techniques

Degenerative cervical myelopathy encompasses a spectrum of age-related structural changes of the cervical spine that result in static and dynamic injury to the spinal cord and collectively represent the most common cause of myelopathy in adults. Although cervical myelopathy is determined clinically, the diagnosis requires confirmation via imaging, and MRI is the preferred modality. Because of the heterogeneity of the condition and evolution of MRI technology, multiple techniques have been developed over the years in an attempt to quantify the degree of baseline severity and potential for neurological recovery. In this review, these techniques are categorized anatomically into those that focus on bone, ligaments, discs, and the spinal cord. In addition, measurements for the cervical spine canal size and sagittal alignment are also described briefly. These tools have resulted collectively in the identification of numerous useful parameters. However, the development of multiple techniques for assessing the same feature, such as cord compression, has also resulted in a number of challenges, including introducing ambiguity in terms of which methods to use and hindering effective comparisons of analysis in the literature. In addition, newer techniques that use advanced MRI are emerging and providing exciting new tools for assessing the spinal cord in patients with degenerative cervical myelopathy.