Does Dynamic Supine Magnetic Resonance Imaging Improve the Diagnostic Accuracy of Cervical Spondylotic Myelopathy? A Review of the Current Evidence

Dynamic Flexion-Extension Magnetic Resonance Imaging of the Cervical Spine: An Evolutionary Tool for Diagnosis and Management of Cervical Spondylotic Myelopathy

Dynamic problems need dynamic solutions. High motility of the cervical spine causes a common age-related degenerative condition called cervical spondylotic myelopathy (CSM), manifested by neurological impairments. An accurate and reliable diagnosis of CSM is crucial for determining appropriate management strategies. Traditional static magnetic resonance imaging (MRI) has been the gold standard for imaging CSM; however, it may not fully capture dynamic changes during neck movement. Dynamic flexion-extension (DFE) MRI is an innovative imaging technique that allows for real-time visualization of cervical spine motion. This review article aims to scrutinize the role of DFE MRI in assessing CSM, its added value to clinical implementations, and its limitations. Finally, by addressing the knowledge gaps, this survey sheds light on the road ahead to incorporate DFE MRI into a standard version of the practice.

Utility of a 2D kinematic HASTE sequence in magnetic resonance imaging assessment of adjacent segment degeneration following anterior cervical discectomy and fusion

OBJECTIVES

To evaluate a dynamic half-Fourier acquired single turbo spin echo (HASTE) sequence following anterior cervical discectomy and fusion (ACDF) at the junctional level for adjacent segment degeneration comparing dynamic listhesis to radiographs and assessing dynamic cord contact and deformity during flexion-extension METHODS: Patients with ACDF referred for cervical spine MRI underwent a kinematic flexion-extension sagittal 2D HASTE sequence in addition to routine sequences. Images were independently reviewed by three radiologists for static/dynamic listhesis, and compared to flexion-extension radiographs. Blinded assessment of the HASTE sequence was performed for cord contact/deformity between neutral, flexion, and extension, to evaluate concordance between readers and inter-modality agreement. Inter-reader agreement for dynamic listhesis and impingement grade and inter-modality agreement for dynamic listhesis on MRI and radiographs was assessed using the kappa coefficient and percentage concordance.

RESULTS

A total of 28 patients, mean age 60.2 years, were included. Mean HASTE acquisition time was 42 s. 14.3% demonstrated high grade dynamic stenosis (> grade 4) at the adjacent segment. There was substantial agreement for dynamic cord impingement with 70.2% concordance (kappa = 0.62). Concordance across readers for dynamic listhesis using HASTE was 81.0% (68/84) (kappa = 0.16) compared with 71.4% (60/84) (kappa = 0.40) for radiographs. Inter-modality agreement between flexion-extension radiographs and MRI assessment for dynamic listhesis across the readers was moderate (kappa = 0.41; 95% confidence interval: 0.16 to 0.67).

CONCLUSIONS

A sagittal flexion-extension HASTE cine sequence provides substantial agreement between readers for dynamic cord deformity and moderate agreement between radiographs and MRI for dynamic listhesis.

CLINICAL RELEVANCE STATEMENT

Degeneration of the adjacent segment with instability and myelopathy is one of the most common causes of pain and neurological deterioration requiring re-operation following cervical fusion surgery.

KEY POINTS

• A real-time kinematic 2D sagittal HASTE flexion-extension sequence can be used to assess for dynamic listhesis, cervical cord, contact and deformity. • The additional kinematic cine sequence was well tolerated and the mean acquisition time for the 2D HASTE sequence was 42 s (range 31-44 s). • A sagittal flexion-extension HASTE cine sequence provides substantial agreement between readers for dynamic cord deformity and moderate agreement between radiographs and MRI for dynamic listhesis.

Upper and lower cervical alignment parameters measured on supine magnetic resonance imaging with the occipital slope as a key marker of cervical alignment

Objectives

Cervical spine alignment is evaluated by measuring the cervical angles or parameters on standing plain radiography. In this study, we aimed to evaluate mainly the upper cervical alignment and the correlation between upper and lower cervical sagittal parameters measured on supine magnetic resonance imaging (MRI).

Materials and Methods

Cervical MRIs of 210 outpatients were reviewed to measure the upper and lower cervical sagittal parameters. Their mean values were compared with normative values measured on standing X-ray from the literature. Correlations between the parameters were analyzed using the Pearson's correlation coefficient.

Results

The C0 slope was correlated with all other parameters, except for the C2-7 sagittal vertical axis. The strongest correlations (r > 0.500) were between the CL and C2 slope, between the CO2 and C0 slope, and between the C2 slope and C0 slope.

Conclusion

On supine MRI, the C0 slope is a key marker of cervical spinal alignment. A strong correlation was observed between the C2 slope and C0 slope; therefore, the relationship between upper and lower cervical alignment could be assessed using slopes on MRI.

The imaging of cervical spondylotic myeloradiculopathy

This review provides a detailed description of the imaging features of cervical spondylotic myelopathy and radiculopathy, with a focus on MRI. Where relevant, we will outline grading systems of vertebral central canal and foraminal stenosis. Whilst post-operative appearances of the cervical spine are outside the scope of this paper, we will touch on imaging features recognised as predictors of clinical outcome and neurological recovery. This paper will serve as a reference for both radiologists and clinicians involved in the care of patients with cervical spondylotic myeloradiculopathy.

Novel Grading Scales for Static and Flexion-Extension Magnetic Resonance Imaging in Patients with Cervical Spondylotic Myelopathy

BACKGROUND

Flexion-extension magnetic resonance imaging (MRI) has potential to identify cervical pathology not detectable on conventional static MRI. Our study evaluated standard quantitative and novel subjective grading scales for assessing the severity of cervical spondylotic myelopathy in dynamic sagittal MRI as well as in static axial and sagittal images.

METHODS

Forty-five patients underwent both conventional and flexion-extension MRI prior to anterior cervical discectomy and fusion from C4 through C7. In addition to measuring Cobb angles and cervical canal diameter, grading scales were developed for assessment of vertebral body translation, loss of disc height, change in disc contour, deformation of cord contour, and cord edema. Data were collected at all levels from C2-C3 through C7-T1. Variations in measurements between cervical levels and from flexion through neutral to extension were assessed using Mann-Whitney, Kruskal-Wallis, and two-way ANOVA tests.

RESULTS

Cervical canal diameter, vertebral translation, and posterior disc opening changed significantly from flexion to neutral to extension positions (P < 0.01). When comparing operative versus nonoperative cervical levels, significant differences were found when measuring sagittal cervical canal dimensions, vertebral translation, and posterior disc opening (P < 0.01). Degenerative loss of disc height, disc dehydration, deformation of ventral cord contour, and cord edema were all significantly increased at operative levels versus nonoperative levels (P < 0.01).

CONCLUSIONS

Flexion-extension MRI demonstrated significant changes not available from conventional MRI. Subjective scales for assessing degenerative changes were significantly more severe at levels with operative cervical spondylotic myelopathy. The utility of these scales for planning surgical intervention at specific and adjacent levels is currently under investigation.

Simulating upright cervical lordosis in the supine position

Cervical alignment or lordosis evolution is still attained by direct radiography in standing position because an ideal cervical curvature is essential to maintain a horizontal gaze with minimal energy consumption. However, upright cervical lordosis changes in supine position. Anterior fusion surgery and more sophisticated radiological examinations, such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI), are performed in lying position. Therefore, if upright cervical alignment can be simulated in the supine position, true (upright) cervical lordosis can be demonstrated on CT and MRI and also a more proper anterior cervical fusion can be performed in operation with better surgical outcomes. Forty-nine (49) adult patients underwent radiological examinations, including upright cervi- cal radiography and three session of supine MRI in different positions. MRI was performed in (1) conventional neutral supine position, (2) supine posi- tion with a 5-cm-high pillow, and (3) supine position with a 10-cm-high pillow under the shoulders. MRI results were analyzed. Wilcoxon, Kolmogorov-Smir- nov, and Spearman correlation tests were used to analyze MRI the validity in compared with those of cervical radiography. Cervical lordosis (C2-C7 Cobb angle) of the radiography group was similar to that of supine MRI group using a 5-cm-high pillow, and they have a strong correlation. The T-1 slope from radiography group was similar to and correlated with that of supine MRI groups with both pillows. Cranial tilt measurements of radiography group were different but correlated with the MRI group using a 5-cm-high pillow. Simulating upright cervical lordosis in the supine position is possible by adding a 5-cm- high pillow under the shoulders of the patients. This simulation reduces the need for direct radiography. Anterior cervical fusion surgery performed in this position can provide better surgical results.

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

STUDY DESIGN

Literature Review (Narrative).

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Diagnostic Role of Flexion-extension Central Motor Conduction Time in Cervical Spondylotic Myelopathy

STUDY DESIGN

Retrospective study.

OBJECTIVE

The purpose of this study was to assess the diagnostic usefulness of flexion-extension central motor conduction time(CMCT) for patients with cervical spondylotic myelopathy (CSM).

SUMMARY OF BACKGROUND DATA

Previous reports have suggested that cervical cord compression can be aggravated by neck motions. Thus, the importance of dynamic magnetic resonance imaging (MRI) has been emphasized. However, authors of this study found no reports conducted at the time of this research on whether flexion-extension CMCT was useful for detecting myelopathy.

METHODS

We enrolled 227 patients with CSM for this study. We acquired CMCT recorded from the abductor pollicis brevis muscle. All patients underwent a dynamic CMCT study during neck flexion and extension as well as a static study during neutral neck. Static and dynamic MRIs were also scanned. We read all MR images using Muhle classification (MC).

RESULTS

CMCT was significantly delayed with flexion (P < 0.01) and extension (P < 0.01) compared to neutral neck position. Patients with MC grade 1 and 2 showed significant lag in CMCT during flexion and extension. No significant lag by neck motion was observed for those in the MC grade 3. We also evaluated the amount of CMCT variation according to MC grade change (G0, G1, G2) by neck motion. Delta-CMCT of both G1 and G2 were significantly larger than those of G0 in both flexion and extension. In neutral neck, the CMCT showed significant difference between MC grades 1 and 3. They also displayed significant delay with delay with high signal intensity on T2 MRI. More than one-third of the patients whose CMCT was within normal range in neutral neck presented abnormal CMCT in neck flexion (35.3%) and extension (37.8%).

CONCLUSION

CMCT is significantly slower in both neck flexion and neck extension than in the neutral neck position. These findings reflect the dynamic cervical cord impingement.Level of Evidence: 4.

Does Spondylolisthesis Affect Severity and Outcome of Degenerative Cervical Myelopathy? A Systematic Review and Meta-analysis

STUDY DESIGN

This was a systematic review and meta-analysis.

OBJECTIVES

Degenerative cervical myelopathy (DCM) with spondylolisthesis remains not well defined, poorly studied, and underreported and plays a minor role in the therapeutic decision-making. Spondylolisthesis, however, is not uncommon and may result in dynamic injury to the spinal cord. We aim to describe the impact of spondylolisthesis in DCM severity and postoperative outcomes.

METHODS

Two independent reviewers conducted a Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA 2015)-based review between 1970 and May 2020 for articles reporting outcome of DCM in patients with degenerative cervical spondylolisthesis. Patient clinical and radiological data was recorded at baseline and during postoperative follow-up (FU). A meta-analysis comparing surgical outcome between DCM patients with and without spondylolisthesis assessed by the regular/modified Japanese Orthopaedic Association Assessment Scale (mJOA) recovery ratio was completed.

RESULTS

A total of 3 studies were included (1 ambispective and 2 retrospective cohorts); 607 patients with DCM were identified, 102 (16.8%) of whom also had spondylolisthesis. DCM patients with spondylolisthesis were significantly older (P < .05), presented with worse baseline mJOA and Nurick grades (P < .05 in 2 studies), and were more commonly operated via posterior approaches (P < .05). All groups experienced a (m)JOA and/or Neck Disability Index score improvement during FU. In the pooled meta-analysis, spondylolisthesis patients showed a significantly lower functional recovery ratio at 2 years compared with other DCM patients (P = .05).

CONCLUSIONS

Spondylolisthesis is frequent in older DCM patients and may be a predictor of a more advanced degeneration and subsequent worse baseline conditions and postoperative outcome.

Cervical and Thoracic Spondylotic Myelopathies

Spondylotic myelopathies are among the most common disorders of the spine, yet the clinical and treatment approach is far from standardized. This article discusses our current understanding of the epidemiology, pathophysiology, clinical assessment, natural history, and treatment options in degenerative myelopathies of the cervical and thoracic spine. We additionally review diagnostic modalities including imaging modalities of the spine and neurophysiological tools such as electromyography/nerve conduction studies, somatosensory-evoked potentials, and motor-evoked potentials. Assessment instruments that can be used for the assessment of myelopathies are reviewed, including the Japanese Orthopedic Association (JOA) score, modified-JOA scale, Nurick scale, nine-hole peg test, and 30-m walking test. We also review common disorders that mimic spondylotic myelopathies, as well as helpful diagnostic clues in differentiating spondylotic and nonspondylotic myelopathies.

The Impact of Anterior Spondylolisthesis and Kyphotic Alignment on Dynamic Changes in Spinal Cord Compression and Neurological Status in Cervical Spondylotic Myelopathy: A Radiological Analysis Involving Kinematic CT Myelography and Multimodal Spinal Cord Evoked Potentials

STUDY DESIGN

A retrospective study of prospectively collected data.

OBJECTIVE

This study aimed to examine how radiological parameters affect dynamic changes in the cross-sectional area of the spinal cord (CSA) in cervical spondylotic myelopathy (CSM) patients and how they correlate with the severity of myelopathy, by evaluating multi-modal spinal cord evoked potentials (SCEPs).

SUMMARY OF BACKGROUND DATA

Appropriate assessments of dynamic factors should reveal hidden spinal cord compression and provide useful information for choosing surgical procedures.

METHODS

Seventy-nine CSM patients were enrolled. They were examined with kinematic CT myelography (CTM), and the spinal levels responsible for their CSM were determined via SCEP examinations. The C2-7 angle, C2-7 range of motion, and percentage of slip were measured on the midsagittal view during flexion and extension, and the CSA was measured on the axial view in each neck position using kinematic CTM. The patients who exhibited the smallest CSA values during extension and flexion were classified into Groups E and F, respectively.

RESULTS

Fifty-two (65.8%) and 27 (34.2%) cases were included in Groups E and F, respectively. The preoperative JOA score did not differ significantly between the groups; however, the preoperative lower-limb JOA score of Group F was significantly lower than that of Group E (2.24 ± 0.82 vs. 2.83 ± 1.09, P = 0.016). In the multiple logistic regression analysis, a small C2-7 angle during extension (β = 5°, odds ratio: 0.69, 95% confidence interval [CI]: 0.54-0.90) and the slip percentage during flexion (β = 5%, odds ratio: 1.42, 95% CI: 1.09-1.85) were identified as significant predictors of belonging to Group F.

CONCLUSION

Exhibiting more severe spinal cord compression during neck flexion was associated with a small C2-7 angle and anterior spondylolisthesis. The neurological status of the patients in Group F was characterized by severe lower limb dysfunction because of a disturbed blood supply to the anterior column.Level of Evidence: 4.

Clinical feasibility of 2D dynamic sagittal HASTE flexion-extension imaging of the cervical spine for the assessment of spondylolisthesis and cervical cord impingement

PURPOSE

To assess the utility of a 2D dynamic HASTE sequence in assessment of cervical spine flexion-extension, specifically (1) comparing dynamic spondylolisthesis to radiographs and (2) assessing dynamic contact upon or deformity of the cord.

METHODS

Patients with a dynamic flexion-extension sagittal 2D HASTE sequence in addition to routine cervical spine sequences were identified. Static and dynamic listhesis was first determined on flexion-extension radiographs reviewed in consensus. Blinded assessment of the dynamic HASTE sequence was independently performed by 2 radiologists for (1) listhesis and translation during flexion-extension and (2) dynamic spinal cord impingement (cord contact or deformity between neutral, flexion and extension).

RESULTS

32 scans in 32 patients (9 males, 23 females) met inclusion criteria acquired on 1.5 T (n = 15) and 3 T (n = 17) scanners. The mean acquisition time was 51.8 s (range 20-95 seconds). Dynamic translation was seen in 14 patients on flexion-extension radiographs compared to 12 (reader 1) and 13 (reader 2) patients on HASTE, with 90.6 % agreement (K = 0.83; p = 0.789). In all cases dynamic listhesis was ≤3 mm translation with one patient showing dynamic listhesis in the range 4-6 mm. Four cases (13 %) demonstrated deformity of the cord between flexion-extension, not present in the neutral position. For cord impingement there was strong inter-reader agreement (K = 0.93) and the paired sample Wilcoxon signed rank test found no significant difference between the impingement scores of the two readers (p = 0.787).

CONCLUSIONS

A sagittal dynamic flexion-extension HASTE sequence provides a rapid addition to standard MRI cervical spine protocols, which may useful for assessment of dynamic spondylolisthesis and cord deformity.

Clinical and Radiologic Features of Degenerative Cervical Myelopathy Depending on the Presence of Cord Signal Change

BACKGROUND

Cord signal change (CSC) on magnetic resonance (MR) imaging is an important radiologic feature of degenerative cervical myelopathy (DCM). Occasionally, DCMs correlate with clinical symptoms with no CSC. The aim of this study was to evaluate clinical and radiologic features, depending on the presence of CSC in DCM.

METHODS

This retrospective study included 73 patients who underwent cervical laminoplasty for DCM. They were divided into 2 groups based on the presence of CSC on static MR imaging (positive CSC in group A and negative CSC in group B). Preoperative radiologic parameters on lateral radiographs and the severity of canal stenosis on MR imaging were analyzed. The functional outcomes were evaluated using the modified Japanese Orthopedic Association score and Nurick grade.

RESULTS

Group A showed more deteriorated canal stenosis (P < 0.001) and kyphotic change than did group B. C2-7 sagittal vertical axis (P = 0.003) of group A and C2-7 range of motion (C27ROM; P < 0.001) of group B were greater than in the opposite groups, respectively. In a multivariate analysis, greater width of the cervical canal (P = 0.002) and increased C27ROM (P = 0.002) were statistically significant radiologic parameters related to negative CSC. Group B showed better functional outcomes until 6 months postoperatively, with statistical significance.

CONCLUSIONS

DCM with negative CSC can be caused by a well-preserved cervical ROM, even with less deteriorated canal stenosis and kyphosis. C27ROM may be a helpful radiologic parameter in diagnosing DCM before CSC appears.

The value of dynamic MRI in the treatment of cervical spondylotic myelopathy: a protocol for a prospective randomized clinical trial

Background

Cervical spondylotic myelopathy (CSM) is the most severe type of cervical spondylosis and the most common cause of spinal cord dysfunction among adults over 55 years old. MRI plays an important role in the diagnosis and evaluation of CSM, which can directly demonstrate the correlation between disc, spinal cord, posterior structures and abnormal signal in spinal cord. Static MRI can only show the static and neutral position of spinal cord, which is not enough to understand the pathogenesis of CSM. Dynamic MRI demonstrating the extension and flexion position of spinal cord can be a better tool for the treatment of CSM, especially the surgical decision making.

Method

A total of 180 CSM patients who have indications for surgery will be recruited in outpatient of Peking University Third Hospital and assigned to three groups (Group A, B and C) based on their static MRI after consent. Group A (incomplete dura compression) means the signal of cerebral spinal fluid (CSF) is still visible. Group B (complete dura compression) means no CSF signal and no shape change of spinal cord. Group C (spinal cord compression) means shape change of spinal cord. Two surgical plans will be made for each participant by one professional surgeon according to the static MRI and dynamic MRI respectively and we will randomly choose one to perform via a random number system. Follow-up will be maintained at 3, 6, and 12 months after surgery through outpatient or telephone interview, including mJOA score, 10-s G&R (grip and release) and 10-s step test, SF-36 score, radiographic examination and complications. Finally, data collection and statistical analysis will be finished by researchers who are blinded to recruitment and treatment.

Discussion

This study will help us to explore the indication of dynamic MRI and the value of dynamic MRI in the treatment of CSM, especially the surgical decision making. Dynamic MRI can be a useful tool in the treatment of CSM patients.

Trial registration

ChiCTR1900023014. Registered on May 7th, 2019.

[Spondylotic cervical myelopathy : Indication of surgical treatment]

BACKGROUND

The pathogenesis of cervical spondylotic myelopathy (CSM) is often multifactorial. Hence, the treatment of this disease requires a differentiated surgical approach in order to adequately address the underlying pathology.

PURPOSE

The aim of this review is to identify factors that influence the choice of treatment strategy and to summarize them in an algorithm that serves as a decision aid in choosing the optimal indication for surgical treatment. An attempt is made to define the threshold values for the indication of surgical treatment and to discuss the ideal timing for performing surgery.

MATERIALS AND METHODS

On the basis of the published data, the influencing factors on the prognosis of CSM, as well as surgical approaches are discussed.

RESULTS

Circumferential spinal cord compression, a sharply defined myelopathy signal in the T2-weighted MRI sequence, and segmental instability at the level of the myelopathy signal mean an unfavorable prognosis for the worsening of CSM. The most important factors that influence the choice of the surgical access point are the sagittal profile of the cervical spine, the extent of myelopathy, the extent of stenosis, and the location of the myelopathy-inducing pathology. Previously existing neck pain and prior cervical surgery must also be considered.

DISCUSSION

On the basis of the research carried out, we developed an algorithm that could serve as an aid in choosing the right treatment in the setting of cervical spondylotic myelopathy.

A comparison of radiological descriptions of spinal cord compression with quantitative measures, and their role in non-specialist clinical management

INTRODUCTION

Magnetic resonance imaging (MRI) is gold-standard for investigating Degenerative Cervical Myelopathy (DCM), a disabling disease triggered by compression of the spinal cord following degenerative changes of adjacent structures. Quantifiable compression correlates poorly with disease and language describing compression in radiological reports is un-standardised.

STUDY DESIGN

Retrospective chart review.

OBJECTIVES

1) Identify terminology in radiological reporting of cord compression and elucidate relationships between language and quantitative measures 2) Evaluate language's ability to distinguish myelopathic from asymptomatic compression 3) Explore correlations between quantitative or qualitative features and symptom severity 4) Investigate the influence of quantitative and qualitative measures on surgical referrals.

METHODS

From all cervical spine MRIs conducted during one year at a tertiary centre (N = 1123), 166 patients had reported cord compression. For each spinal level deemed compressed by radiologists (N = 218), four quantitative measurements were calculated: 'Maximum Canal Compromise (MCC); 'Maximum Spinal Cord Compression' (MSCC); 'Spinal Canal Occupation Ratio' (SCOR) and 'Compression Ratio' (CR). These were compared to associated radiological reporting terminology.

RESULTS

1) Terminology in radiological reports was varied. Objective measures of compromise correlated poorly with language. "Compressed" was used for more severe cord compromise as measured by MCC (p<0.001), MSCC (p<0.001), and CR (p = 0.002). 2) Greater compromise was seen in cords with a myelopathy diagnosis across MCC (p<0.001); MSCC (p = 0.002) and CR (p<0.001). "Compress" (p<0.001) and "Flatten" (p<0.001) were used more commonly for myelopathy-diagnosis levels. 3) Measurements of cord compromise (MCC: p = 0.304; MSCC: p = 0.217; SCOR: p = 0.503; CR: p = 0.256) and descriptive terms (p = 0.591) did not correlate with i-mJOA score. 4) The only variables affecting spinal surgery referral were increased MSCC (p = 0.001) and use of 'Compressed' (p = 0.045).

CONCLUSIONS

Radiological reporting in DCM is variable and language is not fully predictive of the degree of quantitative cord compression. Additionally, terminology may influence surgical referrals.

Dynamic changes in the reflex exam of patients with sub-axial cervical stenosis

Though dynamic changes in the physical exam of patients being evaluated for cervical spine pathology have been reported, there is limited information on the prevalence and clinical features associated with reflex changes in a population undergoing surgical evaluation for cervical spine pathology. Fifty-one patients with at least grade 1 cervical stenosis on MRI underwent initial surgical evaluation for cervical spine pathology. All patients received complete neurologic examinations including dynamic reflex testing in three positions (neck neutral, extended, and flexed) by 2 spine surgeons. The average age was 58.7 years (range, 34-80), with 28 (55%) patients being male. Stenosis at the symptomatic levels was grade 1 in 18 patients (35%), grade 2 in 11 (21%), and grade 3 in 22 (43%). Twenty-one patients (41%) had a dynamic change in reflex exam. The most common change in reflex exam was seen in the Hoffman's reflex with 14 patients (28%). Patients with grade 3 stenosis were more likely to have a static Hoffman's reflex (64%) compared with grade 1 (17%) and grade 2 (18%) (p < 0.05). Patients with grade 3 stenosis had a higher rate of either a static or dynamic Hoffman's reflex (82%) compared with grade 1 (44%) (p < 0.05), but there was no difference between grade 3 and grade 2 (64%) (Table 2). Dynamic changes in reflex exam are commonly seen in patients being evaluated for symptomatic cervical stenosis. The routine neurologic exam can be supplemented with dynamic reflex testing, especially in cases where clinical history or imaging is concerning for cervical myelopathy.

Predictive value of flexion and extension diffusion tensor imaging in the early stage of cervical myelopathy

PURPOSE

Diffusion tensor imaging (DTI) in flexion (F) and extension (E) may serve as a sensitive diagnostic tool in early symptoms of myelopathy. The aim of this study was to compare values of water diffusion parameters on dynamic cervical DTI in early stage of myelopathy.

METHODS

Study enrolled 10 patients with an early stage of cervical myelopathy, in grade I/II of Nurick classification. All subjects were scanned with flexion-extension 3T MRI. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), RD (radial diffusivity), AD (axial diffusivity) and TRACEW (trace diffusion) were measured at C2, compression level (CL) and C7. Parameters were compared between 3 levels and F and E positions.

RESULTS

Flexion DTI revealed significant difference only for TRACEW between C2 and C7 (105.8 ± 18.9 vs. 83.7 ± 14, respectively; p = 0.0029). Extension DTI showed differences for ADC between CL and C7 (1378.9 ± 381.8 vs. 1227.2 ± 269.2; p = 0.001), reduced FA from 664.6 ± 56.3 at C2 down to 553.1 ± 75.5 (p = 0.001) at CL and 584.7 ± 40.7 at C7 (p = 0.002). Differences of RD in E were significant through all levels and reached 612.9 ± 105.1, 955.3 ± 319.4 and 802.1 ± 194.1 at C2, CL and C7, respectively. TRACEW lowered from 92.3 ± 14.4 at C2 to 66.9 ± 21.1 at CL (p = 0.0001) and 64.4 ± 15.5 at C7 (p = 0.0002). Comparison of DTI between F and E showed differences for all parameters except AD. RD was significantly higher in E at CL (p = 0.003) and C7 (0.013), but TRACEW increased in F at CL by 27.4% (p = 0.001) and at C7 by 23.1% (p = 0.013). FA was reduced at CL in E (p = 0.027) and similarly ADC in F (p = 0.048).

CONCLUSION

Dynamic DTI of the cervical spine is feasible and can detect subtle spinal cord damage of functional relevance in cervical myelopathy. A marked increase of RD and decrease of FA and TRACEW values in extension were found to be indicative for an early structural cord injury in myelopathy.

Correlation between the severity of myelopathy and cervical morphometric parameters on dynamic magnetic resonance imaging

BACKGROUND

To compare morphometric factors of cervical spine in the cervical stenosis on dynamic and static magnetic resonance imaging. To analyse the relationship between the severity of myelopathy and morphometric parameters.

METHODS

Patients with cervical canal stenosis scanned with MRI in neutral (N), flexion (F) and extension (E) positions were retrospectively reviewed. All cases were evaluated in Nurick and Muhle grades. Following parameters were measured: anterior and posterior length of the cervical cord (aLCC, pLCC), mid-cord distance (L value), cervical cord angle (CCA), cervical lordosis, spine/cord (S/C) angle ratio, spinal cord (SC) area, cerebrospinal fluid (CSF) area, and CSF reserve ratio (CSF/CSF plus SC). Univariate multiple regression for Nurick grade as dependent factor was used.

RESULTS

Sixty-three patients and 34 men, with the mean age of 58.2 ± 11 years, were analysed. Significant differences were found for pLCC, SC area, C lordosis and CCA. The difference between F and E for C lordosis angle was 42.80° ± 14.4 and for CC angle 30.42° ± 9.6. The mean S/C angle ratio was calculated for 1.4 ± 1.3. Nurick grade positively correlated with age (p = 0.041) and S/C angle ratio (p = 0.011), negatively with SC area (p = 0.006) and flexion-extension difference of L value (0.004).

CONCLUSIONS

Severity of myelopathy correlates with age, spinal cord area on extension and reduced mobility of spinal cord. An association between spine/cervical cord angle mismatch and Nurick grade was found.

Cervical Spine Prospective Feasibility Study : Dynamic Flexion-Extension Diffusion-Tensor Weighted Magnetic Resonance Imaging

PURPOSE

Diffusion tensor imaging (DTI) in flexion-extension may serve as a diagnostic tool to improve the sensitivity for detection of myelopathy. In this study, the feasibility and reproducibility of dynamic DTI in the cervical spinal cord was assessed in healthy volunteers and patients.

METHODS

All subjects were examined in maximum neck flexion-extension in a 3T magnetic resonance imaging (MRI) scanner. Range of motion, space available for the spinal cord, fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured and compared between the neck positions.

RESULTS

Volunteers showed no variation in ADC and FA. In patients, extension produced higher ADC in the diseased than in the control segments (p = 0.0045). The ADC of the affected segments was higher in extension than in the neutral position (p = 0.0030) or in flexion (p = 0.0002). The FA was significantly lower in extension in patients at both the control level C2/3 (p = 0.0154) and the affected segment (p = 0.0187).

CONCLUSIONS

Dynamic DTI of the cervical spine is feasible and ADC increased in the patient group in extension. This finding may open a previously unexplored avenue to attempt an earlier identification of myelopathy.

Cervical Spine and Cord Angle Mismatch in the Pathogenesis of Myelopathy

BACKGROUND

Cervical myelopathy is a complex pathology and dynamic compression of the tethered cervical cord, which may be responsible for clinical symptoms.

METHODS

Patients with cervical canal stenosis who had magnetic resonance imaging in flexion and extension positions were retrospectively reviewed. All cases were evaluated in Nurick grade. The cervical parameters-cervical cord (CC) angle, cervical lordosis, and spine/cord (S/C) angle ratio-were measured on the magnetic resonance imaging. Mean values of these parameters were compared between nonmyelopathic (Nurick grade 0) and myelopathic groups (Nurick grades 1-5). A multinomial ordinal logistic regression was used to predict outcome for Nurick grade using the CC angle, the cervical lordosis angle, and the S/C angle ratio as independent variables.

RESULTS

A total of 65 patients (35 men) with the mean age of 58.6 ± 11.4 years were analyzed. A comparison of means between Nurick grade 0 against each of myelopathic grades 1-5 revealed significant differences only for the S/C angle ratio. A cumulative comparison between nonmyelopathic and myelopathic grades for the S/C angle ratio showed significant difference of 0.29 (1.16 ± 0.5 vs. 1.45 ± 0.6, respectively; P < 0.05). Cumulative comparison for the CC angle difference in flexion and extension lordosis did not show substantial differences. The S/C angle ratio was the only significant parameter in the prediction of the Nurick grade with an odds ratio of 2.63 (95% confidence interval 2.11-2.79).

CONCLUSIONS

A positive correlation between Nurick grade and cervical spine and cord angle mismatch was found.