A Dynamic Magnetic Resonance Imaging Study of Changes in Severity of Cervical Spinal Stenosis in Flexion and Extension

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.

Predictive value of magnetic resonance imaging indications of spinal cord swelling for cervical spondylotic myelopathy prognosis

BACKGROUND

Magnetic resonance imaging (MRI) is the preferred examination approach for patients with suspected cervical spondylotic myelopathy (CSM).

OBJECTIVE

To investigate the predictive value of MRI spinal cord swelling on the prognosis of decompression surgery in patients with CSM.

METHODS

A retrospective analysis of 115 patients with CSM who underwent decompression surgery was performed. According to whether cervical MRI showed spinal cord swelling, they were divided into a spinal cord swelling group and non-swelling group. The Modified Japanese Orthopaedic Association (MJOA) score, MJOA improvement rate and abnormal spinal cord enhancement rate in the two groups were compared before and after surgery. Multiple linear regression was used to analyse the influencing factors of the MJOA improvement rate.

RESULTS

The time from symptom onset to operation (t= 2.400, p= 0.018) and preoperative MJOA score in the spinal cord swelling group were lower than those in the non-swelling group (t= 3.253, p= 0.002). The body mass index (t= 2.895, p= 0.005), anteroposterior diameter of the spinal canal (t= 4.421, p< 0.001), cross-sectional area (t= 3.136, p= 0.002), postoperative improvement rate (t= 4.277, p< 0.001) and proportion of abnormal enhancement of the spinal cord in the swelling group were higher than those in the non-swelling group (χ2= 3.136, p= 0.002). The preoperative MJOA score in the swelling group was lower than that in the non-swelling group (t= 2.583, p= 0.013). A multivariate linear regression model revealed that age and spinal cord swelling were independent predictors of MJOA score improvement, explaining 33.2% of the total variation.

CONCLUSION

Patients with CSM with spinal cord swelling have less time from symptoms to surgery, and the degree of preoperative neurological deterioration is more obvious. Spinal cord swelling is an independent predictor of surgical prognosis in patients with CSM.

Favorable cervical extension capacity preventing loss of cervical lordosis after laminoplasty due to spontaneous restoration of initial lordosis

BACKGROUND CONTEXT

Cervical laminoplasty is a common approach for the treatment of multilevel cervical spondylotic myelopathy (CSM). Postoperative loss of cervical lordosis (LCL) was associated with lower extension motion of the cervical spine before laminoplasty.

PURPOSE

To analyze the possible causes of preoperative cervical extension capacity affecting LCL after laminoplasty by evaluating the changes in cervical lordosis (CL) at different stages.

STUDY DESIGN/SETTING

Retrospective study.

PATIENT SAMPLE

Seventy-two patients undergoing laminoplasty due to multilevel CSM.

OUTCOME MEASURES

Radiographic parameters included CL, extension CL (eCL), flexion CL (fCL), range of motion (ROM), extension ROM (eROM), flexion ROM (fROM) and LCL. Clinical outcomes were assessed using the Japanese Orthopedic Association (JOA) and neck disability index (NDI) score.

METHODS

The data were recorded before surgery and at 3- and 24-month follow-up. All patients completed a cervical extension test preoperatively. A receiver operating characteristic (ROC) curve of eROM was constructed to discriminate the patients with and without postoperative kyphotic deformity.

RESULTS

According to the optimal cut-off value of eROM, the patients were divided into two groups: extension group (eROM≥9.3°) and control group (eROM<9.3°). The radiographic outcomes demonstrated no significant differences in CL, eCL, fCL and ROM between the two groups. Both eROM and fROM were significantly different in the two groups. There was a significant change in CL in the extension group at 3-month follow-up and in the control group at 24-month follow-up. The extension group exhibited significantly lower LCL compared with the control group at follow-up. No significant difference between the two groups was noted in the JOA recovery rate, while the NDI score was significantly different at 24-month follow-up. The positivity ratio of the extension test was significantly greater in the extension group than that in the control group.

CONCLUSIONS

eROM in patients with favorable preoperative cervical extension capacity (eROM≥9.3°) consisted of the actual extension capacity and compensatory flexion. The cervical alignment would be spontaneously restored to its initial lordosis in the short term after laminoplasty. These patients had no substantial LCL at 24-month follow-up and would be good candidates for laminoplasty.

Best cutoff score of cervical-pedicle thickness as a morphological parameter for predicting cervical central stenosis

There are various factors for the cause of cervical central stenosis (CCS), such as osteophyte, cervical-disc degeneration, and cervical ligamentum flavum hypertrophy. However, the pedicle of the cervical vertebra has not yet been analyzed for its relationship with CCS. We created a new morphologic parameter called the cervical-pedicle thickness (CPT) to assess the association between CCS and the cervical pedicle. We obtained morphological cases involving the CPT from 82 patients with CCS. There were also 84 in the normal group who underwent cervical spine magnetic resonance imaging (CS-MR) as part of routine health screening. We obtained the T2-weighted CS-MR axial images from group members, and assessed the CPT at the level of the C6 vertebra on CS-MR. The mean CPT was 3.46 ± 0.57 mm in the normal group, 4.97 ± 0.75 mm in the CCS group, which thus had a significantly higher CPT (P < .01) than did the normal group. For the prognostic value of the CPT as a predictor of CCS, ROC analysis indicated that the best cutoff score for the CPT was 4.18 mm, with 93.9% sensitivity, 92.9% specificity, and AUC 0.97. Greater CPT was highly associated with a possibility of CCS. This conclusion will be helpful for assessing the CCS patients.

Multidimensional assessment of cervical spondylotic myelopathy patients. Usefulness of a comprehensive score system

OBJECTIVE

Cervical spondylotic myelopathy (CSM) is caused by cervical spine degeneration and surgery may be beneficial, but selection for surgery might be challenging. We performed a multimodal analysis to assess predicting factors that may be useful to help surgeons in this choice.

PATIENTS AND METHODS

We retrospectively evaluated clinical, motor evoked potentials (MEP), and MRI data of patients who undergone surgery for CSM. Seventy-six consecutive patients (46 males) were enrolled. The median age was 65.5 [IQR: 57-71] years, and the duration of symptoms was 11 [8-13] months. A multivariate analysis in order to assess predictors of outcome and ROC curve analysis were performed.

RESULTS

Thirty patients (M:18, 39.5%) gained 6 or more points on mJOA and they were collected in good recovery group, whereas 46 patients (60.5%, M:28) showed a fair recovery. We developed a comprehensive score system (CSS) taking into account clinical, neurophysiological, and neuroradiological data. ROC curve analysis was performed to determine the discriminative power of four models derived from the multivariate logistic regression analysis for predictors of good outcome considering only clinical variables, MRI variables, and MEP variables or considering the comprehensive model, demonstrating a good accuracy of CSS model to predict outcome.

CONCLUSION

This study demonstrates that CSS model taking into consideration functional assessment by mJOA score, neurologic evaluation, cervical MRI, and MEP may be a feasible method to predict outcome in patients candidate to surgery, supporting surgeon's decisions both for those patients candidate to surgery and for patients in whom a "wait and see" approach could be proposed.

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.

Dynamic Cord Compression Causing Cervical Myelopathy

Due to the highly mobile nature of the cervical spine, and the fact that most magnetic resonance imagings (MRIs) and computed tomography scans are obtained only in one single position, dynamic cord compression can be an elusive diagnosis that is often missed and not well-understood. In this context, dynamic MRI (dMRI) has been utilized to improve the diagnostic accuracy of cervical stenosis. We performed a literature review on dynamic cord compression in the context of cervical spondylotic myelopathy (CSM), with particular emphasis on the role of dMRI. Cadaveric studies report that the spinal cord lengthens in flexion and the spinal canal dimension increases, whereas the spinal cord relaxes and shortens in extension and the spinal canal decreases. These changes may lead to biomechanical stress in the spinal cord with movement, especially in patients with critical cervical stenosis. The majority of the studies using dMRI in CSM reported that this imaging modality is more sensitive at detecting cervical cord compression compared to routine MRIs done in a neutral position, especially with the neck in extension. Dynamic MRI was also useful to diagnose dynamic cervical cord compression after laminectomies in patients with clinical deterioration without evident cord compression on neutral static MRI. Finally, dMRI is more sensitive in detecting stenosis in patients with CSM than in those with ossification of the posterior longitudinal ligament (OPLL), likely because OPLL patients often have a more limited range of motion than CSM patients. Thus, dMRI is a promising new tool that can help spine surgeons in diagnosing and treating CSM.