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

The Radiological Characteristics of Degenerative Cervical Kyphosis with Cervical Spondylotic Myelopathy

Introduction

In this study, we aim to describe the radiological characteristics of degenerative cervical kyphosis (DCK) with cervical spondylotic myelopathy (CSM) and discuss the relationship between DCK and the pathogenesis of spinal cord dysfunction.

Methods

In total, 90 patients with CSM hospitalized in our center from September 2017 to August 2022 were retrospectively examined in this study; they were then divided into the kyphosis group and the nonkyphosis group. The patients' demographics, clinical features, and radiological data were obtained, including gender, age, duration of illness, cervical Japanese Orthopaedic Association (JOA) score, cervical lordosis (CL), height of intervertebral space, degree of wedging vertebral body, degree of osteophyte formation, degree of disc herniation, degree of spinal cord compression, and anteroposterior diameter of the spinal cord. In the kyphosis group, kyphotic segments, apex of kyphosis, and segmental kyphosis angle were recorded. Radiological characteristics between the two groups were also compared. Correlation analysis was performed for different spinal cord compression types.

Results

As per our findings, the patients in the kyphosis group showed more remarkable wedging of the vertebral body, more severe anterior compression of the spinal cord, and a higher degree of disc herniation, while the posterior compression of the spinal cord was relatively mild when compared with the nonkyphosis group. CL was related to the type of spinal cord compression, as cervical kyphosis is an independent risk factor for anterior spinal cord compression.

Conclusions

DCK might play a vital role in the pathogenesis of spinal cord dysfunction. In patients with DCK, it was determined that the anterior column is less supported, and more severe anterior spinal cord compression is present. The anterior approach is supposed to be preferred for CSM patients with DCK.

Current Concepts of Cervical Spine Alignment, Sagittal Deformity, and Cervical Spine Surgery

There are not many reports on cervical spine alignment, and only a few analyze ideal surgical approaches and optimal amounts of correction needed for the various types of deformity. We comprehensively reviewed the present literature on cervical spinal deformities (with or without myelopathy) and their surgical management to provide a framework for surgical planning. A general assessment of the parameters actually in use and correlations between cervical and thoracolumbar spine alignment are provided. We also analyzed posterior, anterior, and combined cervical surgical approaches and indications for the associated techniques of laminoplasty, laminectomy and fusion, and anterior cervical discectomy and fusion. Finally, on the basis of the NDI, SF-36, VAS, and mJOA questionnaires, we fully evaluated the outcomes and measures of postoperative health-related quality of life. We found the need for additional prospective studies to further enhance our understanding of the importance of cervical alignment when assessing and treating cervical deformities with or without myelopathy. Future studies need to focus on correlations between cervical alignment parameters, disability scores, and myelopathy outcomes. Through this comprehensive literature review, we offer guidance on practical and important points of surgical technique, cervical alignment, and goals surgeons can meet to improve symptoms in all patients.

The Deterioration of Cervical Kyphosis During Neck Flexion after Laminoplasty Affects the Surgical Outcome of Cervical Spondylotic Myelopathy

STUDY DESIGN

A retrospective single-center study.

OBJECTIVE

The present study investigated whether postoperative cervical alignment changes, in addition to preoperative patient backgrounds, imaging parameters, and disease severity, affect outcomes 1 year after laminoplasty.

METHODS

One hundred and three cervical spondylotic myelopathy (CSM) patients who underwent laminoplasty were enrolled. Preoperative and postoperative (1-year) Japanese Orthopedic Association (JOA) scores, cervical alignment, and balance on X-rays were assessed. Patients were classified into 2 groups for a univariate analysis according to the status of the recovery rate (RR) of the JOA score ≥50%. A multiple logistic regression analysis was performed to identify factors associated with good surgical outcomes a.

RESULTS

The mean RR of the JOA score was 47.5% and the loss of cervical lordosis in the neutral position was 5.5°. The univariate analysis revealed slight differences in age, sex, and the duration of disease. Preoperative C2-7 angles were not significantly different. The C2-7 angle during flexion after surgery was significantly smaller in Group F. In the multiple logistic regression analysis, significant factors associated with the status of RR≥50% were a younger age (OR: .75, 95%CI: .59-.96), shorter duration of disease (OR: .94, 95%CI: .89-.99), and a lordotic C2-7 angle during neck flexion after surgery (OR: 1.47, 95%CI: 1.1-1.95).

CONCLUSION

We retrospectively assessed the surgical outcomes of laminoplasty in 103 CSM cases. In addition to an older age and longer duration of disease, postoperative deteriorations in cervical kyphosis during neck flexion had a negative impact on outcomes.

Predictive Effect of Cervical Sagittal Parameters and Corresponding Segmental Paravertebral Muscle Degeneration on the Occurrence of Cervical Kyphosis Following Cervical Laminoplasty

BACKGROUND

Cervical sagittal parameters and paravertebral muscle degeneration are important factors for the occurrence of cervical spondylotic myelopathy. However, the relationship between the 2 risk factors and cervical kyphosis following cervical laminoplasty remains unknown.

METHODS

A total of 130 patients undergoing cervical laminoplasty were enrolled from July 2018 to July 2020 and were followed up for at least 24 months. Clinical recovery was recorded, including the Japanese Orthopedic Association, neck disability index and visual analog scale scores. Radiographic sagittal parameters were measured on cervical lateral radiographs: T1 slope (T1S), C2-C7 Cobb lordotic angle (CLA), C2-C7 sagittal vertical axis, O-C2 angle, and T1S-CLA. The magnetic resonance imaging (MRI) parameters of the paraspinal muscles were also measured, including cross-sectional area and fat infiltration (FI). The patients were divided into a kyphosis group and a lordosis group based on the last follow-up results of CLA. Multivariate logistic analysis was performed to analyze risk factors for kyphosis following laminoplasty.

RESULTS

Thirty-two patients were assigned to the kyphosis group and 98 were assigned to the lordosis group. Patient baseline and surgical information in the 2 groups showed no statistically significant difference. In the comparison of clinical recovery, patients with kyphosis showed a lower Japanese Orthopedic Association recovery rate than the lordosis group. For the radiographic parameters and muscle condition comparison, CLA, T1S-CLA, and FI were the most significant parameters. The logistic regression revealed that T1S-CLA and FI were the most important variables that predicted kyphosis.

CONCLUSIONS

We concluded that FI remarkably differed in the paraspinal muscles in the 2 groups. Multivariate logistic regression demonstrated that T1S-CLA and FI significantly influenced the process of kyphosis after cervical laminoplasty.

Laminoplasty is relevant for degenerative cervical spondylolisthesis when there is little risk of postoperative excessive kyphosis during neck flexion

BACKGROUND

Elderly patients with degenerative cervical myelopathy frequently have severe symptoms due to spondylolisthesis. The effectiveness of laminoplasty for degenerative cervical spondylolisthesis (DCS) is an important question.

OBJECTIVE

The aim of this study is to elucidate factors associated with the outcome of laminoplasty for DCS.

METHOD

Eighty-nine patients with cervical spondylotic myelopathy (CSM) who underwent laminoplasty without instrumented posterior fusion were enrolled. Positive spondylolisthesis was defined as more than 2 mm during neck flexion or extension, from this, 46 DCS cases and 43 non-DCS cases were classified. Radiological parameters, including cervical alignment, balance, range of motion, and slippage along with the Japanese Orthopedic Association (JOA) score, were obtained before and 1 year after surgery. Factors associated with good surgical outcomes for DCS were analyzed using multivariate logistic analysis.

RESULTS

There were no significant differences in background and preoperative JOA score, but the DCS group recovery rate was significantly less (42% vs 53%). Multivariate logistic analysis revealed only the postoperative C2-7 angle during neck flexion was associated with a favorable outcome for DCS (P = 0.0039, Odds ratio: 1.49, 95% CI: 1.14-1.94). Multivariate regression analysis positively correlated the preoperative C2-7 angle in neutral and during flexion with the postoperative C2-7 angle during flexion.

CONCLUSION

The major factor related to poor outcome was the magnitude of postoperative kyphotic C2-7 angle during neck flexion. Slippage was not directly related to outcome and postoperative cervical alignment. Caution is recommended for surgeons performing laminoplasty on patients with risk factors for postoperative excessive kyphotic C2-7 angle during flexion.

Correlation between "Snake-Eyes" Sign and Role of Surgery with a Focus on Postoperative Outcome: A Systematic Review

(1) Background: The "snake-eyes" sign represents a unique finding characterized by bilateral hyperintense symmetric, circular, or ovoid foci on T2-weighted MRI sequences in the anterior horn cells of the spinal cord. There are conflicting opinions as some authors affirm that it does not affect the prognosis of cervical myelopathy while other papers emphasize the opposite, stating how the "snake-eyes" sign constitutes an irreversible lesion and a predictor of poor prognosis. This systematic review evaluates the correlation between the "snake-eyes" sign and the prognosis of cervical myelopathy after surgery including anterior and/or posterior approaches; (2) Methods: A systematic literature review was conducted following the PRISMA statement and a total of seven papers were included; (3) Results: A total of 419 patients were evaluated, with a mean age of 55.72 ± 14.38 years. After surgery, 26.01% of patients experienced a significant clinical improvement, while in 61.81%, there was no significant improvement. In particular, 144 of 196 patients (73.5%) treated through an anterior approach and 114 of 223 (51.1%) that underwent a posterior approach, did not present a significant improvement. Furthermore, in 12.17% of patients, the postoperative outcome was not reported, leading to a high risk of bias in the assessment of the prognostic significance of the "snake-eyes" appearance; (4) Conclusions: The "snake-eyes" sign is usually considered as an unfavorable predictive marker for myelopathic surgical patients, but the pathophysiology is still unclear, and the results have not yet reached unified levels of evidence.

The Utility of Transcranial Stimulated Motor-Evoked Potential Alerts in Cervical Spine Surgery Varies Based on Preoperative Motor Status

STUDY DESIGN

A prospective multicenter observational study.

OBJECTIVE

The aim was to investigate the validity of transcranial motor-evoked potentials (Tc-MEP) in cervical spine surgery and identify factors associated with positive predictive value when Tc-MEP alerts are occurred.

SUMMARY OF BACKGROUND DATA

The sensitivity and specificity of Tc-MEP for detecting motor paralysis are high; however, false-positives sometimes occur.

MATERIALS AND METHODS

The authors examined Tc-MEP in 2476 cases of cervical spine surgeries and compared patient backgrounds, type of spinal disorders, preoperative motor status, surgical factors, and the types of Tc-MEP alerts. Tc-MEP alerts were defined as an amplitude reduction of more than 70% from the control waveform. Tc-MEP results were classified into two groups: false-positive and true-positive, and items that showed significant differences were extracted by univariate analysis and detected by multivariate analysis.

RESULTS

Overall sensitivity was 66% (segmental paralysis: 33% and lower limb paralysis: 95.8%) and specificity was 91.5%. Tc-MEP outcomes were 33 true-positives and 233 false-positives. Positive predictive value of general spine surgery was significantly higher in cases with a severe motor status than in a nonsevere motor status (19.5% vs . 6.7%, P =0.02), but not different in high-risk spine surgery (20.8% vs . 19.4%). However, rescue rates did not significantly differ regardless of motor status (48% vs . 50%). In a multivariate logistic analysis, a preoperative severe motor status [ P =0.041, odds ratio (OR): 2.46, 95% confidence interval (95% CI): 1.03-5.86] and Tc-MEP alerts during intradural tumor resection ( P <0.001, OR: 7.44, 95% CI: 2.64-20.96) associated with true-positives, while Tc-MEP alerts that could not be identified with surgical maneuvers ( P =0.011, OR: 0.23, 95% CI: 0.073-0.71) were associated with false-positives.

CONCLUSION

The utility of Tc-MEP in patients with a preoperative severe motor status was enhanced, even in those without high-risk spine surgery. Regardless of the motor status, appropriate interventions following Tc-MEP alerts may prevent postoperative paralysis.

Clinical Application of Evoked Potentials in the Operation of Cervical Spondylotic Myelopathy with Different Imaging

Objective

To observe the effects of improvement of cervical spondylotic myelopathy with different imaging signals after cortical somatosensory-evoked potentials on the functional recovery of postoperative patients and the effect of surgery.

Methods

A total of 60 patients with cervical spondylotic myelopathy who were hospitalized in our hospital from January 2020 to December 2020 were selected and divided into a case group (30 cases) with MRI-indicated changes in intramedullary signals and a control group (30 cases) with MRI-indicated spinal cord changes. Intragroup and intergroup control studies were conducted through general observation indexes, neurological evaluation indexes, imaging, and evoked potential observation indexes. Somatosensory-evoked potentials were performed before operation, 1 week after operation, and 24 weeks after operation, and the JOA score of each patient was obtained before operation, 1 week after operation, and 24 weeks after operation.

Results

The JOA score of 1 week after operation of the case group is (16.25 ± 1.54) and the control group is (11.89 ± 1.63), and there is a statistically significant difference (P < 0.05). The JOA score of the case group 24 weeks after operation is (25.27 ± 1.03) and the control group is (13.28 ± 1.03), and the difference is statistically significant (P < 0.05). The improvement rate of 1 week after operation and 24 weeks after operation was statistically significant between the two groups (P < 0.05). The case group improvement rate is (70.5 ± 8.72)% and the control group is (40.5 ± 9.81)%, and the difference is statistically significant between the two groups (P < 0.05).

Conclusion

The preoperative intramedullary signal changes can be used as an effective index for patients with cervical spondylotic myelopathy to use somatosensory-evoked potentials to assess the prognosis of patients after surgery.

Evaluating craniovertebral stability in Chiari malformation coexisting with Type II basilar invagination: an observational study based on kinematic computed tomography and its clinical application

BACKGROUND

Treatment of Chiari malformation (CM) is controversial, especially when it coexists with "stable" or Type II basilar invagination (CM+II-BI). Precise evaluation of craniovertebral junction (CVJ) stability is crucial in such patients; however, this has never been validated. This study aimed to dynamically evaluate atlanto-condyle and atlantoaxial stability by kinematic computed tomography (CT) and report its surgical treatment.

METHODS

The study recruited 101 patients (control, CM, and CM+II-BI groups: 48, 34, and 19 patients, respectively). During kinematic CT, the CVJ stability-related parameters were measured and compared between the three groups. The surgical strategy for treating CM+II-BI was based on these results. Pre- and postoperative images were acquired, and functional scores were used to assess the outcome.

RESULTS

Among the three groups, the length of the clivus and the height of the condyle were the shortest in the CM+II-BI group, which was accompanied by the greatest rotation of the atlas and atlanto-condyle facet movement on cervical flexion and extension. Moreover, in such patients, increased Chamberlain's baseline violation indicated the aggregate invagination of the odontoid in the flexed position, and asymmetric displacement of atlantoaxial facets was observed. Seventeen CM+II-BI patients underwent surgical treatment with atlantoaxial distraction and occipitocervical fusion. The syringomyelia width and tonsillar herniation decreased significantly, and functional scores indicated symptom relief and good outcomes.

CONCLUSIONS

CVJ instability, especially the ultra-movement of atlanto-condyle facets, commonly exists in II-BI as evaluated using kinematic CT. The surgical strategy of atlantoaxial distraction and occipitocervical fusion should be considered to treat such patients.

Radiological factors associated with the severity of corticospinal tract dysfunctions for cervical spondylotic myelopathy: An analysis of the central motor conduction time and kinematic CT myelography

Patients with cervical spondylotic myelopathy (CSM) often exhibit symptoms in clinical practice, particularly the elderly, whose lower extremity functions are more likely to deteriorate; however, the underlying mechanisms currently remain unclear. The present study aimed to elucidate the relationship between the neurological severity of CSM based on an electrophysiological examination and radiological findings. Eighty-six patients with CSM were examined using kinematic CT myelography. The cross-sectional area of the spinal cord and dynamic changes in the spinal cord were measured at the affected level. The central motor conduction time (CMCT) using transcranial magnetic stimulation was calculated as follows: motor evoked potential latency - (compound muscle action potential latency + F latency - 1)/2 (ms). A multiple logistic regression analysis was performed to identify the radiological parameters associated with severe lower limb dysfunction. CMCT in the upper limbs correlated with spinal cord compression during neck extension, while that in the lower limbs correlated with a larger C2-7 sagittal vertical axis, cervical lordosis, a small C2-7 range of motion (ROM), and spinal cord compression during neck flexion. In a multiple logistic regression analysis, significant risk factors specific for severe lower limb dysfunction were greater anterior spondylolisthesis during neck extension (P = 0.006, OR: 2.53, 95%CI: 1.13-2.07) and small C2-7 ROM in neutral to flexion (P = 0.035, OR: 0.67, 95%CI: 0.52-0.88). Imaging findings affect upper and lower extremity functions in specific manners. Cervical stiffness or anterior compression factors may be associated with the deterioration of lower limb function.

Impact of various MRI signal intensity changes on radiological parameters, the neurological status, and surgical outcomes in degenerative cervical myelopathy

STUDY DESIGN

A retrospective study of prospectively collected date.

PURPOSE

The present study aimed to identify patient characteristics, radiological factors, the neurological status, and postoperative outcomes associated with MRI signal intensity changes in degenerative cervical myelopathy (DCM).

MATERIAL AND METHOD

One hundred and fourteen DCM patients who underwent posterior decompression surgeries were enrolled. Pre- and postoperative (12 months) Japanese Orthopedic Association (JOA) scores, cervical alignment and balance on X rays, the cross-sectional area of the spinal cord (CSA) in kinematic CT myelography (CTM). The recovery rate (RR) of the total JOA score and those specific for the upper and lower limb items were evaluated. MRI included T1-weighted imaging (WI) and T2WI. Patients were classified into two groups for a univariate analysis according to the presence or absence of a high signal intensity (HIS) in the sagittal view on T2WI, a low signal intensity (LSI) in the sagittal view on T1WI, the distribution of HSI at a single or multiple levels, and the presence or absence of the snake eye appearance. A multiple logistic regression analysis (MLRA) was performed to identify factors associated with signal intensity changes on MRI.

RESULTS

Ninety-six patients (84.3%) were classified into HIS changes in the sagittal view on T2WI. The group with multilevel HSI showed significantly lower RR specific for the lower extremity JOA score (30.8% vs 47.7%; P = 0.016). The snake eye-positive group showed a significantly inferior RR specific for the upper extremity JOA score (40.1% vs 53.2%; P = 0.04). In MLRA, LSI changes on T1WI revealed small CSAF (P = 0.02, Odds ratio; 0.77, 95%CI:0.61-0.97), while HSI changes on T2WI revealed a small CSAF (P = 0.008, Odds ratio;1.36, 95%CI:1.08-1.72) and large C2-7 angle during extension (P = 0.009, Odds ratio;0.73, 95%CI:0.58-0.92). CSAF correlated with multilevel HSI changes (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93). The snake eye appearance correlated with CSAF (P = 0.006, Odds ratio;0.78, 95%CI:0.66-0.93) and the duration of disease (P = 0.05, Odds ratio;1.01, 95%CI:1.0-1.03).

CONCLUSION

Severe and poorly compensated spinal cord compression during neck flexion may cause signal intensity changes. The snake eye appearance may be useful as a sign of the inferior postoperative recovery of upper limb function, and multilevel HSI as a sign of the inferior postoperative recovery of lower limb function.