• anterior cervical discectomy and fusion
• intraoperative neurophysiological monitoring
• motor-evoked potentials
• neck disability index
• pain
• somatosensory-evoked potentials

• Compressive myelopathy
• Diagnosis
• Evoked potentials
• Prognostic factors
• Surgery

• Humans
• Prognosis
• Spinal Cord Compression/surgery
• Cervical Vertebrae/surgery
• Spinal Cord Diseases/diagnosis
• Spinal Cord Diseases/surgery
• Retrospective Studies
• Evoked Potentials, Somatosensory
• Treatment Outcome

• Animal model
• Cervical spinal cord
• Cervical spondylotic myelopathy
• Digital control
• Implantable wireless compression device

Cervical extension and flexion are presumably harmful to patients with degenerative cervical myelopathy (DCM) because they worsen medullary compression visible on dynamic magnetic resonance imaging (MRI). Dynamic somatosensory evoked potentials (SSEPs) are an objective tool to measure the electrophysiological function of the spinal cord at different neck positions. In contrast to previous hypotheses, a considerable proportion of patients with DCM present improved SSEPs upon extension and flexion compared to a neutral position.

Patients with DCM who underwent preoperative dynamic SSEP examinations and subsequent decompression surgeries between 2015 and 2019 were retrospectively evaluated. We compared extension and flexion SSEPs with neutral SSEPs in each patient and classified them into extension-improved (EI) or extension-nonimproved (EN) and flexion-improved (FI) or flexion-nonimproved (FN) groups. Preoperative clinical evaluations, decompression surgical methods and one-year follow-up clinical data were recorded. Cervical spondylolisthesis and cervical alignment types were evaluated on plain cervical lateral radiographs. The number of stenotic segments, Mühle stenosis grade and disc degeneration stage of the most severe segment, and presence of ligamentum flavum hypertrophy and intramedullary T2 weighted imaging (T2WI) hyperintensity were evaluated on lateral and axial MRI. Data were compared between the EN and EN groups or FI and FN groups with T-tests, chi-square tests or Kruskal-Wallis tests. Prediction criteria were determined with logistic regression analyses.

Forty-nine patients were included, and 9 (18.4%) and 11 (22.4%) showed improved extension and flexion SSEPs compared to their own neutral SSEPs, respectively. Interestingly, EI or FI patients had significantly better one-year postoperative mJOA recoveries than EN or FN patients (T-test, P < 0.001). Moreover, the disease duration (T-test, P = 0.024), involved segment number (Kruskal-Wallis test, P < 0.001), and cervical alignment type (chi-square test, P = 0.005) varied significantly between the EI and EN groups. The FI group presented a significantly higher Mühle stenosis grade than the FN group (Kruskal-Wallis test, P = 0.038). Furthermore, ≤ 2 involved segments and straight or sigmoid cervical alignment were significant criteria predicting improved extension SSEPs (probability: 85.7%), while Mühle stenosis Grade 3 and disease duration ≤6 months were significant criteria predicting improved flexion SSEPs (probability: 85.7%).

Our findings provide evidence for neurophysiological improvement in patients with DCM at extension and flexion and its significance in predicting prognoses. Moreover, certain clinical and radiographic criteria may help predict neurophysiological improvement upon extension or flexion.

“[2020]151”. Retrospectively registered on April 30, 2020.

• Cervical spondylotic myelopathy
• Improvement upon extension or flexion
• Relevant factors
• Somatosensory evoked potential
• Surgical prognosis

Degenerative cervical myelopathy (DCM), earlier referred to as cervical spondylotic myelopathy (CSM), is the most common and serious neurological disorder in the elderly population caused by chronic progressive compression or irritation of the spinal cord in the neck. The clinical features of DCM include localised neck pain and functional impairment of motor function in the arms, fingers and hands. If left untreated, this can lead to significant and permanent nerve damage including paralysis and death. Despite recent advancements in understanding the DCM pathology, prognosis remains poor and little is known about the molecular mechanisms underlying its pathogenesis. Moreover, there is scant evidence for the best treatment suitable for DCM patients. Decompressive surgery remains the most effective long-term treatment for this pathology, although the decision of when to perform such a procedure remains challenging. Given the fact that the aged population in the world is continuously increasing, DCM is posing a formidable challenge that needs urgent attention. Here, in this comprehensive review, we discuss the current knowledge of DCM pathology, including epidemiology, diagnosis, natural history, pathophysiology, risk factors, molecular features and treatment options. In addition to describing different scoring and classification systems used by clinicians in diagnosing DCM, we also highlight how advanced imaging techniques are being used to study the disease process. Last but not the least, we discuss several molecular underpinnings of DCM aetiology, including the cells involved and the pathways and molecules that are hallmarks of this disease.

• blood-spinal cord barrier
• cervical spondylotic myelopathy (CSM)
• degenerative cervical myelopathy (DCM)
• microbes
• neck pain
• spinal cord compression
• spinal cord disorder

• cervical spondylotic myelopathy
• magnetic resonance imaging
• retrospective

• Adult
• Aged
• Cervical Vertebrae/diagnostic imaging
• Cervical Vertebrae/surgery
• Diskectomy
• Female
• Humans
• Magnetic Resonance Imaging
• Male
• Middle Aged
• Prognosis
• Retrospective Studies
• Risk Factors
• Spinal Cord Diseases/diagnostic imaging
• Spinal Cord Diseases/etiology
• Spinal Cord Diseases/surgery
• Spinal Fusion
• Spondylosis/complications
• Spondylosis/diagnostic imaging
• Spondylosis/surgery

Dynamic somatosensory evoked potentials (DSSEP) can be used to disclose abnormalities of ascending sensory pathways at dynamic positions and diagnose cervical spondylotic myelopathy (CSM). However, radiographic tests including magnetic resonance imaging (MRI) and dynamic X-ray are used much more widely in the management of CSM. Our study aims to clarify the correlations between several radiographic parameters and the DSSEP results, and further determine their reliability with clinical data.

We retrospectively enrolled 38 CSM patients with surgical intervention. DSSEP tests were performed before surgery. Amplitude ratios of DSSEP N13 and N20 waves at extension and flexion were calculated and recorded as N13_E, N20_E, N13_F, N20_F, respectively. Baseline severity was evaluated with the modified Japanese Orthopedic Association (mJOA) score and the Nurick grades. Prognosis was evaluated based on the 2-year recovery rate. Sagittal diameter and transverse areas of the cord and canal were measured and the the compressive ratios at the compressed site (Compression_Ratio), central (Central_Ratio), and 1/4-lateral points (1/4-Lateral_Compression_Ratio), and spinal cord/Canal Area Ratio were calculated. The intramedullary T2 hyperintensity patterns (Ax-CCM types) were also collected from MRI axial images. Dynamic X-rays were used to test for segmental instability of the cervical spine. The correlations between radiologic findings, DSSEP data, and clinical assessments were investigated.

We found that DSSEP N13_E and N13_F correlated with the Compression_Ratio, Central_Ratio, 1/4-Lateral_Compression_Ratio (Pearson, p < 0.05) and Ax-CCM types (ANOVA, p < 0.05) in MRI axial images and cervical segmental instability in dynamic X-ray (t-test, p < 0.05). Apart from the 1/4-Lateral_Compression_Ratio, these radiographic parameters above also correlated with the baseline clinical assessments (Spearman or ANOVA or t-test, p < 0.05) and postoperative recovery rate (Pearson or ANOVA or t-test, p < 0.05).

We found that the preoperative Compression_Ratio, Central_Ratio and 1/4-Lateral_Compression_Ratio in MRI and cervical segmental instability in dynamic X-ray could reflect the dynamic neural dysfunction of the spinal cord. Different Ax-CCM types corresponded to different DSSEP results at extension and flexion, suggesting divergent pathophysiology. These radiographic parameters could help evaluate disease severity and predict postoperative prognosis.

• Cervical segmental instability
• Cervical spondylotic myelopathy
• Dynamic X-ray
• Dynamic-somatosensory-evoked potentials
• Magnetic resonance imaging

Surgery is the only definitive treatment for degenerative cervical myelopathy (DCM), however, the degree of neurological recovery is often unpredictable. Here, we assess the utility of a multidimensional diagnostic approach, consisting of clinical, neurophysiological, and radiological parameters, to identify patients likely to benefit most from surgery. Thirty-six consecutive patients were prospectively analyzed using the modified Japanese Orthopedic Association (mJOA) score, MEPs/SSEPs and advance and conventional MRI parameters, at baseline, and 3- and 12-month postoperatively. Patients were subdivided into “normal” and “best” responders (<50%, ≥50% improvement in mJOA), and correlation between Diffusion Tensor Imaging (DTI) parameters, mJOA, and MEP/SSEP latencies were examined. Twenty patients were “best” responders and 16 were “normal responders”, but there were no statistical differences in age, T2 hyperintensity, and midsagittal diameter between them. There was a significant inverse correlation between the MEPs central conduction time and mJOA in the preoperative period (p = 0.0004), and a positive correlation between fractional anisotropy (FA) and mJOA during all the phases of the study, and statistically significant at 1-year (r = 0.66, p = 0.0005). FA was significantly higher amongst “best responders” compared to “normal responders” preoperatively and at 1-year (p = 0.02 and p = 0.009). A preoperative FA > 0.55 was predictor of a better postoperative outcome. Overall, these results support the concept of a multidisciplinary approach in the assessment and management of DCM.

• ADC
• DTI
• FA
• MEP
• MRI
• SSEP
• degenerative cervical myelopathy (DCM), surgical outcome
• neurophysiology
• signal changes spinal canal

• Algorithms
• Animals
• Cervical Vertebrae/injuries
• Evoked Potentials, Somatosensory
• Machine Learning
• Rats
• Rats, Sprague-Dawley
• Spinal Cord Compression/diagnosis
• Spinal Cord Compression/physiopathology
• Spinal Cord Diseases/diagnosis
• Spinal Cord Injuries/diagnosis

• Cauda equina lesion
• Cervical spondylotic myelopathy
• Degenerative spondylosis
• Functional diagnostics
• Radiology

• CSF fluid dynamics
• CSF release
• Cervical stenosis
• Intraoperative neuromonitoring
• Spinal decompression

• Cervical Vertebrae/surgery
• Constriction, Pathologic/pathology
• Decompression, Surgical/methods
• Humans
• Intraoperative Neurophysiological Monitoring/methods
• Middle Aged
• Neurosurgical Procedures/methods
• Spinal Cord Diseases/cerebrospinal fluid
• Spinal Cord Diseases/etiology
• Spinal Cord Diseases/surgery
• Spinal Stenosis/cerebrospinal fluid
• Spinal Stenosis/complications
• Spinal Stenosis/surgery
• Treatment Outcome

This study aims to determine whether the time-frequency components (TFCs) of somatosensory evoked potentials (SEPs) can be used to identify the specific location of a compressive spinal cord injury using a classification technique. Waveforms of SEPs after compressive injuries at various locations (C4, C5 and C6) in rat spinal cords were decomposed into a series of TFCs using a high-resolution time-frequency analysis method. A classification method based on support vector machine (SVM) was applied to the distributions of these TFCs among different pathological locations. The difference among injury locations manifests itself in different categories of SEP TFCs. High-energy TFCs of normal-state SEPs have significantly higher power and frequency than those of injury-state SEPs. The location of C5 is characterized by a unique distribution pattern of middle-energy TFCs. The difference between C4 and C6 is evidenced by the distribution pattern of low-energy TFCs. The proposed classification method based on SEP TFCs offers a discrimination accuracy of 80.2%. In this study, meaningful information contained in various SEP components was investigated and used to propose a new application of SEPs for identification of the location of pathological changes in the cervical spinal cord.

• Cervical myelopathy
• Cervical spine
• Neck pain

Early detection of neural conductivity changes at the compressed spinal cord is important for predicting the surgical outcomes of patients with cervical spondylotic myelopathy (CSM). The prognostic value of median nerve somatosensory evoked potential (SEP) has been proposed previously. The present prospective study evaluates the use of trial-to-trial variability in SEP as a valuable predictor of neurological recovery after surgery of CSM.

A total of 35 CSM patients who underwent surgery with up to 6-month follow-up were recruited in this study. SEP signals were recorded preoperatively. The single trial SEP was extracted by a newly developed second-order blind identification method. The postoperative recovery was assessed using the modified Japanese Orthopaedic Association. The correlation between the latency variability of trial-to-trial SEP and post-operative recovery ratio was analyzed. The prognostic value of trial-to-trial SEP for CSM was evaluated using a receiver operator characteristic curve which can accurately reflect the relationship between sensitivity and specificity of a diagnostic method and represent the accuracy of prognosis.

The correlation coefficient of trial-to-trial latency variability and the 6-month recovery ratio was statistically significant (r = −0.82, P < 0.01). The trial-to-trial SEP had a higher prognostic accuracy (AUC = 0.928, P < 0.001) with an optimal prognostic value of 9.25 % compared with averaged SEP when the threshold of recovery ratio was 40 %, and was more sensitive (93.80 %) than the averaged SEP (43.80 %).

These findings indicate that the latency variability of trial-to-trial SEP reflect the recovery ratio of CSM patients after surgery. It is suggested that the latency variability of trial-to-trial SEP is useful for predicting the surgical outcomes for patients with CSM, which would be a potential indication of surgical treatment for CSM to help decision making of surgical planning for CSM patients.

The online version of this article (doi:10.1186/s12984-015-0042-4) contains supplementary material, which is available to authorized users.

• transcranial magnetic stimulation
• central motor conduction time
• cervical spondylotic myelopathy
• cervical spine
• cervical surgery
• modified japanese orthopaedic assessment (mjoa)
• 10-meter walk test
• 9-hole peg task
• grip and release test
• outcome
• prospective study

• ACDF
• CSM
• Cervical spondylotic myelopathy
• Spine
• Surgical outcome

• Adult
• Aged
• Cervical Vertebrae
• Decompression, Surgical
• Female
• Humans
• Intervertebral Disc Displacement/complications
• Intervertebral Disc Displacement/diagnostic imaging
• Intervertebral Disc Displacement/pathology
• Male
• Middle Aged
• Postoperative Complications
• Radiography
• Recovery of Function
• Retrospective Studies
• Spinal Canal/abnormalities
• Spinal Cord Diseases/diagnostic imaging
• Spinal Cord Diseases/etiology
• Spinal Cord Diseases/pathology
• Spinal Fusion
• Spondylosis/complications
• Spondylosis/diagnostic imaging
• Spondylosis/pathology
• Treatment Outcome