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

Abstract

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.

Classification of expert-level therapeutic decisions for degenerative cervical myelopathy using ensemble machine learning algorithms

“…Yoshimatsu et al's (30) multivariable logistic regression model showed that the patient's disease duration, one of the top-five important variables for both our models, should primarily be considered when deciding conservative treatment for DCM. Meanwhile, it was reported that CMCT correlated with the degree of spinal cord compression reported in imaging findings (31,32). CMCT has been known as one of the essential diagnostic tools in myelopathy because it reflects mechanical compression as well as the functional integrity of the motor pathway (33).…”

Differentiation Between Compressive Cervical and Thoracic Myelopathy Using the Central Motor Conduction Time Ratio

“…Most studies evaluating patients with cervical myelopathy using CMCT included ,100 patients, with the largest sample size being 223 patients. [8][9][10][11][12][13][14][15] Previous studies evaluating patients with thoracic myelopathy using CMCT had a sample size of 4-20. 5,[16][17][18] Accordingly, the present study included a relatively larger sample size than previous studies.…”

Application of electrophysiological measures in degenerative cervical myelopathy

“…The Right-Left differences of the same patients’ MEP or SEP parameters are also crucial in detecting abnormalities. DCM patients’ CMCT prolonged significantly at cervical extension or flexion positions compared with that at neutral, and thus the dynamic MEPs could also be used to increase the diagnostic sensitivity ( Park et al, 2020 ). We also developed dynamic SEPs to achieve higher diagnostic sensitivity and specificity for DCM than ordinary SEPs or MEPs ( Qi et al, 2020 ; Yu et al, 2020 ).…”

“…HD and CSA are two kinds of disease characterized with weakness and wasting of upper limb muscles. In HD, dynamic neurophysiological tests show a reversible significant prolonged CMCT in MEP and decreased SEP N13 amplitude and prolonged N13–N20 interval only upon neck flexion ( Restuccia et al, 2003 ; Zheng et al, 2017 ; Park et al, 2019 ), whereas DCM patients show MEP and SEP deterioration at both extension and flexion ( Park et al, 2020 ; Qi et al, 2020 ; Yu et al, 2020 ). Furthermore, Preethish-Kumar et al (2016) used EMG to reveal grossly reduced CMAP amplitudes of affected muscles in HD patients.…”