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Study design:A retrospective study.Objective:To elucidate the correlation between compound muscle action potentials (CMAPs) amplitudes and responsible level of compressive cervical myelopathy (CCM), and the accuracy of level diagnosis by using CMAPs.Setting:This study was conducted at the Department of Orthopedic surgery, Yamaguchi University Graduate School of Medicine, Japan.Method:A total of 28 patients with CCM were investigated in this study. Erb's point-stimulated CMAPs were measured from deltoid, biceps, triceps in all patients as compared with 88 healthy subjects. We performed a level diagnosis on the basis of CMAPs amplitudes. We performed a level diagnosis on the basis of CMAPs amplitudes and using an index that measures the deviation of CMAPs amplitudes between triceps and deltoid or biceps.Results:Significant correlations between the mean CMAPs amplitudes and responsible level were showed for deltoid (6.82±2.33 mV) at C3/4 (P<0.01) and biceps (8.75±4.42 mV) at C4/5 (P=0.015). Despite considerable individual variability in CMAP amplitudes, there were correlations among CMAPs amplitudes for deltoid, biceps and triceps in the same individual. The sensitivity was 75.0%, specificity 75.0% in the index for diagnosis of C3/4. The sensitivity was 75.0%, specificity 66.7% in the index for diagnosis of C4/5.Conclusion:This study showed small CMAPs amplitudes in the deltoid indicated a C3/4 level of myelopathy and in biceps at the C4/5 level and could help exclude clinically silent cord compression and determine the surgical procedure to the suitable level of concern. [ABSTRACT FROM AUTHOR]

Study design:Retrospective study.Objective:To investigate the progression of spinal tract lesions in cervical spondylotic myelopathy (CSM) at C3-4 intervertebral level using spinal cord-evoked potensials (SCEPs).Setting:This study was conducted at the Department of Orthopaedic Surgery, Yamaguchi University Graduate School of Medicine, Japan.Methods:A total of 30 patients with CSM were investigated in this study. In all patients, only the C3-4 intervertebral level was symptomatic, as shown by examination of SCEPs. SCEPs were recorded following median nerve stimulation (MN-SCEPs), transcranial electric stimulation (TES-SCEPs) and spinal cord stimulation (spinal-SCEPs).Results:The incidence of abnormalities varied in the order of MN-SCEPs (100%), TES-SCEPs (90%) and spinal-SCEPs (67%). Patients were grouped into three types according to SCEPs: transverse (all SCEPs abnormal), post-erolateral (abnormalities in the MN-SCEPs and TES-SCEPs) and upper limbs sensory (abnormal only for MN-SCEPs). In all, 20 of the 30 patients (67%) were the transverse type, 7 (23%) the post-erolateral type and 3 (10%) the upper limbs sensory type.Conclusion:The present study showed the lateral part of the posterior funiculus mediating upper limb sensory function was more vulnerable than the lateral corticospinal tract, which is consistent with numbness tending to appear at an early stage of mild CSM. [ABSTRACT FROM AUTHOR]