Value of Paraspinal Electromyography in the Evaluation of Thoracic Myelopathy

Abstract

The authors have performed paraspinal needle EMG studies in twenty five patients with thoracic myelopathy. They were divided into demonstrable thoracic lesions and non-demonstrable thoracic lesions by neuroimaging studies resulting in 12 cases of the former and 13 cases of the latter. There were abnormal paraspinal EMG findings in 83% with demonstrable thoracic lesions. All five patients with thoracic disc diseases revealed abnormalities which indicated subsequent involvement of ventral roots by compressive lesions. In non-demonstrable thoracic lesions, the authors could demonstrate abnormal paraspinal EMGs in a relatively high percentage (62.5%) of preseumed and still occult thoracc myelopathy, but not in all four patients with demyelinating disease. Therefore it is concluded that paraspinal EMG studies are valuable in those patients wih thoracic myelopathy as a method of predicting he presumed nature of their causes and indicating the level of anticipated myelography or spinal CT. However, it was impossible to differentiate among patients with malignancy, those with thoracic disc diseases and those with unknown thoracic myelopathy by the paraspinal EMG studies.