Motor Evoked Potentials in Transverse Myelitis

Kim, Joo Yong; Lee, Kwang Woo

Abstract

BACKGROUND & PURPOSE: Motor evoked potentials (MEPs) by transcranial magnetic stimulation have been proved to be useful for evaluation of central motor pathway. Although there have been many reports on MEPs in various neurological disorders, MEPs in transverse myelitis have rarely been studied. To know the diagnostic value of MEPs in transverse myelitis, we analyzed MEP findings in patients with transverse myelitis and compared them with the findings of somatosensory evoked potentials (SEPs) and made correlations with clinical features.
METHODS
Thirteen patients with transverse myelitis affecting thoracic spinal cord were studied. MEPs were recorded from abductor hallucis and SEPs were performed with posterior tibial nerve stimulation.
RESULTS
Abnormal MEPs were found in 8 of 13 patients (61.5%); unobtainable or poor MEP in 5 patients (38.5%), prolonged central motor conduction time (CMCT) in 1 patient (7.7%), poor MEP and prolonged CMCT in 1 patient (7.7%), and increased interside CMCT difference in 1 patient (7.7%). Abnormal SEPs were found in 10 of 13 patients (76.9%), which showed higher diagnostic sensitivity than MEP. MEP abnormalities were not always correlated with the clinical severity of the pyramidal tract involvement.
CONCLUSION
MEPs may provide an objective method to assess functional integrity of motor pathway in transverse myelitis, as SEPs are useful in the assessment of sensory pathway along the posterior column of the spinal cord.