OBJECTIVES—Recordingtechniques permit the separate analysis of the response from caudaequina roots and the spinal potential that is probably generated by theactivation of dorsal horn cells. To improve the functional assessmentof focal lesions of the lumbosacral cord, lower limb somatosensoryevoked potentials (SEPs) were measured by multisegmental stimulation. METHODS—Commonperoneal and tibial nerves SEPs were recorded in 14 patients in whomMRI demonstrated compressive cord damage ranging from T9 to L1 levels.SEPs were recorded in each patient at the lumbar level (cauda equinaresponse), lower thoracic level (spinal response), and from the scalp(cortical response). RESULTS—Abnormalitiesin spinal response occurred in 50% and 70% of tibial and commonperoneal nerve SEPs respectively; these findings were well explained bythe radiological compression level, involving in most of the patientslumbar rather than sacral myelomeres. The SEPs were often moreeffective than the clinical examination in showing the actual extensionof damage. CONCLUSIONS—Therecording of spinal SEPs after multisegmental lower limb stimulationproved useful in assessing cord dysfunction and determining the cordlevels mainly involved by the compression.
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