An Experimental Study on Spinal Cord Evoked Potentials by Transpharyngeal Stimulation of the Spinal Cord in Cats : Pathway of Conductive Action Potentials in the Spinal Cord

Descending pharyngeal spinal cord evoked potentials (descending pharyngeal SCEPs) were recorded from the lumbar epidural space elicited by transpharyngeal electrical stimulation in cats. Descending pharyngeal SCEPs were composed of two negative waves (N1, N2). We assessed the pathway of descending pharyngeal SCEPs, compared with other potentials, by ascending dorsal epidural stimulation and both dorsal epidural and pharyngeal recordings. Descending pharyngeal SCEPs disappeared after transection of the spinal cord at the craniospinal junction. We analyzed the amplitudes of potentials during and after the partial resection of the spinal cord. In the results of 15 cats, N1 and N2 amplitudes showed almost the same before and after posterior column resection. N1 preserved 65±10% and N2 preserved 9±3% of the original amplitude after posterior and lateral column resections. The field potentials in the spinal cord of N1 in descending pharyngeal SCEPs were recorded in the anterior column. These findings suggested that descending pharyngeal SCEPs were mainly conducted in the anterior and lateral columns of the spinal cord in cats