ABSTRACT
Direct spinal epidural surface of spinal evoked potentials have been made in 16 adult cats with acute spinal cord injuries produced experimentally in which myelotomy was performed in 8 cats 1 hour after the injury. The remaining 8 animals served as control. The spinal cord injury with 20gm - 20 cm was inflicted over the entire dorsal surface of the spinal cord at L2-3 interspace by Allen's weight-drop method which was improved by placing a curved steel plate anterior to the spinal cord to provide a smooth, hard surface for the receipt of posterior cord impact. Under the operating microscope, a median posterior longitudinal myelotomy approximately 10mm to 15mm in length was made at the injury site 1 hour after the injury. Animals were evaluated electrophysiologically either from preinjury state to postinjury 4 hours(control group) or from preinjury state to post myelotomy 3 hours(myelotomy group). The component waves of the spinal somatosensory evoked potentials(SSEP) of control group disappeared sequentially after the injury in the following order : N4, N3, N2, N1. In myelotomy group, N4 and N3 wave also disappeared, but N1 and N2 wave remained. The latencies of the component waves increased & its amplitudes decreased sequentially after the injury. In myelotomy group, as com-with the control group, post-traumatic latency rate increase as well as amplitude were both reduced.