Variety of the Wave Change in Compound Muscle Action Potential in an Animal Model

STUDY DESIGN Animal study. PURPOSE To review the present warning point criteria of the compound muscle action potential (CMAP) and investigate new criteria for spinal surgery safety using an animal model. OVERVIEW OF LITERATURE Little is known about correlation palesis and amplitude of spinal cord monitoring. METHODS After laminectomy of the tenth thoracic spinal lamina, 2-140 g force was delivered to the spinal cord with a tension gage to create a bilateral contusion injury. The study morphology change of the CMAP wave and locomotor scale were evaluated for one month. RESULTS Four different types of wave morphology changes were observed: no change, amplitude decrease only, morphology change only, and amplitude and morphology change. Amplitude and morphology changed simultaneously and significantly as the injury force increased (p<0.05) Locomotor scale in the amplitude and morphology group worsened more than the other groups. CONCLUSIONS Amplitude and morphology change of the CMAP wave exists and could be the key of the alarm point in CMAP.