Alterations in the corticomotor evoked potential following spinal cord ischemia.

A simple yet reliable model of spinal cord ischemia has been previously developed by inserting a Swan-Ganz catheter into the abdominal aorta of rabbits and inflating the balloon just inferior to the renal arteries. Recent investigations have shown that paraplegia is consistently reproduced if the balloon remains inflated for 20 min after loss of the N3 component of the somatosensory evoked potential. Because of its high reliability, this model has been frequently and successfully used to determine the efficacy of pharmacological agents thought to provide protection against spinal cord ischemia. Results from the present report demonstrate that a similar degree of reliability can be achieved in this model for testing motor activity. A simple method of evoking highly reproducible motor potentials, that can be percutaneously recorded from the spinal cord in response to cortical stimulation, was developed. Predictable and repeatable changes in the configuration of the corticomotor evoked potential were found during spinal cord ischemia and reperfusion. With this added dimension of functional assessment, future application of the current spinal cord ischemia model have been greatly expanded.