Experimental spinal cord trauma. III. Therapeutic effect of immobilization and pharmacologic agents

A wide variety of pharmacologic agents has been suggested to serve as therapeutic adjuncts in the management of acute spinal cord trauma. The present study was conducted to determine what effect, if any, these agents have when they are added to immobilization of the spinal column, the most widely used clinical measure. Rhesus monkeys were subjected to different levels of experimental spinal cord injury with and without subsequent immobilization by means of a figure of eight ligature. In the control group, five of six animals impacted at 500 gm-cm were paraplegic. In the immobilized animals, three of four animals impacted at 500 gm-cm recovered completely and the fourth was only mildly paraparetic. Paraplegia could not be uniformly produced in this group until 800 gm-cm forces were routinely employed. In the second phase of the study, only immobilized animals were used, with and without drug therapy. No change in the force-injury curve, above and beyond that from immobilization, can be demonstrated for monkeys given dextran, phenobarbital, methyldopa, phenoxybenzamine or vasopressors. The pathophysiologic concepts upon which such agents are advocated should be reassessed. Spinal immobilization can significantly improve the clinical outcome following experimental spinal cord injury; it may also serve to control some of the variability previously observed in pharmacologic experiments.