| Both weight-dropping and sustained compression injuries have been used by investigators in studies of experimental spinal cord injury. Neither of these methods used alone, however, is quite appropriate, as clinical spinal cord injuries consist of both impact (concussion) and sustained compression. Furthermore, reports utilizing these injury methods suggest that each results in different structural effects on spinal cord. Differing functional effects have in turn been postulated, but not directly investigated in a single model of spinal cord injury.;Effects of injuries on AEPs and ACPs were similar. Following weight-dropping injuries conduction in spinal cord axons was either blocked immediately or was not blocked. At a variable time following injury, affected axons either resumed conduction at preinjury velocities, or did not resume conduction. Following sustained compression injuries, conduction in spinal cord axons was blocked, and following release of compression those axons that resumed conduction during the four hour postinjury period did so with reduced conduction velocities.;In addition to a comparison of functional effects of the two injury types, morphological studies of spinal cord following either weight-dropping or sustained compression injury were done. In spinal cords injured by the weight-dropping method, central hemorrhagic necrosis was more prominent than in spinal cords injured by sustained compression.;These findings confirm that differing functional and morphological effects result from either weight-dropping or sustained compression injuries to canine spinal cord. This in turn raises questions as to the clinical relevance of therapies based on research utilizing either of these injury types alone.;The objective of experiments in this study was to use spinal cord somatosensory evoked potentials (SEPs) to define and compare the functional differences in spinal cord conduction that occur following either weight-dropping or sustained compression injuries of varying severities. Two types of spinal cord SEPs were used: the ascending evoked spinal cord potential (AEP) that is conducted in all parts of the spinal cord, and the antidromically conducted potential (ACP) that is conducted in a discrete population of axons in dorsal columns. Both AEPs and ACPs were monitored prior to, immediately following, and at 30 minute intervals after injury, for a period of four hours. |
