COMPARING MECHANISMS OF SPINAL CORD INJURY – CONTUSION, DISLOCATION AND DISTRACTION

Abstract

Spinal cord damage was compared after an injury was inflicted by three clinically relevant mechanisms (contusion, dislocation, and distraction). A novel SCI multi-mechanism system has been developed. Central hemorrhage was common to all mechanisms. Increased membrane permeability was localized to the injury epicenter in contusion but spread further in distraction. Dislocation showed intermediate characteristics exhibiting both local neuronal losses at the epicenter and extended regions of membrane permeability. These preliminary observations suggest that distinct injury mechanisms result in differences in the primary damage of the spinal cord.

This work compared primary damage after spinal cord injury (SCI) inflicted by three clinically relevant mechanisms.

Different injury mechanisms result in regional differences in damage to the spinal cord.

Differences in acute damage may help guide targeted therapies following SCI.

At greater distances from the lesion, dextran was excluded from neuronal somata and in the white matter only distinct accumulation was seen at the Nodes of Ranvier. At the injury site, hemorrhage was common to all mechanisms although more diffuse in the distraction injuries. Increased membrane permeability was localized to the injury epicenter in contusion but spread further in distraction. Dislocation showed intermediate characteristics exhibiting both local neuronal losses at the epicenter and extended regions of permeability.

A novel SCI multi-mechanism system was developed which uses an electromagnetic actuator to permit the modeling of injuries along any direction. Dextran was infused into the cisterna magna 1.5 to 2 hours prior to injury in order to visualize increases in membrane permeability. Stereotaxic clamps were designed to rigidly hold the lower cervical vertebrae of deeply anaesthetized rats permitting displacements at speeds of 100cm/s. A range of displacements was used in this pilot series: 0.9 to 1.1mm contusion, 2 to 6mm dislocation and 3 to 8mm axial distraction. Animals were sacrificed at five minutes in order to analyse the primary injury. These preliminary observations suggest that distinct injury mechanisms result in regional differences in the primary damage of spinal cord gray and white matter.