Animal models of spinal cord contusion injuries

Background and Purpose: Traumatic spinal cord injury causes initial mechani cal disruption of tissue, leading to a complex secondary sequence of pathop hysiologic changes and neurologic impairment. These sequelae depend on the impact force delivered to the spinal cord at the time of injury. Successful clinical evaluation of the efficacy of any therapeutic regimen depends on the reliability and reproducibility of an experimental animal model. We des cribe a trauma device and the biomechanical parameters required to induce s evere or moderate spinal cord contusion injury in cats and rats. Methods: Recovery after injury was determined by behavioral, electrophysiol ogic, and histologic evaluations, Results: Behavioral and electrophysiologic tests after injury clearly ident ified the experimental groups. A stable severe paraplegic state (defined as 6 months for cats and 8 weeks for rats), without evidence of behavioral or electrophysiologic recovery, was induced by a 65-Newton (N) load for cats and a 35-N load for rats, Moderate spinal cord contusion injury, from which cats and rats partially recovered after approximately 3 months and 4 weeks , respectively, was induced by a 45- and 25-N load, respectively. Conclusion: Use of these injury conditions provides reliable animal models for studies designed to evaluate potential therapeutic regimens for spinal cord injury.