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Updated: Apr 30, 2026
A Contusion Model of Severe Spinal Cord Injury in Rats
Published on: August 17, 2013
Translation of the rat thoracic contusion model; part 1-supraspinally versus spinally mediated pain-like responses
S van Gorp1, R Deumens2, M Leerink3
11] Department of Anesthesiology, Maastricht University Medical Center, Maastricht, The Netherlands [2] Department of Anesthesiology, Neuroregeneration Laboratory, University of California-San Diego, La Jolla, CA, USA.
Study Design:
Experimental animal study.
Objectives:
Stimulus-evoked below-level paw withdrawals in animal models of spinal cord injury (SCI) can be mediated solely by below-level spinal cord reflexes. Interpreting lowered thresholds for such responses as a model for chronic below-level pain after (thoracic contusion) SCI appears not appropriate, which requires reinterpretation of many prior results. However, how to reinterpret the changes in withdrawal thresholds and what can be a better alternative for pain/sensory assessments remains unclear.
Setting:
University of California, San Diego.
Methods:
We introduce a method using supraspinally mediated escape responses to assess pain-like sensitivity thresholds on a continuous/linear scale. To further understand the decrease in hindpaw withdrawal thresholds, we investigated whether they may be interpreted as spasticity.
Results:
The escape response test can be used to assess SCI-induced changes in below-level sensory thresholds. These thresholds were found to increase soon after moderate or severe SCI, while, in parallel, hindpaw withdrawal thresholds decreased. However, the latter did not co-occur with spasticity, suggesting that SCI-induced increased withdrawal responses are probably best interpreted as a form of hyperreflexia with pathophysiological analogies of spasms and/or clonus, or a species-specific phenomenon.
Conclusion:
Decreased below-level withdrawal thresholds do not reflect pain-like hypersensitivity in rodent models of (thoracic contusion) SCI. A large body of previous preclinical SCI pain research needs reinterpretation. We actually found below-level thermal and mechanical hypoesthesia and we also excluded a relation between withdrawal hyperreflexia and spasticity. Withdrawal hyperreflexia might still prove useful to model spasms or clonus, which are, like hypoesthesia, also significant clinical problems after SCI.
