title: Translation of the rat thoracic contusion model; part 1-supraspinally versus spinally mediated pain-like responses and spasticity.
abstract: METHODS
  Experimental animal study.
  
  
  OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: 1] 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.
authors.forename: S
authors.initials: S
authors.lastname: van Gorp
authors.affiliation: Group of Neuropharmacology, Department of Cellular and Molecular Neuroscience, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
authors.forename: R
authors.initials: R
authors.lastname: Deumens
authors.affiliation: Department of Anesthesiology, Neuroregeneration Laboratory, University of California-San Diego, La Jolla, CA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Leerink
authors.affiliation: Department of Anesthesiology, Neuroregeneration Laboratory, University of California-San Diego, La Jolla, CA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Nguyen
authors.affiliation: Department of Anesthesiology, Maastricht University Medical Center, Maastricht, The Netherlands.
authors.forename: E A
authors.initials: EA
authors.lastname: Joosten
authors.affiliation: Department of Anesthesiology, Neuroregeneration Laboratory, University of California-San Diego, La Jolla, CA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Marsala
mesh_terms: D000818:Animals; D001921:Brain / Q000503:physiopathology*; D004195:Disease Models, Animal; D004924:Escape Reaction / Q000502:physiology; D005260:Female; D006614:Hindlimb / Q000503:physiopathology; D009128:Muscle Spasticity / Q000503:physiopathology*; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement; D017288:Pain Threshold; D017207:Rats, Sprague-Dawley; D012026:Reflex, Stretch / Q000502:physiology; D012720:Severity of Illness Index; D013116:Spinal Cord / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*