title: Quantitative sensory studies in complex regional pain syndrome type 1/RSD.
abstract: OBJECTIVE
  Patients with complex regional pain syndrome type I (CRPSD1) may have thermal allodynia after application of a non-noxious thermal stimulus to the affected limb. We measured the warm, cold, heat-evoked pain threshold and the cold-evoked pain threshold in the affected area of 16 control patients and patients with complex regional pain syndrome type 1/RSD to test the hypothesis that allodynia results from an abnormality in sensory physiology.
  
  
  METHODS
  A contact thermode was used to apply a constant 1 degrees C/second increasing (warm and heat-evoked pain) or decreasing (cold and cold-evoked pain) thermal stimulus until the patient pressed the response button to show that a temperature change was felt by the patient. Student t test was used to compare thresholds in patients and control patients.
  
  
  RESULTS
  The cold-evoked pain threshold in patients with CRPSD1/RSD (p <0.001) was significantly decreased when compared with the thresholds in control patients (i.e., a smaller decrease in temperature was necessary to elicit cold-pain in patients with CRPSD1/RSD than in control patients). The heat-evoked pain threshold in patients with CRPS1/RSD was (p <0.05) decreased significantly when compared with thresholds in control patients. The warm- and cold-detection thresholds in patients with CRPS1/RSD were similar to the thresholds in control patients.
  
  
  CONCLUSIONS
  This study suggests that thermal allodynia in patients with CRPS1/RSD results from decreased cold-evoked and heat-evoked pain thresholds. The thermal pain thresholds are reset (decreased) so that non-noxious thermal stimuli are perceived to be pain (allodynia).
authors.affiliation: Department of Neurology, MCP Hahnemann University, Philadelphia, Pennsylvania 19102,USA. albert.tahmoush@drexel.edu
authors.forename: A J
authors.initials: AJ
authors.lastname: Tahmoush
authors.forename: R J
authors.initials: RJ
authors.lastname: Schwartzman
authors.forename: J L
authors.initials: JL
authors.lastname: Hopp
authors.forename: J R
authors.initials: JR
authors.lastname: Grothusen
mesh_terms: D000328:Adult; D003080:Cold Temperature; D005260:Female; D006358:Hot Temperature; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D009475:Neurons, Afferent / Q000502:physiology*; D017288:Pain Threshold / Q000502:physiology*; D010812:Physical Stimulation; D012019:Reflex Sympathetic Dystrophy / Q000209:etiology / Q000503:physiopathology*