Quantitative sensory studies in complex regional pain syndrome type 1/RSD

Clin J Pain. 2000 Dec;16(4):340-4. doi: 10.1097/00002508-200012000-00011.

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.

Setting: 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).

MeSH terms

  • Adult
  • Cold Temperature
  • Female
  • Hot Temperature
  • Humans
  • Hyperalgesia / etiology
  • Hyperalgesia / physiopathology*
  • Male
  • Middle Aged
  • Neurons, Afferent / physiology*
  • Pain Threshold / physiology*
  • Physical Stimulation
  • Reflex Sympathetic Dystrophy / etiology
  • Reflex Sympathetic Dystrophy / physiopathology*