Quantitative sensory studies in complex regional pain syndrome type 1/RSD.
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).
Tahmoush
A J
AJ
Department of Neurology, MCP Hahnemann University, Philadelphia, Pennsylvania 19102,USA. albert.tahmoush@drexel.edu
Schwartzman
R J
RJ
Hopp
J L
JL
Grothusen
J R
JR
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*