Spatial summation of heat induced pain within and between dermatomes.
The aim was to study spatial summation within and between ipsi- and contralateral dermatomes at different painful temperatures. For heat stimulation we used a computer controlled thermofoil based thermode. The thermode area could be varied in five discrete steps from 3.14 to 15.70 cm2. When we applied the stimuli within a dermatome, the mean heat pain threshold decreased significantly from 45.6 to 43.5 degrees C as the area was increased from minimum (3.14 cm2) to maximum (15.70 cm2). When the areas were increased involving different dermatomes (both ipsi- or contralateral), we found similar decreases in pain threshold. Spatial summation was also found within and between dermatomes at supra-threshold temperatures (46, 48, 50 degrees C). The study shows that spatial summation of pain is most likely a mechanism acting across segments and is existing from pain threshold to tolerance.
Nielsen
J
J
Laboratory for Experimental Pain Research, Center for Sensory-Motor Interaction, Aalborg University, Denmark. jn@miba.auc.dk
Arendt-Nielsen
L
L
D000328:Adult; D000344:Afferent Pathways / Q000502:physiology; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D008297:Male; D009619:Nociceptors / Q000502:physiology*; D010147:Pain Measurement; D017288:Pain Threshold / Q000502:physiology*; D011999:Recruitment, Neurophysiological / Q000502:physiology*; D012684:Sensory Thresholds / Q000502:physiology; D012867:Skin / Q000294:innervation*; D013823:Thermoreceptors / Q000502:physiology*; D013697:Thermosensing / Q000502:physiology*