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Updated: Oct 16, 2026

Determining heat and mechanical pain threshold in inflamed skin of human subjects
Published on: January 14, 2009
Topographical distribution of pinprick and warmth thresholds to CO2 laser stimulation on the human skin
R Agostino1, G Cruccu, G Iannetti
1Department of Neurological Sciences, University of Rome 'La Sapienza', Viale Universita' 30, 00185, Roma, Italy.
Abstract:
We studied the topographical distribution of laser sensory thresholds on the human hairy skin, using a small laser beam for pinprick and a large beam for warmth sensations. The threshold for pinprick sensation correlated positively with the distance from the brain, suggesting that Adelta nociceptors, the fibers which convey pinprick sensation, are more dense at proximal than at distal body sites. This finding adds information to skin biopsy studies of epidermal free nerve endings which showed a similar gradient, but could not differentiate small myelinated from unmyelinated fiber afferents. Possibly because of a diffuse low density of warmth receptors, laser warmth thresholds showed no trend.
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